BENDIX TP-3 Service Data

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Bendix TP-3 Tractor Protection Valve
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Tractor
Emergency
Port
Tractor
Service
Port
Exterior View
Figure 1 - Bendix TP-3
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DESCRIPTION
The Bendix TP‑3 tractor protection valve is used in
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combination with the Bendix
on pre‑121 tractors, and the Bendix
valve – or the Bendix
®
post‑121 tractors. It contains a passage for trailer supply
air and a service line shut off valve. It is normally mounted
behind the cab, with the delivery line from the trailer
supply valve connected into the tractor emergency port
and a delivery line from the brake valve connected to the
tractor service port. The trailer supply and service hoses
are mounted in their respective ports in the TP‑3 valve.
See Figure 2.
OPERATION
Air from the trailer supply valve passes through the
emergency ports of the TP‑3 valve to supply the trailer air
system and simultaneously exerts pressure on the end of
the plunger. The TP‑3 valve requires approximately 45 psi
to open the inlet valve. Whenever the pressure from the
trailer supply valve drops below 45 psi, the TP‑3 valve will
close the service line shut‑off valve.
Trailer
Emergency
Port
Trailer
Service
Port
Tractor Protection Valve
PP‑3 trailer supply valve
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PP‑7 trailer supply
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MV‑3 dash control valve – on
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Valve
Spring
Diaphragm
Seat
Diaphragm
Washer
Cap Screw
Cross Section
PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performing any intrusive maintenance procedures. A
warranty may be voided if intrusive maintenance is
performed during the warranty period.
No two vehicles operate under identical conditions; as
a result, maintenance intervals may vary. Experience is
a valuable guide in determining the best maintenance
interval for air brake system components. At a minimum,
the Bendix TP‑3 valve should be inspected every 6 months
or 1500 operating hours, whichever comes first, for proper
operation. Should the TP‑3 valve not meet the elements
of the operational tests noted in this document, further
investigation and service of the valve may be required.
Plunger
O‑Ring (Top)
Plunger
Inlet Valve
Valve Retainer
Valve Retaining
Ring
Plunger O‑Ring
(Bottom)
Plunger Seat
Diaphragm
Seat O‑Ring
Diaphragm Seat
Retaining Ring
1