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Auxiliary coupler pressure relief hydraulic system with pump drive ignition switch relief

  • US 4,881,371 A
  • Filed: 07/26/1988
  • Issued: 11/21/1989
  • Est. Priority Date: 07/26/1988
  • Status: Expired due to Term
First Claim
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1. An auxiliary coupler pressure relief hydraulic system for a mobile vehicle, including:

  • a battery;

    an engine;

    an engine ignition system;

    an operator actuated ignition switch having RUN and OFF positions, for controlling the flow of electricity to the engine ignition system;

    a reservoir of hydraulic fluid;

    a pump coupled to the engine and reservoir for providing hydraulic fluid under pressure;

    coupler means for coupling hydraulic fluid to an attachment;

    an electro-hydraulically actuated control valve connected in a hydraulic circuit between the pump and the coupler means, for controlling the flow of hydraulic fluid to the coupler means in response to valve actuating signals;

    operator actuated auxiliary control switch means coupled to the control valve for providing attachment control valve actuating signals; and

    operator actuated pressure relief switch means coupled to the control valve and capable of providing electrical pressure relief valve actuating signals to the control valve after the ignition switch has been switched to its OFF position and while the engine RPM is decreasing to zero, thereby actuating the control valve and relieving pressure between the control valve and coupler means.

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