ABSTRACT
The function of a gearbox is to transmit rotational motion from a driving prime mover to a driven machine. The driving and driven equipment may operate at different speeds, requiring a speed-increasing or speed-decreasing unit. The gearbox therefore allows both machines to operate at their most efficient speeds. Gearboxes are also used to change the sense of rotation or bridge an angle between driving and driven machinery. The gearbox configuration chosen for a given application is most strongly influenced by three parameters: physical arrangement of the machinery, ratio required between input and output speeds, and torque loading. The size of gearbox required for a given application is dependent primarily on how large the gear pitch diameters and face widths are. These dimensions are determined on the basis of tooth stresses which are imposed by the transmitted tooth load. Parallel offset or concentric shaft gearboxes incorporate gears with spur, single helical, or double helical tooth forms.
