BRAKE CONTROL VALVE
Start the engine and let the air pressure go up.
Push down on the brake pedal and hold it down.
Put soap suds on the air line connections at the air
chambers and check for air leakage. Release the brake
pedal. Put soap suds on the exhaust passage of the
brake control valve. Leakage must not be more than
1.00 in. (25.4 mm) soap bubble in one minute. Correct
any air leaks.
Caliper disc hydraulic brakes need no adjustment.
There is no return mechanism to force the pads away
from the discs. The pads are in slight contact all the
time with the discs to keep them clean.
AIR IN THE HYDRAULIC BRAKE SYSTEM
WATER DISTRIBUTOR AIR CHAMBER AND
7. Master cylinder. B. Air chamber. 9. Air line. 10. Oil
line to water distributor brakes. 11. Valve. 12. Stroke
Indicator. 13. Quick release valve.
Air in the hydraulic brake system cannot be detected
by brake pedal "feel." However, a stroke indicator on
each master cylinder will provide a means of detecting a
"soft" pedal condition which will cause increased master
cylinder piston movement. If the movement of stroke
indicators (6) and (12) is too much, check for hydraulic
leaks or air in the system.
NOTE If the leak results from a damaged cup or seal,
the hydraulic brake system may be contaminated. Drain
the brake fluid and flush the system with denatured
alcohol. If the system is free of leaks, check for air.
Bleed each hydraulic brake system. See the topic, AIR
REMOVAL FROM BRAKES (Bleeding the Brakes).
BRAKE SYSTEM TEST
Check of Operation
The stroke indicator (1) will give an indication when
brake repair is needed. With the brake pedal pushed
down, make note of the stroke of the rod (1) on each
master cylinder. Brake repair is needed when the stroke
indicator moves more than 1.00 in. (25.4 mm) from the
air chamber of the master cylinder.
1. Stroke Indicator.
Start the diesel engine and let the air pressure
in the reservoir go up to cutout pressure.
Push the brake pedal down and keep it in that
Look at the stroke indicator.
Slow movement of the stroke indicator
after it has stopped once, is an indication
that there is leakage in the hydraulic
section of the brake system or that the
cup is cut.
Extra travel of the stroke indicator (with
brake linings in contact with discs) is an
indication that air is in the hydraulic
section of the system.
TRACTOR AIR CHAMBER AND MASTER CYLINDER
1. Air line. 2. Master cylinder. 3. Valve. 4. 011 line
to tractor brakes. 5. Air chamber. 6. Stroke