06 Hoist

Service Training MALAGA

777D Off Highway Truck HOIST SYSTEM HOLD LOAD CHECK VALVE HOIST RELIEF VALVE

BRAKE COOLING RELIEF VALVE TO HOIST & BRAKE COOLER

HOIST PUMP

VI. HOIST SYSTEM 1. 2. 3. 4.

Components Layout Operation Maintenance Testing & Adjusting Adolfo August 1997

777D Off Highway Truck CHAPTER : HOIST SYSTEM

777D HOIST SYSTEM COMPONENT LOCATIONS

ORIFICE PLATE HOIST PUMP OIL COOLER HOIST & BRAKES

SLACK ADJUSTER

CAB

TRANSMISSION NEUTRALIZER SWITCH

HOIST RELIEF HOIST CONTROL VALVE VALVE OIL COOLING RELIEF VALVE

HOIST PUMP

HOIST RELIEF VALVE

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ORIFICE PLATE OIL COOLING HOIST CONTROL RELIEF VALVE VALVE

777D Off Highway Truck CHAPTER : HOIST SYSTEM

TWO STAGE HOIST CYLINDER RAISE

FIRST STAGE

SECOND STAGE

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

TWO STAGE HOIST CYLINDER LOWER

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

HOIST VALVE RELIEF VALVE

HOLD FROM PUMP

LOAD CHECK VALVE

DETENT

TO BRAKE COOLERS

RELIEF VALVE

CYLINDER ROD END PORT

CYLINDER HEAD END PORT

HOIST VALVE RAISE FROM PUMP

LOAD CHECK VALVE

DETENT

TO BRAKE COOLERS

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CYLINDER ROD END PORT

CYLINDER HEAD END PORT

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HOIST SYSTEM HOLD LOAD CHECK VALVE HOIST RELIEF VALVE

HOIST PUMP

777D Off Highway Truck

TO HOIST & BRAKE COOLER

CHAPTER : HOIST SYSTEM

BRAKE COOLING RELIEF VALVE

777D Off Highway Truck CHAPTER : HOIST SYSTEM

HOIST VALVE LOWER RELIEF VALVE FROM PUMP

LOAD CHECK

DETENT

NO FLOW FROM CYLINDERS HEAD END

TO CYLINDERS ROD END

RELIEF VALVE

HOIST VALVE FLOAT FROM PUMP

LOAD CHECK

DETENT

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HOIST SYSTEM RAISE

LOAD CHECK VALVE HOIST RELIEF VALVE

BRAKE COOLING RELIEF VALVE

777D Off Highway Truck

CHAPTER : HOIST SYSTEM

TO DIVERTER VALVE & HOIST/BRAKE COOLER

777D Off Highway Truck CHAPTER : HOIST SYSTEM

LAB EXERCISES Lab A Worksheet Hoist System Component Reference Checklist Directions: Place the correct letter next to the component and give a brief description of each. Example: _____ Hoist Pump(s) Supplies oil flow to the hoist system. The 769D - 777D only have one pump. Hoist System Components

_____ Hoist Pump

_____ Hoist Control Valve

_____ Hoist Relief Valve

_____ Hoist Diverter Valve

_____ Parking Brake Release Valve

_____ Oil Cooling System Relief Valve

_____ Hoist Lever Switch (Transmission Neutralizer)

_____ Orifice Plate (769D - 777D)

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

LAB EXERCISES Lab B: Adjust Hoist Lever Linkage BACKGROUND INFORMATION

This lab allows you to gain hands on experience checking and adjusting the hoist control lever linkage adjustment. The lab also allows you to gain hands on experience checking the transmission neutralizer switch for correct operation.

MATERIALS NEEDED

Mechanic’s Tool Box and hand tools Appropriate Service Manual Modules: Hydraulic System Operation, Testing and Adjusting

GROUP EXERCISE

Check and adjust the hoist control lever linkage on an Off-highway Truck. After the linkage has been checked and adjusted, check for correct operation of the transmission neutralizer switch.

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

LAB EXERCISES Lab C: Hoist System Diagnostic Testing BACKGROUND INFORMATION

This lab allows you to gain hands on experience performing pressure relief, cycle time and drift tests.

MATERIALS NEEDED

Appropriate Service Manual Module Mechanic’s Tool Box and hand tools 1 - 8T0857 Gauge (0-1450 psi) 1 - 8T0859 Gauge (0-3600 psi) 2 - 6V3989 Nipple 2 - 6V4143 Valved Coupler 2 - 6V3079 Diagnostic Hose 2 - 6J3958 1/8-27 NPTF Union 1 - 8T8902 11/16-16 ORFS Tee 1 - Stopwatch 1 - Tape measure 1 - 1U8865 Infrared Thermometer or 1 - 6V9130 Temperature Adapter Group

INDIVIDUAL OR GROUP EXERCISE

Perform relief valve pressure, cycle time and drift tests, and record your answers on the appropriate Lab C Worksheet for Off-highway Truck Hoist Test.

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

LAB EXERCISES 769D-777D OFF-HIGHWAY TRUCK HOIST TEST Machine Model__________________________

Date __________________________________

Serial # ________________________________

Customer ______________________________

Dealer _________________________________

SMH _________________________________

Serviceman _____________________________

Application ____________________________

VISUAL CHECKS Oil Level _______________________________

Oil Viscosity ___________________________

Air/Water in Oil? ________________________

Suction Screen Debris? ___________________

Oil Leaks?______________________________

Oil Filter Examination____________________

TEST

SPECS

ACTUAL

DRIFT RAISE TIME RELIEF VALVE PRESSURE

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

LAB EXERCISES LAB D: TRACING HOIST SYSTEM OIL FLOW

BRAKE COOLING RELIEF VALVE

TO BRAKE COOLER

RAISE

HOIST RELIEF VALVE

HOIST RELIEF VALVE

LOAD CHECK VALVE

769D - 777D HOIST SYSTEM

Directions: Trace the flow of oil in the RAISE position using different colored pencils.

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

POST TEST 769D-777D HOIST SYSTEM POSTTEST

Directions: Modified True/False. If a question is false, underline or circle the word or words that make the statement incorrect and replace with word(s) to make the statement correct. hoist system F Example: _____ 1. This is an engine class. ____ 1. Whenever work is performed under the body while the body is raised, you must install the safety pins AND disconnect the hoist control linkage. ____ 2. Incorrect adjustment of the hoist control linkage can prevent the transmission from shifting into reverse. ____ 3. Screens located on top of the hydraulic tank prevent contamination from entering the hoist system. ____ 4. The hoist system pilot operated relief valve controls the maximum pressure in the brake cooling system. ____ 5. An orifice plate at the rod end of the hoist cylinders prevents the body from raising faster than the pump can supply oil to the cylinders (caused by a sudden shift of the load). Directions: Multiple Choice. Circle the correct letter(s) of the best answer(s) for each question. 6. Supply oil from the hoist pump flows to the brake cooling system when the hoist lever is in the _____ position. A. B. C. D.

Raise Lower Hold Float

7. The _____ holds the hoist lever in the float position after the operator releases the lever. A. B. C. D.

ratchet pawl on the hoist lever centering spring on the directional spool ball detent on the directional spool small gremlin living in the hydraulic tank

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777D Off Highway Truck CHAPTER : HOIST SYSTEM

POST TEST 8. When the hoist valve is in the hold position with the body raised above the frame, the _____ will prevent the body from lowering. A. B. C. D.

directional spool orifice plate centering spring load check valve

9. If the hoist valve is moved from the hold to the raise position with the body raised above the frame, the _____ will prevent the body from lowering until pump supply pressure is higher than the pressure in the head end of the hoist cylinders. A. B. C. D.

directional spool load check valve relief valve orifice plate

10.When the hoist lever is in the _____ position, a small amount of oil pressure in the rod end of the hoist cylinders holds the body firmly down on the frame to prevent the body from bouncing when traveling without a load in the body. A. B. C. D.

Raise Lower Hold Float

Directions: Match the component with the correct location by placing the letter next to the component. ____

Hoist Supply Pump

A. Inside the hydraulic tank

____

Suction Screen

B. Rod end port of the hoist cylinders

____

Pilot Operated Relief Valve

C. On the hoist valve directional spool

____

Hoist Control Valve

D. Below the hoist valve

____

Brake Cooling Relief Valve

E. On the pump drive near the torque converter

____

Float Position Ball Detent

F.

____

Transmission Neutralizer Switch

G. Behind the hoist pump suction hose in the tank

____

Orifice Plate

H. Near the inlet port on the hoist control valve

____

Hoist System Pressure Tap

I.

Head end port of the hoist cylinders

Behind the operator’s seat in the cab

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