Patent GB-450246-A (GB)
Title: Improvements relating to variable speed power transmission
IPC: F16D67/00
Filed: 1934-12-12
Abstract: 450,246. Variable-speed gearing. YOXALL, J., York House, Deganwy, Carnarvonshire. Dec. 12, 1934, No. 35650. [Class 80 (ii)] Variable - speed gearing which has the advantage that manual disengagement of a mechanical engine clutch is dispensed with comprises in combination an hydraulic coupling or centrifugal mechanical clutch C, Fig. 1, and a three-element spur planetary train T controlled by toric precessional gearing P. In the arrangement of Fig. 1, the main part of the power passes through the toric gearing P to the planet carrier 26 of the train T without passing through the coupling C, but, in the arrangement of Fig. 7, both the coupling C and the variable-speed gearing are self-contained. An annulus 28 of the train T is the driven element, and a sun gear 27 the reaction element. In Fig. 1, the sun gear 27 is connected by a central shaft 6 to the loose hydraulic coupling member 2, while the coupling member 3 rigid with the driving member 1 is connected by a dog member 102 to a first toric disc 11. The member 3 restrains the member 2 through the coupling, rather than drives it. The disc 11 drives through rollers 12 fixed parallel to the gear axis to a middle disc 17 which is reversed in direction so that other speed-changing rollers 55 can drive a last or driven toric disc 24 in the forward direction. A spider 14 supporting the rollers 12 and a spider drum 18 supporting the rollers 55 are positively connected at 16 to rotate together, and a sleeve 54 which passes loosely through these spiders and through the disc 17 serves to transmit the thrust generated by torque load balls 9, and required to produce traction friction, from the back of the disc 11, to a flange 113 at the back of the disc 24. Precession of the rollers 55 to initiate speedchanging in the combined gear device is induced by displacing angularly a barrel 20. During geared drives, the spiders 14, 18 of the rollers 12, 55 are held against rotation by a brake 19, 19<1> applied to the spider drum 18. A turning of the barrel 20 as seen in Fig. 3 rocks three triple levers 22 each of which has outer arms 121 formed as worm-wheels. The spindles 60 of the roller carriers 58 are slid in their bearings in the drum 18 so that precession begins and continues until worms 59, which are carried at both ends of the spindles 60, have screws back to symmetrical position on a different ratio. This angular displacement of the drum 20 is effected through inclined slots by the axial sliding of a sleeve 65, Fig. 1, which is effected by a lever 53, Fig. 4, engaging an hydraulic double-ended control piston 39. The piston 39 follows up axial displacements in both directions of a central barrel valve 44 which slides owing to a screw 47, as a control lever 52, Fig. 1, is canted one way or the other. As the rollers 55 approach the parallel position shown correspondingly to a substantial 1 to 1 over-all drive, the brake 19, 19<1> automatically opens to allow both trains of toric gearing P to turn solid with the toothed train T. An annular groove 172 in the valve 44 connects an exhaust port 42 to the space in a cylinder 150, Fig. 5, between. twin pistons 23 which are thereupon collapsed inwards by spring toggles 158 so as to release both of the twin brake bands 19, 19<1> from the spider drum 18. One end 151 of each band such as 19 is anchored as at 154 on a lever 155 pivoted at 176 while the other end 152 is thrust upon by the toggle 158 which bears at 162 upon the same lever. The source of the hydraulic power for the servo control is an eccentric 10, Fig. 1, which drives an oil pump 31 preferably of the type described in Specification 440,686, [Group XXVIII]. In the arrangement of Fig. 7, the whole of the power passes through the automatic clutch from member 3 to member 2 fast on the shaft 6, which carries the sun gear 27 of the train T, and which drives the first disc 11 of the toric gearing P through the torque load balls 9. When a fluid coupling is used, it may be according to Specification 414,641, [Class XXIX].