GB560379A - Improvements in or relating to power transmission apparatus - Google Patents

Abstract

560,379. Variable speed gearing; clutches. HOBBS, H. F. Sept. 23, 1942, No. 13365. [Class 80 (ii)] A layshaft type of gear-box having at least two gear wheels permanently in mesh with two other gear wheels includes at least three dog clutches each actuated by a piston subjected to fluid pressure against spring action, so that at least three different gear ratios are obtainable by the actuation of the different clutches. As shown, the gear-box is similar to the gear box shown in Fig. 22, of Specification 549,988, and comprises an input shaft C having a gear 401 meshing a gear 451 fixed on a layshaft, and an input shaft D having a gear 402 meshing a gear 456 loose on the layshaft. Gear wheels 430, 431, loose on the output shaft F mesh with gears 457, 455, respectively loose and fixed on the layshaft. Members 405, 406, fixed to the output shaft F and a disc 452 fixed to the layshaft have clutch parts so that the loose gear wheels may be clutched to their respective shafts. All the clutches are similar to one another. The gear 431, Fig. 3, houses an annular piston 442 having teeth 418A engaging axial splines in the gear 431 and clutch teeth 441 engageable with clutch teeth 440 on the member 406. Clutch disengaging springs 501 act between the piston 442 and a floating ring 503, and light springs 453 between the ring 503 and a baulk ring 500 urge the latter into frictional contact with the member 406. The baulk ring 500 has three arms 51 engaged in slots 52 in the piston 442. Each slot 52 has a part 552 and a smaller part 553 connected by inclined steps 554, 555, and the arms 51 have corresponding inclined surfaces 556, 557. When, under fluid pressure, the piston 442 moves towards the clutching position, then, if the parts 406, 442, are not synchronised, one of the surfaces 556, 557, engages a step 554 or 555 and further movement of the piston is prevented by the baulk ring. When the parts 406, 442, are brought into synchronism the arms 51 drop into the small parts 553 of the slots 52 and the clutch teeth 440, 441, then engage without shock. The teeth 441 are inclined on one side so as to prevent engagement, or to be forced out of engagement, should another set of clutch teeth fail to disengage. The shafts C, D, carry clutch plates 12, 16, respectively, so that either may be clutched to an engine shaft A. The clutches are actuated by fluid pressure which acts on pistons 20, 24. Reference has been directed by the Comptroller to Specification 549,988.