Rotor and End Plates

The rotor in the single-phase motor is similar to the rotor in the three-phase induction motor. The single-phase rotor also has the basic shape of a squirrel cage, so it's also called a squirrel-cage rotor. It has fan blades cast into the aluminum frame to provide cooling air for the motor.

The ends of the rotor provide the shaft for the load and the bearings. The rear part of the shaft is machined to mount inside the shaft bearing, and the front part of the shaft is extended 3 to 4 inches beyond the front bearing to provide a means of mounting pulleys or gears to drive the load.

The end plates are located on each end of the stator. They are secured in place by four bolts that are inserted completely through the stator. They house the bearings for the rotor shaft to ride on. The bearings can be the sleeve type or ball type. The ball bearing is usually lubricated for life and sealed, while the sleeve bearing must be lubricated frequently with several drops of high-grade electric motor oil. Recall that the sleeve bearing uses felt wicking to hold the excess lubricating oil in contact to the shaft. That is, the end plates must be mounted with the lubricating port pointing upward so that the oil will be pulled to the wicking by gravity.

Centrifugal Switch for the Start Winding