This gear box is composed of an input set of helical gears, two spur gears and a planetary. The main advantage of the arrangement of this gear box is the fact that it is possible to have an equal power distribution to two output shafts. The equal division of torque (or power) takes place at the planetary.
A planetary is composed of three principle members: a sun pinion (in this case the input power member), a planetary carrier (the output torque member which powers an output pinion), and a ring gear. This ring gear has two sets of teeth; an internal set of teeth which is used in a planetary in a normal way and an external set of teeth which is on an external gear which is splined to the ring gear. This gear is mounted on bearings to rotate independently from the planetary carrier. This gear with the external is used as an output power member to power the output gear.
The three principle planetary members are conveniently used to again divide the power into two paths, one being the output carrier and the second one being the external ring gear. It can be seen that the carrier powers one output pinion (marked A) and the ring gear at the same time powers a second output pinion (marked B).
Simply summarizing the arrangement; there is one input source of power which happens to be a helical gear in this case. There is a power and speed division at the planetary to provide two paths of power flow. This allows the one input source of power to be divided into two sources of power, which are the two output pinions (A and B) that drive the single output gear. This method obtains the power multiplication that is desired.
May 1999