GB484816A - Improvements in or relating to change-speed mechanism - Google Patents

Abstract

484,816. Controlling change speed gearing. OLIVER, A. V. Nov. 17, 1936, No. 31408. [Class 80 (ii)] Striking-forks a, controlling synchromesh change-speed gearing of the kind described below, are all loosely mounted on a single rod b, reciprocated by operation of an executive and main-clutch pedal, a selected one of the forks being locked to the rod when in the neutral position, under control of a sliding preselector rod c, carrying selectively-placed spring-loaded pegs i, which, through pellets f, depress spring- loaded plungers d, carried by the forks a (or rod b), freeing them from holes in a fixed locking- plate e and causing them to engage holes in the rod b (or forks a). The change-speed gear (not shown) is of the kind described in Specification 459,556, i.e. in which the striking-forks are moved in one direction (from right to left Fig. 1) on downward movement of the executive pedal, to neutralize the gear and then synchronize the selected speed frictionally, and in the opposite direction on upward movement of the pedal, to engage the dog-clutch of the selected speed. The plunger-receiving holes in the rod b (or forks a) are constituted by a groove in the rod (or forks), receiving sliding ribs h, which form an interlock ensuring that only one plunger at a time can engage the rod b (or forks a). The rod b is loaded in the gearengaged direction by a spring m, and is moved in the opposite direction by a cam k on a shaft l, turned by the executive pedal. A second cam p on the shaft l, disengages the main-clutch through a spring-returned rod o. The cam contours are so arranged that the following sequence takes place on depression of the executive pedal. First the main-clutch is disengaged, after which the rod b is moved to the left, returning to neutral any previously engaged striking-fork a. In this neutral position there is a dwell to allow time for one of the spring- loaded pegs i to depress the plunger a of the preselected fork, locking it to the rod b. The rod b then continues its leftward movement, taking with it the preselected fork, thereby frictionally synchronizing the new speed. The upward return movement of the executive pedal permits the spring m to return the rod b and with it the preselected fork which engages the dog clutch of the speed which it controls. Following this, the main clutch is allowed to engage. In order to reduce the effort required to depress the executive pedal, the shaft l may carry a third cam subjected to the pressure of a spring-loaded roller, the contour of the cam being chosen to produce any desired assistancecharacteristic.