Manitowoc NATIONAL CRANE 900A - ANTI-TWO BLOCK TROUBLE DIAGNOSIS - ELECTRICAL

5-
72,"7
$74<)$6
3$&'$%4;4&
'%56K$%
Check for voltage across
leads of limit switch with
weight supported
Fuse blown
Check limit switch or actuator
arm for sticking - Repair or
replace switch
Test HCAS & ATB relays for
proper operation (see
Schematic)
Replace fuse
Replace relay
Examine solenoid valve for
sticking spool due to corrosion,
burrs, contamination, etc.
YES NO
YESNO
NORMAL
RELAY OPERATION
FAULTY
RELAY OPERATION
Reference Only