Patent GB-486589-A (GB)
Title: Improvements in or relating to variable-speed power-transmission gearing
IPC: F16H3/08
Filed: 1936-11-04
Abstract: 486,589. Change - speed gearing. SINCLAIR, H. Nov. 4, 1936, Nos. 30077/36 and 683/37. [Class 80 (ii)] [Also in Group XXIX] Change-speed gearing comprises a one-way clutch 17, 21, Fig. 1, in a low-speed train set to allow a driven shaft 14 to overrun a driving- shaft 11 on that speed, and a one-way clutch 16, 20 in a high-speed train set to prevent the driven shaft 14 overrunning the driving-shaft 11, this clutch 16, 20 being bidirectionally locked to establish the high-speed drive. The low-speed drive is through a reducing train 10, 12, 13, the gear 13 being loose, and the highspeed drive is direct to the clutch member 16 splined on the shaft 14. Springs 29 arranged between the ratcheting members 16, 17 allow one only of these members to be engaged at a time. These springs pass through a collar 15 rigid with the shaft 14 upon which collar is splined a striking sleeve 22 adapted to cooperate with bolts 23, 24 adapted to be pressed inwards alternatively against biassing springs to lock either the clutch member 16 or the member 17 positively to the shaft 14. On low speed, the teeth 17, 21 are engaged, the latter moving downwards of Fig. 1 driving the former. If a preselector 28 has been moved right, then the sleeve 22 thrusts the bolts 24 inwards to engage recesses 26 and that drive is locked against overrunning. To change to high speed. the preselector 28 is moved left so that the bolts 24 are released and slip out of the recesses 26 and the bolts 23 are pressed inwards against the shaft 14. The engine is now decelerated, which causes the ratchet member 17 to overrun and in so doing to disengage from the member 21 and thrust the ratchet member 16 towards the member 20. So long as the driving member 20 is moving downwards of Fig. 1 faster than the member 16, the latter is held out of engagement. When the member 20 has slowed down sufficiently, the teeth of the member 16 snap in and the bolts 23 snap into recesses 25, so that when the engine accelerates the drive is transmitted through the inverted teeth 20, 16 and the bolts 23. To change to low, the rod 28 is moved right and the engine momentarily decelerated to relieve the torque and allow the bolts 23 to disengage, acceleration of the engine then forcing the ratchet members 16, 17 to the right. Where there is an hydraulic engine clutch, disengagement of the high speed can be facilitated by imparting a slight reversed rotation to the shaft 11 as described in Specification 365,998. In practice, it is preferred to use a, Legge positive one-way clutch such as is described in Specifications 354,711 and 410,083, but roller one-way clutches such as are shown in Figs. 1 and 2 of Specification 261,486, [Class 80 (ii)]. or in Figs. 10 and 11 of Specification 366,081 are also suitable. By the construction of Fig. 10, alternative direct drive and drive through a three-element hydraulic torque converter is obtainable. The impeller 141 and turbine 142 are secured respectively to the driving and driven shafts 140, 145, and the reaction member 146 to the screw member 147<1> of a Legge coupling of which the nut member 147 is engageable with the teeth of a stationary member 151. A second Legge coupling 148 connects the driving and driven shafts. With the parts at rest in the position shown, rotation of the shaft 140 maintains the coupling 148 in the position shown to overrun the driven shaft and the tendency of the reaction member 146 to rotate backwards within the nut 147, which is prevented from backward rotation by the pawls 1472 on the nut, moves the nut to the right so that its teeth engage the member 151 and the drive is transmitted through the hydraulic gear. On decelerating the engine and putting pressure to the left on a locking-sleeve 150, the nut 148 moves to the left to engage its teeth 148a with the teeth 145a on the driven shaft and when it has rotated sufficiently the locking-sleeve 150 engages teeth 144 on the shaft 140 to lock together the driving and driven shafts. The tendency of the reaction member to move forward moves the nut 147 back to the position shown in which the reaction member can rotate freely forwards. A locking-sleeve 149 may be provided to lock together the screw 147<1> and nut 147 when the latter is in its righthand position so as to prevent forward running of the reaction member and allow braking under overrunning conditions. Fig. 2 shows a construction employing epicyclic gearing and giving direct and overspeed drives and a reverse. The annulus 39 is connected to the driven shaft 32, the planet carrier 31c is connected to an intermediate shaft 31 adapted to be connected to the driving-shaft 30 by movement of a lever 35 to produce the forward drives, and the sun 37 is formed on a, sleeve 41 carrying a double Legge coupling 41, 40, 46. 40a, 47 moved by change of engine speed alternatively into engagement with the drum 33 on the driving shaft and a stationary member 44 for direct drive and overdrive respectively. The bidirectional locking is provided by a sleeve 49 controlled by the preselector-rod 51. For reverse drive, the drum 33 is engaged with teeth 36 on the sun - wheel sleeve 41 and the planet cage is connected with stationary teeth 34a. In Fig. 5, a Legge clutch connects the intermediate shaft 61 either with the driving- shaft 60 or with the driven gear 63 of a reduction train 65, 64, 63. A clutch sleeve 66 sliding on the planet spindles 68 of an opicyclic train, of which the annulus 71 is secured to the driven shaft 62 and the sun 69 to the shaft 61, connects the planet carrier either to the wheel 63, to the annulus to lock the epicyclic train solid, or to a stationary part 72 for reverse. In the Legge coupling bolts 81 engage holes 82, 82<1> alternatively for bidirectional locking. A preselector lever controls movement of a sliding lockcontrolling sleeve 84 and the clutch sleeve 66, so that three forward speeds, one solid, one with the epicyclic gear solid and the reduction gear effective, and one with the sun and planet carrier driven at different speeds, and two reverse speeds with the planet. carrier stationary and the sun driven either directly or through the reducing train are obtainable. A gear giving three forward speeds is shown in Fig. 8. Two reduction trains 112, 122, 119, 114. and 113, 123, 119, 114 respectively, are controlled alternatively by a double Legge coupling 124, a master control Legge coupling 115 connecting the driving-shaft 110 either to both reduction gears or directly to the driven wheel 114. A two-forward-speed gear A, Fig. 9, of Fig. 2 type may be combined in series with a three-forwardspeed gear B of Fig. 8 type to provide four useful speeds if the forward speed range of B is greater than that of A, and six speeds if the range of A is the greater. In the latter case, the change between third and fourth speeds will necessitate substantial changes of speed of the driven shaft 32 of gear A and the driving- shaft 110 of gear B to which it is directly connected. To effect these changes rapidly a gear-wheel 131 slightly smaller than the gearwheel 113 of Fig. 8 is secured on the shafts 32, 110 and meshes with a wheel 132 slidable loosely on the countershaft 118 of Fig. 8 into contact alternatively with a clutch member 135 on the countershaft and a brake member 136 on the casing. After the speed of the engine shaft 30 has been changed to effect the change in the gear A, the wheel 132 is moved appropriately by a lever 134 to speed up the shafts 32, 110 from the countershaft 118 or to slow them. The coupling member 124 of Fig. 8 must be locked in either of its end positions if the reverse drive of Fig. 2 is to be utilized..