Abstract: A cooling system includes a rotor structure, a first end plate and a second end plate. The rotor structure includes a silicon steel, magnets and a shaft. The first end plate is at a first end of the silicon steel, and the first end plate is recessed with a first-shaped oil groove and a second-shaped oil groove. The second end plate is at a second end of the silicon steel, and the second end plate is recessed with a first-shaped oil groove and a second-shaped oil groove. The first-shaped oil groove of the first end plate is connected to the second-shaped oil groove of the second end plate to form a first cooling path. The second-shaped oil groove of the first end plate is connected to the first-shaped oil groove of the second end plate to form a second cooling path.

Abstract: A gear-skipping prevention mechanism including a first gear, a second gear, and a positioning member is provided. The first gear is sleeved on an axle. The second gear meshes with the first gear and has a first guiding groove. The positioning member includes at least one body and at least one engaging portion. Each of the at least one body has a sleeving hole. The sleeving hole is sleeved on the axle, and each of the at least one engaging portion is slidably disposed in the first guiding groove to limit a relative position between the first gear and the second gear.

Abstract: A gear-skipping prevention mechanism including a first gear, a second gear, and a positioning member is provided. The first gear is sleeved on an axle. The second gear meshes with the first gear and has a first guiding groove. The positioning member includes at least one body and at least one engaging portion. Each of the at least one body has a sleeving hole. The sleeving hole is sleeved on the axle, and each of the at least one engaging portion is slidably disposed in the first guiding groove to limit a relative position between the first gear and the second gear.