SM07-012-0
Page 3
DESCRIPTION
The pressure protection valve is a normally closed
adjustable, however, the valve comes preset and is
pressure sensitive control valve which can be re-
installed in the system at this pressure setting. The
ferred to as a non-exhausting sequence valve. The
preset pressure setting of the valve installed between
valve functions to protect or isolate one reservoir
the primary and secondary reservoirs is 85 psi (586
supply from another, by closing automatically at a
kPa/5.86 bar) and the pressure setting of the valve
preset pressure. The valve contains two ports which
installed between the secondary reservoir and the
are identified on the valve as supply port and delivery
transmission range and axle disconnect circuits is 75
port. Two holes through the body provide for mount-
psi (517 kPa/5.1 7 bar).
ing the valve. The closing pressure of the valve is
THEORY OF OPERATION
Air entering the supply port is initially prevented from
fixed to the valve. Opening pressure of the valve is 15
flowing out the delivery port by the inlet valve which
to 20 psi (103.4 to 138 kPa/1 .03 to 1.38 bar) higher
is held closed by the pressure regulating spring above
than closing pressure.
the piston. When sufficient air pressure builds be-
neath the piston to overcome the setting of the regu-
If for any reason system air pressure is decreased
lating spring, the piston will move, causing the inlet
below the specified closing pressure, the regulating
valve to unseat (open), and allow air to flow out the
spring will move the piston closing the inlet valve
delivery port. As long as air pressure at the supply
The remaining air pressure at either the supply or
port and beneath the piston remains above the speci-
delivery side, (depending upon where the pressure
fied closing pressure, the inlet valve will remain
drop has occurred) will be retained.
open. Closing pressure is noted on the label af-
