Patent ID: 8424405

Claim:
A mainshaft assembly for a gearbox, the mainshaft assembly comprising: a mainshaft; a first and a second drive gear, each carried for rotation about the mainshaft; a first and a second hub, each hub being associated with a respective drive gear, each hub including engagement means operable to selectively couple the hub with the drive gear causing the drive gear to rotate with the hub or uncouple the hub from the drive gear to allow the drive gear to rotate with respect to the hub; respective drive connection means associated with each hub being operative to connect the hub to the mainshaft for rotation with the mainshaft or to allow rotation with respect to the mainshaft, the connection means including connection elements having a deployed position in which the connection elements prevent relative movement between the hub and the mainshaft and a withdrawn position in which such relative movement is allowed; in which, upon connection of both the first and second hubs by their respective engagement means to each corresponding drive gear, the drive connection means operates to connect one of the hubs to the mainshaft when torque is applied to the mainshaft through the hub and to connect the other one of the hubs to the mainshaft when torque is applied to the other one of the hubs through the mainshaft; wherein the drive connection means includes biasing means providing a biasing force that causes the connection elements to adopt their deployed position, and control means which, in an engaged condition, retains the connection elements in their deployed position, and in a disengaged condition, allows the connection elements to be moved against the biasing force to their withdrawn position.