TM 55-1930-209-14&P-13o.With forward button pushed, check voltage at inputs to resistor across terminal pairs K1 and K2, K1 andK3, and K2 and K3 for 440 Vac. If voltage across all terminal pairs is 440 Vac, go to step p. If voltageacross any terminal pair is not 440 Vac, replace wire(s) from 1 M to resistor.p.With reverse button pushed, check voltage at inputs to resistor across terminal pairs K1 and K2, K1 andK3, and K2 and K3 for 440 Vac. If voltage across all terminal pairs is 440 Vac, go to step q. If voltageacross any terminal pair is not 440 Vac, replace wire(s) from 2M to resistor.q.Open (OFF) disconnect switch and make continuity check as follows:WARNINGMake sure bridge crane motor controller is electrically dead before making continuity checks. Red tagcircuit breaker wire with: “WARNING - DO NOT ACTIVATE. REPAIRS BEING MADE.”(1) Check resistance of three resistors between point P1 and Q1, P2 and Q2, and P3 and Q3 for 3ohms. If resistance is 3 ohms, go to step (2). If resistance is not 3 ohms, reset or replace resistor(s).(2) Check continuity of wires between points Q1 and R1, Q2 and R2, and Q3 and R3. If continuityexists, go to step (3). If open circuit exists, repair or replace wire(s).(3) Check continuity of overload protection B-OL’S between points R1 and S1, R2 and S2, and R3 andS3. If continuity exists, replace wire(s) from B-OL’S to motor connections. If open circuit exists,replace overload protection B-OLS.r.Check voltage between points A and B to brake inputs for 440 Vac. If voltage is 115 Vac and magneticcoil is not energizing, replace magnetic coil. If voltage is not 115 Vac, replace wire(s) from points J1 andJ2 to magnetic coil points A and B.2-16.5 Bridge Crane Trolley BrakeWARNINGShut down bridge crane system before attempting maintenance. Be sure to open (OFF) circuitbreaker 6P5 on power panel 1. Red tag circuit breaker with: “WARNING- DO NOTACTIVATE.REPAIRS BEING MADE.” However, if one of the bridge crane assemblies must be operational,disconnect and tape voltage input wires at crane reel of bridge crane to be shut down.2-16.5.1 Cleaning and inspectiona.Make sure bridge crane system is electrically dead by opening (OFF) power panel 1 circuit breaker 6P5. Ifone of the bridge cranes must be operational, open (OFF) and secure circuit breaker 6P5 and disconnectand tape voltage input cable terminals at crane reel of bridge crane to be repaired. Then close (ON) circuitbreaker 6P5 so other bridge crane is operational.b.Wipe clean exterior of brake with clean cloth. Vacuum clean or clean inside with electrician’s brush. Avoidusing solvents for cleaning inside of brake. Solvents leave a greasy film on components that may reduceelectrical continuity.c.Visually inspect exterior and interior for damage. Check friction disk for wear. Check springs and othercomponents for damage or loose parts. Check magnet assembly for indications of burns, corrosion, looseconnections, or damaged wires. Check exterior for chipped paint. Clean corrosion from terminals, tightenloose connections, and replace damaged parts. Adjust or replace worn friction disk. Replace bad magnetassembly.2-26
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