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Illustration 1 | g06618121 |
Under Operator Platform (1) Propel pump |
Propel pump (1) is under the operator platform. This pump is driven by the engine. A door on the left side of the machine provides access to this component.
Propel pump (1) is a piston-type pump with variable displacement. The pump housing contains a single rotating group that provides flow to the propel motors.
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Illustration 2 | g06618536 |
Propel Pump (2) Port "X1" (3) Pump neutral adjustment (electronic displacement control) (4) Port "R" (5) Input shaft (6) Port "X2" (7) Solenoid "B" (8) Port "PS" (9) Pump neutral adjustment (mechanical) (10) Port "T2" (11) Port "P" (12) Solenoid "A" (13) Port "FE" (14) Port "S" (15) Combination valve for port "A" (16) Port "MB" (17) Interlock solenoid (18) Port "G" (19) Charge orifice (20) Port "MA" (21) Combination valve for port "B" (22) Port "A" (23) Port "B" (24) Port "T1" |
Each port in the pump housing is identified by a numeric or an alpha-numeric designation. The function of each port is as follows:
- Port "A" (22) is a system port. Port "A" is the reverse pressure port for the propel system when the seat is facing forward. This port is the forward pressure port when the seat is facing rearward.
- Port "B" (23) is a system port. Port "B" is the forward pressure port for the propel system when the seat is facing forward. This port is the reverse pressure port when the seat is facing rearward.
- Port "FE" (13) is the charge inlet port. Filtered charge oil is directed into port "FE".
- Port "G" (18) is a charge pressure port for auxiliary circuits. This port is plugged.
- Port "MA" (20) is a gauge port for system port "A". A pressure tap is installed in this port.
- Port "MB" (16) is a gauge port for system port "B". A pressure tap is installed in this port.
- Port "P" (11) directs oil from the interlock valve to the propel motors to release the parking brakes.
- Port "PS" (8) is a control supply pressure port. This port is plugged
- Port "R" (4) is a case drain port. This port is plugged.
- Port "S" (14) is a suction port. This port is plugged.
- Port "T1" (24) is a case drain port. Case drain oil from the propel pump is sent to port "L1" of the vibratory pump.
- Port "T2" (10) is a case drain port. This port is plugged.
- Port "X1" (2) is plugged. Port "X1" (5) can be used to measure reverse servo pressure.
- Port "X2" (6) is plugged. Port "X2" (4) can be used to measure forward servo pressure.
The direction control valve is equipped with two proportional solenoids. Solenoid "A" (12) controls forward operation when the seat is facing forward, and reverse operation when the seat is facing rearward. Solenoid "B" (7) controls reverse operation when the seat is facing forward, and forward operation when the seat is facing rearward.
The propel pump is equipped with two combination valves. Combination valve (15) for port "B" is on the top face of the pump, and combination valve (21) for port "A"is on the bottom face. Each combination valve contains a makeup valve and a relief valve. The relief valves limit the pressure in the circuit to
The propel pump is equipped with charge orifice (19). This orifice allows charge oil to flow into the pump case drain.
An interlock valve is inside the propel pump. The machine ECM controls this solenoid-operated valve. When the parking brake is engaged, interlock solenoid (17) is not energized. When the parking brake is released, the solenoid is energized.
When interlock solenoid (17) is energized, charge oil is available at the direction control valve in the propel pump. Charge oil is also sent to the parking brakes. When the solenoid is not energized, charge oil is blocked. In this case, the direction control valve and the parking brakes are open to case drain. Under these conditions, the rotating group of the propel pump is at zero angle, and the parking brakes are engaged.
The propel pump is equipped with two pump neutral adjustment mechanisms. Pump neutral adjustment (3) on the top face of the pump adjusts the zero position of the displacement control spool. This adjustment mechanism zeros the control spool so no oil can reach the pump servo when the pump is in neutral.
Pump neutral adjustment (9) on the front face of the pump is used to adjust the mechanical zero setting of the pump swashplate.
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Illustration 3 | g06618549 |
Propel Pump Cross Section (5) Input shaft (25) Servo piston (26) Swashplate (27) Slipper pad (28) Piston (29) Barrel assembly (30) Port plate |
Engine rotation turns pump input shaft (5), which then rotates barrel assembly (29). Pistons (28) rotate with the barrel assembly. Piston slipper pads (27) allow the pistons to follow the angle of swashplate (26). The barrel assembly only generates flow when the swashplate is not at zero angle.
When the machine electronic control system sends an output signal to a control solenoid, corresponding servo piston (25) moves. As the servo piston moves, the action of the control linkage causes the angle of swashplate (26) to change. The swashplate angle is proportional to the signal from the machine electronic control system.
Slipper pads (27) follow the angle of swashplate (26). This action causes pistons (28) to move in and out of barrel assembly (29) as input shaft (5) rotates. As a piston moves out of the barrel assembly, oil in the low-pressure circuit is drawn into the piston chamber. As a piston moves into the barrel assembly, oil is forced out of the piston chamber and into the high-pressure circuit.