Drive Coupling Device
A drive coupling device comprises an outer drive shaft adapted to be driven for rotation by a gearbox output, an outer quill shaft coupled to the outer drive shaft and arranged to be driven for rotation thereby, an inner quill shaft arranged coaxially with the outer quill shaft and moveable, axially, between an engaged position in which a dog clutch arrangement is engaged to transmit drive between the outer quill shaft and the inner quill shaft, and a disengaged position in which the dog clutch arrangement is disengaged, a support rod, and support bearing means provided on the support rod and by which the outer quill shaft is supported for rotation relative to the support rod, wherein the outer quill shaft is further supported, when the dog clutch arrangement is engaged, by the inner quill shaft.
1 . A drive coupling device comprising an outer drive shaft adapted to be driven for rotation by a gearbox output, an outer quill shaft coupled to the outer drive shaft and arranged to be driven for rotation thereby, an inner quill shaft arranged coaxially with the outer quill shaft and moveable, axially, between an engaged position in which a dog clutch arrangement is engaged to transmit drive between the outer quill shaft and the inner quill shaft, and a disengaged position in which the dog clutch arrangement is disengaged, a support rod, and support bearing means provided on the support rod and by which the outer quill shaft is supported for rotation relative to the support rod, wherein the outer quill shaft is further supported, when the dog clutch arrangement is engaged, by the inner quill shaft.
2 . A device according to claim 1 , wherein the inner quill shaft includes a sleeve within which a part of the outer quill shaft is located, the sleeve providing support for the outer quill shaft when the dog clutch arrangement is engaged.
3 . A device according to claim 1 , wherein the outer drive shaft is coupled to the outer quill shaft by a splined coupling.
4 . A device according to claim 1 , wherein an actuator arrangement is provided to drive the inner quill shaft for axial movement relative to the outer quill shaft.
5 . A device according to claim 1 , wherein, when the dog clutch arrangement is disengaged, the inner and outer quill shafts do not engage one another, and so the outer quill shaft is no longer supported by the inner quill shaft.
6 . A device according to claim 5 , wherein the part of the outer quill shaft located, in use, within the sleeve is conveniently of stepped form, including a support section which, when the dog clutch arrangement is engaged, is located within and engages the sleeve, and which is retracted from the sleeve when the dog clutch arrangement is disengaged, and a reduced diameter section.
7 . A device according to claim 1 , wherein the outer drive shaft is of two part form.