1
®
SD-03-4650
Bendix
®
TR-2
™
, TR-3
™
& TR-4
™
Inversion Valves
DESCRIPTION
GENERAL
The TR-2
™
& TR-3
™
valves are normally open pilot-operated,
inverting, on-off, two-way valves. The TR-4
™
valve is lever
operated. With normal operating pressure at both supply
and control ports, the delivery port will be exhausted to
atmosphere. As control pressure is reduced to the point
that the piston return spring or springs overcomes the force
on the control piston, the valve will deliver full supply pressure
at the delivery port.
TR-2
™
INVERSION VALVE
Referring to Figure 1, the TR-2
™
valve was used primarily in
early DD-3
™
Safety Actuator control systems to apply air
pressure to the emergency diaphragm of the DD-3
™
actuator’s from a protected reservoir as control pressure is
released from the lock mechanism. The TR-2
™
valve is
available in 1
1
/4" bulk head mount only.
TR-3
™
INVERSION VALVE
Referring to Figure 2, the TR-3
™
valve is similar in function to
the TR-2
™
valve, but with a die cast body. Referring to Figure
3, some TR-3
™
valve’s have an internal passage in the body
connecting supply pressure to control. The external control
port is permanently plugged in such valves.
TR-4
™
INVERSION VALVE
Referring to Figure 4, the TR-4
™
valve is a TR-3
™
valve with
the internal passage connecting supply and control plus a
manual lever control which permits the valve to be locked in
the open position.
OPERATION
TR-2
™
& TR-3
™
INVERSION VALVES
When sufficient air pressure is present in the control cavity
to overcome the setting of the piston return spring, the piston
is held away from the inlet valve which is held closed by the
inlet valve return spring. The delivery lines are vented to
atmosphere through the hollow exhaust stem of the piston.
When air pressure in the control cavity falls to a
FIGURE 1 - TR-2
™
INVERSION VALVE
CONTROL PORT (3)
CAP SCREW
DELIVERY PORT (2)
CAP NUT
SEAL RING
PISTON
MOUNTING NUT
& LOCKWASHER
INLET & EXHAUST
VALVE
PISTON GROMMET
(SMALL)
PISTON GROMMET
(LARGE)
EXHAUST
DIAPHRAGM
COVER PLATE
DIAPHRAGM WASHER
RETAINER RING
PISTON SPRINGS
BODY
INLET & EXHAUST
VALVE SPRING
SUPPLY PORT
EXHAUST
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