Figure 7-21. - Magnetic switch controlled by three start-stop stations.

Figure 7-22. - Control circuit for three start-stop stations.

Figure 7-23. - Control circuit for two start-stop stations.

Greasing Ball Bearings

Only a high grade of grease with the following general characteristics should be used for ball-bearing lubrication:

1. Consistency, a little stiffer than that of petroleum jelly, maintained over the operating temperature range

2. Melting point preferably over 150°C

3. Freedom from separation of oil and soap under operating and storage conditions

4. Freedom from abrasive matter, acid, and alkali

In greasing a motor, you must take care not to add too much grease. Overgreasing will cause too high an operating temperature with resulting expansion and leaking of the grease, especially with large bearings operated at slow speeds.

CAUTION

Always review the Material Safety Data Sheet (MSDS) for greases, oils, lubricants, and other hazardous materials before use. Avoid pro- longed skin contact with lubricants. Dispose of waste materials in an environmentally responsible manner.

Pressure-Relief Systems

The following procedures are recommended for greasing ball-bearing motors equipped with a pressure-relief greasing system.