Patent GB-849426-A (GB)
Title: Improvements in or relating to automatic change-speed control means
IPC: F16H63/02
Filed: 1958-05-29
Abstract: 849,426. Change-speed control. BAUER, J. May 29, 1958 [May 29, 1957], No. 17119/58. Class 80 (2). A motor car having the conventional arrangement of an engine driving through a main clutch to a stepped ratio change-speed and reverse gear has the selection of the gear ratios effected automatically by an engine-driven centrifugal governor controlling a simple auxiliary forward-reverse mechanical servo gear, which disengages the main clutch and alters the engine throttle setting through the actuation of a cam and simultaneously selects and establishes a new ratio through a further two cams. As shown, a centrifugal governor 11 driven from the car engine through a friction-wheel 8 and a pulley belt 9, is effective with increasing speed to slide a shaft 3 rotating therewith axially rightwards against the bias of a spring 14 and engage a clutch disc 16 frictionally with a driven disc 17, decreasing engine speed sliding the shaft 3 leftwards to engage it instead with a disc 18 which drives through friction idler wheels 21 to rotate the disc 17 in the opposite direction. The discs 17, 18, &c. are journalled in an axiallyslidable casing 25, and the disc 17 is integral with a worm 27, journalled at its end in an axiallyslidable bearing 28, and meshing a worm-wheel 30 fast with a worm 32 meshing worm-wheels 33, 34 secured to two parallel shafts 35, 36. The shaft 36 carries a cam 41 which acts through a follower to disengage the motor car main clutch and adjust the engine throttle during a ratio shift, and also carries a cam 40 which establishes ratios in the change-speed gear. The shaft 35 carries a cam 37 which effects cross-shifts in the change-speed gear. When the clutch disc 16 is initially engaged with one or other of the driven discs 17, 18, as described above, the worm 27 is turned, but, due to the inertia of the worm and worm-wheels 30, 32, 33, 34, screws itself axially along and takes with it the slidable housing 25. A stop disc 38 fast upon the shaft 35 lies between two abutments 52, 53 carried by the housing 25. As soon as one or other of the abutments 52, 53 contacts the stop-disc 38, axial movement of the housing 25 is arrested, and accordingly the worm 27 then starts to rotate the worm-wheel 30, the shafts 35, 36 geared thereto and the cams 40, 41, 37. A locking-disc 39 is journalled upon the shaft 35 and is connected for rotation therewith by a radial lug 62 fast on the shaft engaging between two springs 64, 65 carried between lugs projecting axially from the disc. Four slots 59, 60, 61, 59<SP>1</SP> around the periphery of the locking-disc 39 correspond in position to the four ratios of the change-speed gear, and are cut obliquely to co-operate with a correspondinglyobliquely cut pin 57 rigid with the axiallyslidable housing 25. When the cam-shafts 35, 36 start to rotate, as described above, to establish a new ratio, the locking-disc 39 is initially retained in the position corresponding to the already established ratio by its engagement with the pin 57, the rotation of the shaft 35 merely serving to stress one or other of the springs 64, 65. Eventually the spring 64 or 65 is sufficiently stressed for the inclined slot 59 &c. of the locking disc 39 to cam the pin 57 out of engagement and slide axially the whole housing 25. Accordingly, the clutch disc 16 is maintained in engagement with one or other of the discs 17, 18 until the new ratio has been established, irrespective of the action of the centrifugal governor 11. When the new ratio has been fully established, the next adjacent slot 60 &c. in the locKing disc 39 lies adjacent to the pin 57, which accordingly slides back to the position shown. Kick-down of the motor car accelerator pedal acts upon a locking fork 82 which engages the pin 83 and thereby prevents axial movement of the slidable housing 25, with establishment of a new ratio, until the accelerator pedal is released. The stop-disc 38 is provided with a single hole 54 and the two abutments 52, 53 are angularly spaced to co-operate therewith in such a way that should the device try to initiate establishment of a ratio below the first ratio, or above the fourth ratio, the conesponding abutment enters the hole 54 so that no reaction is produced for the worm 27 to start rotation of the cam-shafts 35, 36, &c. Establishment of the first ratio and of reverse are effected manually by the motor-car driver.