GB622932A - Improvements in or relating to variable-speed power transmissions - Google Patents

Abstract

622,932. Variable-speed epicyclic gearing; frictional and ratchet clutches. BORG-WARNER CORPORATION. April 10, 1946, No. 10979. Convention date, Oct. 21, 1944. [Class 80 (ii)] A helical gear forming one element of an epicyclic gearing meshes a helical gear axially slidable under torque reaction to engage positive braking means and act as a gearing reaction member. Blocking means may be provided allowing engagement of the slidable gear with the braking means only in one direction of rotation of the gear. As shown, a sun gear 138 and an annulus 140, powered from the input shaft 10 through friction clutches 16, 20 respectively either alternatively or simultaneously, are connected to a driven planet carrier 150 on the output shaft 12 by interengaging planets 142, 144 the latter of which carries on an axial extension a second and helical-toothed planet 146 meshing an axially slidable reaction gear 24 freely journalled on the shaft 12. Torque reaction on the gear 24 slides it either rearwardly to engage fixed teeth 156 on the gear casing and act as a stationary reaction member or forwardly to bring a ratchet-toothed clutch member 34 fixedly splined on the gear into engagement with coacting ratchet teeth on the carrier 150. Manual control means (not shown) act on the member 34 to over-ride the torque reaction-when required, but an oscillatory balk ring 160 on the gear 24 is spring-pressed to frictionally engage the gear casing and prevent the gear engaging the teeth 156 when the torque reaction is such as to urge the gear forwardly. The movement of the gear 24 under torque reaction is facilitated by the frictional drag of the balk ring 160. The gear 24 may be locked in engagement with the teeth 156 by radial struts 164 movable to co-act with a groove 166 upon rotation of a cam ring 168. Friction clutches. The clutches 16, 20 are mounted together between a common driving flywheel 40 and cover plate 42 and have driven members 100, 130 connected through inner and outer shafts 18, 22 to the sun gear 138 and annulus 140 respectively, the member 100 being coupled to its shaft by circumferentially arranged springs 102. The clutch 16 is conditioned for operation hydraulically by admitting pressure fluid via a conduit 58 to the rear of a piston 44 so that plate members 60, 66 mounted on a cylindrical extension 116 of the piston are moved with it to the left against the pressure of springs 80, until lugs 62 on the member 60 which move in axial slots in the flywheel rim engage the bottoms of these slots. When thus conditioned for operation, the clutch may be engaged centrifugally by weights 86 acting between the members 60, 66 and urging the latter to the left, against the pressure of the springs 80 and of a Belleville washer 96, to bring a presser plate 74 rigid with the member 66 into engagement with the member 100. The clutch 20 is engaged hydraulically by admitting pressure fluid via a conduit 118 to the rear of a combined piston and presser plate 120, which has sufficient range of movement to the left against the pressure of springs 126, 128 to engage the member 130 against the rear of the member 74 whether the clutch 16 is engaged or disengaged. The pistons 44, 120 are spaced apart by perforated lugs 114 on the latter. Operation. The clutches 16, 20, when engaged alone, give low and intermediate forward speeds respectively, the torque reaction on the gear 24 being such as to move it rearwardly to act as a stationary reaction member. If it is desired to prevent the transmission free-wheeling in these speeds, the gear 24 is locked to the teeth 156 by the struts 164. With both clutches 16, 20 engaged together the gearing is locked solid for a high speed direct drive, the torque reaction on the gear 24 being reversed so that the gear moves forwardly and rotates freely. For reverse drive, the annulus 140 is stationed by a positive detent 154 and the clutch 16 is engaged, the gear 24 being held by the manual control means from moving into engagement with the teeth 156 as urged by the torque reaction. To rotate the input shaft 10 from the output shaft 12, the clutch 20 is engaged, when the torque reaction on the gear 24 moves the latter forwardly and locks the member 34 to the carrier 150 to transmit drive.