| 摘要 |
A hydraulic shift gear mechanism for a bicycle having a positioning mechanism for controlling the motion of the piston of a master cylinder assembly 300 is disclosed, wherein the master cylinder assembly 300 is in communication with a slave cylinder for operation of a derailleur. The positioning mechanism preferably includes a pivot shaft spaced apart from the handlebar, a rotating member rotatable about the pivot shaft, a push mechanism for rotating the rotating member in a first direction P and a return mechanism for rotating the rotating member in a second direction R. The push mechanism preferably includes a first latch segment which engages a corresponding push pawl 470 to rotate the rotating member. The return mechanism preferably comprises a second latch segment and a return pawl 460, the return pawl 460 having a first claw 463 and a second claw 464 which alternately engage the second latch segment. The rotating member is preferably operatively engaged with the piston of the master cylinder 300, wherein the rotation of the rotating member translates to an axial motion of the piston rod 332. In a more preferred embodiment of the invention, an adjuster piston is threadingly engaged with the master cylinder assembly 300 for adjusting the initial position of the slave cylinder. <IMAGE> |
