GB980801A - Improvements in fluid pressure control systems - Google Patents

Abstract

980,801. Reverse controls. M. J. ROXBURGH, (representative of A. G. ROXBURGH). April 21, 1961 [Jan. 26, 1960], No. 2868/60. Heading F2D. [Also in Division G3] A three-position servopiston 6 suitable for operating the ahead and astern clutches of a ship is controlled from an input lever 1 which operates a drum 2, similar to the selector drum disclosed in Specification 873,619, controlling an hydraulic motor 3 by which a selector drum or valve 5, also according to the disclosure in Specification 873,619, is operated to control shuttle valves 7, 8. With the parts in the neutral positions shown a cam 16 on a slider 15 operated by the piston 6 opens a valve 13 so that motive fluid from a source 10 passing through a restricted passage 9a in a valve 9 is vented to exhaust through the valves 13, 5 causing the valve 9 to be moved upwardly so that it connects to exhaust a motive fluid supply conduit leading to the valves 5, 7, 8. Movement of the valve 5 in either direction from the neutral position terminates the venting through the valve 13 whereupon the valve 9 is depressed and pressure liquid is supplied to the valve 5 and thence to one of the valves 7, 8 which is moved against a spring loading to connect one side of the piston 6 to the pressure liquid. When the piston reaches the end of its stroke a cam 17 or 18 opens a valve 14 to vent the space above the valve 9. Interposed between the drum 2 and motor 3 is an interlock valve 25 whose purpose is to ensure that on movement of the lever 1 from, say, an ahead to an astern position, the motor 3 is brought to the neutral position and held there until the motor 6 reaches the neutral position. To this end a gate 21 moved by the motor 6 coacts with a roller 23 on the stem of the valve 25 such as to permit movement of the latter only when the motor 6 is in neutral position. Also operated by the motor 3 is an auxiliary selector 5a which controls a valve 31 governing a propeller shaft brake motor 32 and a valve 30 controlling the supply of motive fluid to an engine throttle servomotor 27 the regulator 26 of which is actuated through cam and follower mechanism 28, 29 by the lever 1. The selector 5a also controls a pressure fluid circuit to an engine speed responsive controller for a fluid scoop. Instead of a single motor 6 a separate motor for each clutch may be employed.