GB325146A - Gear change mechanism for motor vehicles - Google Patents

Abstract

325,146. Stanley, G. E. March 16, 1929. Variable-speed gearing.-To facilitate change of speed, a constantly meshed wheel 4 can be freed from a layshaft 5 by means of a positive dog clutch which is interconnected with either the main clutch or the changespeed mechanism so that during a change of speed the layshaft is relieved of the inertia of the main clutch &c. The positive clutch may comprise a sliding dog, or as in Fig. 1, the wheel itself may have two internal rows of dogs 6, 7 engaging dogs 8, 9 on the shaft, alternate end portions of the dogs on each row being cut away to facilitate engagement. The driving wheel 2 is wide to ensure mesh in all positions of the wheel 4. For operation from the main clutch, Fig. 2, the striking fork, slidable on a rod 15 is biased by a spring 16 and the fork is withdrawn by an extension 21 of the main clutch lever 22, which moves a bell crank lever 18 through a spring loaded plunger 19. The latter spring is substantially stiffer than the spring 16 so that depression of the clutch pedal always frees the main clutch even if the torque on the dogs is too great for them to disengage, the reduction of torque consequent upon declutching allowing the spring to affect disengagement. The main clutch can thereby also engage even if the dogs come opposite one another upon engagement. Alternatively, the plunger 19 may be adjustably fixed in the housing 20 and when the clutch pedal is fully raised there may be clearance between the plunger and the arm 18, and a further modification comprising lost-motion means at 22a allows adjustment of the main clutch member. In this case, the stiffer spring and the operating plunger may be carried in a recess in the boss of the fork. The fork may also be located resiliently between collars on the shaft. When the operating-means are interconnected with the change-speed lever, Fig. 4, the fork is moved by a pivoted lever 23, the upper end of which carries a lateral peg 25 engaging a V-shaped slot 26 in a member 27 moved by the change-speed lever 31. The slot is such that whichever way the lever is moved from the neutral position (Fig. 4) the wheel 4 is always reclutched. In a modification, the slot is replaced by a corresponding cam surface. In order to facilitate engagement of a sliding gear when the car is stationary, the wheel 4 may have a conical end surface which, when completely declutched, is pressed into engagement with a corresponding surface associated with the layshaft by means of a spring-loaded plunger 34 having limited axial movement.