 | |
| Illustration 1 | g00472599 |
Gear Pump (1) Bleed orifice. (2) Priority Valve. (3) Pilot signal passage. (4) Pump gears. (5) Relief Valve. (6) Charge oil outlet. | |
The gear pump is a fixed displacement pump that is mounted to the accessory drive on the engine. The gear pump supplies oil to the steering system. The gear pump also provides charge oil for the propel system and the vibratory system. Priority valve (2) is a pressure compensated flow divider. The priority valve divides the flow between the steering circuit and the charge circuit. The steering circuit has priority, and the return flow from the steering circuit returns into the charge circuit.
Relief valve (5) empties into the inlet of the steering pump. The relief valve is the pressure relief for the steering cylinders.
Output oil from pump gears (4) of the gear pump acts against the lower end of priority valve (2). Oil goes through bleed orifice (1) and the passage in the priority valve. Oil pressure forces priority valve (2) upward in order to allow oil flow to charge oil outlet (6).
Oil from the metering pump enters pilot signal passage (3). This oil acts against the upper end of the priority valve in addition to the force of the spring pressure. The pilot signal oil also acts against relief valve (5). The relief valve empties into the pump inlet and the relief valve serves as the pressure relief for the steering cylinders.
Bleed orifice (1) serves as a flushing passage for the oil that puts pressure on the bottom of the priority valve. The bleed orifice minimizes the bottoming of the priority valve against each stop. During operation, the priority valve oscillates.