Patent GB-633494-A (GB)
Title: Improvements in or relating to centrifugally operated clutches
IPC: F16H61/02
Filed: 1947-04-22
Abstract: 633,494. Friction clutches; change-speed gear. SELF-CHANGING GEAR CO., Ltd., MILLER, A. A., and WILSON, A. G. April 22, 1947, No. 10696. [Class 80 (ii)] A friction disc-, or expanding- or contracting-shoe clutch, which may be used in a change-speed gear, is controlled jointly by centrifugal and torqueresponsive means acting in opposition to disengage the clutch with a progressive snap-action above a predetermined speed, and re-engage it below that speed, the clutch-engaging force being provided by springs which thus limit its gripping power independently of the torque and speed. In Figs. 1 and 2, compression coil-springs 17, on pins 13 secured to a driving flange 2, act through a presserplate 11, to clamp a driven disc 14, splined to a driven flange 4, against a disc 9, which has a freelyrotatable tongue-and-groove mounting 10 on the driving flange 2 and is in driving connection therewith through centrifugal masses 18, pivoted at 19 on the disc 9 and connected to the driving flange 2 by links 21 or by equivalent pins and inclined slots. Centrifugal force, opposed by drive-torque acting through the links 21, causes the masses 18 to pivot outwards and act through abutment-screws 26 on axially-arranged bell cranks 25, which they rock about fulcra 27, to bear on the presser-plate 11 at 28 and urge it away from the disc 9, thus releasing the driven clutch-disc 14 and disengaging the clutch. The torque component results in rapid disengagement without speed increase above that required to produce the initial slip, re-engagement on speed-decrease being similarly rapid. The disc-clutch 106 shown in Fig. 7 operates in identical manner with the exception that the engaging coil-springs are replaced by a pack of corrugated or crimped annular plate-springs 105. In Fig. 4, not shown, centrifugal ball masses float in grooves in opposed radially tapering members which are oppositely screw-threaded on a driving member and are splined to a pair of friction discs which are axially spring-loaded to clamp a driven friction disc between them. Speed increase, opposed by drive-torque acting through the screw-threads, causes the balls to move centrifugally outwards, screwing the members apart on their threads until they contact with and finally separate the clamping discs to release the driven clutch disc. In Fig. 5, segmental shoes 56 are expanded radially into frictional engagement with a surrounding driven drum 54 by springs 59, and are drawn inwardly through pairs of links 65, 67 by centrifugal masses 61, 62, pivoting on fulcra 63, 64 on a floating plate (not shown) and driven by a driving member 53 through tension links 71, which provide torqueresponse to oppose centrifugal force. Pins 73 on the floating plate limit movement of the masses and prevent the torque-links 71 from acting in compression. In Fig. 6, not shown, a centrifugal mass is pivoted to one end of each of a pair of segmental external shoes, and is linked to the adjacent end of the opposite shoe so as to expand the shoes out of engagement with an underlying driven drum in opposition to direct-acting tension coil-springs contracting them into engagement therewith. The masses are driven through an inclined pin-and-slot connection with the driving member so that drivetorque opposes centrifugal force. In the two-speed gear shown in Fig. 7, an overdrive, between aligned driving and driven shafts 97, 120, through an automatic disc clutch 106, as above described, and a stepped countershaft gear-pair 113, 114, is superseded above a predetermined clutchrelease speed by a direct-drive through a bridging one-way roller clutch 126. A lubricating oil-pump 123 is driven by the first-motion pinion 112. Epicyclic gearing may alternatively be used, and the Provisional Specification describes also such a gear, in which the planet-carrier is driven through the automatic clutch, the sun is connected to the driven shaft and the ring- gear is stationary. The clutch-drive is overdrive, direct being through an overrunning clutch, as above.