Patent GB-638330-A (GB)
Title: Improvements relating to variable speed gearing
Inventor: SANDELL KENNETH CHARLES
IPC: F16H61/02
Filed: 1947-12-24
Abstract: 638,330. Change-speed gearing ; friction clutches. FREEBORN POWER CONVERTERS, Ltd. Dec. 24, 1947, No. 34228. [Class 80 (ii)] In epicyclic change-speed gearing for motor vehicles of the same general type as disclosed in Specifications 439,828 and 439,855, i.e. having a series arrangement A, B, C, Fig. 1, of epicyclic trains having reaction members held by one-way detents for reduced speeds and locked to another epicyclic member by torquespeed responsive clutches for solid drive, the characteristics of the various clutches are so selected that all the possible train combinations may be automatically brought into action. As shown, the trains are powered through a centrifugal main clutch 17. 29 of the kind set out in Specification 426,407, but having five sets of eccentric discs 30, Fig. 4, supported by ball bearings 32. The individual trains are generally similar and are of the kind described in Specification 584,735 having, in the case of the train C, centrifugal weights 150 pivoted on a flanged extension 149 secured to a member 144 also supporting the driven planet carrier 135. The weights 150, Fig. 3, are shaped to nest round the adjacent shaft members when retracted, and bear through noses 151 on axial extensions 152 of a final driven member 153. The direction of rotation is such that torque passing through the weights tend to retract them against the action of centrifugal force thereon. The members 149, 153 have pin and slot connections 156, 157 to limit their relative rotation. The extensions 152 are secured to a clutch presser plate 145 having a helical spline connection 146 with the member 144 so that relative rotation between the members 149. 153 due to centrifugal action causes axial motion of the presser plate 145 to engage a multiplate clutch 140 between the carrier 135 and the reaction annulus 132. The gearing operates as follows. Starting from rest, all three trains A, B, C are engaged giving first speed. As the vehicle speed increases, train A, which has the lightest centrifugal weights, is locked giving second speed with the trains B, C engaged. Further speed increase locks the train B, but, owing to the relative gear ratios of the trains, the resulting ratio is too high for the engine whose speed falls until the train A re-engages giving third speed with the trains A, C engaged. As the speed increases still more, the train A is again locked, giving fourth speed with the train C only engaged. Still greater speed locks the train C, which has the heaviest centrifugal weights, but, as before, the resulting ratio is too high for the engine whose speed falls until both the gears A, B re-engage giving fifth speed. Sixth speed is brought in by the gear A locking in the normal way leaving gear B only engaged, but later locking of train B again engages train A as before which is alone operative for seventh speed. Eighth speed is direct drive when train A finally locks. On changing down the above changes occur in reverse order. According to the Provisional Specification, the one-way detents holding the reaction members may be of the kind described in Specification 622,595. As shown, they comprise pawls 99, Fig. 2, pivoted on the reaction members of the trains and spring-loaded to engage ratchet teeth 100 on the fixed gear casing. At a speed corresponding to the engagement of the direct drive clutch across the train the weighted ends 101 of the pawls swing outward to obviate ratchetting. In Fig. 5 (not shown) the train A is omitted to give a four speed gearing.