Patent GB-406314-A (GB)
Title: Improvements in or relating to power transmission mechanism
IPC: F16H3/12
Filed: 1932-08-22
Abstract: 406,314. Facilitating changing speed. NAPIER & SON, Ltd., D., 211, Acton Vale, Acton, and SEWELL, C. W., 2, Holly Park, Finchley, both in London. Aug. 22, 1932, No. 23500. [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 variable gearing of the epicyclic type. In Fig. 1, the main change gearing is the four-speed arrangement described in Specification 406,313 which has a synchronizing sleeve 46 integral with a gear 47 constantly driven through the lay shaft 53 from the driving- shaft 43, such sleeve 46 projecting outside the main gear casing 42 and surrounding the driven shaft 45. The synchronizing gearing comprises epicyclic trains arranged about the shaft 45 and adapted to establish driving connection between the shaft 45 and the sleeve 46 on ratios corresponding to the ratios of the main gear box, such synchronizing ratios being connected gradually by brakes 70, 78 and a clutch 71 all of which allow slip and are provided with means to prevent change of gear being effected in the main gearing before synchronization. A spider 64 connected at 64a to the shaft 45 carries the planets 65 of one epicyclic train and the annulus 66 of a second train. On the end of the sleeve 46 is a drum 72 carrying the annulus 73 of the first train and stepped planets 75 of the second. The sun gear 67 of the first train is connected by a loose sleeve to a brake and clutch drum 69 and the sun 76 of the second train to a brake drum 77. To synchronize the third speed clutch 59, 60, the epicyclic gearing is caused to turn solid by engaging the clutch 71. To synchronize the fourth speed or direct drive clutch 61, 62, the brake 78 is applied. To synchronize a pair 49, 57 yielding second speed, the brake 70 is applied. The first speed pair 50, 58 is not synchronized. The coupled main pinions 57, 58 are operated by a fork 59, Fig. 2, secured to a sliding selector 81. The coupled wheels 49, 50 are operated by a fork 51 secured to a sliding selector 79. In the position shown, a selector arm 84 engages the forked upper ends 83a, 86a of levers 83, 86 pivoted on the selectors 79, 81, respectively. The initial rocking of the arm 84 to change speed rocks both these levers. The rocking of the lever 86 unlocks the selector 81 by means shown in Fig. 9. The rocking of the lever 83 through links 99, 100, Fig. 13, and levers 101, 102 operates the brake 70 and clutch 71 alternatively by means shown in Figs. 4, 5, and 6. Continued rocking of the arm 84 then slides both selectors 79, 81 to engage the clutches 62, 60, Fig. 1, alternatively for fourth and third speeds while preventing the toothed gears from mutually engaging. To select first and second speeds, the arm 84, Fig. 2, is slid so as to disengage the lever 83 and, while remaining engaged with the lever 86, to engage the forked upper end 87a of a lever 87 which is connected through a link 103, Fig. 13, to the control arm 104 of the brake 70. The initial rocking movement of the arm 84 towards second speed position rocks the lever 87 as shown in Fig. 9 so as to engage the brake 70. A bowl 98 on the lever 86 has thus been raised clear of a stop 97 so that continued leftward rocking of the arm 84 would carry the sliding selector 81 with it. But the brake is constructed to resist being disengaged so long as it is operative against torque. The lower end of the lever 87, Fig. 9, is thus held from moving leftwardly. It is only after substantial synchronization that the continued striking movement of the arm 84 to second speed position can take place. This brings the lower end of the lever 87 back to its original position with the brake 70 disengaged. Figs. 4, 5, and 6 show the double-acting arrangement when the selectors 79, 81 are being slid together to alternative synchronized positions. The initial rocking of the arm 84 from the neutral position of Fig. 4 to the position of Fig. 5 raises a bowl 92 above one of a pair of stops 90 which are pivoted at 89 upon a plate 88 fixed between the selectors 79, 81, Fig. 2. The lower end of the lever 83 has thus been tilted and through the link 99 has engaged the clutch 71 or the brake 78. Continued striking movement of the arm 84 to the gear-engaged position of Fig. 6 is then prevented until the clutch 71 or the brake 78 has been disengaged after being relieved of torque upon synchronization. The stops 90 are yieldingly pivoted as shown to render the sequence correct during the return stroke of the arm 84. The above effect in the case of the clutch 71 is effected by pins 112, Fig. 13, engaging shoulders in the sides of grooves as described with reference to Figs. 2 and 3 of Specification 406,316. The control for the brake 78 is shown in Fig. 14. The lever 101 applies the brake by turning a cam shaft 105. The drum 77 turning anticlockwise pulls the shaft 105 to the right so that a clutch head 108 upon it engages fixed teeth on a casing 63. The brake thereafter cannot be disengaged until it is unloaded that is when synchronization has been effected.