Figure 3-12. Rotary-Selector Switch

TM 1-1500-204-23-4 Figure 3-12. Rotary-Selector Switch h. Motors. Motors transform electrical energy into mechanical energy. Many aircraft devices, from the starter to the automatic pilot, depend on motors for mechanical energy. (1) Types. Series, shunt, and compound motors are the three basic types of dc motors. Induction and synchronous motors are the two general types of ac motors. (2) Inspection. General inspection procedures for motors are as follows: (a) Check the operation of the unit driven by the motor in accordance with the instructions covering the specific installation. (b) Check all wiring, connections, terminals, fuses, and switches for general condition and security. (c) Check brushes for condition, length, and spring tension. Minimum brush lengths, correct spring tension, and procedures for replacing brushes are given in the applicable maintenance manual. (d) Inspect commutator for cleanness, pitting, scoring, roughness, corrosion or burning. (e) Check for high mica (if the copper wears down below the mica, the mica will insulate the brushes from the commutator). WARNING Drycleaning solvent is flammable and solvent vapors are toxic. Use P-D-680, Type II Solvent in a well- ventilated area. Keep away from open flames. Avoid prolonged solvent contact with skin. (f) Clean dirty commutators with a cloth moistened with the recommended cleaning solvent. CAUTION When polishing, never use emery paper since it contains metallic particles which may cause shorts. Damage to equipment may occur. When using compressed air reduce pressure to 30 psi or lower. (g) Polish rough or corroded commutators with fine sandpaper (000 or finer) and blow out with compressed air. (h) Inspect all exposed wiring for evidence of overheating. (i) Adjust and lubricate the gearbox, or unit which the motor drives, in accordance with the applicable maintenance manual covering the unit. Change 3 3-18