| 摘要 |
A motor vehicle fluid power circuit is disclosed which includes a primary pump, a closed center brake booster, and an open center steering valve. These components are hydraulically connected in series with the fluid flowing from the pump to the closed center brake booster and then to the open center steering valve. The brake booster includes valve means throttling fluid flow from the pump to the steering valve and maintaining the outlet pressure of the pump at at least a predetermined pressure differential above the working pressure of the brake booster under normal operating conditions in order to conserve output load requirements of the pump while assuring adequate pump pressure for brake booster actuation. In a second embodiment, a back-up pump is also provided in the circuit, and a pilot valve hydraulically disconnects the primary pump and hydraulically connects the back-up pump to the brake booster in response to a fluid pressure failure in the primary pump.
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