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

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Note that pressure protection valve C will open if trailer supply
air is greater than 70 psi. But check valves B and D will not
open unless release pressure from the tractor exceeds trailer
reservoir pressure.
ANTI-COMPOUNDING (SEE FIGURE 7)
The SR-5 ™ valve has an optional anti-compounding feature.
(See Figure 7.) A single check valve in the SR-5 ™ valve cover
prevents brake compounding (simultaneous spring brake and
service brake application), which creates extra load on
foundation brake components.
If a trailer service application is being made and at the same
instant a park application is made, air in the service line
flows through single check valve E in the SR-5
™ valve cover.
Pressure is maintained on the control piston, while air also
flows out the trailer supply line and exhausts through the
tractor protection control. Future compounding is prevented
by the closed tractor protection valve.
FIGURE 7 OPTIONAL ANTI-COMPOUNDING
ANTI-COMPOUNDING
LINE
SPRING BRAKE
CHAMBER
EXHAUST
TRAILER SERVICE
CHECK
VALVE F
SERVICE/SPRING
BRAKE
RESERVOIR
CONNECTION
SERVICE
RELAY
VALVE
TRAILER SUPPLY
CHECK
VALVE E
DELIVERY