GB619226A - Improvements in or relating to variable-ratio power transmission apparatus - Google Patents

Abstract

619,226. Change-speed gear; friction and positive clutches. HOBBS TRANSMISSION, Ltd., and HOBBS, H. F. April 17, 1946, No. 11847. [Class 80 (ii)] Relates to a change-speed gear of the kind (e.g. as described in Specification 549,988) wherein a pair of hydraulically-actuated nested friction disc-clutches 17, 18, in a driving drum 10, drive selectively or together a planetcarrier 25 and sun 20 of an epicyclic train the third element, a ring-gear 22, of which is fast with the final driven shaft 19, to which the sun 20 can also be drivingly connected through wheels 35, 36, a counter-shaft 37 and a combined sliding-wheel and dog-clutch 33 splined on the driven shaft, whereby in some ratios a simultaneous differential drive is imparted to the driven shaft 19 both directly and through the countershaft. According to this invention a hydraulically-operated disc-brake 30 can be applied to the sun 20, which, by engagement of the disc-clutch 17 and disengagement of the dog-clutch 33, produces overdrive, during which the countershaft is also held stationary by the brake. The two lowest speeds are produced by sliding the dog-clutch wheel 33 into mesh with a countershaft-wheel 47, first speed being by engaging the disc-clutch 18 alone to drive through the countershaft-wheel 47, and second by engaging the disc-clutch 17 alone for a differential drive both direct and through the same countershaft-wheel 47. By meshing an idler, not shown, with the wheels 33, 47, two reversed speeds are obtained in the same manner. With the dog-clutch wheel 33 slid to the left to clutch the wheel 39 to the driven shaft, two higher reduced speeds are obtained, first by engaging the disc-clutch 18 alone to drive through the countershaft-pairs 35, 36 and 38, 39; second by engaging the discclutch 17 alone for a differential drive both direct and through the same countershaft pair. Disengaging the dog-clutch 33 and engaging the disc-clutches 17, 18 together, locks the epicyclic train solid for direct-drive, which, with the overdrive above described, makes six forward and two reverse ratios. A coned balkring 42, Fig. 3, for the dog-clutch, has its teeth cut thin at the tops and the inner ends of the teeth 28 of the sliding dog 33 are cut away for a short distance as at 45 to provide circumferential balking clearance. The disc-clutches 17, 18 and brake 30 are operated by diaphragms 11, the clutches being disengaged by common springs 15. Control is as described in Specification 619,234.