GB569924A - Improvements in control apparatus for hydraulically operated elements - Google Patents

Abstract

569,924. Fluid-pressure servomotor-control systems. GEIGER, G. M. July 7, 1943, No. 11034. Convention date, March 26. [Class 135] [Also in Group XXXIII] Means for controlling the movement of a device, e.g. the tiller of a steering unit, includes a reciprocable cylinder 56 adapted to be operative selectively hydraulically or mechanically and locked automatically hydraulically against inadvertent movement whether actuated hydraulically or mechanically. The cylinder 56 connected to rudders 67, 68 is movable on a fixed piston and carries a valve box 34 in which a distributing valve 43 is movable by a cable 49 from the steering wheel. Pumps 10, 11, operable through one-way clutches from propeller shafts 18, 19, whereby they are inactive during astern movement of the ship, supply pressure liquid through check valves 16, 17 to the valve box. A further check valve 38 is arranged in a connection between the inlet and exhaust ports of the valve. Movement of the steering wheel operates the valve 34 to supply pressure liquid to either end of the cylinder 56, thereby moving the rudders. The valve box moving with the cylinder reestablishes the valve in its central position and locks the cylinder against further movement. In the event of failure of pressure supply, or when moving astern, an abutment 48 or 54 on the end of the valve engages the valve box after movement of the valve by the steering wheel and the cylinder is moved mechanically in the required direction. The valve can then be re-centred to lock the device, but if this is not done, inadvertent movement in one direction is prevented by the check-valve 38, and a slight movement in the opposite direction recentres the valve and effects the hydraulic lock.