WINCHES
SUB-SECTION 5J
adjust each brake assembly as described under the topic
W inch Brake.
INSTALLATION. Use the following procedure to install a
new of overhauled winch:
1. Position the winch on the winch mounting. Install three
of the four mounting screws with a hardened washer on
each screw. Tighten the screws to 300 ft-lbs (41.5 m-kg)
lubricated.
2. Measure the clearance between the winch base and
winch mounting at the remaining mounting hole. Install
shim stock as required to fill any gap that may exist.
3. Install the remaining screw with a hardened washer and
tighten the screw to 300 ft-lbs (41.5 m-kg) lubricated.
WINCH BRAKE (15U26)
DESCRIPTION. The winch brake used on the P&H winch
Figure 5J-22. Dimensions for Spring Setting
is a spring set, hydraulically released disc type brake. When
pressure is applied to the brake cylinder, as it is when the
winch lever is in the lower position, the brake springs are
NOTE
compressed. This relieves the pressure on the friction pads,
and allows the brake disc to turn freely.
It may be necessary to reduce the spring pressure by
backing off nuts (1) to obtain the clearance required
When the pressure is vented from the brake cylinder, the
to remove and replace the friction pads.
brake springs force the friction pads into contact with the
brake disc. This applies braking torque to the winch drum
3. Install the new pad assemblies on the piston side car-
through the Sprag clutch, driveshaft and planetary re-
riers, and secure them with the screws, lockwashers,
duction.
washers, and bushings. Check that the pad assembly nearest
the piston housing slides freely on the bushings.
ADJUSTMENT. Maximum recommended brake torque is
4. Adjust the brake as described under the topic Adjust-
obtained by tightening the two large nuts (1, Figure 5J-22).
ment.
compressing the springs evenly. until the dimension
measured from the inside surface of spring retainer plate (2)
SEAL REPLACEMENT. The piston which releases the
to the machined back surface of casting (3) is exactly 1/8
brake has an D-ring seal and a back-up ring which must be
inch (3.17 mm). Never over-compress the springs; always
replaced if Ieakage around the piston Is excessive. To re-
maintain the 1/8 inch (3.17 mm) check dimension.
place the O-ring seal, proceed as follows (see Figure 5J-23):
To ensure even spring pressure and reliable operation of the
1. Carefully loosen nuts (1) to relieve spring pressure. Then
hydraulic release mechanism, check that dimension "A", as
remove the nuts, retainer plate, and color coded springs. Be
measured at the end of the spring retainer plate and casting,
sum to note the location of the springs before removing
is the same on both sides. Failure to maintain even spring
them.
pressures may cause the hydraulic piston to jam or malfunc-
tion.
2 Disconnect the hydraulic pressure line connected to the
piston housing if the brake has not been removed from the
FRICTION PAD REPLACEMENT. The friction pads of
winch.
the winch brake should be replaced when they have worn
to a thickness of 1/8 inch (3.17 mm). To replace the
3. Slide the piston housing off the studs. Open the bleeder
screw to allow air to enter the piston housing bore while
friction pads, proceed as follows (see Figure 5J-23):
the piston is removed. Then remove the piston from the
1. Remove the screws, lockwashers, washers, and bushings
piston housing, and remove the O-ring and backup ring
securing the friction pads to the piston side carriers.
from the piston.
2. Withdraw the friction pad assemblies, noting that the
4. Examine all components for damage. Replace any defec-
assembly with the slotted holes is nearest the piston hous-
tive parts, especially weak springs. All springs should
ing.
exhibit the same free Iength.
5J-10
