GB1171659A - Hydraulic starting system and valves therefor - Google Patents

Abstract

1,171,659. Hydraulic reciprocating motors and pumps; engine turning gear. NEW YORK AIR BRAKE CO. Aug. 1, 1967 [Aug. 3, 1966], No. 35199/67. Headings F1A and F1K. In the engine starting and pumping system of Specification 1, 005, 679, comprising a hydraulic swash plate unit 13 with a valve assembly 37, 61 controlling movement of the swash plate by pistons 24, 29 and 35, for operation of the unit as a motor for starting the engine and then as a pump driven by the engine, severe oscillation of the swash plate between its pumping and motoring positions, when the engine fails to start and the accumulator empties, is avoided by the provision of a check valve 104 in the pressure supply line to the piston 57 which actuates valve assembly 37, 61. Check valve 104 acts to maintain piston 57 at full accumulator pressure to hold the swash plate in its motoring position until the engine starts and opens a speedresponsive switch 114 or, if the engine fails to start, when engine starting switch 113 is opened. Opening of either switch de-energizes the start valve solenoid 19a and also a solenoid 111 which releases a vent valve 107 to vent piston 57, and thereby move the swash plate to its pumping position. In other embodiments, Figs. 2 to 8 (not shown), the engine start valve is incorporated in the same housing as valves 104,107 and controlled by a pilot valve operated by the same solenoid as valve 107. A restriction may be provided in the start valve operating circuit so that full operating pressure is not developed in the motor until valve assembly 37, 61 has moved the swash plate to its motoring position, to prevent reverse rotation of the engine. Reference has been directed by the Comptroller to Specification 1, 005, 679.