Compressor FH

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 A 760766

5611/Description, 5611/Description, Design and function//Compresso function//Compressor  r 

FH

130036052

1/26/11

Compressor  2COMP900 Compressor, general information

2COMP900 is a twin-cylinder compressor. compressor. The task of the compressor is to provide the vehicle with compressed air. Compressed air is mainly used in the service brake system, but is also used for other functions such as air suspension, suspension, ride height adjustment, gear change systems, gearbox, clutch and differential lock.  Air consumption consumption of the various various vehicle models models varies with their their size and the the amount of equipment equipment which which uses compressed air. When replacing a compressor with another size, the parameters must be changed. All calibration and changes to parameter data is done via VCADS-Pro.

COPYRIGHT © Volvo Group North America The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.

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The compressor for the vehicles which are covered here, has two cylinders and they are driven by a gearwheel directly from the engine timing gears. The crankcase and the cylinder block are air-cooled, while the cylinder head is cooled by liquid from the cooling system of the engine. The compressor receives its lubrication via the pressure lubrication system of the engine and the main and large end bearings are thus pressure lubricated. The small end bearing and piston are splash lubricated. The oil used by a piston compressor to lubricate the piston and piston rings, is separated in the air drier and drains out of the air drier during the compressor pressure relief phase (together with a considerably larger quantity of water). Note: A certain amount of oil will show on the air drier silencer, which is normal and does not require any action. The size of the compressor is intended to fulfil the air requirements of the vehicle rapidly and to fill the compressed air  system. Its function can be divided into two phases; charging phase and pressure relief phase. This compressor has a Power Reduction (PR) function. The function is a relief function that closes off the compressor  air delivery to the compressed air system when the predetermined system pressure has been reached. A small amount of the normal air volume will be allowed to flow from the air drier silencer when the compressor is relieved. The PR signal to the compressor originates from the air drier relief function. When the system pressure has decreased to the pre-set connecting pressure, the pressure regulator closes the release valve of the air drier which drains the PR connection, which closes the PR valve with the aid of a return spring. The compressor now begins to recharge the compressed air system. The idling speed of the electrically controlled cooling fan (FAN-VISE) is lower compared with earlier fans which reduces the cooling capacity of the cooling loop at low speed. To secure the cooling capacity of vehicles with this type of fan, an intelligent fan control has been introduced which ensures that the fan is engaged at a higher speed when the compressor is charging. The fan control is only activated when the outer temperature is higher than zero degrees C, the engine speed is greater  than 700 rpm and the road speed is less than 45 km/h.

Compressor, design Compressor 2COMP900 is used on 9, 11, 13 and 16 litre engines. Air capacity is 725 dm³/min at a backpressure of  800 kPa (8 bar) and engine speed of 1525 rpm. Maximum working pressure is 1300 kPa (13 bar). The compressor is driven by a gear wheel from the engine timing gears. The cylinder head and cylinder block with crankshaft are separate and separable units. The crankcase and the cylinder block are air-cooled, while the cylinder  head is cooled by liquid from the engine cooling system. Each piston has three piston rings, two compression rings and an oil scraper ring. The compressor receives its lubrication via the pressure lubrication system of the engine and the main and large end bearings are thus pressure lubricated. The small end bearing and piston are splash lubricated. On the cylinder head's lower part are located inlet and outlet valves. On the cylinder head's lower part are located inlet and outlet valves. Each outlet valve is mounted on a holder on the valve plate's upper side between the cylinder block and the cylinder head. The inlet valves are integrated in the cylinder head gasket. The Power Reduction (PR) function's reed valves is also placed on the underside of the cylinder head, they are opened pneumatically and closed by spring force. The PR function is controlled by two pistons. Each piston is, via a pin, connected to a movable reed valve. The PR connection to the compressor is via the arrow A illustrated below.

COPYRIGHT © Volvo Group North America The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.

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Note: Do not change these nipples for other types of standard nipples. Other types of nipples can put the PR function at risk. The compressor is driven by a gear wheel fixed on the tapered shaft, without a Woodruff key. The compressor flange and rear end plate of the crankshaft is fitted with bushings. The gudgeon pin is mounted directly in the connecting rod without bushings. The O-ring that seals on the timing gear cover is located radially.

COPYRIGHT © Volvo Group North America The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.

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Compressor, function  A vacuum is created in the cylinders as the pistons travel downwards and makes the inlet valves open. Induction air, cleaned in the engine air filter, flows into the cylinders. When the piston travels upwards, the inlet valve closes (by the pressure in the cylinder) and the induction air is compressed. When the pistons approach their top positions and the pressure in the cylinders exceeds the pressure from the spring and the air above the exhaust valves, the exhaust valves will open and the compressed air will flow into the compressed air system. The size of the compressor is intended to fulfil the air requirements of the vehicle rapidly and to fill the compressed air  system. This function can be divided up into two phases, the charging phase and the relief phase (Power Reduction Function). For further information about the charging phase and relief phase, refer to service information  Air drier in group 56.  Air flowing into the compressor is cleaned, dust and dirt particles being removed by the air filter of the engine. Before the air flows into the pneumatic system, the air is dried in a separate air drier to prevent water from getting into the system. The air flowing from the compressor, which is frequently hotter than 150°C is directed through a coil of piping of  between 3 and 5 metres in length, to be cooled to about 60°C, before it enters the air drier. This is done to get the highest possible efficiency in the air drier and to protect rubber components.

Compressor, power reduction function

COPYRIGHT © Volvo Group North America The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.

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 A. Open position, compressor idle. B. Closed position, compressor pumping. On this compressor, the energy saving function Power Reduction (PR) has two pistons. The function is a relief function that closes off the compressor air delivery to the compressed air system when the predetermined system pressure has been reached. The PR signal to the compressor comes from the air drier relief solenoid valve. When the predetermined system pressure has been reached, the vehicle control unit sends a signal to the air drier  relief solenoid valve, so that it opens and releases the compressed air together with any water collected from the air  drier.  At the same time, the PR valves in the compressor cylinder head are activated by a pressure signal from the air drier  relief solenoid valve, which causes the air to be pumped back and forth between the cylinder heads instead of  delivering the air to the compressed air system. A small proportion of the normal amount of air from the compressor  now flows out through the release valve of the air drier and silencer, when the compressor runs unloaded. When the system pressure has dropped to the predetermined engaging pressure, the air drier's relief valve is closed and the PR line is drained from air pressure, which closes the PR valves by means of return springs. The compressor  now begins to recharge the compressed air system. In the PR function, it is important to have the correct signal speed in order that the functions should work satisfactorily. Signal connections which are not sealed cause the signal speed to be incorrect. For additional information about relief, refer to service information  Air drier in group 56.

COPYRIGHT © Volvo Group North America The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.

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