Motor cooling
Electric motors generate heat during operation and must be supplied with cooling air. A radial fan is mounted on the motor shaft which takes in the required volume of air. The open construction of a universal motor allows a stream of cooling air to flow directly through the motor and to dissipate the heat quickly.
AC motors apply external cooling of the closed motor housing. Reserve capacity and overload resistance are slightly limited by this.
Industrial power tools benefit from direct cooling. In addition, they are equipped with a seal against dirt and dust between rotor and stator.