Patent GB-704907-A (GB)
Title: Hydraulic steering gear
IPC: B63H25/28
Filed: 1951-08-17
Abstract: 704,907. Hydraulic machines. ETABLISSEMENTS P. DUCLOS. Aug. 17, 1951 [June 28, 1951], No. 19484/51. Class 69 (2). [Also in Group XXXIII] In a hydraulic distribution arrangement having various combinations of operation in a hydraulic installation comprising four presses for steering a ship, wherein the four presses form part of two groups each formed of two oppositely acting presses associated with automatic bye-pass means and with a slide valve for reversing the control circuits of the bye-pass means, the connection of the two groups to a common reversible pumping group is effected by two similar distributers, each distributer being capable of occupying at least two positions, namely a common position for operation with four presses and a second position for operation with two presses associated with the other group in which the distributer of this other group remains in the first position and the distributer in the second position interrupts all communication and the bye-pass moves into the short circuit position. A rudder helm 10 is connected to two pairs of oppositely acting presses 11, 12 and each pair is controlled by a distributing valve 17 and includes a byepass valve 13 associated with a reversing slide valve of a control device 14. On one side the distributing valve 17 is connected by a separate pipe 19 to the press 11; by a separate pipe 16 to one side of a byepass control piston through the reversing slide valve and to one bye-pass port ; by a branched pipe 15 to the press 12, the other side of the bye-pass control piston through the reversing slide valve and to the other bye-pass port. The byepass ports are controlled by a slide valve connected to the control piston which is biased by a spring to normally close the byepass connection. The other side of the distributer 17 is connected by pipes 20, 21 to the suction and delivery sides of a common pumping group comprising separate pumps 25 reversible by means of the control device 14; a further pipe 22 interconnects the distributers 17. The pipes 20, 21, 22 are fitted with stop valves 33, 34, 35, 36 which can be closed to isolate the group. The distributers 17 each comprise a slide 18 movable into three positions I, II, III. Assuming pipe 20 to be the pressure pipe, in position I pipe 20 is connected by a groove 26 in slide 18 to the press 12 and the underside of the byepass control piston. Press 11 exhausts through pipe 19 to pipe 21 through grooves 29, 31 in the slide 18 the latter groove being also connected to the pipe 16 through groove 30 in the distributer 17. The upper side of the bye-pass control piston is therefore subjected to exhaust pressure only and the bye-pass remains closed. Both groups actuate the helm. Failure of pressure on the underside of the bye-pass piston, however, causes the bye-pass to open and the presses 11, 12 on that side are short circuited and the helm is actuated by the other group. The pipe 22 is connected by a passage 32 in the slide 18 to the pipe 21 and.acts as a balance pipe between the distributers. With a distributer 17 in position II that group is isolated and the byepass connects the presses 11, 12 while the helm is actuated by the other group. With one distributer in position III and the valve 33 of the other group closed, pressure is supplied to the press 12 of that other group by the pipe 20 which is blocked by the distributer in position III while the pipe 21 is connected by the grooves 29, 31 with the pipe 19 and press 11 which exhausts therethrough. The press 11 of the other group exhausts through the pipe 22 only, since the valve 33 is closed, through a groove 28 in the distributer in position III, a passage 27 in the slide 18 and grooves 26, 30 to the pipe 16, which exhaust pressure causes the bye-pass to open and connect the exhaust from pipe 16 to the press 12. The helm is thus actuated by one press of one group and one press of the other. The distributers may have only two positions with a consequent limited number of combinations. Specification 414,615, [Group XXXIII], is referred to.