Patent GB-376468-A (GB)
Title: Improvements in variable speed gearing particularly for use with hydraulic couplings
IPC: F16H3/089
Filed: 1931-06-15
Abstract: 376,468. Change-speed gearing. SINCLAIR, H., 6, The Crest, Surbiton Hill, Surrey. June 15, 1931, No. 17389. [Class 80 (ii).] Change-speed gearing comprises auxiliary clutching means 50, Fig. 1, arranged in parallel and adapted to slip while transmitting substantial torque, the clutch members being connected invariably to the driving and driven shafts 3, 20 of the change gearing. The invention is specially applicable for driving locomotives and the auxiliary clutch 50 acts as a clutch stop, or maintains the torque in changing to a higher speed. The engine clutch may be a friction clutch automatically controlled by centrifugal force, but is preferably a friction coupling 1 which need not have valve or like control. One auxiliary clutch member or disc 62 is fast on the shaft 20 and the other 60 is fast with the loose gear 24 of the fourth or highest-speed pair 14, 24. With the vehicle stopped and the engine running, the drag in the coupling 1 causes the rotation of loose gears 21 .. 24 on the driven shaft 20, and also of the body part 60 of the clutch 50, the disc 62 being at rest. To start the vehicle, the driver lifts a finger-ring 107, Fig. 2, which makes trigger connection at 112 so that by depressing a pedal 101 he engages the clutch 50. This acts as a clutch stop bringing the whole gearing to rest and allowing a double clutch 29 to be slid to the left of Fig. 1 to engage the low-speed train 11, 21, whereupon the clutch 50 is opened. The selector mechanism may be of any suitable kind. In the form described, preselection is effected by a lever 70, Fig. 2, moving in a gate 78, Fig. 6. When the lever 70 is turned about a pivot 76, Fig. 3, the lever heel 73, Fig. 4, moves to select one of two primary selector bars 75a, 75b, the other being locked by a member 77. The primary selectors 75a, 75b are connected to secondary selectors 90a, 90b by spring boxes 81a, 81b with an interlock ball 95. In each box is a spring 89, Fig. 3, which abuts at each end on both the primary selector and on the spring box so as to allow relative motion under spring stress in both directions. Bolts 92a, 92b normally connect the two spring boxes to the two primary selectors. To change up from first to second speed, the lever 70 is moved from slot G1, Fig. 6, to slot G2 thereby moving the primary selector 75a, Fig. 3, from left to right. Stress on the clutch teeth 31, Fig. 1, prevents the selector 90a and the box 81a from following. The bolt 92a, Fig. 3, is cammed upwards striking a pivoted plate 99 which carries upwards with it the finger-ring 107. This brings the trigger 112, Fig. 2, carried by the pedal lever 101 into engagement with a lever 109 connected to the striker 114 of the auxiliary clutch 50. Depression of the pedal 101 now engages the clutch 50 with slip. The dog clutch 29 being unloaded is shot to the right by the spring box 81a, and, on synchronism, its teeth 32, Fig. 1, engage teeth 34 on the loose rotating gear 22 ; at the same time the bolt 92a drops back allowing the finger-ring 107 to fall and disconnect the trigger 112 so automatically releasing the clutch 50 which has prevented the drive from being interrupted. For the next step up, the lever 70 is moved to slot G3, Fig. 6, whereby the spring box 81a, Fig. 4, is returned to neutral and the box 81b shot to the left. The bolt 92b rises and sets the trigger so that depression of the pedal engages the clutch 50 and so on. Movement into highest speed is different because the dog clutch 36, Fig. 1, must engage teeth 41 on the gear 24 which is already being driven by the slip clutch 50. For this reason, the clutch 50 may be arranged to act with a gear pair for the sole purpose, say 5 per cent above the highest drive speed ratio. Whereas the dog clutches for the second and third speeds may be provided with balking- rings 35 stepped for engagement in both directions, the clutch 36 has a balking-ring 43 stepped for engagement for one direction of relative rotation only. Synchronism for the other direction is effected by the use of bevelled ends to the clutch teeth. To make a change down, the selector lever 70 is set for the new speed and the engine throttle closed and reopened. The loaded clutch teeth of the last speed are released and the fresh engagement is effected on synchronism, by the spring box which has been stressed, the time required being no longer than is required for the engine to accelerate to the speed corresponding to the lower gear. The auxiliary slip clutch 50 may be situated in any part of the transmission. The arrangement at the end of the driven shaft 20 shown in Fig. 1 is suitable as it allows the clutch to be of large enough diameter to prevent deceleration of normal load while changing up. This auxiliary clutch 50 may be of an hydraulic vane type instead of being mechanical. Specifications 285,970, [Class 79 (ii), Motor vehicles, Driving &c.], 292,549, 297,793, 309,134, [all in Class 80 (ii), Gearing, Variable-speed &c.], and 365,998, are referred to.