Patent GB-599070-A (GB)
Title: Improvements in or relating to variable speed power transmissions
IPC: F16D67/00
Filed: 1943-10-26
Abstract: 599,070. Variable-speed gearing. CHILTON, R. Oct. 26, 1943, No. 17628. Convention date, Oct. 14, 1942. [Class 80(ii)] A power transmission having a driving and a driven shaft, speed ratio means operative to drivably associate said shafts at any one of a plurality of speed ratios, and mechanism for effecting a speed ratio shift including means operative to relieve said speed ratio means of driving torque includes means automatically responsive to said shift to restore said torque prior to completion of the shift in the case of a downshift and upon completion of the shift in the case of an upshift. As shown, an engine shaft 10, Fig. 1, drives at high speed, through epicyclic gears 22, 26, one half 30 of a fluid coupling, the other half 36 of which is fixed to the output shaft 38. Coupling half 30 has a gear 34 meshing with a plurality of countershaft gears 62 rotatably locked to gears 64, 66, 68, 70. The latter mesh with nested gears 72, 74, 76, 78, having internal clutch teeth 73, 75, 77, 79 engageable with teeth 48 on a sleeve 46 splined helically on the shaft 38. The coupling 30, 36, when filled will drive the shaft 38 faster than the toothed gears 64-70. A locking collar 42, Fig. 3, is axially splined to the shaft 38. The adjacent faces of the parts 42, 46, have interengaging clutch jaws 50, 52, with axial faces 54, 56, and helical backs 58, 60, of the same pitch as the helical splines 44 on the shaft 38. The locking collar 42, Fig. 7, is engaged by a shifting yoke 80 carried by a lever 82 pivoted upon a shaft 92 mounted in bearings 84. The shaft 92 has a valve 96 co-operating with a seating 98 in the hub 94 of the lever 82 and an arm 102 with a detent 104 engageable with four notches in a rack 108, Fig. 8. The distance between successive notches corresponds to movement of the members 42, 46, equal to the distances between adjacent clutch teeth 73-79. At one end of the shaft 92 balls 110 engage opposed V-notches 111 in the hub 94 and shaft 92 and at the other end a spring 100 holds the valve 96 to its seat 98 when the ball notches are in alignment. Oil is supplied continuously to the left hand side of the valve 96 the other side of which is connected by ducts 116, 118, to the interior of the coupling 30, 36. The latter has a leak duct 120. To shift into a lower gear, i.e., to move the members 42, 46, one step to the right, Fig. 1, the shaft 92 is turned by a control shaft 88, Fig. 7, so that the detent 104 engages the next notch. The yoke 80 cannot follow this movement due to the friction at the driving faces 54, 56. The camming action of the balls 110 thus moves the shaft 92 slightly to the left against the action of the spring 100 to open the valve 96 and supply oil to the coupling 30, 36. The drive is thus gradually taken by the fluid coupling and when the resistance to movement of the locking collar 42 is reduced sufficiently the latter snaps suddenly to the right to disengage the teeth 50, 52, and cause closure of the valve 96 to shut off the fluid flow to the coupling 30, 36, which then proceeds to drain. The sleeve 46 then moves helically into engagement with the locking collar 42, the teeth 48 engaging the clutch teeth of the next gear. For a shift into a higher gear the control shaft 88 is moved to bias the locking collar 42 to the left, Fig. 1. The fluid coupling 30, 36, is again filled and transmits the drive. As the speed of the driven shaft 38 increases the sleeve 46 is screwed to the left, and when the teeth 50, 52, are just disengaged the locking collar 42 snaps to the left to close the valve 96 and the gears again take on the drive. The helical movement of the sleeve 46 is controlled by oppositely-acting ratchet pawls 122, 124, on opposite sides of the clutch teeth 48. A slipping friction clutch may replace the fluid coupling 30, 36. In another modification and relative movement of the hub 94 and shaft 92 causes disablement of the driving engine ignition system or control of the engine throttle valve. The control shaft 88 may be operated in response to engine speed, manifold pressure, or by other automatic means. Specification 599,069 is referred to.