Spur gears certainly are a type of cylindrical gear, with shafts that are parallel and planetary gearbox coplanar, and teeth that are straight and oriented parallel to the shafts. They’re arguably the simplest and most common type of gear – simple to manufacture and ideal for an array of applications.
One’s teeth of a spur gear have an involute profile and mesh one tooth at a time. The involute type means that spur gears only produce radial forces (no axial forces), however the method of tooth meshing causes high pressure on the gear the teeth and high noise production. Due to this, spur gears are usually used for lower speed applications, although they can be utilized at almost any speed.