GB487951A - Improved automatic selecting mechanism for change speed gearing - Google Patents

Abstract

487,951. Controlling variable speed gearing ; linkwork ; valves. HALLPIKE, A. W. Jan. 1, 1937, No. 65. [Classes 80 (i) and 80 (ii)] [Also in Group XXIX] Automatic variable-speed gearing for motor vehicles &c. comprises a governor which is driven from the. driven shaft of the gear, selects mechanically the appropriate gear, and operates valve mechanism to charge a servo-motor to execute the gear change. Manual selection may override the automatic selection, the executive gear-change movement being effected by the servomotor or manually. The selector shaft 10, Fig. 2, of the gear-box 2 is operated directly through linkage 14 from a hand-control 13 on the steering-wheel and by a linkage 11, 9 from a lever 46, Fig. 4, controlled from a selector unit 5, Figs. 2, 4 and 5, the driving-shaft 29 of which is driven from the driven shaft 3 of the gear-box. The shaft 8 executing the gear-change is controllable by a pedal 104 if the power system fails but normally is operated by a servomotor 7 controlled by a valve chest 205, Figs. 2 and 7, in which the valves are operated from the unit 5. The valves also control a servomotor 25 employed for closing the throttle during changing-up. The shaft 29, Fig. 3, actuates a governor 36 which moves a sleeve 39 against a series of graded springs 42 to rotate a pinion 43 secured directly, or by lost-motion or rotation-augmenting means described later, to a shaft 44 on which is secured the lever 46 connected to one part 94, Fig. 9, of the flexible link 9, operating the selector shaft 10, the part 93 of the link forming a rigid interconnection between the shaft 10 and a lever 47, Fig. 4, secured on a sleeve 48 loosely mounted on the shaft 44, so that the lever 47 flexibly follows the movement of the lever 46 and non-flexibly that of the shaft 10. The sleeve 48 carries a gear-wheel 50, Fig. 5, and a gapped stop-wheel 49, the latter engageable by a stop-lever 60 which alternatively may engage a gap 62 in a plate 51 secured on a shaft 52 and carrying pivoted spring-pressed teeth 53, 54 engaging the wheel 50. A spring- link 57 effects a limited rotation of the plate 51 in either direction as soon as it is moved off its dead centre position by engagement of the gear teeth when the stop 60 engages the gap 62. The shaft 52 carries a plate 63, Fig. 7, connected by links 79 to levers 64.. 67, the arrangement being such that rotation of the shaft in either direction moves valves 70, 69 in opposite directions, in the operative movement connecting the servomotor 7 to engine suction to actuate the gear-changing executive shaft 8 and in the opposite movement to atmosphere. In the operative clockwise direction, for changing-up, a valve 78 also is opened and excites the servo-motor 25, to close the throttle, the valve 70 in the return movement opening a port 82 to connect the servomotor 25 to atmosphere. At the end pf the gear change, the servomotor 7 through linkage 17, 18, Fig. 2, trips a toggle device 15 to actuate a lever 16 to restore the valves to neutral position. For overriding manual gearchange, a tripper 103, Fig. 2, is operated to lower the stop 60, and the control 13 is moved to actuate directly the selector-shaft 10 and at the same time the lever 37 to initiate the executive action. Changes to first speed, neutral, and reverse are entirely manual, the pinion 43 being gapped to permit of this, and blocking means, Fig. 11 (not shown), are used for preventing operation by the governor when the car is in neutral or reverse. To provide for changing-down at lower or higher roadspeeds than when changing-up, in the first case a lost-motion driving device is provided at the point 45, Fig. 4, between the shaft 44 and the pinion 43, or in the second case, the apparatus of Figs. 4 and 13 is used. The pinion is secured to a disc 110, Fig. 4, on which are carried links 113, 114 connected to levers 111, 112 on shafts 117, 118 in an intermediate, normally free, disc 119, the shafts 117, 118 carrying also levers 120, 121 linked to a disc 122, Fig. 4, secured to the shaft 44. Spring-pressed pawls 127, 128 carried on the disc 119 co-operate with stationary ratchets 129, 130 and are adapted to be withdrawn; according to the direction of rotation, by lugs 137, 138 on the levers 112, 120. A lost-motion connection 139, 141 between the discs 110, 119 limits the advance movement of the disc 122 and the drive then becomes solid, the pawl in action overrunning its ratchet. Specifications 328,660, [Class 80 (ii)], and 370,442 are referred to.