Patent GB-540098-A (GB)
Title: Improvements in gear shifting mechanism
Filed: 1940-04-01
Abstract: 540,098. Variable-speed gearing. BENDIXWESTINGHOUSE AUTOMOTIVE AIR BRAKE CO. April 1, 1940, No. 5827. Convention date April 20, 1939. Addition to 471,999. [Class 80 (ii)] In the control mechanism of the parent Specification, in which a member oscillatable to select, and shiftable to establish, a desired gear relation, is actuated by two fluid motors, the shifting-motor is controlled from the selecting- motor through a pair of valve-units, in order to prevent operation of the shifting-motor until the selecting-motor acts. The selecting and shifting finger 22. Fig. 1, is operated by a selecting-motor 23 and a shifting-motor 26, the pistons of which are controlled by double-acting springs, so as to be returned to central or neutral positon, when the fluid pressure is cut off. The gear changes are effected by three sliding bars 15, 16, 17 carrying shift forks. The central bar 16 is moved to left or right to establish second or third gear, and the outer bars 15, 17 are moved to establish first gear and reverse respectively. The finger 22 is oscillated by the motor 23 to select one of the bars, and is given a sliding movement by the motor 26 to operate the selected rod. The admission of fluid to the motors is controlled by valve-mechanism contained in a housing 72 on the steering-column 10 of the vehicle and operated by a hand-lever 106, which is guided in an H-shaped slot, so as to move in a similar manner to the shifter-finger 22. Fluid is supplied from a reservoir 13 to the housing 72 and is conducted therefrom to the selecting- motor 23 and to two valve-units 46, 47 which control its admission to the two sides of the piston of the shifting-motor 26. Each valveunit contains a sliding spring-pressed valve 52. Fig. 6, having two spherical heads 53, 54 and serving to admit fluid to a pipe 28 leading to the shifting-motor, the fluid being supplied from the housing 72 through one or other of two pipes 68, 70 according to the position of the valve. The valve is shifted by a sliding member 59 operated by cams on the piston-rod 33 of the selecting motor 23. Fluid is supplied to the valveunit through one or the other of the pipes 68, 70 in accordance with the setting of the valvemechanism in the housing 72, and, if the new setting requires operation of the selecting- motor, the movement of its piston-rod 33 shifts the valve 52 into position to admit fluid to the pipe 28 leading to the shifting-motor. The other valve-unit 47 controls the admission of fluid through a pipe 27 to the other side of the piston of the shifting-motor in a similar way. The housing 72 on the steering-column contains four valves of similar form to those of the valve units 46, 47 the valves being adjusted by a sliding and rotatable cam-bar operated by the hand-lever 106. Means are provided for locking the selecting-piston against movement unless the particular shifting bar 15, 16, 17, with which the finger 22 is engaged, is in the mid or neutral position. To diminish noise caused by the shifting-motor, the casing enclosing it contains lubricant. Noise is further reduced by pairs of dished washers mounted on the piston rod, which are compressed against the casing at the ends of the stroke, so that the lubricant, between them is squeezed out.