Demco CR 108, Operator'S Manual

Page: 36 / 104

36
CARE AND ADJUSTMENT OF BRAKES
The trailer brake system will perform safely and efficiently only as long as you maintain
it properly and do not abuse it. Trailer brakes should be inspected and adjusted
frequently in connection with a Trailer Preventative Maintenance program. Out-of-
adjustment brakes can cause increased stopping distance, shorter brake component
life, and a greater tendency for the trailer to jackknife.
AIR SYSTEM AND BRAKE OPERATION
• Proper operation of the brake system requires a firm seal between the air brake glad
hands. Inspect the glad hands for rubber washer damage and cracked housing. Inspect
the air hoses for cracking and for frayed connections.
• Keep the air system clean. Primary and emergency air tanks should be drained daily
to remove moisture and other contaminants, especially during cold weather operations.
• Some air valve manufacturers discourage the use of any kind of air line antifreeze.
It may result in deterioration of seals in these valves.
• If you use Teflon tape or other thread sealers to seal threaded connections in your
air lines, be careful not to allow pieces of the sealer to enter the air system. They can
clog passages into the valves.
• Keep the air system tight. The air system cannot be charged properly if there are
leaks in reservoirs, lines, hoses or valves. Always check the tractor pressure gauge for
unusual drops or extended buildup times.
• Run the tractor engine until the air brake system pressure gauge shows at least 70
psi. Listen for air leaks. With the engine off, check the gauge reading with no brakes
applied. The gauge reading loss should not exceed three pounds in one minute.
• With the engine still off, apply the brakes fully for two minutes. The gauge reading
loss should not exceed four pounds per minute.
• With engine still off, slowly open a drain cock in an emergency or supply line and
allow the pressure to drop gradually.
• In a system that does not employ spring brake control valves, the relay emergency
valve should function and apply the brakes.
AIR SYSTEM AND BRAKE OPERATION
• In a system employing spring brake control valves, spring brakes
should function and apply the brakes.Remember that serious air losses are extremely
hazardous conditions that are likely to cause accidents or breakdowns.
Adjustment and Operation of Brakes