Park Release With Trailer Charged - BENDIX SR-5 TRAILER SPRING BRK VALVE Manual

SERVICE
FIGURE 5 PARK APPLICATION
PARK APPLICATION (SEE FIGURE 5)
To park the trailer, either the trailer air supply valve or the
system park control valve (in the tractor) is actuated. This
vents the trailer supply line. The control piston, no longer
under supply pressure, is moved by air pressure on its
delivery side. This allows the control piston to move to the
exhaust position. The control inlet valve closes and the
exhaust valve opens, allowing air from the spring brakes to
exhaust through the passage in the control piston and apply
the brakes. Check valves B and D close, preventing trailer
reservoir air pressure loss through passage A.
FIGURE 6 PARK RELEASE WITH TRAILER CHARGED
4
TRAILER SERVICE RES.
CHECK
VALVE D
CHECK
VALVE B
SERVICE/SPRING
BRAKE RESERVOIR
RELAY CONNECTION
VALVE
TRAILER SERVICE RES.
CHECK
VALVE
SERVICE/
SPRING
BRAKE
SERVICE
RESERVOIR
RELAY
CONNECTION
VALVE
SPRING
BRAKE
CHAMBER
TRAILER SERVICE
EXHAUST
SPRING
BRAKE
CHAMBER

PARK RELEASE WITH TRAILER CHARGED

(SEE FIGURE 6)
To release a park application with the trailer charged, the
trailer supply valve (in the cab) is actuated. Air flows through
the trailer supply line and enters the SR-5
port. With a minimum of 55 psi on the control piston, the
piston will move, sealing its exhaust passage. As piston
travel continues, the inlet valve opens. Reservoir air (approx.
110 psi) then flows through check valve F, past the open
inlet, and out to the spring brake chambers to release the
brakes.
TRAILER SERVICE
CHECK
VALVE D
CHECK
VALVE B
F
EXHAUST
PASSAGE
PRESSURE
PROTECTION
VALVE C
PASSAGE A
TRAILER SUPPLY
CONTROL PISTON
™ valve trailer supply
TRAILER SUPPLY
CONTROL PISTON