Patent GB-1479938-A (GB)
Title: Operating mechanism for a bicycle attachment
IPC: B62M25/04
Filed: 1974-07-26
Abstract: 1479938 Bicycle control lever assemblies SHIMANO INDUSTRIAL CO Ltd 26 July 1974 [31 July 1973] 33030/74 Heading B7E A control lever assembly for controlling a bicycle attachment, e.g. a multiple speed gear or brakes, through a control wire 10, comprises a shaft 2 fixed to a bracket 1 for mounting on the bicycle frame, a winding body 3 for receiving the wire 10 rotatably mounted on the shaft 2 and having means to retain an end 10a of the wire thereon, a lever 4 rotatable relative to the shaft, means causing the lever 4 and body 3 to rotate together when the resistance to rotation of the body 3 is below a predetermined value and the lever 4 to rotate independently of the body 3 when the resistance to rotation of the latter is above the predetermined value, and means which enable the body 3 to rotate through more than a predetermined arc in one direction of rotation but which prevent the body from rotating through more than the predetermined arc in the opposite direction of rotation. In the embodiment of Figs. 2, 6 and 8 the winding body 3 has a winding portion 32 and an axle portion 31 on which the lever 4 is rotatably mounted. A spring 7 mounted around the shaft 2 has an end 7a disposed in an arcuate groove 35 at the inner periphery of the winding portion 32. A screw 5 screwed into a bore in the shaft 2 retains the body 3 and lever 4 on the shaft and maintains a dished spring disc 6 in frictional engagement with the lever 4 and body 3 so that the lever and body will rotate together unless rotation of the latter is resisted. In operation of the mechanism of Figs. 2, 6 and 8 with a multiple speed gear the lever 4 is in the position shown in Fig. 6 at one end of the gear range. To move to the other end of the gear range the lever 4 and body 3 need to be rotated clockwise through 90 degrees only, if the control wire 10 is correctly adjusted, this movement of the body 3 being permitted by the groove 35 without engagement of the end face 35a of the groove with the spring end 7a. If however the wire 10 has become elongated through constant use it will be necessary to rotate the lever 4 and body 3 through a larger angle, (90 + α) degrees-Fig. 8, to take up the slack in the wire 10 in order to reach the other end of the gear range. In this case the end face 35a will be urged against the spring end 7a causing the spring 7 to unwind from the shaft 2 and thus allowing the body 3 to rotate beyond 90 degrees. On returning to the said one end of the gear range the body 3 can rotate through 10 degrees only before the end face 35b of the groove 35 contacts the spring end 7a and when this occurs the spring 7 tightens on the shaft 2 thus preventing further rotation of the body 3. However the spring disc 6 now allows the lever 4 to be rotated independently of the body 3 to be restored to its Fig. 6 position, whereby the position of the lever corresponding to said one end of the gear range is always the same even if adjustment of the control wire 10 has been effected. The spring 7 may be replaced by a ratchet 22 and pawl 9 device-Fig. 4, and a spring (8) (Fig. 5 not shown) coiled around the axle portion 31 and connected to the lever 4 may be used in place of the spring disc 6, the spring (8) being released from the axle portion 31 when rotation of the winding body 3 is stopped.