Patent GB-755435-A (GB)
Title: Improved fluid pressure power transmission mechanism
Inventor: LIGHT JAMES WILBUR
IPC: F15B15/14
Filed: 1954-02-12
Abstract: 755,435. Hydraulic machines. GENERAL MOTORS CORPORATION. Feb. 12, 1954, No. 4146/54. Class 69 (2). The power operation of e.g. the wing tips, stabilizers or rudder of an aircraft is effected by a hydraulic motor or, alternatively, by an electric motor on failure of the hydraulic motor. The hydraulic motor comprises a power piston 22, Fig. 1, working in a cylinder 21 secured in a housing 20 mounted on the aircraft. The piston is reciprocable on a threaded shaft 30 through balls 32 located in helical grooves formed in the piston and the shaft. The shaft extends into a tube 24 carried by the piston and secured to a member 26 connected to the part to be operated, and is formed with a head 35 supported by a ballbearing and carrying a cup-shaped member 38 formed with teeth 39 engageable by similar teeth on a ring 40 having radial prongs 73 engaging axial slots 72 in an extension of a wormwheel 70 operable, when desired, through worm and spur gearing from & shaft 88 driven by a reversible electric motor 89 supported by the housing. The teeth on the member 38 and the ring 40 are urged apart by springs 45 and into engagement by stronger springs 50 acting through a piston 51 having rods 52 passing through guide holes in a sleeve 56 and pressing against a thrust bearing 54 abutting the ring 40. The springs 50 may, however, be opposed by pressure liquid admitted to an annular space between the piston and the sleeve. When the teeth are engaged, the screw 30 is locked against rotation, except by the electric motor, and reciprocation of the piston by pressure liquid prevented. Reciprocation of the piston is effected by the electric motor by rotation of the screw through the wormwheel 70 and the ring 40. Reciprocation by the hydraulic motor is effected by admitting pressure liquid to the space between the piston 51 and the sleeve 56 to separate the teeth on the member 38 and the ring 40, and the application of pressure liquid to either side of the power piston 22. The supply of pressure liquid to the hydraulic motor is controlled by hand-operated valve mechanism contained in a housing 90 secured to the housing 20 and having a port 55 communicating with the space between the piston 51 and the ring 40 and ports 60, 61 communicating with the opposite sides of the power piston 22. The valve mechanism housing comprises parts 91, 92, Fig. 11, bolted together, the part 91 having a liner 120 with bores 121, 122, 123, the bore 121 containing a spring-loaded piston 125, and the bore 123 a piston valve having lands 130, 131, 132 and pressed against a partition 124 by a spring 180 in the bore 122. The part 91 also includes a spring-loaded piston valve having lands 166, 167, and has pressure liquid supply ports 135, 136, 137 connected to the ports 61, 55, 60 respectively. The port 92 has an extension 150 forming a liner for a shuttle valve having lands 151, 152, and ports 98, 99 to either of which pressure liquid may be supplied and a drain port 105 connected to a tank. In operation, pressure liquid is supplied through a handactuated control valve to either of the ports 98, 99 to retract or extend respectively the operating member 26 of the hydraulic motor, and at the same time to the space between the sleeve 56 and the piston 51 to disengage the member 38 from the ring 40 to unlock the screw shaft 30 and permit free rotation thereof upon reciprocation of the power piston 22 by liquid pressure. Failure of hydraulic pressure permits engagement of the member 38 with the ring 40 and rotation of the shaft 30 and reciprocation of the piston 22 by the electric motor. Fig. 13 is an amplified diagram of a hydraulic motor and control means according to the invention including a piston B carrying a load L and having a screw-threaded shaft C to which is secured a notched disc D engageable by a detent E carried by a spring-loaded piston in a cylinder F connected via pipes 136, 160 and an intermediate piston valve (not shown) with a cylinder M having a shuttle valve K and liquid supply and exhaust pipes 153, 154. The ends of the motor cylinder A communicates through liquid supply and exhaust pipes 97, 100 with a manually-operable piston valve H, the centre supply port of which is connected to a pump P drawing from a supply tank S, while the end exhaust ports are connected directly to the tank. Specification 732,465 is referred to.