Probable causes:
port "D" and charge the emergency tanks thru port
"C", until the pressure in the system becomes great
1. Dirt blocking by-pass port
enough to move the emergency spool to the right
2. Swollen cup seal blocking the port (Swollen
against spring tension.
cup seals are caused by using the wrong brake
fluid.)
Problem 5: Air in the hydraulic lines.
P r o b a b l e causes:
1. Low fluid level
2. Blocked filler cap vent
3. Worn cup seals
4. Residual check not seating
Problem 6: Poor braking.
P r o b a b l e causes:
1. Low air pressure
2. Low fluid level
3. Air in the hydraulic system
4. Oil leaks in the system
OPERATION OF THE EMERGENCY,
AIR TANKS FULL-BRAKES RELEASED
RELAY, QUICK RELEASE VALVE
(Figure "B") When the air pressure in the system
becomes great enough, the emergency spool moves
to the right against spring tension. The shuttle valve,
within the emergency spool, moves left. The air that
was on top of the diaphragm is exhausted thru port
"B" which leads to the foot valve. The diaphragm is
pushed up by the large spring. The air that was in
the power cluster exhausts thru port "D", past the
diaphragm seat at "E", and out the exhaust port.
A i r trapped in the emergency tank because the
shuttle within the emergency spool is closed and
the check valve is closed.
CHARGING THE SYSTEM
(Figure "A") When the engine is started with the
system empty, air from the compressor enters the
valve at port "A". Air lifts the check valve from its
s e a t : flows thru the emergency spool which is
moved to the left by spring tension, and thru the
passage in the right side of the valve to port "C"
Port "C" leads to the emergency tank. Air also
flows past the seat on the diaphragm at "E", and
thru port "D" which leads to the power cluster. Air
p r e s s u r e will hold the power cluster applied thru
[6]
