A gearbox transmits rotational movement from a driving member to a driven member. The gearbox includes a pinion gear disposed inside a housing. The gear defines an axial bore and rotates in response to rotation of the driving member. An output member extends through the axial bore and engages therewith such that the output member rotates in response to rotation of the gear. The output member extends to a position outside the housing to rotate the driven member. A clamping nut is threadably coupled to the output member and abuts the gear thereby retaining the output member and the gear together. A bearing is disposed radially between the gear and the housing. The bearing rotatably supports the gear and the output member.