Patent GB-401070-A (GB)
Title: Improvements in or relating to automatically variable changespeed gearing
IPC: F16H61/02
Filed: 1932-08-17
Abstract: 401,070. Change-speed gearing. KAMPER, M., Hallston, near Leongatha, Victoria, Australia. Aug. 17, 1932, Nos. 23121, 27327, and 32582. [Class 80 (ii).] In change-speed gearing suitable for vehicles, a counter-shaft 40, Fig. 1, yields in an arc about a main shaft 17 and through a cam 54, Fig. 2, operates nested plate clutches in succession so as automatically to adjust the speed ratio to the load. A driving-shaft 1 is preferably driven through an hydraulic coupling 112, 114, Fig. 7, so that the drive is automatically disconnected on low engine speeds. This shaft 1 carries a clutch body 3, Fig. 1, with three fixed clutch plates 4, 9, 11 and three movable plates 5, 10, 12. Springs 15 tend to hold the plate 12 so as to grip a driven plate 16 between the plates 12, 11 and so drive the driven shaft 17 direct in high speed. Springs 14 similarly cause a driven plate 19 to be gripped between the plates 10, 9 so that a sleeve 21 and pinion 22 are driven for lowest speed. Springs 13, Fig. 2, in like manner cause a driven plate 23 to be gripped between the plates 5, 4 so as to drive a sleeve 26 and wheel 27 for middle speed. These clutches are disengaged in the order high, middle, low, as the countershaft is automatically displaced, by shoulders on pins 6 engaging the spring-pressed plates 12, 5, 10 in succession as a spider 32 carrying the pins 6 is moved to the left by the cam 54. The cam 54 formed as a face helix or as a screw is on a sleeve 50 projecting from a rockable frame 43 which supports the live countershaft 40. A wheel 65 meshing with the low-speed pinion 22 is connected to the countershaft by a one-way clutch 68. A wheel 63 meshing with the middle-speed wheel 27 is fast on the countershaft and the necessary freewheel in the middle-speed train is at 31 between the shaft 17 and a wheel 30 driven from a pinion 64 fast on the countershaft. For forward drives, a gear 72 slidable on a propeller shaft 69 makes clutch connection with the main shaft 17. The frame 43 carries gear teeth at 80, Fig. 2, engaging a circular rack 81. The load reaction on the frame 43 thrusts the rack 81 upwards of Fig. 4 against a spring 86 which is adjustable by screwing its containing cylinder 85. This load reaction is balanced against the spring 86 and against the clutch springs 13, 14, 15 acting through the cam 54.. As the load varies, so the frame 43 rocks and the cam 54 moves the spider 32 axially to change the clutch engagement, the lower speeds overrunning as a higher speed is engaged. Unwanted oscillations of the frame 43 are damped out by a dashpot shown in Fig 4. To the upper end of the rack 81 is secured a cupped piston 84 fitted into the cylinder 85 of the auxiliary torque-responsive spring 86. To the lower end of the rack is secured a piston 82 sliding in a cylinder 83 fixed to the gear casing 47. As the rack rises, a check valve 89 closes and oil is forced out through a throttle 92 so as to return to drain by a passage 93. At the same time, oil is sucked into the cylinder 83 from the casing 47 through a port 88. As the rack falls, a check valve 87 closes and the valve 89 opens so that oil is forced through a second throttle 91 and into the spring cylinder 85. Upon the automatic control is superposed a manual control by a pedal 62, Fig. 1, which acts on the spider 32 through levers 60, 56 so as to reinforce the action of the cam 54 against the gear-clutch springs. Reversed driving is effected by fully depressing the pedal 62 and sliding the gear 72 to the right of Fig. 2 into mesh with a gear 77 by a separate hand lever 73, Fig. 7. In order that the engine may be used for braking the vehicle on second speed, the free-wheel clutch 31, Fig. 1, may be locked by a jaw clutch, not shown, operated by the reversing lever 73, and the high-speed clutch may be simultaneously disconnected by a suitable connection between this lever 73 and the pedal 62. Means are described with reference to Figs. 5 and 6, not shown, for facilitating the disengagement of the direct-driving clutch of the nested clutch assembly in the case of an engine which develops maximum torque at relatively low speed. Torque on that clutch extends torque springs so as to trip three-armed levers which hold the clutch in, and so allow that clutch to slip until a lower speed clutch picks up the drive. According to the first Provisional Specification the counter-shaft may yield axially instead of circumferentially.