Patent GB-387022-A (GB)
Title: Improvements in and relating to semi-automatic roller clutch transmission
IPC: F16D41/08
Filed: 1931-08-19
Abstract: 387,022. Clutches ; variable-speed gearing. BLACKSTOCK, G., 52, Warren Road, Toronto, Canada. Aug. 19, 1931, No. 23404. [Class 80 (ii).] In a semi-automatic roller clutch such as those described in Specifications 349,492, 353,010, 377,733, 384,710, and 386,024, of the kind wherein the clutching rollers are brought into and out of driving condition by the motion of a torque-transmitting floating member 19 interposed between the rollers and a main clutch element 28 and shiftable along a limited path relative to the said clutch element between driving and release (or reverse driving) positions, the floating member having means to lock it in the driving position which means can be unlocked to allow the floating member to be carried, partly without transmission of load, to the release position, the locking device is provided with means operable at will, either manually, electrically, or by a governor, to release the floating member. The semiautomatic clutch comprises a driving drum 11 having a hardened lining and the floating member 19 carries wedge faces 21, 23 between which and the driving drum are driving rollers 20 and " catch" rollers 22. The driven shaft 2 fixedly carries a plate 28 with which the floating member 19 has a limited lost motion between a driving position, Fig. 3, and an idle position, Fig. 6. The floating member is locked in the driving position by a manually shiftable collar 40, slidable axially on pins 42 fixed to the driven plate 28 and carrying pairs of friction-reducing wheels 36, 37 which in the driving postion lie in a recess formed by lugs 32, 30 carried by the driven plate 28 and floating member 19 respectively and prevent their relative movement. When the collar 30 is moved to the right by a fork 88, the wheels 36, 37 leave the recess and allow the floating member to be carried round by the driving member until the wheel 37 drops into a detent pocket on the lug 30. Simultaneously the relative movement causes the drive rollers 20 to be struck from their wedges 21 whilst under no load, by strikers 49 carried by a flange 47 bolted to the driven plate 28. The clutch remains in this idle position, Fig. 6, until the speed of the driver is retarded to below that of the driven member, when the " catch " rollers 22, which have been free-wheeling in the idle position, grip and turn the floating member 19 to the driving position, permitting the collar to be shot back to its locking position by a spring 94. Simultaneously the strikers 49 strike off the " catch " rollers and allow the driving rollers to engage. The clutch freewheels in the driving position until the driver is accelerated to take up drive. In place of the friction-reducing wheels 36, 37, interengaging tongues 108 .. 111, Fig. 10, may be provided on the floating member 19 and collar 40. In this form, the collar 40 must be momentarily moved to the right to allow the clutch not only to disengage but also to engage, and when locked in the release position the engine can transmit braking torque through the " catch " rollers. The opposing faces of the tongues 108, 111 may be bevelled to give automatic re-engagement. In the motor-vehicle 3-speed and reverse gear shown in Fig. 7, the semiautomatic clutch is used for direct drive and the second speed is through a sliding pinion 76 connected to the driven shaft 2 by a free-wheel clutch 77 of normal construction. Low speed and reverse are of usual form and an additional normal second speed pinion 82, or a train of one-to-one ratio is provided for using the engine as a brake. A slider rail 89 for operating the fork 88 of the semi-automatic clutch is provided with a pivoted latch 91 which holds the clutch in the disengaged position whilst the ordinary gears are engaged, the latch being released only when the free-wheel gear 76 is meshed, the rail for moving this gear having a cam engageable with a pin on the latch to tilt it from the obstructing position permitting the spring 94. to move the collar 40 to the driving position. The rail 89 projects from the end of the gear box and is pushed in, to disengage the semi-automatic clutch, by depression of a pedal 101, Fig. 8, connected also through a spring 106 stronger than spring 94, to the main clutch pedal 102 so that the semiautomatic clutch is released when the freewheel gear 76 is meshed and also so that the semi-automatic clutch cannot be overloaded by too sudden engagement of the main clutch, since it will be released if the engine runs too fast. For a change up, the free-wheel second speed gear 76 being meshed, the throttle is closed and the semi-automatic clutch assumes the driving condition where it free-wheels until the throttle is re-opened to take up drive, the second speed then free-wheeling. To change down, the throttle is opened and the pedal 101 or the main clutch pedal is momentarily depressed, freeing the semi-automatic clutch, which assumes the idle position and allows drive through the free-wheel second speed. By providing a semi-automatic clutch on an intermediate speed, automatic gear change may be obtained amongst three ratios instead of two as shown.