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6. If minor adjustment is necessary, loosen the 1/4" lock nut located on the control arm, which will allow
the control arm to oscillate approximately +/-1". Retighten the 1/4" adjusting lock nut from 2 to 4 ft-lbs.
Air brake maintenance
Successful maintenance of the air brake system depends upon systematic inspection and repair at regular
intervals. The length of these intervals depends upon the trailer operation and mileage.
Adjustments, inspections, and minor repairs that can be performed by you are listed below. These
procedures must include immediate replacement of all worn or damaged parts.
Reservoir tank
The first requirement in an air brake system is clean air at proper pressure. The operator must open the drain
cock on the underside of the reservoirs until all moisture has escaped. Drainage should be done periodically to
remove water the sludge from the system. This is especially important in cold weather to forestall freezing and
obstruction of the lines and valves. Each tank must be drained completely to insure removal of condensation.
After removing moisture, close the drain cock and inspect reservoirs for looseness or damage. Make sure all
connections are tight and brake lines are properly supported.
Gladhands
Inspect gladhands to insure proper operation without obstructions. With the trailer connected to the truck
tractor and air in the system, coat the gladhands and mounting with soapsuds to make sure there is no leakage.
Be certain gladhands seals are in good condition and not saturated with grease, oil or other foreign material.
We recommended annual replacement of gladhands seals.
Brake tubing, lines, fittings & hoses
Visually inspect brake lines and hoses for loose connections, chafing, cracks, breaks, cuts, bruises, broken-out
sections and deterioration. Replace immediately upon first sign of the above. Exercise extreme caution when
working or welding around nylon tubing, if so equipped. It is recommended that tubing in areas where welding
operations are performed be removed prior to welding operations, and reinstalled after welding is completed.
If tubing removal is not practical, the tubing must be shielded from welding sparks and/or heat damage.
Service and spring brake chambers
Visually check air chamber clamp bands and mounting nuts for tightness. Torque chamber mounting nuts 75
to 100 ft. lb. Check chambers for damage or dents and sign of leaks.
CAUTION!
Disassembly and repair of any spring brake is a dangerous and complex task, which should not be undertaken
by an inexperienced mechanic. Special tools and information are required if serious personal injury is to be
avoided. Refer problems of this sort to
Pratt
Air valves
Inspect all air valves for leaks. If excessive leakage is found, the valve must be repaired or replaced. We
recommend that air valves be replaced when necessary with new or rebuilt valves. Replacement maintenance
and seal kits are available from Your PRATT Dealer. Call 1-800-546-7728 for the Pratt authorized Service
Center nearest you. Inspect brake drums. Any accumulation of mud, dirt or rust on the drums should be
removed. Any broken or cracked drums should be removed from service.
Brake lining
Inspect and check the brake lining thickness. Brake lining must be replaced if excessively worn or if coated
with oil, grease, or foreign material
.
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