Truck Technology:The Facts You Need (II)Chassis
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Descripción: The structure of a truck can be broadly divided into the chassis and the body. The chassis includes system...
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Truck Technology:
The Facts You Need (II) – Chassis –
The Professor The professor explains everything about trucks in a way that’s easy to understand. He says: “Everything you’re going to learn is vital for your work, so I hope you’ll pay close attention.” The Assistant The assistant sees considers everything from your point of view and supplements the professor’s explanations. She says: “I have a lot to learn, so I’m studying hard.”
What trucks are all about Truck Technology:
Canter Canter explains Mitsubishi Fuso technologies. He says: “I hope you’ll do your best to understand the technologies used in trucks like me.”
The Facts You Need (II) – Chassis – Contents What is the chassis? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 What’s the structure of a chassis? . . . . . . . . . . . . . . . . . . . 2 2 How does a truck move? . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. What’s the clutch? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. What clutch types exist? . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. What’s the transmission? . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. What transmission types exist? . . . . . . . . . . . . . . . . . . . . . . 8 5. What is an automatic transmission? . . . . . . . . . . . . . . . . . 10 6. What is overdrive? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. What is a power takeoff (PTO)?. . . . . . . . . . . . . . . . . . . . . 13 8. What is a reduction gear? . . . . . . . . . . . . . . . . . . . . . . . . . 14 9. What is a differential gear? . . . . . . . . . . . . . . . . . . . . . . . . 15 How is a truck steered? . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1. How is the steering gearbox structured? . . . . . . . . . . . . . . 17 2. What is power steering? . . . . . . . . . . . . . . . . . . . . . . . . . . 18 How does a truck stop? . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1. What are hydraulic brakes? . . . . . . . . . . . . . . . . . . . . . . . . 20 2. What types of braking system are used?. . . . . . . . . . . . . . 21 3. How does light pedal action cause strong brake operation?. . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4. What types of brake exist?. . . . . . . . . . . . . . . . . . . . . . . . . 23 5. What other kinds of brake exist on a truck? . . . . . . . . . . . . 24 6. What are ABS and ASR?. . . . . . . . . . . . . . . . . . . . . . . . . . 25 What types of tire exist? . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 How does a truck give a comfortable ride? . . . . . . . . . . . 28 1. What suspension spring types exist?. . . . . . . . . . . . . . . . . 29 Where does electricity in a vehicle come from? . . . . . . . 30 1. How is a flat battery dealt with? . . . . . . . . . . . . . . . . . . . . . 31 What technologies are used in the Canter? . . . . . . . . . . 32
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CHECK SHEET INDEX
The Salesman The salesman wants to be a great success with customers. He says: ”Technical things are hard for me to understand, but I’m doing my best.”
Introduction
What is the chassis? About the chassis The structure of a truck can be broadly divided into the chassis and the body. The chassis includes systems and components that are needed for the truck to move and be driven. With a passenger car, the term ‘body’ refers to the overall covering of the vehicle. With a truck, though, it refers to the structure or equipment that is attached to the truck to meet a specific need. It can, for example, be a flatcargo-bed body, a dump-truck body, a cement-mixer body, or a crane body. Bodies are produced by specialist body makers. Simply stated, the chassis is the truck without its body. A chassis completed by Mitsubishi Fuso is known as a ‘bare’ or ‘nude’ chassis. It contains all the components and systems needed for on-road driving, so it can be driven to a body maker for attachment of a body. When a body has been attached by a body maker, the vehicle is a complete truck. The chassis is the structural foundation of the truck, so it’s important for you to have a good understanding of it.
Truck body (produced by specialist body maker)
Chassis (produced by Mitsubishi Fuso)
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What’s the structure of a cha The makeup of the chassis
The chassis consists of a frame; the engine; systems needed to transmit the engine’s power so the vehicle can move; a steering system, a suspension system, and other systems that are needed for operation of the vehicle. Let’s look at the basic structures and roles of the items that make up the chassis.
Cab-over-engine type Cab-behind
Cab The cab can be either of two types: a cab-over-engine type, which is mounted above the engine, or a cab-behind-engine type, which has the engine mounted in front of it. The cab-over-engine type is more easily affected by engine noise and vibration because of its position above the engine, but liquid-filled rubber parts and springs are located between the cab and frame to ensure good ride comfort. In Japan, which has regulations on overall vehicle lengths, the cab-over-engine type which permits more space to be used for the load bed, is more popula
Steering wheel (See page 16.) The steering wheel is part of the steering system. It allows the driver to change the truck’s direction as desired.
Headlamps Mitsubishi Fuso trucks have discharge headlamps. These headlamps have projector lenses, which help realize long illumination distances, and they produce light by means of discharge tubes, which have about twice the brightness and three times the service life of conventional halogen bulbs.
Engine (See the ‘Engine’ section for details In a vehicle with a manual transmission, the clutch and transmission are located aft of the engine.
Clutch (See page 5.) In a vehicle with a manual transmission, the engine’s power is initially applied to the clutch. Using the clutch pedal, the driver can make or break the flow of engine power.
Transmission (See page 7.) The transmission is full of gears, so it is also called a gearbox. Using many gears of different sizes, it adjusts the torque (rotational force) and speed of the engine’s output.
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Propeller shaft The propeller shaft transmits power from the output side of the transmission to the reduction and differential gear.
Reduction and differential gear (See pages 14 and 15.) This item is generally known as a differential. It contains a reduction gear, which reduces the rotational speed of the power from the propeller shaft, thereby increasing the torque. It also contains a differential gear, which allows the left and right wheels to turn at different speeds when the vehicle is steered (essential for smooth motion around curves).
Suspension system (See page 28.) The suspension system works between the frame and wheels. It absorbs vibration received by the truck from the road surface.
Frame: The frame consists of two side rails and a number of crossmembers. From above, it looks like a ladder. The body is mounted on the frame.
Crossmember Side rail
Mitsubishi Fuso Super Frame The type of frame used on Mitsubishi Fuso trucks is called a Super Frame because it has a number of unique features. With the Super Frame, the side rails and crossmembers are joined by web joints (in other words, they are joined sideways), not by flange joints (vertical joints). Since the web joints link the crossmembers to the side rails’ side surfaces, which are extremely rigid, they help make the frame extremely strong. Also, the absence of rivets in the top surfaces of the side rails allows easier body attachment.
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How does a truck move? The driveline
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Customer: The clutch seems to be slipping. Salesman: I don’t know what you mean. Help! ➾ See
‘What is clutch slippage?’ on page 5.
The clutch, transmission, and reduction and differential gear are together known as the driveline. All of the items in the driveline are essential for propulsion of the truck. The engine’s power is transmitted from the clutch to the transmission and is transmitted from there by the propeller shaft to the reduction and differential gear, which transmits it to the wheels.
The term ‘4x4’ (or ‘four by four’) indicates the total number of wheels and the number of wheels that are driven by engine power. In other words, it shows that a vehicle has four wheels and that all four wheels are driven by engine power.
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What’s the clutch? About the clutch
The clutch is located between the engine and transmission. It is used to make and break (as necessary) the flow of power from the engine toward the wheels. The clutch is used to interrupt the flow of power when the engine is being started, when gear changes are performed using the transmission, and when the brakes are used to stop the vehicle. At other times (for example, when the vehicle is driven away from a standing start), the clutch is used to smoothly transmit power toward the wheels. E
The principle of clutch operation In its simplest form, the clutch can be seen as two discs that are pressed together or moved apart from each other to transmit power or interrupt the transmission of power as needed. When the clutch pedal is pressed, the discs move apart from each other. In other words, the clutch is disengaged. When the pedal is released, spring force pushes one disc firmly against the other. In other words, the clutch is engaged. The disc on the engine side is called the flywheel. The disc on the transmission side is called a clutch disc.
What is clutch slippage?
Clutch disc Flywheel
Like the customer talking to the salesman in the cartoon at the beginning of this chapter, you may have heard someone say that a clutch is ‘slipping’. This means that the friction material (called the clutch facing) on the clutch disc has worn so thin that it does not make good contact with the flywheel. When a clutch slips, pressing the accelerator pedal causes the engine speed to rise but the vehicle does not accelerate. When the clutch facing of a Canter truck becomes worn, a warning light illuminates to inform the driver.
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What clutch types 2 exist? Clutch types As mentioned on the previous page, the clutch disc of a clutch is pushed against the other disc by spring force. Clutches are classified according to the type of spring. There are two types: the diaphragm-spring type and the coil-spring type. They are also classified according to the number of clutch discs. Although our examples thus far have mentioned only one clutch disc, some clutches in the real world have more than one disc. A clutch with one disc is called a single-disc clutch. A clutch with more than one clutch disc is called a multi-disc clutch. Heavy-duty trucks have multi-disc clutches because their high engine power necessitates high power transmission capacity.
Diaphragm-spring type Most current clutches are of the diaphragm-spring type, in which clutch engagement is achieved by the pushing force of a diaphragm spring (a disc-shaped spring). When the clutch pedal is depressed, the diaphragm spring is pushed back to disengage the clutch. [Merits] • The required pedal effort can be made low. • The spring applies pressure uniformly to the disc. • The number of parts is small; the structure is simple. • Since the spring is disc-shaped, it does not deform when subjected to strong centrifugal force at high speeds of rotation; its good balance permits consistent clutch performance.
Dia ap
Flywheel
Clutch disc
Flywheel
(Clutch engaged)
(Clutch disengaged)
Coil-spring type Truck clutches are and have been most often of the coil-spring type. With this type of clutch, engagement is achieved using the pushing force of a coil spring (also called a pressure spring). When the clutch pedal is depressed, a release lever is pushed to disengage the clutch. [Merits] • The force that pushes the clutch disc is extremely great.
Mitsubishi Fuso trucks offer the benefits of both of the types described above. It is usual for coil-spring clutches to be used in some heavy-duty trucks and for diaphragm-spring clutches, which have a lighter pedal action and better balance, to be used in other trucks. With the Super Great (a heavy-duty truck with extremely high engine power), however, a diaphragm-type clutch is combined with a special device that enables the diaphragm spring to produce more pushing force than a coil spring.
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What’s the 3 transmission? About the transmission
The transmission combines gears with differing numbers of teeth to change the torque and speed of the engine power while transmitting the power to the propeller shaft. There are two transmission types: manual and automatic. With a manual transmission, the driver manually uses the transmission to change gears. With an automatic transmission, the transmission automatically performs gear changes as the vehicle is driven. The role of the transmission A vehicle must allow itself to be driven in a wide range of ways. (For example, it must allow itself to be driven away from a standing start, driven at various speeds, and reversed.) Consequently, the transmission allows the engine’s characteristics to be exploited effectively under widely varying driving conditions. Consider a bicycle that has selectable gears. The rider selects gears in order to lighten the pedal action on uphill roads and to be able to ride fast on level roads. The transmission of a motor vehicle is basically the same as the gears of the bicycle. It allows gears (actually combinations of gears) to be selected in order, for example, to realize lots of power for standing starts and on uphill roads and to enable the truck to be driven fast on long downhill slopes. The terms ‘1st’, ‘2nd’, and ‘3rd’ (or ‘low’, ‘second’, and ‘third’) refer to the combinations of gears. Precise gear changes are necessary with a truck that carries heavy cargo. For this reason, some Mitsubishi Fuso Super Great models have a 16-gear (or 16-speed) transmission.
Gear ratios The gear ratio is the ratio between the speed of the engine and the speed of the propeller shaft. For forward motion, 1st gear has the highest gear ratio and 2nd and 3rd gears have smaller ratios in that order. NOTE Even if two engines have identical performance, the torque reaching the wheels can be very different depending on the transmission gear ratios and the final reduction ratio (see page 14). A vehicle’s power performance does not depend on the engine alone. The transmission gear ratios and the final reduction ratio must also be taken into account when vehicles are compared.
Torque
Speed
High gear ratio
High
Low
Low gear ratio
Low
High
Reversing a vehicle
When gears with different numbers of teeth are brought together, the speed of rotation changes.
sed urn
In the figure on the left, for example, four turns of the small gear on the left cause two turns of the gear in the middle and one turn of the gear on the right. In other words, the speed is reduced to one quarter. At the same time, the torque that can be used to move an object is increased.
Small force
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Adding a gear can reverse the direction of rotation. This principle enables a vehicle to be driven backward.
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What transmission types ex Transmission types
Manual transmissions have been made in different types that bring together their internal gears using different methods. The synchromesh type is used in today’s vehicles. Sliding-mesh type This is the most elementary type of transmission. With this type, gears that are turning are directly brought together. Smoothly meshing gears is not easy for the driver. A grinding sound can occur when gears hit each other.
Clutch disc
Countershaft
Constant-mesh type The constant-mesh type is an improvement upon the sliding-mesh type. The upper gears and lower gears are constantly meshed but turn freely (not transmitting power) until a sliding gear is meshed.
Clutch disc
Sliding gear
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ist? Synchromesh type The synchromesh type is the most common type today. Whereas the constant-mesh type involves directly meshing a sliding gear, the synchromesh type contains synchronizer rings (conical clutches) that equalize the speeds of gears before meshing the gears. Since the gears are turning at the same speed when they mesh, the meshing takes place smoothly.
A : Synchronizer ring
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A
B
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How a synchromesh transmission works (1) Neutral Power from the engine is transmitted through the gears as follows: 1 → 2 → 3 → 4 . However, gear 4 is not connected to the propeller shaft so it turns freely (not transmitting the power).
(2) Synchronization When the gearshift lever is moved, gear B moves sideways. A metal fitting on the inside of gear B (the black part in the figure) moves sideways together with it, pushing gear A against gear 4 . At this time, gear B is still not meshed with gear A . Owing to friction that occurs between gear A and gear 4 , gears 4 , A , B , and C then gradually start turning together. Thus, the friction has a synchronizing effect.
(3) Meshing of gears If the gearshift lever is moved further, gear B moves further sideways. Owing to the synchronizing effect described above, gear B and gears A and 4 then turn together and are smoothly meshed together. The gear change is then complete.
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B A 4 C
B
B A 4 C
B
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What is an automatic trans
About automatic transmissions Whereas a manual transmission requires the driver to continually change gears while driving, an automatic transmission performs gear changes automatically. An automatic transmission has two main parts in addition to the actual gearbox: (1) a fluid coupling, which transmits power from the engine to the gears, and (2) a torque converter, which boosts the torque received from the engine.
Fluid coupling
Fluid coupling (fan analogy) The fluid coupling is located between the engine and gearbox. It transmits power by means of fluid. It operates in basically the same way as the two fans illustrated on the left. When one fan (the one on the engine side) runs, the power transmitted by the air causes the other fan (the one on the driveshaft side) to start turning too. In the fluid coupling, there is hydraulic fluid instead of air. The fluid serves the same purpose in that it transmits power.
Torque converter In the fluid coupling described above, rotation of the engine-side impeller causes fluid to hit the other (impeller, thereby causing it to turn such that power is transmitted. Fluid that has hit the driveshaft-side impeller is then forcefully thrown back toward the engine-side impeller, assisting its rotation and thereby boosting the torque. The torque-boosting function is provided by the torque converter. Torque converter
[Merits] Since the engine’s power is transmitted by fluid, there is no need for the driver to engage and disengage a clutch. Also, standing starts and later acceleration are smooth and occur without any risk of an engine stall. [Demerits] Since the engine’s power is transmitted by fluid, fuel economy and acceleration are slightly inferior to those occurring with a manual transmission. Also, the mechanism is relatively complex, heavy, and costly.
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mission? INOMAT (fuzzy-logic-controlled mechanical-type automatic transmission) The INOMAT is basically a manual transmission that is automatically controlled by a computer. Unlike a regular automatic transmission, it does not use fluid to transmit power. Consequently, it has higher transmission efficiency. And since a computer optimally selects gears to suit driving conditions, the driver’s physical burden is lessened and fuel economy is, regardless of the driver’s skill, enhanced. INOMAT The clutch pedal is used for a standing start. Subsequently, the computer effects control, so the transmission gives relaxing automatic operation. Computer
INOMAT
Three pedals Clutch pedal
INOMAT II All transmission operation from starting to stopping is automatically controlled by the computer, so there is no clutch pedal.
Manual transmission
Two pedals
Further advances in automatic transmissions Lockup mechanism When the vehicle reaches and exceeds a certain speed, a lockup mechanism engages a clutch in the torque converter to cause direct power transmission for enhanced fuel economy and exhaust-braking effectiveness. Power mode and economy mode These modes can be used to change the timing of upshifts and downshifts for powerful performance, for delicate standing starts on snowy roads, and for superior fuel economy.
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What is overdrive? About overdrive
A gear that causes the engine and propeller shaft to turn at the same speed is known as ‘direct drive’; the gear ratio with direct drive is 1. A gear that causes the propeller shaft to turn faster than the engine is known as ‘overdrive’. On a level road, resistance is low, meaning that there is a surplus of torque even in top gear. Selecting overdrive causes the propeller shaft to turn faster than the engine. Thus, the engine speed can be kept relatively low for quietness and fuel economy.
What is overrunning? Unless the vehicle speed is kept under control when a vehicle is driven down a steep hill, the vehicle speed and engine speed can continue to increase such that the engine’s maximum speed is exceeded and the engine emits a severe noise. This condition is known as ‘overrunning’. Overrunning (and engine damage) can also occur if a gear change is made from 5th to 3rd while the vehicle is moving at high speed. For every gearshift, a limit on the initial vehicle speed is specified. The limits must be observed.
Transmission shapes Box-type case Transmission
Originally, a transmission was located in a square case. This kind of case was structurally simple, but it was not greatly resistant to twisting caused by vibration.
Cylinder-type case
Nowadays, a transmission is located in a cylindrical case. This kind of case has high rigidity and contributes to suppression of vibration and noise. It can be made of aluminum alloy for lightness. Transmission
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Mitsubishi Fuso uses cylindrical-case transmissions owing to their benefits in terms of high rigidity and low vibration and noise.
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What is a power 7 takeoff (PTO)? About PTOs
A PTO is a device that allows power to be taken from a special-purpose vehicle’s engine or transmission to drive equipment that is mounted on the vehicle. There are three types of PTO: transmission PTO; flywheel PTO; and full-power PTO. Any type of PTO is only optionally available for all chassis types with some exceptions. Transmission PTO A transmission PTO is mounted on the left-hand side of the transmission. A PTO control lever, which acts through a control device, allows the takeoff of power to be turned ON and OFF. This type of PTO is used mainly while the vehicle is stationary. [Features] Low cost; easy installation [Applications] Dump trucks; tank lorries, vacuum trucks, garbage collection trucks; simple crane trucks; ladder (highelevation working platform) trucks Flywheel PTO A flywheel PTO is mounted in the top of the engine’s flywheel housing. (See page 21 of the Engine section.) Since power is taken directly from the engine, vehiclemounted equipment can, provided the engine is running, be driven whether the vehicle is stationary or moving. When ON-OFF control over the PTO is needed, an electromagnetic clutch is used. [Features] Power is taken directly from the engine. This kind of PTO can be used on only a limited number of vehicle types. [Applications] Cement mixer trucks, garbage collection trucks Full-power PTO A full power PTO can be either of two kinds. One kind (used on heavy-, medium-, and light-duty trucks) is located between the clutch housing and transmission. The other kind (used on light-duty trucks) is located at the back of the transmission. A full-power PTO uses all of the engine’s power, so can be used while the vehicle is stationary. [Features] 100% of the engine’s power is used. However, this kind of PTO is costly and can be used on only a limited number of vehicle types. [Applications] Fire engines and sludge suction (pumping) vehicles
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Engine
Engine
Clutch
Clutch ion
Engine
Clutch Transmission n
onal. A PTO is opti
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What is a 8 reduction gear? About reduction gears
The reduction gear turns the power from the propeller shaft through an angle of 90° and transmits it to the rear axle shafts. It also effects a speed reduction and a torque increase. Since it effects the final speed reduction, it is also known as a final reduction gear unit and its reduction ratio is known as the final reduction ratio.
R
r shaft on pinion
What types of reduction gear exist? There are two types of reduction gear: the spiral-bevel-gear type and the hypoidgear type. Mitsubishi Fuso uses the hypoid-gear type.
Spiral bevel gears The axis of the reduction pinion and the axis of the ring gear are both on the same centerline. The teeth of the reduction pinion and the teeth of the ring gear are curved to create large tooth-to-tooth contact surfaces. [Merits] Rotation is smooth with low noise, vibration, and wear.
Rear axle shaft
Hypoid gears The axis of the reduction pinion and the axis of the ring gear are offset from each other, and the degree of curvature of the teeth is great. Gears of this type are widely used today. [Merits] A low center of gravity promotes stability. The tooth-totooth contact areas are large, so meshing is firm and quiet.
Reduction pinion
Ring gear
Ring gear
Reduction pinion
Final reduction ratio Since the reduction pinion and ring gear set performs the final speed reduction, it is also known as a final reduction gear unit. The high-speed rotational output of the engine first has its speed reduced (and thus the torque increased) by the transmission through combinations of gears. It then undergoes final reduction to the rotational speed of the wheels by means of the reduction gear set. Why is the speed reduction not performed in one step using the transmission? It’s partly because using just the transmission would necessitate a much bigger, heavier transmission containing many more gears. Also, the torque from the transmission would be so great that the propeller shaft would need to be thicker. The gear ratios (1st, 2nd, 3rd, and so on) shown in a catalog indicate the reduction ratios of the transmission. The final reduction ratio shown in a catalog indicates the reduction ratio of the reduction gear set. The final reduction ratio indicates the speed ratio of the propeller shaft and rear wheels. The formula for calculating it is shown below. Final reduction ratio = No. of revolutions per minute of driving wheels = No. of revolutions per minute of propeller shaft
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Number of teeth on ring gear Number of teeth on reduction pinion
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What is a differential 9 gear? About differential gears
The role of the differential gear For a truck to smoothly move around a curve, the outer wheels must travel a longer distance than the inner wheels. In other words, the outer wheels must turn faster than the inner wheels. Also, allowing the left and right wheels to turn at slightly different speeds is essential for smooth progress on uneven road surfaces. The left and right driving wheels are automatically permitted to turn at different speeds as necessary for smooth vehicle movements by the differential gear (also known simply as the differential). Principle of differential operation When the same level of resistance is acting on the left and right wheels, the left and right wheels turn at the same speed.
When more resistance acts on one wheel than on the other (on a curve, for example), the central gear in the illustration (representing the differential pinions) turns, causing the wheel that is subjected to less resistance to turn faster and further.
R
)
The differential’s action With the left and right wheels turning at the same speed, the differential pinions, which mesh with the differential gears, do not turn on their own axes. Consequently, the two differential gears turn at the same speed as the ring gear.
Differential pinion (Turns on its own axis.)
The differential’s action Since the distance to be covered by the left and right wheels is different, the inner wheel encounters greater resistance and slows down. The outer wheel speeds up by the same amount. Consequently, the differential pinions turn on their axes (spider shafts), allowing the differential gear that is being subjected to the greater resistance to turn. A left-right speed difference is thus created.
Limited-slip differential (LSD) If, with a regular differential, the driving wheel on one side of the vehicle slips on ice or sinks into mud, it spins because most of the torque is transmitted to the wheel with lower resistance. As a result, moving the vehicle away from that location becomes extremely difficult. An LSD prevents this problem. When the driving wheel on one side of a vehicle with an LSD starts to spin owing to loss of traction, a clutch inside the LSD automatically restricts the differential action.
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How is a truck steered? The steering system Customer: How does power steering lighten the steering wheel? Salesman: I don’t know. Help! ➾ See page 18.
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A truck’s steering system allows the driver to change the truck’s direction as desired. Specifically, it allows the driver to use the steering wheel to change the direction in which the front wheels are pointing. The system consists of the three mechanisms described below. Control mechanism The direction control mechanism includes the steering wheel and steering shaft. It transmits rotation of the steering wheel to the steering gearbox (a gear mechanism). Steering gearbox In the steering gearbox, the rotation of the steering shaft undergoes a speed reduction and a torque increase before being transmitted to the link mechanism. Link mechanism The link mechanism includes a pitman arm, a drag link, a knuckle arm, and tie rods. It transmits movement from the steering gearbox to the front wheels. It also keeps the left and right front wheels at the correct angles relative to each other.
T
Why are the inner and outer wheels at different angles? The steering system is made such that the right wheel turns through a greater angle than the left wheel when the vehicle is steered to the right (and vice versa). This arrangement is necessary because the left and right wheels follow different lines as shown in the figure.
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How is the steering 1 gearbox structured? About the steering gearbox
The steering gearbox makes the steering wheel feel light to turn and boosts the force that is transmitted from the steering wheel. There are two types of steering gearbox: the ball-and-nut type and the rack-and-pinion type. Ball-and-nut type Numerous steel balls are enclosed between the contact faces of a worm shaft (part of the steering shaft) and a ball nut. The balls transmit the rotation of the steering shaft to the ball nut. Their rolling action keeps friction low, thereby allowing the steering wheel to be turned with little effort. This type of steering gearbox is characterized by light steering action and high durability.
Steering shaft Worm shaft
Ball nut
Rack-and-pinion type A pinion gear is attached to the end of the steering shaft and is meshed with a rack gear. Rotation of the pinion gear causes the rack gear to move sideways. By means of tie rods, the rack gear’s sideways movement causes changes in the directions in which the wheels point. This type of steering gear is structurally simple and compact. It tends to transmit shock from the road surface to the steering wheel, but it gives sharp directional response to turning of the steering wheel.
Sector shaft
Pitman arm
Steering gearbox
Steering shaft
Mitsubishi Fuso uses the ball-and-nut type in heavy- and mediumduty trucks and the rack-and-pinion type in some Canter models.
Rack gear Pinion gear Tie rod
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What is power 2 steering? About power steering A power steering system is a steering system in which a booster uses hydraulic pressure to reduce the effort needed to turn the steering wheel. Typically, the hydraulic pressure is produced by a dedicated oil pump that is driven by engine power. The oil circulates back to the oil pump.
Vehicle-speed-sensitive power steering A vehicle’s steering action naturally becomes lighter as the vehicle speed rises. For stability, it’s desirable for a power steering system to give reduced assistance to steering action at high speeds. With a vehicle-speedsensitive power steering system, therefore, the vehicle speed is transmitted by a sensor as an electrical signal that causes the booster to adjust the degree of power assistance. Consequently, the steering action does not become too light as the vehicle speed increases.
At low plenty vehicle sp eeds, o assis f power ta lighte nce is give n n action the steerin to . g
, speeds vehicle is n At high o ti c a ring the stee light so not tly inheren er ow much p iven. nce is g ta is s s a
Power assistance: low
Power assistance: high
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How does a truck stop? About the braking system
Four basic functions of truck performance
Do you know what the basic functions of a truck’s performance are? There are four of them: carrying, running, turning, and stopping. The stopping function is an extremely important part of a truck’s performance. The braking system that realizes this function is said to be the most safety-critical of a truck’s systems. It must work effectively and reliably, and it must be durable and easy to inspect and service.
Carrying Turning
Running Stopping The principle of brake operation A truck’s brakes operate on basically the same principle as a bicycle’s brakes: They use friction to stop the wheels from turning. With a bicycle, the friction is produced by rubber blocks that are pressed against the wheel rims. With trucks, however, the usual arrangement involves drums and brake shoes. The shoes have friction material on them. When the brakes are applied, the friction material is pressed firmly against the drums to produce friction that stops the wheels from turning.
Brake shoe
Drum
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What are hydraulic 1 brakes? About hydraulic brakes
Hydraulic brakes With a bicycle, the strength of the rider’s hands is sufficient to apply the brakes. With a truck, however, much greater force is needed. For this reason, hydraulic brakes are generally used on trucks. The operating principle of hydraulic brakes is as follows: When the brake pedal is depressed, a piston is pushed, causing the pressure of brake fluid in a master cylinder to increase. The pressurized fluid flows through brake pipes and acts upon wheel cylinders (one for each wheel). In each of the wheel cylinders, the pressure pushes a piston that, in turn, pushes the brake shoes against the drum. Master cylinder
Master Vac (See page 22.
eel cylinder
If a brake pipe becomes holed and brake fluid leaks out, the brakes served by that pipe can stop working. Consequently, the hydraulic brakes on a truck are divided into two circuits: one circuit for the front wheels and one circuit for the rear wheels. If one circuit suffers a fluid leak, the other circuit still enables safe brake application. Tandem master cylinder This kind of master cylinder is internally divided into two parts that independently produce hydraulic pressure for the front brakes and rear brakes, respectively.
Brake chamber Mitsubishi Fuso uses wedgetype brakes, which give good responsiveness. In a wedge-type brake, the hydraulically pushed wedge acts directly upon the brake shoes, meaning that energy losses are not great.
Tandem master cylinders are used on current Mitsubishi Fuso light-duty trucks.
(Wedge-type brake)
20
4
What types of braking 2 system are used? Types of braking system
In addition to hydraulic brakes, the types of braking system that are used on trucks are air-over-hydraulic brakes (these combine pneumatic and hydraulic functions) and full air brakes. Air-over-hydraulic brakes In an air-over-hydraulic braking system, a brake valve of the kind used for air brakes is combined with Air Masters (brake boosters using compressed air). (See page 22.) Compressed air from an air tank is controlled by a brake valve that is directly linked to the brake pedal. The air controls the Air Masters. The brakes beyond the Air Masters are the same as those of a hydraulic braking system. Compared with hydraulic braking systems, air-over-hydraulic braking systems give a lighter pedal action. Consequently, they are used on large-sized buses and medium-duty trucks.
Air tank or
Full air brakes
Compressor
In a full air braking system, the brake pedal itself forms an open/close valve mechanism. When the pedal is depressed, the brake valve opens, allowing compressed air from an air tank to flow to the brake chambers. The pistons in the brake chambers are pushed by the compressed air. In turn, they push the brake shoes against the brake drums to create braking force. Full air brakes give an extremely light pedal action and high braking force, so they are used on all heavy-duty trucks.
Air tank Brake chamber
Brake chambers A brake chamber works using the force of compressed air. There is one brake chamber just inside each wheel. A pushrod that emerges from each brake chamber mechanically pushes the brake shoes.
21
4
How does light pedal action 3 cause strong brake operation? About brake boosters
Since a truck carries heavy cargo and moves at high speeds, appropriately great force is needed to slow and stop it. And given that the driver applies the brakes hundreds of times each day, a truck’s brakes must be easy for the driver to apply. Otherwise, the driver would, particularly on long journeys, become fatigued. A brake booster is used to meet the need for a light pedal action and strong braking force. By realizing ample braking force with a low level of pedal effort, a brake booster keeps driver fatigue low. A brake booster works using the difference between the atmospheric pressure and a pressure produced by a vacuum pump or an air compressor. Let’s look at the different types of brake booster. Master Vac A master Vac uses vacuum pressure. It is built into the master cylinder. Engine power is used to maintain a vacuum in chamber A and chamber B of the Master Vac. When the brake pedal is depressed, atmospheric pressure enters chamber B and moves the large piston inside it, thereby pushing the piston of the master cylinder to create high hydraulic pressure. Master Vacs are used in passenger cars and in Canter trucks.
Power piston
Air Master An Air Master works using the force of compressed air. The brake pedal itself forms a valve mechanism. When the pedal is depressed, compressed air from an air tank acts directly upon the power piston in the Air Master. (The compressed air is produced by a compressor.) As a brake booster, an Air Master has greater capacity than a Master Vac. Air Masters are used mainly on medium-duty trucks.
Master Vac
Master cylinder Tandem master cylinder
Air master
22
4
What types of brake 4 exist? About brakes
A vehicle’s brakes produce braking force using hydraulic pressure or pneumatic pressure. They can be either drum brakes or disc brakes.
Drum brakes With a drum brake, a drum rotates with the wheel. Shoes, which are lined with friction material, are pressed against the inside surface of the drum to stop the wheel’s rotation. To achieve good effectiveness, there are various shoe mounting arrangements. Leading/trailing-shoe brake The shoes are arranged such that, as the drum rotates, one of the shoes is pulled against it for good effectiveness. The shoe that is pulled against the drum is called the leading shoe. The other shoe is, by contrast, pushed away from the drum, meaning that its effectiveness is not great. This shoe is called the trailing shoe. A brake with its shoes arranged in this manner is called a leading/trailing-shoe brake.
Two-leading-shoe brake In this kind of brake, both shoes are arranged such that they acts as leading shoes for great effectiveness.
Dual-two-leading-shoe brake With a two-leading-shoe brake, both shoes act as leading shoes when the vehicle is moving forward but not when the vehicle is moving backward. A dual-two-leading-shoe brake is designed such that both shoes act as leading shoes whether the vehicle is moving forward or backward.
g shoe Leading sh
Disc brakes Drum brakes tend to become too hot internally and consequently ineffective if they are used continuously and excessively. Disc brakes were conceived to avoid this shortcoming. With a disc brake, a disc rotates with the wheel and is squeezed from both sides by pads to stop the wheel’s rotation. Unlike the friction components of a drum brake, the disc is exposed to the air, meaning that heat escapes easily. Braking performance is therefore consistent.
Disc Pad
Caliper Pad
The Super Great’s brakes are amazingly powerful. Because a truck carries cargo, it is extremely heavy. Consequently, its brakes have much higher performance than those of a passenger car. The pads of disc brakes are pushed against the discs by pistons. Conventionally, one piston is used per disc brake. On the Super Great, however, each disc brake has six pistons. These pistons are pushed by force that has been boosted by means of compressed air. The disc is 45mm thick. Each disc contains holes for heat dissipation but is extremely sturdy.
23
4
What other kinds of 5 brake exist on a truck?
Parking brake (handbrake) The parking brake is used to prevent the vehicle from moving when it is parked or otherwise stationary. One type of parking brake (called the center parking brake) takes the form of a drum brake that that is activated by means of a cable and acts on the propeller shaft. Another type of parking brake (known as the wheel parking brake) locks the wheels by means of compressed air that acts on the wheel brakes.
Engine braking If the accelerator pedal is released while a vehicle is being driven, the vehicle slows down owing to resistance caused by the engine. The effect that causes the resistance is called engine braking. Lock brake A lock brake is a device used for safety on a vehicle (for example, a crane or cement mixer) that is used for work while stationary. It is used together with the parking brake. Whereas the parking brake acts upon two wheels, the lock brake directly acts upon all of the wheels to hold the vehicle stationary.
Exhaust brake An exhaust brake is basically a valve in the exhaust pipe. When the valve is closed, it restricts the flow of exhaust gases, thereby slowing the engine. The result is more powerful engine braking.
Other brakes
Powertard (See page 31 of the Engine section.) A Powertard is a device that provides stronger engine braking. Retarder A retarder suppresses rotation of the propeller shaft by means of the power of an electromagnet or the resistance of oil. EZGO The EZGO is a braking system that incorporates a device that makes it easy to perform hill starts. Once the driver has depressed the brake pedal to hold the vehicle in place on a slope, the device maintains the braking force acting on the wheels even the driver releases the brake pedal. The driver can thus more easily perform a hill start.
Load-sensing valve (LSV) An LSV is a device that optimizes the balance of braking force between a vehicle’s front wheels and rear wheels. When a truck that has a short overall length is not carrying cargo and consequently its rear wheels are lightly loaded, the rear brakes tend to have a quicker effect than the front brakes. This can cause the rear of the vehicle to fishtail during braking. An LSV prevents this problem by sensing the load (weight) applied to the rear wheels and adjusting the braking force applied to the rear wheels in accordance with that load. The LSV automatically senses the load by monitoring the extent of sagging of the rear suspension springs, and it supplies hydraulic pressure or pneumatic pressure at the level necessary.
[A safety device that aids parking is available as an option. ] If the vehicle slips downhill by approximately 50cm owing to insufficient holding power of the parking brake, the safety device automatically applies the wheel brakes to stop the vehicle.
24
4
What are ABS and 6 ASR?
Antilock braking system (ABS) Hard braking on a slippery road (for example, a snow-covered road or a wet expressway) can cause a vehicle’s wheels to lock, with the result that the driver loses control over the vehicle’s direction. (The steering wheel becomes ineffective.) An ABS is intended to prevent this problem. With an ABS, a computer detects any slipping of the vehicle’s tires and modulates the pressure applied to the brakes so as to help prevent the wheels from locking. The ABS thereby enhances the vehicle’s directional stability.
What is wheel lockup? Wheel lockup is the term given to the condition in which a vehicle’s wheels stop turning but the vehicle continues moving. Under this condition, there is a lack of friction between the tires and road surface and the steering wheel is ineffective.
NOTE An ABS is intended only to supplement normal brake application. Even in a vehicle that has an ABS, it is essential to decelerate adequately when approaching curves. The ABS will not compensate for excessively uncontrolled driving.
Antispin regulator (ASR) When a standing start is attempted on a slippery road surface, the wheels can spin, preventing smooth motion and acceleration. An ASR is intended to prevent this problem by effecting control that prevents the driving wheels from spinning without traction. It is fitted as part of a set with an ABS. Just as the ABS suppresses wheel lockup without needing the driver to carefully modulate his or her brake pedal depression force, the ASR suppresses wheelspin without needing the driver to carefully control the exact extent to which he or she depresses the accelerator pedal. 25
5
What types of tire exist? Tire types
Radial tires A radial tire is a tire in which cloth threads (ply cords) run radially inside the rubber. The most notable benefit of radial tires is good grip (and accordingly good stability) on the road surface even on curves. A steelbelted radial tire is a radial tire in which a steel belt is added under the tread for reinforcement. [Merits] • Structurally sturdy • Effective in improving fuel economy
Radial tire
Bias tires A bias tire is a tire in which cloth threads (ply cords) run diagonally (at a bias angle to the direction of travel) inside the rubber. Bias tires are inferior to radial tires in terms of grip on the road surface, but they are relatively inexpensive and quiet. [Merits] • Soft ride [Demerits] • Inferior to radial tires in terms of tread durability
Bias tire
Steel radial tire
Tubeless tire
Tubeless tires A tubeless tire does not suffer a sudden air leak when pierced by, for example, a nail. Most radial tires and bias tires are tubeless.
26
Tire terminology (1) Bias tire
Tire section width
7.00 - 15 - 8PRLT
Section width (7.00 inches in this case) Tire structure (A ‘-‘ indicates a bias tire.)
(2) Radial tire
Rim diameter (15 inches in this case)
Tire strength (ply rating (8 in this case))
Tire application (‘LT’ indicates light-duty trucks. The code for a truck/bus tire is ‘TB’, but it is not usually written.)
Tire section tion heig height
7.00R15 - 8PRLT Rim m diame diameter
Tire structure (An ‘R‘ indicates a radial tire.)
(3) Low-profile radial tire
225 / 80R17.5 - 14PRLT Tire width (225mm in this case)
Tire structure (An ‘R‘ indicates a radial tire.)
Aspect ratio (80% in this case [Aspect ratio = tire section height / tire section width x 100 (%)])
Rim diameter (17.5 inches in this case)
Tire tread patterns The surface of a tire that makes contact with the road surface is called the tread. The tread contains grooves to help prevent the tire from slipping and to promote heat radiation. The patterns are classified as shown below. (1) Ribbed type
(2) Lugged type
Grooves are cut in the circumferential direction. This pattern is well suited to highspeed driving on good road surfaces. It resists skidding, gives good controllability and ride comfort, and creates little noise. It is widely used on trucks (including lightduty trucks) and buses.
(3) Block type
Grooves are cut sideways across the tread. This pattern prioritizes towing capability and braking force. It is intended for use on rough road surfaces and on unpaved roads. It is not suitable for highspeed driving. If subjected to high-speed driving, it is prone to skidding and to uneven wear. It is widely used on light-duty trucks (mainly light-duty dump trucks and other light-duty construction-use trucks).
(4) Ribbed and lugged type This pattern is well suited to sand, snow, and soft ground. Since the blocks move greatly during vehicle movement, however, tires with this kind of tread wear relatively quickly.
This pattern is a combination of the ribbed type and lugged type. The ribs are located in the center to promote controllability and help prevent skidding. Lugs are positioned on either side to provide the traction that is not adequately provided by the ribs. This pattern is used mainly on light-duty trucks.
27
6
How does a truck give a comfortable ride? Suspension system
?
Customer: Leaf springs are used in suspension systems, aren’t they? I know that making a leaf spring shorter makes it stiffer. But what’s the effect of putting leaf springs on top of each other? Salesman: I guess it makes them even stiffer? Customer: Are you sure? Salesman: Sorry, to be honest I don’t really know. How embarrassing!
A vehicle’s suspension system locates springs between the frame and wheels. The springs support the body while absorbing vibration from the road. The suspension system thus promotes ride comfort and helps keep the tires positioned properly to grip the road for handling stability. Suspension systems can be broadly classified into two types: independent suspension, in which the left and right wheels move independently of each other, and rigid-axle suspension, in which the left and right wheels are linked by an axle.
Independent suspension allows the left and right tires to move independently of each other while absorbing shock, so ride comfort and stability are superior.
Resistance
Stabilizer
Stabilizer A stabilizer is a beam that suppresses the vehicle’s tendency to roll (tip sideways) when the vehicle goes around corners. Stabilizers are widely used on front wheels to supplement the suspension system.
There are various types of spring. They include leaf springs (these have been used since the time of rickshaws and horse-drawn carriages); coil springs; torsion-bar springs (this type of spring works using torsion on a steel bar); and air springs (these work using the elasticity of air). Leaf spring Trucks typically have leaf springs, which are inexpensive and durable. A leaf spring consists of several steel leaves placed on top of one another for strength. It works using the elasticity of the steel. Leaf springs with longer and fewer leaves flex more easily than leaf springs with shorter, more numerous leaves, thereby giving a softer ride. Leaf springs with shorter, more numerous leaves give a harder ride. To meet different needs for ride comfort and cargo support, leaf springs are available with various numbers and lengths of leaves. Helper spring A helper spring is a secondary spring that works to complement a main spring. If there were only a single spring for each wheel and the spring’s stiffness were adjusted to the heaviest cargo the truck might carry, ride comfort would be poor even with the truck unladen. If the truck’s suspension is of a dual spring design consisting of main springs and helper springs, the frame is suspended only through the main springs when the vehicle is lightly loaded and through both the main and helper springs when the vehicle is heavily loaded. The problem of poor ride is thus resolved.
28
6
What suspension 1 spring types exist? Suspension employing leaf springs
Trunnion-type suspension Leaf spring
Tires
This type of suspension is used on the rear wheels of heavy-duty trucks. It is highly durable and is well suited to operation on uneven road surfaces. The rear axle is located by torque rods. Each end of the spring slides in accordance with changes in cargo weight. [Merits] • Durable; well suited to operation on uneven road surfaces • Spring strength is high enough to carrying heavy loads.
Torque rod
Trunnion base
Suspension employing air springs Air suspension Two-bag air suspension Shock absorber
Air spring
Trailing leaf
Four-bag air suspension Shock absorber
Air spring
Air suspension works using air springs, which exploit the elasticity of air. It is used for the rear wheels of trucks, where it is effective at protecting cargo and promoting ride comfort. If used on a tractor, air suspension allows the height of the coupler (the component to which the trailer is hitched) to be varied. It thus facilitates trailer hitching. Two-bag air suspension consists of two sets of trailing leaves that extend from front to rear and a large air spring on each side. It is structurally simple and light. (The term ‘bag’ is commonly used for an air spring.) Four-bag air suspension uses four air springs on each side to absorb vibration. It incorporates a relatively large number of torque rods, so aluminum is used to mitigate the weight of the structure.
When a suspension spring that does not have a shock absorber is compressed, it reacts by extending. It then reacts again by retracting, and so on; the extension and retraction continue without soon settling. A shock absorber is used to effectively damp the up and down motion. Its damping action is produced by the resistance that occurs as oil passes through small holes in a piston. 29
7
Where does electricity in a vehicle come from? Batteries
The power supply used to provide electricity to a vehicle’s starting system is the battery. While the engine is running, the battery is used to complement the supply of electricity provided by the alternator (generator) to the vehicle’s electrical systems. The battery stores electrical energy by converting it to chemical energy. As the battery is charged, the proportion of sulfuric acid in the fluid in the battery increases, causing the specific gravity of the fluid to increase. As the battery is discharged, the proportion of water in the fluid increases and the fluid’s specific gravity decreases.
Alternator
How to read battery type indications Example: Canter 2.0-ton truck Battery (type x quantity)
75D26R x 2
Performance rating (a number indicating the battery’s performance for driving the starter (the higher the number, the higher the performance)) Width x height category (All batteries in a given category have the same width x height.)
Terminal polarity position (‘R’ indicates that the ‘+’ terminal is on the right-hand side.) Length (nearest round number (26cm in this case))
Number of batteries (The number of batteries determines the power supply voltage. One battery is 12V.)
How to read alternator type indications
24 – 35
(V – A) 35: Current (amperes) (the supply current at a given operating speed)
24: Voltage (volts)
The alternator capacity (generating capacity) is determined taking into account the balance between charging and discharging. If an electricity consumer is added to the vehicle, the alternator must be replaced with a higher-capacity one. 30
7
How is a flat 1 battery dealt with?
How to use booster cables
(1) Stop the engine of the boost-giving vehicle. (2) Clip one end of the red booster cable onto the ‘+’ terminal of the boost-receiving battery and the other end onto the ‘+’ terminal of the boost-giving battery. (3) Clip one end of the black booster cable onto the ‘-’ terminal of the boost-giving battery and the other end onto the frame of the boost-receiving vehicle at a point as far as possible from the battery. You must not clip the booster cable directly onto the boost-receiving battery because of the risk that a spark emitted at the moment of connection would ignite gas emerging from the battery. (4) Start the engine of the boost-giving vehicle. Run the engine slightly faster than idling speed. Next, start the engine of the boost-receiving vehicle. (5) Disconnect the booster cables in the order opposite to that in which you connected them. In other words, first disconnect the black cable from the frame.
Handling a battery that is being charged While a battery is being charged, it emits hydrogen gas. Striking a light or creating a spark near the gas could cause an explosion. Great care is required.
31
8
What technologies are used I hope you understand everything.
You’re now ready to explain everything to customers.
Direct-injection 4M42 (T1)
Diesel engines
Direct-injection 4M50 (T4) Direct-injection 4M42 (T2) Direct-injection 4M50 (T5) Direct-injection 4M50 (T3)
Diaphragmspring clutch
Rack-and-pinion steering Cab-over-engine configuration Vehicle-speed-sensitive power steering
Halogen headlamps
Discharge headlamps
• DX-specification, pecification, 118kW or highe higher • Custom m vehicles EZGO
Tandem master cylinder
Independent front suspension
Master Vac
32
Disc brakes Two-leadingshoe brakes
in the Canter?
Five-speed manual transmission Six-speed manual transmission with overdrive
Synchromesh transmission
Super Frame
Four-speed automatic transmission with torque q converter
Reduction and differential gear
INOMAT-II (five-speed or six-speed)
Electromagnetic retarder
LSD Exhaust brake
Dual-two-leadingshoe brakes
ABS
ASR
gs Battery 75D26R 2 55D26R 2
LSV Air springs
Steel radial tires (7.00R15-8 etc.) Low-profile radial tires (205/70R16 etc.)
Bias tires (6.50-16-10 etc.)
432 434
632
33
Disc brakes
I understand everything!
CHECK SHEET Write the correct words in the parentheses (
).
1.
An engine with four cylinders is called a (
2.
The four stroke cycles of an engine are as follows: (
3.
The up-down motion of an engine’s pistons is converted into rotational motion by the ( ( ).
4.
When an explosion occurs in a cylinder, the force of the explosion pushes the piston. The force is then transmitted by the ( ) to the crankshaft, causing the crankshaft to turn.
5.
The indication ‘210PS/2,900rpm’ means that the engine produces power of ( revolutions per minute. It has the same meaning as ( ) kW/2,900rpm.
6.
The indication ‘180kgf·m/1,200rpm’ means that the engine produces ( ) of 180kgf·m at speed of 1,200 revolutions per minute. It has the same meaning as ( ) N·m/1,200rpm.
7.
With a gasoline engine, a mixture of fuel and air is drawn into the cylinders and compressed. With a diesel engine, however, only ( ) is drawn into the cylinders and compressed.
8.
If the compression ratio of a gasoline engine and that of a diesel engine are compared, it can be seen that the compression ratio of the ( ) engine is higher.
9.
The combustion chambers of a diesel engine can be one of three types: ( chamber type, or swirl-chamber type.
10. A diesel engine is an OHV type or an ( camshaft.
) engine. ) → compression → (
) → exhaust. ) and
) at a speed of 2,900
) type, precombustion-
) type depending on the positions of its valves and
11. A device that is attached to an engine and effects forced induction is called a ( 12. An intercooler is used together with a ( ). It cools ( increasing the ( ) for more effective forced induction.
).
) that has become hot, thereby
13. If air enters the fuel system of a diesel engine, the engine becomes unstartable, making it necessary to perform ( ). 14. The part of an injection pump that pushes fuel out is called a (
).
15. The device that stabilizes and controls the speed of a diesel engine is called a ( 16. The fuel injection timing of a diesel engine is controlled by a ( 17. An (
).
).
) uses an engine’s exhaust gases to boost the engine braking effect.
18. If the brakes are applied continuously, they can become so hot that the friction material on the brake shoes gets burned and slippery. The brakes then become ineffective for stopping the vehicle. This phenomenon is called ( ). 19. In a water-cooled engine, coolant is continuously circulated around the cylinders. Coolant that has become hot is cooled by the ( ) before being recirculated for further use. 20. To ensure smooth engine operation, engines are supplied with lubricating ( frictional resistance low.
), which keeps
21. The device that charges a vehicle’s battery and generates electricity as the engine runs is called an ( ).
1.
A frame consists of side rails and (
2.
Power is transmitted from the transmission to the differential by the (
3.
The clutch makes or interrupts the flow of power as necessary by pushing a ( flywheel or separating it from the flywheel.
4.
Depending on the spring type, a clutch is a coil-spring type or a (
5.
The transmission combines gears with different numbers of teeth, thereby changing the torque and ( ) as it transmits power.
6.
There are three types of meshing arrangement for the gears in transmissions. The most widely used one is called ( ).
7.
An automatic transmission has a fluid coupling function and a ( boosts torque.
8.
A function that makes the propeller shaft turn faster than the engine is called (
9.
A device that takes engine power and allows it to be used to drive equipment that is mounted on a vehicle is called a ( ).
10. A (
). ). ) against the
) type.
) function. The latter function
).
) is also called a final reduction gear unit.
11. A device that allows the left and right rear wheels to turn at different speeds is called a ( 12. There are two types of steering gearbox: the (
) type and the rack-and-pinion type.
13. There are three types of braking system: hydraulic brakes; ( 14. Compared with drum brakes, ( consistent braking performance.
) gear.
); and full air brakes.
) brakes have better heat-release performance and more
15. A brake that acts upon all of the wheels of, for example, a crane vehicle or cement-mixer vehicle while the vehicle is stationary and the onboard equipment is operating is called a ( ). 16. A suspension system includes springs, stabilizers, and shock absorbers. Among these items, the ones that prevent unwanted sideways tipping of the body are the ( ). 17. The type of suspension in which the left and right wheels are linked by an axle is called ( suspension. 18. (
)
) suspension gives better ride comfort than rigid-axle suspension.
19. A suspension spring absorbs vibration. Once it has started moving, it tends to continue oscillating up and down for a while. A ( ) is used to damp the oscillation. 20. Truck suspension works using either leaf springs or ( 21. Tires can be broadly classified into (
).
) and radial tires.
22. In a ‘225/80R17.5 — 14PRLT’ tire indication, the ‘80’ indicates the (
).
23. A tire’s aspect ratio is expressed as follows: Tire section height x 100 ( ) 24. When using booster cables to draw power from another vehicle’s battery, you must first connect the ( ) cable.
CHECK SHEET Answers
1. four-cylinder
1. crossmembers
2. intake, power
2. propeller shaft
3. connecting rods, crankshaft
3. clutch disc
4. connecting rod
4. diaphragm-spring
5. 210PS, 154
5. speed
6. torque, 1765
6. synchromesh
7. air
7. torque converter
8. diesel
8. overdrive
9. direct-injection
9. power takeoff (PTO)
10. OHC
10. reduction gear
11. turbocharger
11. differential
12. turbocharger, air, air density
12. ball-and-nut
13. air bleeding
13. air over hydraulic
14. plunger
14. disc
15. governor
15. lock brake
16. timer
16. stabilizers
17. exhaust brake
17. rigid-axle
18. fade
18. independent
19. radiator
19. shock absorber
20. oil
20. air springs
21. alternator
21. bias tires 22. aspect ratio 23. tire section width 24. + (positive)
This index covers part I ‘Engine’ and part II ‘Chassis’. [E] denotes the items appearing in the engine section and [C] denotes those appearing in the chassis section.
A
Clutch facing .....................................................[C] 5
ABS .................................................................[C] 25
Coil springs .....................................................[C] 28
Air bleeding .....................................................[E] 25
Coil-spring type .................................................[C] 6
Air cooling........................................................[E] 34
Combustion chamber ......................................[E] 18
Air Master..................................................[C] 21, 22
Common-rail system .......................................[E] 29
Air spring .........................................................[C] 29
Compression ratio ...........................................[E] 15
Air suspension.................................................[C] 29
Compressor wheel ..........................................[E] 23
Air-over-hydraulic brakes.................................[C] 21
Connecting rod ................................................[E] 13
Alternator.........................................................[E] 36
Constant-mesh type ..........................................[C] 8
API ..................................................................[E] 33
Control rack .....................................................[E] 27
ASR.................................................................[C] 25
Cooled EGR system........................................[E] 17
Automatic transmission ...................................[C] 10
Cooling fan ......................................................[E] 35 Cooling system................................................[E] 34
B
Crankcase .......................................................[E] 20
Ball-and-nut type .............................................[C] 17
Crankshaft .................................................[E] 13, 21
Battery ..................................................[E] 36/[C] 30
Crossmember....................................................[C] 3
Bias tires ...................................................[C] 26, 27
Cylinder ...............................................[E] 10, 12, 21
Block type........................................................[C] 27
Cylinder block ..................................................[E] 20
Booster cables ................................................[C] 31
Cylinder head ..................................................[E] 20
Bore.................................................................[E] 20
Cylinder liner ...................................................[E] 21
Bottom dead center .........................................[E] 15
Cylinder-type case ..........................................[C] 12
Box-type case .................................................[C] 12 Brake chambers ..............................................[C] 21
D
Brake fade .......................................................[E] 31
Diaphragm-spring type......................................[C] 6
Braking system................................................[C] 19
Diesel engine ...........................................[E] 14 - 19 Diesel knock ....................................................[E] 18
C
Differential gear ...........................................[C] 3, 15
Cab-behind-engine type....................................[C] 2
Direct drive ......................................................[C] 12
Cab-over-engine type........................................[C] 2
Direct injection type .........................................[E] 18
Caliper.............................................................[C] 23
Disc .................................................................[C] 23
Camshaft .........................................................[E] 21
Disc brakes .....................................................[C] 23
Chassis .............................................................[C] 1
Discharge tubes ................................................[C] 2
Clutch ............................................................[C] 2, 5
Distributor type ................................................[E] 26
DPF .................................................................[E] 17
H
Drag link ..........................................................[C] 16
Halogen headlamps ........................................[C] 32
Driveline....................................................[E] 8/[C] 4
Handbrake .............................................[E] 31/[C]24
Drum brakes..............................................[C] 19, 23
Heater plug......................................................[E] 19
Dual-chamber type ..........................................[E] 19
Helper spring...................................................[C] 28
Dual-two-leading-shoe brake ..........................[C] 23
Horsepower .....................................................[E] 11 How to read alternator type indications...........[C] 30
E
How to read battery type indications ...............[C] 30
EGR cooler......................................................[E] 17
Hydraulic brakes..............................................[C] 20
Electronic governor .........................................[E] 28
Hypoid gears ...................................................[C] 14
Engine braking......................................[E] 31/[C] 24 Engine oil.........................................................[E] 33
I
Engine performance curves ............................[E] 11
Ignition point ....................................................[E] 16
Engine speed ..................................................[E] 13
Independent suspension .................................[C] 28
Engine’s displacement.....................................[E] 20
Injection nozzle..........................................[E] 19, 25
Exhaust brake .......................................[E] 31/[C] 24
Injection pump ...............................[E] 17, 22, 25, 26
Exhaust manifold .............................................[E] 30
Inline engine ....................................................[E] 10
Exhaust system .........................................[E] 22, 30
Inline type ........................................................[E] 26
Exhaust valve ..................................................[E] 12
INOMAT...........................................................[C] 11
EZGO ..............................................................[C] 24
INOMAT II........................................................[C] 11 Intake manifold ................................................[E] 30
F
Intake system ............................................[E] 22, 30
Feed pump ................................................[E] 25, 26
Intake valve .....................................................[E] 12
Final reduction ratio.........................................[C] 14
Intercooler .................................................[E] 17, 24
Flange joint........................................................[C] 3 Flash point.......................................................[E] 16
K
Fluid coupling ..................................................[C] 10
Knuckle arm ....................................................[C] 16
Flywheel..................................................[E] 21/[C] 5 Flywheel PTO..................................................[C] 13
L
Four-stroke-cycle engine .................................[E] 12
Lead ................................................................[E] 27
Frame ................................................................[C] 3
Leading/trailing-shoe brake .............................[C] 23
Fuel filter..........................................................[E] 25
Leaf spring ......................................................[C] 28
Full air brakes..................................................[C] 21
Load-sensing valve (LSV) ...............................[C] 24
Full-power PTO ...............................................[C] 13
Lock brake.......................................................[C] 24 Lockup.............................................................[C] 25
G
Low-profile radial tire .......................................[C] 27
Gasoline engine ..............................................[E] 14
LSD .................................................................[C] 15
Generator..............................................[E] 36/[C] 30
Lubrication system ..........................................[E] 32
Glow plug ........................................................[E] 19
Lugged type ....................................................[C] 27
Governor .............................................[E] 22, 26, 28
M
R
Main combustion chamber ..............................[E] 19
Rack gear........................................................[C] 17
Manual transmission .......................................[C] 10
Rack-and-pinion type ......................................[C] 17
Master cylinder................................................[C] 20
Radial tires ......................................................[C] 26
Master Vac ......................................................[C] 22
Radiator...........................................................[E] 34
Mechanical governor .......................................[E] 28
Reduction gear............................................[C] 3, 14
Multigrade oil ...................................................[E] 33
Retarder ..........................................................[C] 24 Ribbed and lugged type ..................................[C] 27
N
Rigid-axle suspension .....................................[C] 28
Naturally aspirated engine...............................[E] 23 Nitrogen oxides ...............................................[E] 17
S
Nox (Nitrogen oxides)......................................[E] 17
SAE .................................................................[E] 33 Sector shaft .....................................................[C] 17
O
Service brakes.................................................[E] 31
OHC engine.....................................................[E] 21
Shock absorber ...............................................[C] 29
OHV engine.....................................................[E] 21
Side rail .............................................................[C] 3
Oil cooler .........................................................[E] 35
Single-chamber type .......................................[E] 19
Oil filter ............................................................[E] 32
Sliding-mesh type..............................................[C] 8
Oil pan .............................................................[E] 20
Spark plug .......................................................[E] 12
Overdrive.........................................................[C] 12
Spiral bevel gears............................................[C] 14
Overrunning ....................................................[C] 12
Stabilizer .........................................................[C] 28 Starter motor ...................................................[E] 36
P
Starter switch...................................................[E] 36
Pad .................................................................[C] 23
Starting system ...............................................[E] 36
Parking brake........................................[E] 31/[C] 24
Steel radial tire ................................................[C] 26
Performance classifications (Engine oil)..........[E] 33
Steering gearbox.............................................[C] 16
Pinion gear ......................................................[C] 17
Steering shaft ..................................................[C] 16
Piston ........................................................[E] 12, 13
Steering system ..............................................[C] 16
Piston rings......................................................[E] 21
Steering wheel ................................................[C] 16
Pitman arm......................................................[C] 16
Stroke ..............................................................[E] 20
Plunger ......................................................[E] 26, 27
Suction hose....................................................[E] 25
Plunger barrel..................................................[E] 27
Suspension system .....................................[C] 3, 28
Positive crankcase ventilation (PCV)...............[E] 17
Swirl-chamber type..........................................[E] 19
Power ..............................................................[E] 11
Synchromesh type ............................................[C] 9
Power takeoff (PTO)........................................[C] 13 Powertard .............................................[E] 31/[C] 24
T
Precombustion-chamber type .........................[E] 19
Tandem master cylinder ..................................[C] 20
Priming pump ..................................................[E] 25
Thermostat ......................................................[E] 35
Propeller shaft...........................................[E] 9/[C] 3
Tie rod .............................................................[C] 16
Pushrod ................................................[E] 21/[C] 21
Timer .........................................................[E] 26, 28
Top dead center...............................................[E] 15 Torque .............................................................[E] 11 Torque converter .............................................[C] 10 Torque rod .......................................................[C] 29 Torsion-bar springs..........................................[C] 28 Transmission .................................................[C] 2, 7 Transmission PTO ...........................................[C] 13 Tread patterns .................................................[C] 27 Trunnion-type suspension ...............................[C] 29 Tubeless tires ..................................................[C] 26 Turbine wheel ..................................................[E] 23 Turbocharger .......................................[E] 17, 22, 23 Turbocharging..................................................[E] 23 Two-leading-shoe brake ..................................[C] 23
V Valve................................................................[E] 21 Vapor locking ...................................................[E] 31 Vehicle-speed-sensitive power steering ..........[C] 18 Viscosity categories (Engine oil) .....................[E] 33 V-type ..............................................................[E] 10
W Water cooling...................................................[E] 34 Water jacket....................................................[E] 34 Water pump .....................................................[E] 35 Web joints .........................................................[C] 3 Wedge-type .....................................................[C] 20 Worm shaft......................................................[C] 17
You’re an important part of the Mitsubishi Fuso team. If there’ anything you need to know, don’t hesitate to ask a more experienced salesperson or someone in your service department.
Your name
Well do ne
!
T-No. 04 - '05
www.mitsubishi-fuso.com
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