GB627601A - Improvements in or relating to piston and cylinder assemblies - Google Patents

Abstract

627,601. Hydraulic motors. PARKER APPLIANCE CO. Nov. 14, 1946, No. 33771. Convention date, Feb. 18, 1944. [Class 69 (ii)] [Also in Groups XXVIII and XXXII] A device for cushioning relative movement between a cylinder element and a piston element during their approach to a limit of relative movement, comprises a member carried by and movable with respect to one of the elements near the limit of movement and having a bore therethrough, which is adapted to be displaced relative to a tapered member carried by that element and extending into the bore to form therewith a restricted passage reducible in size by relative movement of the members and through which liquid trapped between the two elements, must pass, the members being normally urged towards a relative position in which the passage is of maximum size. In the construction shown a sleeve 21 carried in a recess in the piston 17 has a shoulder 24 at its outer open end which forms a stop for a hexagonal-shaped member 22 which is slidably mounted in the sleeve 21 and outwardly urged by a spring 26. A tapered bore 23 in the member 22 co-operates to form an annular passage 41 with a tapered plug 40 carried by a shank 28 mounted in adjustable threaded relationship in a closure member 25 of the inner end of the sleeve 21. A washer 32 having a registering-projection engaging a keyway 35 in the shank 28, has two diametrically-spaced projections engageable under the action of a spring 33 in one pair of a circumferential series of registering notches in a boss-portion 29 of the closure 25. In operation, as the piston approaches its limit of movement (to the right of Fig. 2), a sleeve 19 projecting from the cylinder head 37, engages the slidable member 22. Liquid remaining in the cylinder can no longer pass directly into the exhaust port 12 but must pass around the periphery of the member 22 into the interior of the sleeve 21 from which it escapes to the port 12 by the passage 41. On continued outward piston movement the sleeve 19 displaces the member 22 leftwards to reduce progressively the area of the passage 41. Rotation of the shank 28 varies the initial area of the passage 41. The piston is double-headed and the pipe 12 and a similiar pipe leading from the other end of the cylinder are connected to a control valve (Fig. 1, not shown), which connects either pipe selectively to pressure or exhaust pipes respectively. The device is applicable to hydraulic steering installations, turret operation mechanisms and flight control devices on aeroplanes.