Classification of Gears:
There are different kinds of arrangement of shafts that are utilized in practice. Accordingly to the relative positions of shaft axes, different kinds of gears are used.
Parallel Shafts:
In this, the shaft axes lie in parallel planes and keep parallel to one another.
Intersecting Shafts:
The motion among two intersecting shafts is corresponding to rolling of two conical frustums from kinematical view point.
Skew Shafts:
These shafts are non-intersecting and non-parallel.