BENDIX TP-3DC TRACTOR PROTECTION VALVE User Manual

1
SD-03-3656
Bendix
®
TP-3DC
™
Tractor Protection Valve with Double Check
FIGURE 1 - TP-3DC
™
TRACTOR PROTECTION VALVE WITH DOUBLE CHECK
AUXILIARY SUPPLY
1/4" -18 NPT
DATE CODE
STAMPED HERE
TRACTOR SUPPLY
1/4"-18 NPT
TRACTOR CONTROL
(PRIMARY) 3/8"-18 NPT
LABEL WITH
TP-3DC
™
VALVE
O.E. PC. NO. HERE
TRAILER CONTROL
1/2"-14 NPT
QR-L
™
VALVE FACTORY
INSTALLED ON SOME
TP-3DC
™
VALVE MODELS
1/2"-14 NPT
1/2"-14 NPT
TRACTOR
CONTROL
(SECONDARY)
3/8"-18 NPT
STOP LIGHT
SWITCH
1/4"-18 NPT
TRAILER CONTROL
1/2"-14 NPT
DESCRIPTION
The tractor protection valve system protects tractor air
brakes during trailer breakaway and/or when severe air
leakage develops in the tractor or trailer. This function is
required by law.
In normal use the tractor protection valve is used to shut off
the trailer control line before disconnecting the tractor from
the trailer. It is usually mounted at the rear of the tractor
cab, and it is used in conjunction with a dash-mounted
control valve.
The TP-3DC
™
valve integrates tractor protection and double
check valve functions. It also has an integral single check
valve that prevents trapping of air in the trailer control line.
This prevents service and spring brake compounding, and
it avoids a trailer roll away situation if the trailer is parked
with the air applied.
A stoplight switch port allows direct stoplight installation,
and the auxiliary supply port, when connected to the
BP-R1
™
control port, eliminates a tee in the tractor
supply line. Also, a QR-L
™
valve can be factory installed
in the trailer control and/or supply port to meet timing
requirements.
Port Embossed I.D. Thread Size
Tractor Supply TRAC SUP 1/4"-18 NPT
Auxiliary Supply AUX SUP 1/4"-18 NPT
Tractor Control (Primary) TRACT CONT 3/8"-18 NPT
Tractor Control (Secondary) TRAC CONT 3/8"-18 NPT
Stop Light Switch STP LT SW 1/4"-18 NPT
Trailer Supply TRLR SUP 1/2"-14 NPT
Trailer Control TRLR CNTL 1/2"-14 NPT
Weight: 1.5 lbs.
Material: Die-cast aluminum
Operating pressure: 150 psi maximum
Operating temperature: -40° to 200° F
Figure 1 shows the TP-3DC
™
valve with its port designations,
O.E. piece number, and date code identifi cations.
Figure 2 is a sectional view of the TP-3DC
™
valve, and
Figure 3 presents the TP-3DC
™
valve in a partial air brake
system schematic.

BENDIX TP-3DC TRACTOR PROTECTION VALVE Specifications

General

Brand	BENDIX
Model	TP-3DC TRACTOR PROTECTION VALVE
Category	Control Unit
Language	English

Summary

Product Description and Functionality

Valve Operation Modes

Initial Air Charge Process

Explains initial charge of air pressure into the TP-3DC™ valve and its transition to run mode.

Service Brake Application

Details how service air pressure from the tractor controls valve operation and trailer brake application.

Service Brake Release Procedure

Describes how air returns from the trailer control line upon release of service brakes.

Tractor Protection Functionality

Explains how the valve protects the tractor when trailer supply is pulled out or pressure drops.

Anti-Compounding Mechanism

Details how the internal check valve prevents simultaneous trailer brake applications.

Critical Safety Warnings and Precautions

General Safety Guidelines

Provides essential safety precautions for working on or around the vehicle and its air brake system.

Service Checks, Tests, Removal, and Installation

Service Checks and Inspections

Covers visual inspection of contaminants, air lines, and fittings for wear or damage.

Operational and Leakage Tests

Details procedures for testing valve operation and detecting leaks using soap solution.

Component Removal Process

Steps for identifying, marking, and disconnecting air lines for valve removal.

Valve Installation Guide

Instructions for installing the TP-3DCT™ valve and reconnecting air lines.

Valve Disassembly and Assembly Procedures

Component Disassembly Steps

Step-by-step guide for taking apart the TP-3DCT™ valve, including part identification.

Cleaning and Inspection of Parts

Procedures for cleaning metal parts and inspecting components for wear or damage.

Assembly and Lubrication Guidelines

Instructions for lubricating and reassembling the valve, including torque specifications.