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| Illustration 1 | g00457375 |
Steering Metering Pump | |
The steering metering pump is attached to the bottom of the steering column, and located under the floor of the operator's cab.
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| Illustration 2 | g00277946 |
Steering Metering Pump (1) Spool. (2) Sleeve. (3) Outlet to the hydraulic oil tank. (4) Load sensing line port. (5) Inlet port. (6) Rotor. (7) Rotor ring. (8) Drive shaft. (9) Centering springs. (10) Pin. (11) Left turn port. (12) Right turn port. (13) Housing. | |
Control section (A) consists of spool (1), sleeve (2), and housing (13). The sleeve is connected to the spool by pin (10). Pin (10) is installed through a slot in spool (1) and a hole in sleeve (2). Centering springs (9) are installed through both spool (1) and sleeve (2) .
Metering section (B) consists of rotor ring (7) and rotor (6). Spool (1) is connected to rotor (6) by drive shaft (8). Drive shaft (8) has a slot that engages with pin (10). Drive shaft (8) is splined to rotor (6) of the metering section.
The steering column is connected to spool (1) by a splined coupling. Pump oil flows into the control section through inlet port (5) .
When the steering wheel is not being turned, most of the flow is blocked by spool (1) and sleeve (2). A small amount of oil flows through a restriction on the way to the hydraulic oil tank. This ensures that a supply of oil that is at the operating temperature is always available at the metering pump.
When the steering wheel is turned, spool (1) turns a small amount until springs (9) are compressed. When pin (10) contacts the ends of the slots, sleeve (2) also turns.
While the steering wheel is turning, spool (1) and sleeve (2) turns as one unit. Centering springs (9) are compressed.
This initial movement of spool (1) opens the passages between the control section and the metering section. This allows the oil to flow from inlet port (5) to the metering section.
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| Illustration 3 | g00277947 |
Metering Section (6) Rotor. (7) Rotor ring. | |
Steering wheel rotation causes the rotation of rotor (6) inside rotor ring (7). As rotor (6) turns, a controlled flow of oil flows through housing (13). This oil flows to right turn port (12) or to left turn port (11). The oil then flows to the steering control valve.
When the steering wheel rotation is stopped, centering springs (9) move both spool (1) and sleeve (2) into alignment. This closes the passages between the metering section and the control section.