Bendix Commercial Vehicle Systems QR-N QUICK RELEASE VALVE - Manual

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Bendix ® QR-N ™ Quick Release Valve
SD-03-905
MOUNTING HOLE (2) SUPPLY PORT
FIGURE 1
EXHAUST PORT
DELIVERY PORT
DESCRIPTION
The function of the Bendix ® QR-N ™ quick release valve is to
“speed up” the exhaust of air from the actuators it serves. It
is generally mounted on the vehicle axle midway between
the two actuators connected to it.
In the standard (Refer to Figure 1) QR-N ™ valve a flat circular
diaphragm is installed between the nonmetallic upper body
and stamped steel lower body. An o-ring seals the two body
halves which are held together using four 1/4" machine
screws and flange nuts.
In its standard configuration the QR-N ™ valve is supplied
with a 1 psi (6.9 kPa) maximum differential. For example
with supply pressure at 10 psi (68.9 kPa) delivery pressure
is 9 psi (61.8 kPa). Higher differential pressures are available
for special applications and are obtained by the addition of a
spring and diaphragm follower to the standard QR-N
™ valve
(Refer to Insert A). The QR-N ™ valve also comes in sustained
(black body) and non-sustained (gray body) differential
versions.
Various pipe thread sizes are available for the single supply
port and two delivery ports of the QR-N
™ valve. Some versions
of the QR-N ™ valve have a threaded exhaust port. (Refer to
Insert B). QR-N ™ valve mounting is accomplished via two
11/32" diameter holes on 1-1/2" centers.
OPERATION
With no air pressure applied to the QR-N ™ valve (Refer to
Figure 1), the diaphragm is slightly flexed by the upper and
lower body. In this condition the center portion of the
diaphragm rests on the exhaust port in the lower body while
the outer edge and opposite side of the diaphragm rests
against the sealing lip of the upper body.
APPLY
Air entering the supply port of the QR-N ™ valve causes the
center portion of the diaphragm to seal the exhaust port.
Simultaneously, the outer edge of the diaphragm moves away
from the sealing lip of the upper body allowing air to flow
from the supply port out the delivery ports.
BALANCE
When air pressure on both sides of the diaphragm is
approximately equal (1 psi differential), the natural resiliency
of the diaphragm material causes the outer edge of the
diaphragm to move into contact with the upper body sealing
lip. The QR-N
™ valve exhaust remains sealed because air
pressure bears against the center portion of the diaphragm
from one side only.
UPPER BODY
DIAPHRAGM
DELIVERY PORT
SEALING RING
LOCKWASHER
CAP SCREW
SPRING FOLLOWER
DIFFERENTIAL SPRING
THREADED EXHAUST PORT
LOWER
BODY
INSERT B INSERT A