Paccar BRADEN HP125B, Installation Maintenance And Service Manual

21

TROUBLESHOOTING

TROUBLE

PROBABLE CAUSE

REMEDY

A

The winch will not lower the 
load or not lower the load 
smoothly.

1. The problem could be a plugged or 

loose pilot orifi ce. The pilot orifi ce 
is a small pipe plug with a hole 
drilled through it, located behind 
the pilot port fi tting on the brake 
valve. If it becomes plugged, it will 
prevent the pilot pressure, from 
the manifold, from opening the 
brake valve. If it becomes loose, 
it will allow an unregulated amount 
of oil in to operate the brake valve 
which causes erratic brake valve 
operation.

2. The friction brake may not be re-

leasing as a result of a defective 
brake cylinder seal.

NOTE: If the brake cylinder seal is 
defective you will usually fi nd oil leak-
ing from the winch vent plug.

3. Friction brake will not release as a 

result of damaged brake discs.

Remove the pilot hose and fi tting from the 
brake valve, then use a 5/32 inch Allen 
wrench to remove the pilot orifi ce.  The  di-
ameter of the orifi ce is approximately .020 
inches. Clean and install the pilot orifi ce 
tightly in the brake valve.

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 gauge and shut-off valve 
to the –4 J.I.C. fi tting in the brake release 
port.

B. Apply 1000 psi to the brake. Close shut-
off valve and let stand for fi ve (5) minutes.

C. If there is any loss of pressure in fi ve (5) 
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. 
Check stack-up height as described in “Mo-
tor Support-Brake Cylinder Service”.

B

Oil leaks from vent plug.

1. Same as A2.

2. Motor seal may be defective as a 

result of high system back pres-
sure or contaminated oil.

Same as A2.

System back pressure must not exceed 150 
psi.  Inspect hydraulic system for a restric-
tion in the return line from the control valve 
to the reservoir. Be sure control valve and 
plumbing is properly sized to winch motor. 
Ensure case drain line is connected and 
adequate size.

Oil analysis may indicate contamination 
has worn motor shaft and seal.  Thoroughly 
fl ush entire hydraulic system and install 
new fi lters and oil. Install new motor seal.