GB523174A - Improvements relating to gear change mechanism for motor vehicles - Google Patents

Abstract

523,174. Controlling change-speed gear; ratchet gearing. BIRMINGHAM SMALL ARMS CO., Ltd., and PERKINS, H. Dec. 28, 1938, No. 37578. [Classes 80 (ii) and 80 (iii)] In Specification 486,144 a gear changing mechanism, more particularly for motor cycles, is described in which a-shaft 7, Fig. 2, connected to the gear change mechanism is adapted to be moved step-by-step by repeated movements of a lever 13. This is effected by a pair of pawls 11, Fig. 5, mounted on a carrier plate 10 and adapted to engage a ratchet member 3 fixed on a shaft 1 which also carries a toothed quadrant 4 engaging a pinion 6 on the shaft 7, the quadrant having notches 8 engaged by a spring detent 9. The lever 13 is integral with a sleeve rotatable on the shaft 1, which sleeve carries a pawl actuating plate 14 having a lug 15 adapted to engage the tail of the pawls which are normally held clear of the ratchet teeth by light springs 27. The lever 13 is brought to mid-position by a spring 16 coiled around the sleeve and having its ends crossed to engage a pin 17 fixed to the gear casing, and a pin 20 on the pawl carrier plate. This spring does not satisfactorily ensure tilting of a pawl to cause it to engage the ratchet teeth and, to overcome this objection, according to the invention a spring-controlled detent 23 is employed and arranged to engage a notch or gap 24 in the edge of the carrier plate when in its central position. This detent prevents movement of the carrier plate before the nose of the pawl is brought into engagement with the ratchet teeth, thus obviating the possibility of a gear being slipped, which is liable to occur when the spring 16 has become weakened.