| |
| Illustration 1 | g03432053 |
|
Hydraulic Schematic for Steering Systems that use Metering Pumps (1) Steering pump. (2) Hand metering unit (HMU). (3) Left steering cylinder. (4) Right steering cylinder. (5) Breather. (6) Hydraulic oil tank. (7) Load sense signal line. (8) Secondary steering pump/motor. (optional attachment). (9) Secondary steering valve. (optional attachment). (AA) Pressure tap for checking steering pump pressure. (BB) Pressure tap for checking signal pressure. | |
| |
| Illustration 2 | g06111097 |
|
Right Side View Steering Components (1) Steering pump. (2) Hand metering unit (HMU). (4) Right steering cylinder. (6) Hydraulic oil tank. | |
| |
| Illustration 3 | g06111107 |
| |
| Illustration 4 | g06111102 |
|
Right Side View Steering pressure tap locations. (AA) Pressure tap for checking steering pump pressure (BB) Pressure tap for checking signal pressure | |
| |
| Illustration 5 | g06111128 |
|
Left Side View Steering Components (3) Left steering cylinder (8) Secondary steering pump/motor. (optional attachment) (9) Secondary steering valve. (optional attachment) | |
The primary steering system consists of a single high-pressure circuit. When a machine is equipped with the optional secondary steering attachment, an extra high-pressure supply circuit is added.
The primary steering system consists of the following components: Steering pump (1), HMU (2), left steering cylinder (3), right steering cylinder (4), and hydraulic oil tank (5).
The HMU (2) is attached to the bottom of the steering column, and is located under the floor of the operator compartment. The steering cylinders (3, 4) are on the right and left side of the machine and attached to the frame. The hydraulic oil tank (5) is located behind the cab. The steering pump (1) is located under the operator cab on the right side of the machine. A pressure and flow compensator valve is attached to the steering pump (1)
The steering pump (1) is a variable piston pump. The pressure and flow compensator valve helps control the output of the pump. The steering pump draws oil from hydraulic oil tank (5). Pressure oil from the steering pump flows to the metering pump. The HMU (2) is a small hydraulic pump that is used as a metering valve and a directional control valve. Oil from the steering piston pump goes through a port to the control section of the valve. When the steering wheel is turned, the control section sends oil through the metering section producing a specific amount of oil flow. Metered oil from metering section is then directed by the control section to either the left turn port or right turn port . This oil flows to the appropriate steering cylinder (3, 4).
Reference: Refer to Service Manual, UENR4583, "Metering Pump (HMU Steering)" for more information.
Reference: Refer to Service Manual, UENR4583, "Secondary Steering System (HMU Steering)" for more information.