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| Illustration 1 | g00509594 |
(2) Hydraulic displacement control valve (3A) Port from the diverter valve for a left turn in forward or for a right turn in reverse (3B) Port from the diverter valve for a right turn in forward or for a left turn in reverse (4) Port to the steering motor for a left turn in forward or for a right turn in reverse (7) Port to the steering motor for a right turn in forward or for a left turn in reverse (11) Multifunction valves (12) Output line to the steering control (13) Line for case drain (14) Pump drive housing (15) Line for case drain | |
The steering pump is located on the right side of the machine. The steering pump is driven in the counterclockwise direction when the pump is viewed from the drive end. The steering pump drives the tandem charge pump at the rear of the steering pump.
The steering pump consists of the following components:
- Charge relief valve
- Two multifunction valves (11)
- Two servo relief valves
- Hydraulic displacement control valve (2)
- Swashplate (1)
- Servo cylinder
- Barrel (8)
- Pistons (9)
- Charge pump (5)
Top output line (4) routes oil to the steering motor for a left turn in forward or for a right turn in reverse. Bottom output line (7) routes oil to the steering motor for a right turn in forward or for a left turn in reverse. Case drain line (13) and case drain line (15) route oil to the differential for lubrication. Output line (12) routes oil to the steering control.
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| Illustration 2 | g00486220 |
(1) Swashplate (2) Hydraulic displacement control valve (3A) Port from the diverter valve for a left turn in forward or for a right turn in reverse (3B) Port from the diverter valve for a right turn in forward or for a left turn in reverse (4) Port to the steering motor for a left turn in forward or for a right turn in reverse (5) Charge pump (6) Coupling (7) Port to the steering motor for a right turn in forward or for a left turn in reverse (8) Barrel (9) Pistons (nine) (10) Input shaft | |
The steering pump is a bidirectional variable displacement axial piston pump. The rotation of the pump is counterclockwise when the pump is viewed from the drive end.
Input shaft (10) drives barrel (8). Barrel (8) carries nine pistons (9). Pistons (9) move oil into the cylinders that are inside of barrel (8). Then, the pistons move oil out of the cylinders that are inside the barrel.
Hydraulic displacement control valve (2) and the steering control valve control the amount of displacement and the direction of oil flow from the steering pump. The displacement is controlled by the angle of swashplate (1). The direction of the oil flow is controlled by the direction of the tilt of swashplate (1) .
Swashplate (1) tilts when pilot oil is sent to one of the two actuator pistons. The tilted swashplate causes pistons (9) to move in and out of barrel (8). The movement of pistons (9) causes oil to flow from port (4) or from port (7) .
Pilot oil for a left turn in forward enters port (3A). This causes oil flow from port (4). Pilot oil for a right turn in forward enters port (3B). This causes oil flow from port (7) .
Input shaft (10) also drives coupling (6). Coupling (6) drives charge pump (5). Charge pump (5) provides makeup oil for the closed loop and pressure oil for the hydraulic displacement control valve. Charge pump (5) also provides pilot oil to the steering control.
At rated speed, charge pump (5) produces approximately 83 L/min (22 US gpm). Charge pressure from charge pump (5) is controlled by a charge relief valve. The charge relief valve maintains a charge pressure of 2480 ± 170 kPa (360 ± 25 psi) above case drain pressure. The oil flow from the charge relief valve flows through the case of the steering pump.
There are pressure relief valves for the servos. The servo relief valves are located in the end cap of the steering pump. The servo relief valves limit the oil pressure for destroking the pump to 5170 kPa (750 psi) over the charge pressure.