Combined air and hydraulic fluid supply apparatus and control therefor

Claim 1

A combined compressed air and hydraulic fluid supply apparatus comprIsing: a. a pneumatic portion including: i. an air compressor, ii. a storage reservoir, iii. first conduit means via which compressed air is transmitted from said air compressor to said storage reservoir, iv. an unloader valve device operably mounted on said air compressor and having a cut-in position in which compressed air output from the air compressor is directed through said first conduit means to said storage reservoir, and being operable responsively to air pressure to a cut-out position in which said compressed air output is diverted from said first conduit means to atmosphere, v. second conduit means interconnecting said storage reservoir and said unloader valve device, vi. a governor device interposed in said second conduit means and operable responsively to compressed air in said storage reservoir at a certain maximum pressure to one position in which air pressure from the reservoir is communicated to said unloader valve device via said second conduit means for effecting operation thereof to its said cut-out position, said governor device being operable responsively to a reduction of air pressure in the storage reservoir to a certain minimum pressure to a different position in which said unloader valve is relieved of air pressure for effecting restoration thereof to its said cut-in position; b. a hydraulic portion including: i. a hydraulic fluid pump having an inlet and an outlet, ii. a hydraulic sump connected to said inlet, iii. a hydraulic accumulator for receiving hydraulic fluid from said hydraulic pump, iv. bypassing conduit means interconnecting said outlet with said sump in bypassing relation to said accumulator, and v. hydraulic pressure responsive regulator means interposed in said bypassing conduit means and being operable responsively to hydraulic fluid in said accumulator at a certain minimum pressure to a closed position in which communication between said outlet and said sump via said bypassing conduit means is interrupted, said regulator means being operable responsively to hydraulic fluid in said accumulator at a certain maximum pressure to an open position in which said communication is opened for diverting hydraulic fluid from the pump outlet to said sump via said bypassing conduit means; c. common driving means comprising an electric motor for driving said compressor and said pump concurrently; d. electrical circuitry effective when closed for actuating said motor and effective when opened for shutting down the motor; e. first electrical switch means interposed in said circuitry and pneumatically connected to said governor device, said first electrical switch means being operable, in response to air pressure supplied thereto by said governor device concurrently with that supplied to the unloader valve device, to an open position for opening said circuitry, and operable in response to relief of air pressure therefrom by said governor device concurrently with relief of compressed air from the unloader valve device, to a closed position for closing said circuitry; f. second electrical switch means interposed in said circuitry in parallel relation to said first electrical switch means and operable, in response to hydraulic pressure supplied to said regulator means at said minimum pressure, to a closed position for closing said circuitry, and operable, in response to hydraulic pressure supplied to said regulator means at said maximum pressure, to an open position for opening said circuitry.