Patent GB-599074-A (GB)
Title: Improvements in or relating to speed ratio shifting means for power transmissions
IPC: F16H47/06
Filed: 1944-05-22
Abstract: 599,074. Variable-speed gearing. CHILTON, R. May 22, 1944, No. 9854. Addition to 599,069. [A Specification was laid open to inspection under Sect. 91 of the Acts, Sept. 23, 1944.] [Class 80(ii)] In the mechanism of the parent Specification comprising driving and driven shafts with a gear shift member and a locking member having different relative angular co-action with one of the shafts, a releasable locking means is provided to prevent movement of the shift member away from the locking member. As shown, a shaft 10, through gear pairs 1, 1L-4, 4L, drives layshafts 23 which rotate gears 26, 28, in opposite directions, the final driven shaft 99 being connected to either of the gears 26, 28, by a clutch member 97. A screw-shift member 18 helically splined at 22 to the driving shaft 10 has clutch teeth 20 engageable with teeth 30 on the gears 1-4, and jaws engageable with jaws 16 on a locking member 14 splined axially at 12 to the shaft 10. The jaws have axial and helical faces, the pitch of the helical faces being the same as the helical splines 22. The driving torque is transmitted from the shaft 10 through the splines 12 to the locking member 14 and thence by the axial jaw faces and member 18 to the clutch teeth 20, 30. Over-running torque would tend to screw the member 18 to the right, Fig. 1. According to the invention such movement is prevented by jaws 32 on the member 18 engaging jaws on an auxiliary locking member 34 splined axially to the shaft 10. The jaws 32 have axial and helical faces, the pitch of the helical faces being equal to or less than that of the jaws 16. When it is desired to move into a higher gear the auxiliary locking member 34 is moved to the right to disengage the jaws 32 by fingers 42 on a slidable collar 44 actuated by control mechanism. To move into a higher gear a control lever 70, Fig. 8, is moved one step so that (a) a roller 76 on an arm 74 moves the collar 44, and (b) a shaft 62, due to the action of balls 68 in conical recesses, moves axially and angularly relatively to the hub of a forked lever 56 engaging the locking member 14. Movement of the shaft 62 opens a valve 60 to permit oil supplied to a duct 91 to pass through a tube 92 to fill a fluid coupling 78, 86, provided with permanent drain apertures 96. The member 78 of the coupling is geared to planets 82 having a carrier 90 splined to the driving shaft 10. As the next higher gear is synchronised the member 18 screws to the right gradually disengaging the jaws 16 until the clutch teeth 20, 30, are fully engaged. The action is facilitated by oppositely acting ratchet pawls 46, 48, on opposite sides of the teeth 20. When the member 18 has completed its movement, the locking member 14 snaps to the right, due to the action of a spring 64 and the balls 68 to engage the jaws 16 and close the valve 60. The member 18 also engages the auxiliary locking ring 34 as this time. The oil supplied to the coupling 78, 86, is thus stopped and the coupling drains through the holes 96. In moving into a lower gear the action is similar except that when the fluid coupling is filled the locking member 14 snaps to the left, Fig. 1, before the member 18 screws in the same direction. The member carrying the gear 28 may have an extension 98, Fig. 1, with teeth 30 to give a one-to-one drive. A friction clutch may be substituted for the fluid coupling. Such friction clutch is actuated by fluid pressure and is arranged to provide also a one-to-one drive. Change of speed may be rendered automatic by providing a rod 126 fixed to the shaft 62 and having its lower end connected to speed and torque responsive means.