Spur gears certainly are a type of cylindrical equipment, with shafts that are parallel and coplanar, and the teeth that are directly and oriented parallel to the shafts. They’re arguably the simplest and most common type of gear – easy to planetary gearbox manufacture and suitable for a wide variety of applications.
The teeth of a spur gear have an involute profile and mesh one tooth at a time. The involute type means that spur gears only create radial forces (no axial forces), but the method of tooth meshing causes high stress on the gear the teeth and high noise production. For this reason, spur gears are usually used for lower velocity applications, although they can be used at nearly every speed.