DESCRIPTION OF OPERATION
Description of Operation
When the knob is in released position, the “IN” port is
closed to supply pressure and “OUT” port is open to
exhaust.
Note in the diagrammatic, when the knob is rotated to
increase pressure, the shaft and cam are also rotated. The
rotation of the knob allows the cam to push down the
pressure control plunger, closing the lower exhaust valve
and opening the upper supply valve which permits air flow
to out port delivery and the upper diaphragm chamber. As
the pressure builds up in the delivery line it acts through
the sensing port orifice and deflects the control diaphragm
downward, compressing the control spring. When sufficient
diaphragm deflection is reached to allow the upper supply
valve in the pressure control portion to close, the pressure
in the delivery line is held to that valve. The valve of the
pressure delivered to the outlet port is proportional to the
pressure control plunger movement. This movement in turn
is controlled by the cam contour and is therefore
proportional to the knob travel.
The Controlair Valve will automatically compensate for
downstream air pressure changes in the graduated
pressure delivery line. These air pressure changes can be
caused by line leakage, temperature change or load
feedback. If air pressure at the outlet port increases over
that called for by handle position, the diaphragm in the
control portion will deflect downward opening the lower
exhaust valve and exhausting air until the original setting is
obtained. If the pressure drops below that called for by the
handle position, the decreased force on the diaphragm will
allow the control spring to force the diaphragm upward,
opening the upper supply valve to restore the set pressure.
The range of pressure is controlled by the strength of the
diaphragm spring. Various values are available as shown
on Identity Schedule, page 5.
The H-4 Controlair is factory set to provide normal 240
degree rotation of the control knob. However, the 240-
degree rotation can be reduced by changing the
relationship of the stop with the cam brake.
Outlet
VALVE
FUNCTION
Exhaust
Inlet
DIAGRAMMATIC VIEW
Exhaust Port
Adjusting Screw
Range Control
Spring
Diaphragm
Exhaust Valve
Supply Valve
Inlet & Exhaust
Valve Unit
Page 4
