Usage:
NOTE: In June 2001 Paccar began using a new slotted housing brake assembly in winches (Serial Number 0100878 and higher). Basic service instructions are unchanged from the splined housing brake assembly. New friction discs are used in both the clutch and brake and are interchangeable with oil discs, however, new and old discs should not be mixed in the same assembly. A complete slotted brake assembly can replace a splined assembly.
The brake system consists of a multi-disc, spring applied, hydraulically released oil brake. No periodic brake adjustment is required.
Standard Brake
The brake may be used on an intermittent basis to lower a load. However, partially releasing the brake and lowering the load through the brake causes excessive heat build-up after repeated cycles. Allow the brake to cool between lowering cycles to avoid overheating and brake damage. Lowering of loads should be accomplished by moving the joystick to the Reel-Out position, completely engaging the Reel-Out clutch and using the tractor throttle to vary the lowering speed.
The brake assembly is located on the right hand side of the winch in the lower winch case bore on a low PTO and upper winch case bore on a STD PTO winch. Standard PTO shown.
The winch gear train is connected to the brake assembly by the brake hub, attached to the end of the clutch shaft. The brake hub is splined to eight friction discs (15). The friction discs are alternately stacked between steel discs (16), which are splined to the brake housing (14), which is anchored to the winch case.
Two large disc type springs (19) exert a tremendous force against the brake piston (13) and retainer (11) to hold the brake disc pack compressed, locking the winch gear train to the winch case.
Whenever the operator applies a clutch or shifts to "Brake-Off", hydraulic pressure is directed to the brake chamber to overcome the spring force and relieve the compression of the discs. When released, the brake hub and gear train can turn as the brake friction discs slip freely between the brake steel discs.
If the operator returns the controls to the neutral "Brake-On" position, the hydraulic pressure will be exhausted from the brake chamber and the brake springs will quickly reapply to lock the winch gear train to the brake housing through the brake discs.
In most applications, the brake assembly may be removed for service with the winch mounted on the tractor
Removal
Drain oil from the winch into a suitable container and recycle or dispose of used oil in an environmentally responsible manner.
Remove the six 1/2 in. capscrews securing the brake assembly to the winch case. Do not remove the two 3/8 in. capscrews (2) which secure the bearing carrier to the brake housing at this time.
The brake housing has two through-tapped holes which may be used with 1/2 in. NC jackscrews to push the brake housing out of the winch case bore.
If jackscrews are not available, the brake may be removed from the winch case by carefully using a pry bar between the brake housing and winch case. Be careful not to damage the shim set.
Remove the brake assembly from the winch case. The brake assembly weighs approximately 50 lbs (22.7 kg). Retain the shim set for reassembly.
Disassembly
Place the brake assembly onto a work bench with the disc end down. Remove the two 3/8 in. capscrews (2) securing the bearing carrier (18) to the brake housing (14) and remove the carrier. Remove the retaining ring from inside of the carrier and remove the rotary seal and o-ring assembly; replace as required. Inspect the bearing cup in the bearing carrier; replace as required.
Remove and discard the three o-rings (4) from the oil port grooves in the brake housing. Remove the two brake springs (19). Note the position of the springs for reassembly.
Place the brake assembly on the work bench with the disc end facing up.
Remove retaining ring(s) (10) and pressure plate (9).
Remove the friction discs and steel discs (15 and 16).
Inspect the friction discs for wear and flatness. Original friction disc thickness is .138-.144 in. (3.5-3.8 mm). The oil groove depth of a new disc is .015 in. (.38 mm) minimum. Replace friction discs if oil groove is .005 in. (.13 mm) or less, the disc is not flat or friction material is worn unevenly.
Inspect the steel discs (16) for scoring and warping. Replace steel discs as required.
Remove retaining ring (8) and piston retainer (11). Push brake piston (13) free of brake housing. Remove and discard o-rings (5 and 7) from the inner grooves of the brake housing.
Assembly
Thoroughly clean and carefully inspect all components for wear and damage prior to reassembly. Replace components as required.
Install brake piston o-rings (5, 7) into grooves of brake piston. Lubricate o-rings after installation with winch oil or light general purpose grease.
Lubricate brake piston sealing surfaces and install brake piston (13) into the brake housing until full seated.
Install piston retainer (11) over piston hub (13) with the large diameter end facing up. Secure in place with retaining ring (8).
The PA55 and PA56 brake pack requires no adjustment.
Brake Disc Installation
Position the brake housing with the disc end of the housing facing up.
Install the inner pressure plate (12) into the brake housing against the piston retainer (11).
If the clutch shaft group has been disassembled, install the brake hub into the brake housing to keep the friction discs aligned.
NOTE: Pre-lubricate the discs in winch lubricant prior to assembly.
Install the discs by starting with a friction disc (15) (teeth on inside diameter) and alternate with a steel disc (16) (teeth on outside diameter) until a total of eight friction and seven steel discs have been installed.
Install the outer pressure plate (9) and secure in place with a retaining ring (10).
Brake Spring Installation
Position the brake housing with the disc end facing down.
Install the two brake springs (19) into the housing against the brake piston with the dished (concave) side of the springs facing away from each other.
Install three o-rings (4) into the oil port grooves on the outer end of the brake housing.
Lubricate and install the rotary seal with o-ring into the bore of the bearing carrier cover, with the flat side of the rotary seal facing toward the back-up washer and retaining ring. Secure in place with the retaining ring.
If the bearing cup was removed, install a new bearing cup (1) into the bearing carrier cover.
Install o-ring (7) into the groove on the pilot of the bearing carrier.
Install the bearing carrier (18) onto the brake housing while aligning the oil ports between the two housings. Install the two 3/8 in. capscrews (2) and tighten to 31 lb-ft (42 N·m) torque.
Brake Assembly Test Procedure
The following test procedure may be used to check the condition of the brake piston seals and the actual pressure required to fully release the brake.
Lubricate and install an o-ring (4) into the grooved brake housing port labeled with a "B" cast onto the bearing carrier.
Clamp a piece of steel bar over the port now sealed by the o-ring.
Locate the external brake release port next to the "B" cast into the bearing carrier. The port is -6 ORB on current units. Attach a hand pump with an accurate 0-500 PSI (0-3450 kPa) gauge teed into the line.
With the hand pump, slowly increase pressure applied to the brake and record what pressure is required to fully release the brake and permit free movement of the brake discs with a screwdriver.
The brake should be fully released at approximately 230-250 PSI (1590-1720 kPa).
Continue to increase pressure to 350 psi (2410 kPa). Close the hand pump valve and let stand for five minutes. If there is any loss of pressure in five minutes, the brake cylinder should be disassembled for inspection of the seals and sealing surfaces.
While pressure is applied and the brake is released, align the friction discs. If the clutch shaft group has been disassembled, use the brake hub to align the splines of the discs.
Installation
Refer to "Clutch Shaft Service" for additional information.
Install three o-rings in the grooves on the brake housing and three o-rings in the grooves on the winch case.
Install the original shim set between the brake housing and winch case. If the shim set must be replaced, refer to the "Clutch Shaft Service" section for additional information.
Lubricate and install the o-ring into the groove on the outer diameter of the brake housing.
Install the brake assembly into the winch case, aligning all ports of winch case, shim set and brake assembly.
Install the six capscrews which secure the brake housing to the winch case. Coat threads of capscrews with non-hardening thread sealant and tighten to 75 lb-ft (102 N·m) torque.
Refill winch to proper level with recommended oil.