SERVICE MANUAL
GENERAL INSTRUCTIONS
Air brake equipment on trucks and truck-tractors
provides a means of controlling the brakes through the
medium of compressed air. Air brake equipment
consists of a group of devices; some maintain a supply
of compressed air, some direct and control the flow of
compressed air and others transfer the energy of
compressed air into the mechanical force and motion
necessary to apply the brakes. Different types and sizes
of devices are in use on different types of vehicles to
meet operating requirements.
Refer to AIR BRAKE SYSTEM FMVSS 121 AIR
SYSTEM
(SECOND
GENERATION),
GENERAL
INFORMATION for description of the dual air system
used on the particular vehicles covered by Federal Motor
Vehicle Safety Standard 121 (FMVSS 121).
The components used to make up a typical dual
air system on a chassis are listed in this section with a
brief
description,
operation,
service
checks
and
maintenance procedures. Disassembly and reassembly
instructions are provided for some components.
CAUTION
Whenever any component is serviced or
removed from the air system, be sure to
set the parking brake and/or block the
vehicle to prevent it from moving while
the service is being performed.
The various components which apply directly to
the Antilock System, as well as trouble shooting the
system, will be found in ANTILOCK section.
LUBRICANT SPECIFICATIONS
Throughout the text whenever reference is made
to a particular lubrication note or a particular item
number, refer to the following list of item numbers and
use the lubricant specified.
Item 1
IH 251H EP grease or equivalent to NLGI #2
multi-purpose lithium grease (same as BW 226M and
204M lubricant).
Item 2
Bendix 239277 (57 g - 2oz) molybdenum
disulfide lubricant in liquid carrier. A lubricant suited for
O-ring
powder
suspended
in
synthetic
lubricant
(polyalkylene glycol derivative) and rubber parts as well
as metal lubrication, especially at low temperatures.
Item 3
Bendix 291126 (7.08 g - 1/4 oz) or BW 291127
(57 g - 2 oz) silicone grease intended primarily for
dynamic lubrication between oil resistant rubber seals
and metal parts. Meets MIL-L-4343A requirements. Can
be used in serviceable range of -54 C (-65 F) to +426 C
(+800 F). Causes less swelling and hardness change of
rubber parts than normally encountered with petroleum
based
lubricants
(apprbved
source:
Dow
Corning
Corporation -- DC-55 pneumatic grease).
LEAKAGE TESTS
In
some
cases
where
leakage
tests
are
performed on various components, a soap bubble test
can be made to determine if the items need repairs.
However, to assist in locating any leakage at connections
or at any components, we suggest that a Leak Detector
Tester (SE-2326) be used to locate any air leaks.
With special attachments contained in the tester
a very small air leak can be detected easily; for example,
in a confined area where a brush with soap is obstructed.
Fig. 1 Leak Defector Tester (SE-2326)
1
Amplifier
4
Sound Concentrator
2
Contact Probe
5
Hand Probe
3
Headphone
PRINTED IN UNITED STATES OF AMERICA
CTS-4079 - GENERAL
Page 2
