Patent GB-396376-A (GB)
Title: Improvements in or relating to centrifugal clutches and like mechanism
IPC: F16D43/08
Filed: 1931-12-28
Abstract: 396,376. Disc brakes applied by speed-responsive devices. RICKWOOD, H. J. and TROJAN, Ltd., Vicarage Road, Croydon. Dec. 28, 1931, Nos. 35838/31 and 25582/32. [Class 103 (i).] In a centrifugal clutch or brake, outward movement of weights 65, Figs. 1 and 2, pivoted in the driving member 57, is resisted by primary springs 73 interconnecting the weights and an auxiliary spring control comprises a cam ring 77 which is journalled on a bracket 79 secured coaxially to the member 57, is connected to the weights by links 78, and is engaged by a roller 75 carried by a leaf spring 74 secured to the member 57. During outward movement of the weights under centrifugal action, the ring 77 moves angularly relative to the member 57, whereby the roller rides up the ramp 80 and the spring 74 thus acts to impose an additional resistance to the movement until the roller passes over the dead point 82, corresponding to initial engagement of the clutch parts, and the spring 74 then acts to assist the movement. The pivotal hubs 66 of the weights are threaded to engage screwed pins 67 on the member 57, whereby outward movement of the weights produces an inward axial movement of the hubs, causing a friction disc 58 splined on the driven shaft 68 to be gripped between discs 55, 56 which rotate with the member 57 but are moved axially, the disc 55 being loaded by springs 69 ; alternatively, the angular movement of the ring 77 may be utilized to effect movement of the clutch discs. The clutch may be disengaged manually by operation of a collar 86 acting on the disc 55 through bellcrank levers 83. In the form shown in Fig. 3, each pivoted weight 87 has a tooth 96 engaging a recess 96<1> in the cam ring 95, the primary control comprising a plunger 90 engaging a lug 89 on the weight and the auxiliary control comprising a plunger 92 engaging a pivoted member 99 carrying a roller 102 engaging the cam, the two plungers being slidable in a cylinder 91 secured to the driving member 57 and being loaded by a common spring 93. After the roller passes the dead point of the cam, a certain amount of lost motion between the tooth 96 and the recess 96<1> has to be taken up before the auxiliary control can act to assist the outward movement of the weights. In a modification of this form, the member 99 is weighted and has an arm 116, Fig. 4, adapted to co-operate with a part 117 of the cam. When the weight 87 is at the limit of its possible outward travel, the roller 102 has not quite reached the dead point of the cam, but on a further increase of speed the member 99 moves outward under centrifugal action, carrying the roller clear of the cam and bringing the arm 116 into contact with the surface 117 so as to impart a further angular shift to the cam sufficient to take up the lost motion between the tooth 96 and the recess 96<1>. When the speed diminishes the member 99 moves back towards the cam and the roller comes into contact with the portion of the cam beyond the dead point so as to resist inward movement of the weight 87 until the dead point is passed. According to the second Provisional Specification the clutch may be of the expanding-band type. Specification 389,866 is referred to.