Patent GB-465463-A (GB)
Title: Control mechanism for power operated devices
IPC: B62D5/24
Filed: 1935-11-01
Abstract: 465,463. Fluid-pressure servomotors. MANLY CORPORATION. Nov. 1, 1935, No. 30218. Convention date, Dec. 5, 1934. [Class 135] Means for controlling power-operated devices include a manually rotatable shaft, a driving gear member rotatable with and having limited rotational movement with respect to the shaft, a driven gear member coacting with the driving member, power-operated means for actuating the driven gear member and control mechanism for the power operated means comprising an actuating member rotatable with the shaft and axially movable thereon and having a screwthreaded connection with the driving member to impart axial movement to the actuating member when the shaft rotates with respect to the driving gear member. As applied to steering gear of a motor vehicle, the steering shaft 10 is enclosed by a hollow post 11 secured to a hub 12 of a cover 13 of the casing 14 the lower cover 16 of which supports the steering shaft at 18. The worm 20 has hubs 21, 22 in bearings 23, 24 the inner races of which prevent axial movement of the worm which is keyed to shaft 10 by a key 27 which is narrower than the worm key-way 28 so as to allow of limited relative rotation of shaft and worm. The worm meshes with a sector 32 keyed to a shaft 33 connected to the vehicle wheels. The power apparatus, which includes a follow-up device, consists of a cylinder 40, a double-acting piston 44 in which is connected to the sector 32. The movements of piston 44 are controlled by a valve 60 slidably fitted in a bore 50 in the bottom cover 16 of the casing 14, and adapted to be actuated, through a lever 79, by a member 70 against the pressure of a spring 82. The bore 50 has a pressure-fluid inlet port 51, outlet ports 55, 56 to pipes 57, 58 leading to opposite ends of cylinder 40, and an exhaust port 53 leading to pipe 54. The control valve has three heads 62 .. 64 separated by reduced portions 65, 66. The heads 63, 64 cover the ports 55, 56 in the neutral position. An axial passage 67 extends through the valve from the end adjacent the exhaust port to a cross passage 68 near the other end. When the valve is moved toward the exhaust port, pressure fluid is admitted to pipe 58, the pipe 57 being open to exhaust and vice versa. The valve is moved in accordance with relative movement of shaft 10 and worm 20. For this purpose, the member 70, Figs. 1, 3, is keyed at 71 to shaft 10 but is slidable thereon and it is also connected to hub 22 of worm 20 by helical slots 76 and helical thread segments 75 as shown in Fig. 3. The outer surface of member 70 has a groove 77 with which engages a pin on lever 79 which presses against the valve. Initial movement of shaft 10 causes member 70 to move axially and the valve is likewse moved to cause movement of piston 44 and sector 32. This movement of the sector causes worm 20 to rotate and when this rotation exceeds that of shaft 10 the parts 75, 76 move the member 70 to return the valve to neutral position. The apparatus gives and maintains a definite. position of piston 44 for every position of the steering control members. If the power fails, the gear can be actuated manually.