GB360628A - Improvements in or relating to fluid control mechanism - Google Patents

Abstract

360,628. Hydraulic apparatus; motor vehicle steering gear. VICKERS, Inc., 7752, Du Bois Avenue, Detroit, Michigan, U.S.A.-(Assignees of Vickers, H. F. ; 225, Covington Avenue, Detroit, Michigan, U.S.A.) Oct. 20, 1930, No. 31409. Convention date, Oct. 18, 1929. [Class 79 (v).] Fluid-pressure servomotor apparatus for steering vehicles and for other purposes comprises a piston and a cylinder, one of which members is fixed and the other movable, and valve means operated by a steering or other control and having a " followup action with the movable member so as to cause them to return to a relative netural position when the operating effort on the control ceases, in which independent means are provided for positively causing the valve and the movable member to assume a predetermined relative neutral position when the operating effort ceases so as to compensate for any back-lash in the connections between the control and the valve. In the construction shown applied to vehicle steering-gear the piston a is fixed, being connected by a rod b to the vehicle frame, and .the. cylinder d is movable and connected by the drag-link 3 to the road wheels. Liquid is admitted to the ends of the cylinder by passages 1, 2, respectively, and is controlled by a valve f connected by a rod y and a strong spring z to a sleeve operated by a ball t on a rocker arm s actuated by. the steering handwheel o through the usual gearing r. The sleeve is formed with an annular groove w adapted to be engaged by two spring-pressed detents x carried by an extension of the cylinder so that these detents tend to hold the valve and cylinder in a predetermined neutral position shown in Fig. 2. In this position pressure fluid is supplied by a pump (not shown) through a pipe e to the space surrounding the central part of the valve, and, since the ports h are wider than the rings g of the valve, passes continuously to the passages 1, 2 communicating with the cylinder ends, finally exhausting from the space j<1> at the left-hand of the valve through a pipe j back to the pump. Thus, when the valve is in the neutral position, fluid pressure is maintained equally on both sides of the piston. When the rocker arm s is moved to the right (say), as shown in Fig. 6, the sleeve w<1> is moved to the right and moves the valve with it, the detents x being raised during this movement. The passage 1 is cut off from the pressure side of the valve but is opened more fully to exhaust, while the passage 2 is cut off from the exhaust and opened more fully to the pressure side of the valve; so that full pressure is maintained only on the right-hand side of the piston and the cylinder is consequently moved to the right. When the valve movement stops the cylinder catches up, and, as soon as the relative neutral position is reached the detents engage in the groove wand prevent any further accidental movement due to play in the various connections. If the supply of pressure fluid fails the gear can be operated by hand as the valve can move only a slight distance in the cylinder extension; during hand working a non-return ball valve n permits fluid to circulate by passing from the exhaust side of the valve to the pressure side through a passage m.