Patent GB-406315-A (GB)
Title: Improvements in or relating to variable speed power transmission mechanism
IPC: F16H3/38
Filed: 1932-08-22
Abstract: 406,315. Facilitating changing speed. NAPIER & SON, Ltd., D., WILKINSON, G. S., 211, Acton Vale, Acton, and SEWELL, C. W., 2, Holly Park, Finchley, both in London. Aug. 22, 1932, No. 23501. [Class 80 (ii).] Change-speed gearing suitable for vehicles in which the changes are effected by changing the engagement of toothed wheels or claw clutches is combined with auxiliary synchronizing variably-speed gearing in which to bring in each synchronizing ratio an unloaded dog clutch is engaged followed by a friction clutch to effect smooth speeding up or down. In Fig. 1, the main change gearing is the four-speed arrangement described in Specification 406,313, which has a synchronizing sleeve 53 integral with a gear 52 constantly driven through the lay shaft 48 from the driving-shaft 43, and the lay shaft 48 extended at 48a to form a second synchronizing member. Two toothed gears 65, 66, a claw clutch member 70 and a friction clutch member 67 are fast to a sleeve 64 loose on the driven shaft 45. To synchronize the third speed clutch, 62, 63, the synchronizing sleeve 53 is connected by a dog clutch 70, 71 to the sleeve 64 which is afterwards gradually clutched to the driven shaft by engaging a splined cone 68 with the clutch member 67. Two other speeds are synchronized from the extension 48a. In the case of the fourth speed or direct drive clutch 60, 61, the gear 65 and its mating wheel 77, which correspond to the pair 49, 50, are brought into action by engaging a claw clutch 74 followed by the friction cone 68. To synchronize a pair 54, 57 yielding second speed in the main gear box, the gear 66 and its mating wheel 72 are brought into action by engaging a claw clutch 76 followed by the same friction cone. The first speed is not synchronized. The coupled main pinions 57, 58 are operated by a fork 59, Fig. 4, secured to a sliding selector 86. The coupled wheels 54, 55 are operated by a fork 56 secured to a sliding selector 85. In the position shown, a selector arm 90 engages the forked upper ends 89a, 92a of levers 89, 92 pivoted upon the selectors 85, 86, respectively. The initial rocking of the arm 90 to change speed rocks both these levers. The rocking of the lever 92 unlocks the selector 86 by means shown in Fig. 11. The rocking of the lever 89 operates the appropriate dog clutches of the auxiliary gearing by means shown in Figs. 6, 7, and 8. Continued rocking of the arm 90 then slides both selectors 85, 86 to engage the clutches 61 and 63, Fig. 1, alternatively, for fourth and third speeds while preventing the toothed gears from mutually engaging. The shaft 91 of the arm 90 carries a strut 109, Fig. 3, the displacement of which allows a lever 108 to be raised by a spring 112 so as to rock to the left the shaft 84, Fig. 1, of the friction cone 68 and so complete the synchronizing train whose dog clutch has already been engaged. An abutment 113, Fig. 3, of the spring 112 is so connected to the engine clutch control that the synchronizing cone 68 cannot be engaged until the engine clutch is disengaged. To select first and second speeds, the arm 90, Fig. 4, is slid so as to disengage the lever 89 and, while remaining engaged with the lever 92, to engage the forked upper end 93a of a lever 93 which is connected by a link 82, Fig. 1, to the dog clutch 76. The initial rocking movement of the selector arm 90 towards second speed position rocks the lever 93 as shown in Fig. 11 so as to engage the dog clutch 76 and then the cone 68. A bowl 98 on the lever 92 has thus been raised clear of a stop 103 so that continued leftward rocking of the arm 90 would carry the sliding selector 86 with it. But the teeth of the clutch 76 are undercut so as to resist disengagement as long as there is torque in the clutch. It is only after substantial synchronization that the continued striking movement of the arm 90 to second speed position can take place. This brings the lower end of the lever 93 back to its original position with the clutch 76 disengaged. Figs. 6, 7, and 8 show the double-acting arrangement when the selectors 85, 86 are being slid together to alternative synchronized positions. The initial rocking of the arm 90 from the neutral position of Fig. 6 to the position of Fig. 7 raises a bowl 98 above one of a pair of stops 97 which are pivoted at 95 upon a plate 94 fixed between the selectors 85, 86, Fig. 4. The lower end of the lever 89 has thus been tilted and through a link 80, Fig. 1, has engaged one of the dog clutches 71 or 74 followed by the cone 68. Continued striking movement of the arm 90 to the gear-engaged position of Fig. 8 is then prevented until the dog clutch 71 or 74 has been disengaged after having been unloaded upon synchronization. The stops 97 are yieldingly pivoted as shown to render correct the operation of the dog clutch during the return stroke of the arm 90.