Bendix Commercial Vehicle Systems SR-5 TRAILER SPRING BRK VALVE 4/11 - Manual (Page 4)

4
FIGURE 6 PARK RELEASE WITH TRAILER CHARGED
FIGURE 5 PARK APPLICATION
TRAILER SUPPLY
SPRING
BRAKE
CHAMBER
TRAILER SERVICE RES.
CONTROL PISTON
EXHAUST
PASSAGE
TRAILER SERVICE
CHECK
VALVE B
SERVICE/
SPRING
BRAKE
RESERVOIR
CONNECTION
SERVICE
RELAY
VALVE
PRESSURE
PROTECTION
VALVE C
SPRING
BRAKE
CHAMBER
TRAILER SERVICE RES.
EXHAUST
PASSAGE A
TRAILER SERVICE
CHECK
VALVE B
SERVICE/SPRING
BRAKE RESERVOIR
CONNECTION
SERVICE
RELAY
VALVE
CHECK
VALVE D
CONTROL PISTON
TRAILER SUPPLY
CHECK
VALVE
F
CHECK
VALVE D
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.
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
™ valve trailer supply
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.