Bendix Commercial Vehicle Systems QR-L INLINE QUICK RELEASE VALV 3/04 - Manual (Page 2)

Figure 1 shows the QRN-2 ™ valve with its port designations,
date code, piece number and T.M.C. identifications. Figure
2 is a sectional view. Note that the standard QRN-2
™ valve,
which has a 1 psi maximum differential, does not include a
differential spring. Figure 3 shows a partial air brake system
schematic with a QRN-2
™ valve. Receiving its signal from
the secondary brake circuit, the QRN-2 ™ valve is controlling
the front axle brake chambers.
OPERATION
APPLY
As shown in Figure 4, when air pressure enters the supply
port, it causes the center portion of the diaphragm to seal
the exhaust. Supply air pressure simultaneously forces the
edges of the diaphragm away from the sealing lip in the
body, allowing air to flow out the delivery ports. Delivery
pressure will be within 1 psi of supply pressure for the
standard QRN-2
™ valve.
BALANCE
Figure 5 shows the QRN-2 ™ valve balanced mode. When
air pressure beneath diaphragm is approximately 1 psi less
than air pressure above the diaphragm, the outer edges of
the diaphragm seal against the body’s sealing lip. The
exhaust remains sealed because air pressure bears against
the center portion of the diaphragm from one side only.
RELEASE
When air pressure is removed from the QRN-2 ™ valve supply
port, the air pressure on the delivery side of the diaphragm
holds the outer edge of the diaphragm against the sealing
lip in the body while simultaneously moving the center portion
away from the exhaust port. Air from the delivery ports flows
out the exhaust. When delivery air pressure is fully
exhausted, the diaphragm will return to its natural state,
with its outer edges sealing the delivery and its center portion
sealing the exhaust.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO
AVOID
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
DELIVERY
DELIVERY
DELIVERY
SEALED
SUPPLY
DIAPHRAGM
EXHAUST
EXHAUST
SEALED
DELIVERY
SUPPLY
DIAPHRAGM
EXHAUST
DELIVERY
FIGURE 4 - QRN-2 ™ QUICK RELEASE VALVE APPLY
FIGURE 5 - QRN-2 ™ QUICK RELEASE VALVE BALANCE
FIGURE 6 - QRN-2 ™ QUICK RELEASE VALVE
RELEASE
DELIVERY DELIVERY
SUPPLY
EXHAUST DIAPHRAGM