BENDIX R-12P PILOT RELAY VALVE User Manual

1
SD-03-1063
FIGURE 1 - CUTAWAY AND EXTERNAL VIEW
DESCRIPTION
The R-12P
™
pilot relay valve is designed to speed up
control signal application and release on long non-towing
trailers, towing trailers, dollies, and long wheelbase tractors.
It does this without adversely affecting the control signal.
The R-12P
™
valve replaces the current R-8P
™
valve.
Unlike a standard relay valve used as a “booster,” which
typically has a 2-4 psi differential between control and
delivery, the R-12P
™
valve has zero differential. It “speeds”
up control line signal application and release in a train
of vehicles, and it delivers the same air pressure that it
receives. This provides a uniform brake signal to all trailer
and dolly brakes, even during light applications.
The unique R-12P
™
valve feature is that it uses a supply
air pressure load to quicken the valve’s response time. By
balancing the pressure signal to all trailer and dolly brakes,
the R-12P
™
valve aids in achieving overall vehicle brake
pressure balance, timing balance, and stability.
It also substantially improves brake lining wear balance
on combination vehicles by making even the most distant
brake contribute its share of braking effort.
Figure 2 shows the R-12P
™
valve in a trailer air brake
schematic. Note that additional air lines for a towing trailer
are shown as dashed lines.
The R-12P
™
valve uses the R-12
™
valve family lower body
and standard Bendix mounting brackets. It can also be
reservoir-mounted.
The body and cover are die-cast aluminum, and the valve’s
weight is approximately 2.3 lbs. Porting is as follows:
Qty. Size
Supply (SUP) 2 1/2”
Delivery (DEL) 4 3/8”
Control (CON) 1 1/4”
Exhaust (EXH) 1 --
Bendix
®
R-12P
™
Pilot Relay Valve
3/8”
DELIVERY
1/2” SUPPLY (2)
RESERVE
SPRING
1/4” CONTROL
LOAD
PISTON
BODY
EQUALIZING
ORIFICE
EXHAUST
INLET/EXHAUST
VALVE
COVER
1/2”
SUPPLY
3/8” DELIVERY (4)
RELAY
PISTON
1/4” CONTROL

BENDIX R-12P PILOT RELAY VALVE Specifications

General

Brand	BENDIX
Model	R-12P PILOT RELAY VALVE
Category	Control Unit
Language	English

Summary

Bendix® R-12P™ Pilot Relay Valve Introduction

Product Description and Key Features

Detailed description of the R-12P™ valve, its purpose, and benefits.

R-12P™ Valve Operation: Charging

Charging Phase Functionality

Explains how the R-12P™ valve operates when the air brake system is charging.

R-12P™ Valve Application Modes

Achieving Air Pressure Balance

Details how the R-12P™ valve achieves air pressure balance using its equalizing orifice.

Normal (Rapid) Service Application

Describes the valve's operation during a rapid service brake application.

R-12P™ Valve Response and Exhaust

Rapid Exhaust Functionality

Explains the valve's function during a rapid release of service brakes.

Equalizing (Slow) Application Mode

Details the valve's operation during a slow service brake application.

Reduced Supply Pressure and Safety

Equalizing Exhaust with Reduced Supply

Describes slow exhaust function with reduced supply pressure.

Critical Safety Warnings

Essential safety instructions to prevent injury or death during handling and maintenance.

Maintenance and Testing Procedures

Preventive Maintenance Schedule

Guidelines for routine inspection, testing, and preventive maintenance.

Service Checks and Leakage Tests

Procedures for inspecting the valve for external contaminants, damage, and leaks.

Valve Removal Procedure

Step-by-step instructions for safely removing the R-12P™ valve from a vehicle.

Valve Installation and Disassembly

Valve Installation Steps

Procedures for installing the R-12P™ valve onto a vehicle or reservoir.

Disassembly of the R-12P™ Valve

Detailed steps for disassembling the R-12P™ valve for maintenance or repair.

Component Servicing: Cleaning and Assembly

Cleaning and Inspection Guidelines

Guidelines for cleaning and inspecting all parts of the R-12P™ valve during maintenance.

R-12P™ Valve Assembly Process

Step-by-step instructions for reassembling the R-12P™ valve after maintenance.