Troubleshooting - BRADEN CH400B Installation Maintenance And Service Manual

TROUBLE
A
The hoist will not lower the
load or not lower the load
smoothly.
B
Oil leaks from vent plug.

TROUBLESHOOTING

WARNING
CAUTION
!
If a hoist exhibits any sign of erratic operation or load-
control difficulties (such as load creeping or chattering),
appropriate troubleshooting tests and repairs should
be performed immediately. Continued operation in this
manner may result in property damage, serious person-
al injury, or death.
PROBABLE CAUSE
1. The friction brake may not be releasing
as a result of a defective brake cylinder
seal.
NOTE: If the brake cylinder seal is defec-
tive you will usually find oil leaking from
the hoist vent plug.
2. Friction brake will not release as a re-
sult of damaged brake discs.
1. Same as A1.
2. Motor seal may be defective as a result
of high system back pressure or con-
taminated oil.
!
Check brake cylinder seal as follows:
A. Disconnect the swivel tee from the brake
release port. Connect a hand pump with ac-
curate 0-2000 PSI (0-13,000 kPa) gauge
and shut-off valve to the –4 JIC fitting in the
brake release port.
B. Apply 1,000 PSI (6,900 kPa) to the brake.
Close shut-off valve and let stand for five
minutes.
C. If there is any loss of pressure in five
minutes, the brake cylinder should be dis-
assembled for inspection of the sealing sur-
faces and replacement of the seals. Refer
to "Motor Support-Brake Cylinder Service."
Disassemble brake to inspect brake discs.
Same as A1.
System back pressure must not exceed 150
PSI (1,030 kPa) for gear motor, 30 PSI (207
kPa) for piston motor. Inspect hydraulic sys-
tem for a restriction in the return line from
the control valve to the reservoir. Be sure
control valve and plumbing is properly sized
to hoist motor.
Oil analysis may indicate contamination has
worn motor shaft and seal. Thoroughly flush
entire hydraulic system and install new fil-
ters and oil. Install new motor seal.
14
REMEDY