GB896670A - Semi-automatic two-speed hub gearing - Google Patents

Abstract

896,670. Variable-speed gear. BENDIX CORPORATION. Sept. 19, 1960 [Oct. 5, 1959], No. 32171/60. Class 80 (2). [Also in Group XXXI] A two-speed gear for velocipedes which is shifted by momentarily back-pedalling comprises a driving-sprocket 22 fast with a highspeed shaft 6 having a threaded connection with a coned clutch member 18 frictionally engageable with a surface 21 on a wheel hub 8. The sprocket 22 is fast with a ring gear 23 of a planetary reduction gear having a permanently stationary sun and a planet carrier fast with a low-speed shaft 5 having a threaded connection with a coned friction clutch member 17 engageable with a surface 19 on the hub. The clutch member 18 is formed with an axial extension 36 formed with peripheral ratchet teeth 37 and a facial cam, the number of crests 39 of which is equal to half the number of the ratchet teeth 37. A sleeve 32 is frictionally swivelled on the shaft 6 by spring arms 33 engaging a groove 34 in the shaft, and has pawl arms 35 engaging the ratchet teeth and inwardly-directed projections 38 cooperating with the facial cam. In the position shown, the projections 38 register with troughs 41 of the cam and the clutch member 18 is permitted to engage to drive the hub at high speed. Momentary back-pedalling causes reverse movement of the shaft 6, but not of the clutch member 18 due to a frictional connection of the member 18 with a stationary anchor member 2, and the pawl arms 35 are caused to snap over one ratchet tooth 37. The crests 39 of the cam are now aligned with the members 38 which consequently prevent engagement of the clutch member 18 upon subsequent forward rotation of the sprocket 22. The low speed clutch member 17 is thus permitted to engage.