Patent ID: 7770480

Claim:
A transmission system comprising first and second rotatable shafts, said first shaft having a longitudinal axis, and means for transferring drive from one of the shafts to the other shaft comprising first and second gear wheels each rotatably mounted on the first shall and having drive formations formed thereon, a selector assembly for selectively transmitting torque between the first shaft and the first gear wheel and between the first shaft and the second gear wheel, wherein the selector assembly comprises an actuator assembly and first and second sets of engagement members, wherein each engagement member includes a first engagement face for engaging the first gear wheel, a second engagement face for engaging the second gear wheel, and a body that is substantially rigid such that the first and second engagement faces are arranged in a fixed relationship to one another, said actuator assembly including a shift fork assembly arranged to move each of the first and second sets of engagement members in first and second directions along the longitudinal axis of the first shaft into and out of engagement with the first and second gear wheels independently of each other, the arrangement being such that when one of the first and second gear wheels is selected by the first and second sets of engagement members backlash between the first and second sets of engagement members and the drive formations when moving between acceleration and deceleration is less than or equal to four degrees, and the transmission being further arranged such that when the first gear is selected by the first and second sets of engagement members and a driving force is transmitted the second set of engagement members drivingly engages the selected first gear wheel, and the first set of engagement members is then in an unloaded condition, wherein the shift fork assembly is arranged to move the unloaded first set of engagement members into driving engagement with the second gear wheel to effect a gear change.