has become body oxidized, a preliminary flushing with a hot aqueous emulsion may be required, followed, if necessary, by flushing with a mixture of alcohol and light mineral solvent. always be with hot light oil. The final flushing should Relubricate in accordance with the recom- mendation given in the instructions for lubrication of ball bearings. BEARING WEAR A ball bearing is subject to negligible friction wear unless the lubricant becomes contaminated with abrasive material, Thus, if properly lubricated, a ball bearing will not wear gradually, and air-gap measurements are unnecessary. If ball bearings fail, they will do so ina relatively short space of time, generally as a result of excessive abuse. A bad bearing can usually be detected by the presence of vibration and noise long before complete failure can cause damage to the machine. eoMOVAL OF BEARINGS In removing ball bearings fron the shaft, pressure should be applied against the inner race, otherwise the bearing may be seriously damaged. Bearings may be removed by pressing out the shaft in an arbor press, or by means of bearing pullers. Always press or pull straight and square to avoid scoring the shaft or damaging the bearing. CARE OF WINDINGS Machines and spare coils should be stored in a clean, dry place until they are installed, Heat should be supplied to prevent "sweating" due to sudden temperature changes. -fachines that have been subjected to moist atmosphere in transit, have been idle for some time without heat, or have become wet by accident, should be thoroughly dried out before being placed in service. Heating may be accomplished by passing current 3-34