Spur gears certainly are a type of cylindrical equipment, with shafts that are planetary gearbox parallel and coplanar, and teeth that are straight and oriented parallel to the shafts. They're arguably the easiest and most common kind of gear – easy to manufacture and ideal for an array of applications.
One's teeth of a spur gear have got an involute profile and mesh one tooth at a time. The involute form implies 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. Because of this, spur gears are typically used for lower rate applications, although they can be utilized at almost any speed.