TM 55-1930-209-14&P-13
o.
With forward button pushed, check voltage at inputs to resistor across terminal pairs K1 and K2, K1 and
K3, and K2 and K3 for 440 Vac. If voltage across all terminal pairs is 440 Vac, go to step p. If voltage
across 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 and
K3, and K2 and K3 for 440 Vac. If voltage across all terminal pairs is 440 Vac, go to step q. If voltage
across 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:
WARNING
Make sure bridge crane motor controller is electrically dead before making continuity checks. Red tag
circuit 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 3
ohms. 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 continuity
exists, 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 and
S3. 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 magnetic
coil is not energizing, replace magnetic coil. If voltage is not 115 Vac, replace wire(s) from points J1 and
J2 to magnetic coil points A and B.
2-16.5 Bridge Crane Trolley Brake
WARNING
Shut down bridge crane system before attempting maintenance. Be sure to open (OFF) circuit
breaker 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 inspection
a.
Make sure bridge crane system is electrically dead by opening (OFF) power panel 1 circuit breaker 6P5. If
one of the bridge cranes must be operational, open (OFF) and secure circuit breaker 6P5 and disconnect
and tape voltage input cable terminals at crane reel of bridge crane to be repaired. Then close (ON) circuit
breaker 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. Avoid
using solvents for cleaning inside of brake. Solvents leave a greasy film on components that may reduce
electrical continuity.
c.
Visually inspect exterior and interior for damage. Check friction disk for wear. Check springs and other
components for damage or loose parts. Check magnet assembly for indications of burns, corrosion, loose
connections, or damaged wires. Check exterior for chipped paint. Clean corrosion from terminals, tighten
loose connections, and replace damaged parts. Adjust or replace worn friction disk. Replace bad magnet
assembly.
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