TM 55-2210-224-12 Table 4-1.  Unit Preventive Maintenance Checks and Services (continued) W - Weekly M - Monthly Q - Quarterly Interval Item Item to be No. W M Q Inspected Procedures 16 Trainline Air Inspect trainline air hoses and fittings for Hoses and breaks, cracks, and damage.  Check for Fittings leakage and tighten fittings as required. 17 Multiple-unit Check Mulitple-unit control jumpers for Control Jumpers breaks and frayed wires and for loose connections. 18 Multiple-unit Check receptacles for cracks, breaks, and Control and damage.  Check terminals for corrosion and Engine Jacket loose contacts.  Check covers and springs Heater Recept- for damage. acle. 19 Resistors and Inspect resistors and shunt devices for Shunt Devices broken porcelain, loose connections, and open or touching resistance elements. 20 Safety Warning Remove clapper (para 4-20) and lubricate in Bell Assembly accordance with LO 55-2210-224-12.  Inspect for wear.  Install clapper. 21 Wiring Inspect wiring for cracks, breaks, and deterioration 22 Main Generator a.  Remove brush covers and inspect interior for grit, dust, and dirt. WARNING Compressed air used for cleaning purposes will not exceed 30 psi (207 kPa).  Do not direct com- pressed air against skin.  Use goggles or full face shield. b.  Service main generator by blowing out with dry compressed air.  Lubricate in accordance with LO 55-2210-224-12. c.  Inspect brush holders and brushes for grit and dirt.  Check that brushes do not stick in holders.  Check for proper spring pressure (para 4-35).  Check for minimum brush length of 1-1/2 inches (38.10 mm). 4-6