GB913806A - Improvements in or relating to power transmission systems providing automatic changes of gear ratio - Google Patents

Abstract

913,806. Change-speed gear; friction clutches. AUTOMOTIVE PRODUCTS CO. Ltd. June 26, 1961 [June 27, 1960], No. 22451/60. Class 80 (2). In a change-speed gear for a motor car, in which the engine drives through an hydrodynamic torque converter (not shown) to a pinion 11, Fig. 1, fast with a shaft 10, a bevel gear 18 fast with the latter engages the larger bevel pinions 23 of bevel planet pinion clustters 22 mounted in a carrier 29, smaller bevel pinions 24 of the planet clusters meshing coaxial sun gears 25, 26 fast with a shaft 12 and a sleeve 27, respectively, application of a band brake 31 stationing the carrier of the planet clusters so that the sun gears 25, 26 rotate in opposite directions, whereby on engagement of one or other of two hydraulically-actuated friction cone clutches 36, 37, drive is transmitted either from the sleeve 27 to an output shaft 13, or, in the opposite direction, from the shaft 12 to the output shaft 13. In the form as shown, the two friction cone clutches 36, 37 comprise pistons 50, 51 moved against the bias of disengaging springs 56 when liquid under pressure is admitted to spaces 38, to clamp frusto-conical members 46 splined to the output shaft 13 between the pistons and housing members 39, 44 fast with the sleeve 27 and the shaft 12, respectively. In a modified form, an intermediate shaft 81, Fig. 2, corresponding to the shaft 12 of Fig. 1, and sleeve 82 corresponding to the sleeve 27, carry frusto-conical driving clutch members 105, 101, respectively, a frustoconical extension 86 of a driven clutch ring fast with an output clutch member 84 and a driven shaft 83 lying between the two driving clutch members. A first piston 91 is moved leftwards against the bias of a disengaging spring 108 when liquid under pressure is admitted through a shaft duct 115, 113 to engage the driving clutch member 101. A second piston 98 is moved rightwards against the bias of a disengaging spring 109 when liquid under pressure is admitted through shaft ducts 117, 114, to slide a surrounding housing 95 rightwards into engagement with the driving clutch member 105. In the form shown, the gearing gives both forward and reverse drive, and automatic shifts between its forward ratios. To establish forward drive, a manually-operated valve 62, Fig. 1, is set to connect a source of liquid pressure 64 through a pipe 65 to the clutch 37, which is thereby engaged. Drive is then transmitted through the train 18, 22, 24, 25 to the shaft 12, the clutch 37 and the output shaft 13, and a reduced ratio is obtained. With increasing speed of the car, an output driven centrifugal governor 76 acting in opposition to accelerator pedal depression shifts a valve 75 to connect the source of fluid pressure 64 through a pipe 68 to a pipe 66, and thence to the clutch 36, which is also engaged. The gearing is accordingly locked-up, and directdrive is obtained. An intermediate ratio may be obtained by engaging a brake band 35 on a drum 34 connected through a one-way detent 33 to the sleeve 27, while the clutch 36 is disengaged and the clutch 37 is engaged, whereby the sun gear 26 is stationed but the carrier 21 of the planet pinions 22 rotates forwardly, as permitted by the one-way detent 28, thus turning the bevel sun gear 25 faster than when the carrier is stationed. Reverse is obtained by setting the manual valve 62 to connect the source of liquid pressure 64 directly to the pipe 66 and thence to the clutch 36, simultaneously applying a brake band 31 to the carrier 21 of the planet pinion clusters 22, so that the carrier is held against forward rotation, the bevel gears 24 driving the sun gear 26 in the opposite direction to the input bevel gear 18. Specification 910,003 is referred to.