Location and Function
Locations
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| Illustration 1 | g00951218 |
Top View of Pump Stack | |
The illustration above shows the correct orientation of the propel pumps in relation to the pump drive system.
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| Illustration 2 | g00976338 |
Left Side View of the Machine | |
The propel pumps are mounted to the pump drive and the propel pumps are run directly from the engine flywheel housing through the pump drive.
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| Illustration 3 | g00983784 |
Left Side View of the Machine | |
There are a few ways to access the propel pumps. Access can be obtained through the pump compartment on the left side of the machine.
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| Illustration 4 | g00983763 |
Top View of the Machine | |
Access to the right propel pump can be obtained from the top of the machine through the left engine access panel.
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| Illustration 5 | g00983768 |
Front View of the Machine | |
Access to the left propel pump can be obtained through the front engine access panels in the hopper chamber.
Function
There are two identical piston pumps (propel) on the AP-655C Asphalt Paver. One propel pump controls the left side of the machine and the other propel pump controls the right side of the machine. The propel pumps are located on the left side of the machine in the pump compartment. The propel pumps are mounted to the pump drive and the propel pumps are run directly from the engine flywheel housing.
The propel pumps receive hydraulic oil through suction strainers on the hydraulic tank. Return hydraulic oil is sent to the cooler bypass valve and on to the return filter in the hydraulic tank.
The propel system has an internal charge system. Hydraulic oil that enters the propel pumps will first route through the internal charge pump. The internal charge pump will route charge oil to the charge filters and back into the pump housing. This movement of oil occurs during engine operation. In the NEUTRAL position, charge oil is maintained by the internal charge relief valves on each propel pump.
The propel pumps are axial piston pumps with a variable displacement. The propel pumps are capable of delivering a flow rate of 245 L/min (63.9 US gpm). This flow rate is proportional to the pump input speed and pump displacement. The propel pumps have a cradle swashplate design and the propel pumps are intended to function within a closed loop circuit. The hydraulic flow may be reversed by tilting the swashplate beyond the NEUTRAL position in the opposite direction. The propel pumps deliver hydraulic flow to the piston motors, which will turn the final drive planetaries.
Components
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| Illustration 6 | g00986510 |
Hydraulic Schematic of the Left Propel Pump (1) Left propel pump (2) Supply line to propel motor "Port B" (FORWARD) (3) Supply line to propel motor "Port A" (REVERSE) (4) Pressure port "B" (FORWARD) (5) Pressure port "A" (REVERSE) (6) Shuttle valve (7) Left charge filter (8) Charge pressure port (9) Multifunction valve (FORWARD) (10) Multifunction valve (REVERSE) (11) Case drain "Port L1" (12) Displacement piston (13) Pump swashplate (14) Gerotor charge pump (15) Pump inlet "Port S" (16) Charge relief valve (17) Pressure limiter valve (18) Internal orifice (19) High pressure relief valve (20) Charge check valve (21) Displacement control valve (22) EDC valve (REVERSE) (23) EDC valve (FORWARD) (24) EDC body | |
Operation and Oil Flow
Note: The left propel pump and the right propel pump are identical. For all information and illustrations in this module, the left propel pump will be examined. Apply the same principles to the right propel pump.
The propel system has an internal charge system. Hydraulic oil that enters propel pump (1) will first route through internal charge pump (14). Charge pump (14) will route charge oil to charge filter (7) and back into propel pump (1). This movement of oil occurs during engine operation. In the NEUTRAL position, charge oil is maintained by charge relief valve (16) .
Propel pump (1) is capable of delivering a flow rate of 245 L/min (63.9 US gpm). This flow rate is proportional to the pump input speed and the pump displacement. The propel pumps have a swashplate (13) with a cradle design and propel pump (1) is intended to function within a closed loop circuit. The hydraulic flow may be reversed by tilting swashplate (13) beyond the NEUTRAL position in the opposite direction. Propel pump (1) delivers hydraulic flow to the piston motors, which will turn the final drive planetaries at a speed that is proportional to pump output and motor speed.
Propel Lever in the FORWARD Position
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| Illustration 7 | g00986591 |
Hydraulic Diagram of the Left Propel Pump (1) Left propel pump (2) Supply line to propel motor "Port B" (FORWARD) (3) Supply line to propel motor "Port A" (REVERSE) (4) Pressure port "B" (FORWARD) (5) Pressure port "A" (REVERSE) (6) Shuttle valve (7) Left charge filter (8) Charge pressure port (9) Multifunction valve (FORWARD) (10) Multifunction valve (REVERSE) (11) Case drain "Port L1" (12) Displacement piston (13) Pump swashplate (14) Gerotor charge pump (15) Pump inlet "Port S" (16) Charge relief valve (17) Pressure limiter valve (18) Internal orifice (19) High pressure relief valve (20) Check valve (21) Displacement control valve (22) EDC valve (REVERSE) (23) EDC valve (FORWARD) (24) Electronic displacement control (EDC) (25) EDC solenoid (FORWARD) (26) EDC Solenoid (REVERSE) (27) Left valve envelope (28) Right valve envelope (29) Left valve envelope (30) Right valve envelope (31) Left solenoid (32) Flow cartridge (33) Right shift valve spool (34) Left shift valve spool (35) Right solenoid (36) Servo pressure ports (37) Charge check valve | |
The operation and the description of oil flow in this module will examine the left propel pump. The left propel pump and the right propel pump are identical. For all information and illustrations, please apply these principles to the right propel pump.
As the machine propels forward, a signal from the ECM is sent to (FORWARD) EDC valve (25). As this occurs, valve envelope (28) is active. The position and the amount of flow from displacement control valve (21) is dependent on the intensity of the signal from the ECM. The ECM analyzes the signals, which are made by one of the several different operator controls, in order to determine the magnitude of the signal that is sent to displacement control valve (21). As EDC valve (23) is energized, a signal is sent to solenoid (35) and shift valve spool (34) will be active. Shift valve spool (34) will shift and allow the movement of hydraulic oil to pump swashplate (13). Hydraulic oil will force displacement piston (12) to a displacement that is proportional to the signal. As displacement piston (12) varies the angle of swashplate (13), propel pump (1) generates pressure oil to the FORWARD circuit.
Oil flow in the FORWARD circuit flows to multifunction valve (9) and on to the propel motor from "Port B" (2). The multifunction valve performs the following functions:
- Shuttle Valve (6)
- Charge Check Valve (37)
- High Pressure Relief (19)
- Pressure Limiter (17)
Shuttle valve (6) acts against pressure limiter (17) and high pressure relief valve (19). As pressure in the propel circuit rises above 37250 ± 1400 kPa (5400 ± 200 psi) plus charge pressure, pressure limiter (17) will open in order to rapidly destroke pump swashplate (13). Displacement control valve (21) will shift and the flow will reverse in flow cartridge (32). This will move displacement piston (12) in the REVERSE direction. The propel system is designed to maintain a constant pressure. As charge pressure rises above 2600 ± 105 kPa (380 ± 15 psi), charge relief valve (16) will open and return oil to the charge circuit. As pressure increases in the propel system 3550 kPa (500 psi) above the pressure limiter setting, high pressure relief valve (19) will open and route oil to the charge circuit.
The FORWARD circuit will reduce flow on the REVERSE circuit. As the operator moves the propel lever, the controls will act proportionally.
Propel Lever in the REVERSE Position
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| Illustration 8 | g00986605 |
Hydraulic Diagram of the Left Propel Pump (1) Left propel pump (2) Supply line to propel motor "Port B" (FORWARD) (3) Supply line to propel motor "Port A" (REVERSE) (4) Pressure port "B" (FORWARD) (5) Pressure port "A" (REVERSE) (6) Shuttle valve (7) Left charge filter (8) Charge pressure port (9) Multifunction valve (FORWARD) (10) Multifunction valve (REVERSE) (11) Case drain "Port L1" (12) Displacement piston (13) Pump swashplate (14) Gerotor charge pump (15) Pump inlet "Port S" (16) Charge relief valve (17) Pressure limiter valve (18) Internal orifice (19) High pressure relief valve (20) Check valve (21) Displacement control valve (22) EDC valve (REVERSE) (23) EDC valve (FORWARD) (24) Electronic displacement control (EDC) (25) EDC solenoid (FORWARD) (26) EDC Solenoid (REVERSE) (27) Left valve envelope (28) Right valve envelope (29) Left valve envelope (30) Right valve envelope (31) Left solenoid (32) Flow cartridge (33) Right shift valve spool (34) Left shift valve spool (35) Right solenoid (36) Servo pressure ports (37) Charge check valve | |
The operation and the description of oil flow in this module will examine the left propel pump. The left propel pump and the right propel pump are identical. For all information and illustrations, please apply these principles to the right propel pump.
As the machine propels in reverse, a signal from the ECM is sent to (REVERSE) EDC valve (26). As this occurs, valve envelope (29) is active. The position and the amount of flow from displacement control valve (21) is dependent on the intensity of the signal from the ECM. The ECM analyzes the signals, which are made by any one of the several different operator controls, in order to determine the magnitude of the signal that is sent to displacement control valve (21). As EDC valve (22) is energized, a signal is sent to solenoid (31) and shift valve spool (33) will be active. Shift valve spool (34) will shift and allow the movement of hydraulic oil to pump swashplate (13). Hydraulic oil will force displacement piston (12) to a displacement that is proportional to the signal. As displacement piston (12) varies the angle of swashplate (13), propel pump (1) generates pressure oil to the REVERSE circuit.
Oil flow in the REVERSE circuit flows to multifunction valve (10) and on to the propel motor from "Port A" (3). The multifunction valve performs the following functions:
- Shuttle Valve (6)
- Charge Check Valve (37)
- High Pressure Relief (19)
- Pressure Limiter (17)
Shuttle valve (6) acts against pressure limiter (17) and high pressure relief valve (19). As pressure in the propel circuit rises above 37250 ± 1400 kPa (5400 ± 200 psi) plus charge pressure, pressure limiter (17) will open in order to rapidly destroke pump swashplate (13). Displacement control valve (21) will shift and the flow will reverse in flow cartridge (32). This will move displacement piston (12) in the FORWARD direction. The propel system is designed to maintain a constant pressure. As charge pressure rises above 2600 ± 105 kPa (380 ± 15 psi), charge relief valve (16) will open and return oil to the charge circuit. As pressure increases in the propel system 3550 kPa (500 psi) above the pressure limiter setting, high pressure relief valve (19) will open and route oil to the charge circuit.
The REVERSE circuit will reduce flow on the FORWARD circuit. As the operator moves the propel lever, the controls will act proportionally.