Fig. 7 Brake Valve Releasing
Primary Exhaust Valve Open
Secondary Exhaust Valve Open
Secondary Inlet Valve Closed
Primary Inlet Valve Closed
Rubber Graduating Spring
Every Three Months or 32,000 km (20,000 Miles) Clean
any accumulated dirt, gravel or foreign matter away from
heel of treadle, plunger boot and mounting plate.
Lubricate plunger, roller, roller pin and hinge pin using
Item 1 in LUBRICANT SPECIFICATIONS. Check rubber
plunger boot for cracks, holes or deterioration and
replace if required. Check mounting plate for integrity.
Free pedal travel should be checked as follows. Be sure
plunger is in contact with spring seat. The stop button
should be adjusted so that the roller and plunger just
contact. Clean exhaust port.
Every Year or 160,000 km (100,000 Miles)
Disassemble brake valve; clean and inspect all parts.
Install new parts where they are found to be worn or
Check delivery pressure of both primary and
secondary systems using test gauges known to be
accurate. Depress pedal or treadle to several positions
between the fully released and fully applied positions and
check the delivered pressure on the test gauges to see
that it varies proportionately with the movement of the
After a full application is released, the reading on test
gauges should fall off to zero promptly. It should be
noted that the primary system delivery pressure will be
about 14 kPa (2 psi) greater than the secondary system
delivery pressure with both supply reservoirs at the same
pressure. This is normal for these valves.
warning may indicate a malfunction in
one or the other brake systems and,
although vehicle should not be operated
until necessary repairs have been made
and both braking systems, including
pneumatic and mechanical devices, are
vehicle brakes after performing brake
work and before returning the vehicle to
Make and hold a high pressure application. Check the
exhaust port for leakage. Using a soap solution , a 25
mm (1") soap bubble in 3 seconds is permitted.
If the brake valve does not function as described, the
valve should either be replaced or repaired.
Apply parking brake or block wheels to prevent
vehicle from moving.
Drain all air from all reservoirs.
Disconnect all supply and delivery lines at brake
valve. Mark all air lines in relation to valve to
assist reconnecting lines.
CTS-4079 - CHAPTER