Bendix Commercial Vehicle Systems AD-4 AIR DRYER 10/04 - Manual (Page 11)

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Bendix parts outlet or sales representative for additional
information.
1. Charge Cycle Time - The AD-4 ™ air dryer is designed to
provide clean, dry air for the brake system. When a
vehicle’s air system is used to operate non-brake air
accessories it is necessary to determine that during
normal, daily operation the compressor should recover
from governor “cut-in” to governor “cut-out” (usually 100
psi to 120 psi) in 90 seconds or less at engine RPMs
commensurate with the vehicle vocation. If the recovery
time consistently exceeds this limit, it may be
necessary to “bypass” the air accessory responsible for
the high air usage. Consult your local authorized Bendix
parts outlet or sales representative for additional
information.
2. Purge Cycle Time - During normal vehicle operation, the
air compressor must remain unloaded for a minimum
of 20 seconds for the standard AD-4
™ air dryer or 30
seconds for the extended purge model. These
minimum purge times are required to ensure complete
regeneration of the desiccant material. If the purge time
is occasionally shorter than the times specified, no
permanent ill effect should be expected, however, if the
purge time is consistently less than the minimum, an
accessory by-pass system must be installed.
3. European Air Brake Systems - Brake systems that
incorporate compressors without integral unloading
mechanisms and/or utilize a compressor discharge line
unloader valve have special AD-4
™ air dryer installation
requirements. Consult your local authorized Bendix parts
outlet or sales representative for additional information.
4. Air Compressor Size - Although the AD-4 ™ air dryer can
be used in conjunction with larger compressors, it was
designed primarily for units rated for up to 17 CFM. It is
recommended that when using the AD-4
™ air dryer with
a compressor which has a rated displacement exceeding
17 CFM that an authorized Bendix parts outlet or Bendix
marketing representative be contacted for assistance.
5. Holset “E or QE” Type Air Compressors - In order for the
AD-4 ™ air dryer to function properly when installed with
the Holset Type “E or QE” compressor, several
specialized Holset components are required. Consult
your local authorized Holset parts outlet or sales
representative for additional information.
6. Use of Standard or Extended Purge AD-4 ™ Air Dryer -
Use the following guidelines:
Total Vehicle Reservoir
Volume
Requirement
Less than 9,000 cu. in. ................... Standard AD-4 ™ Air Dryer
9,000 - 12,500 cu. in. ............................ Extended Purge AD-4 ™
Air Dryer
Greater than 12,500 cu. in. ............. Contact Bendix Rep. or
Bendix Engineering
RE-INSTALLATION
1. Install the assembled AD-4 ™ air dryer (if an AD-4 ™ air
dryer with a lower right angle bracket instead of a lower
mounting strap is being serviced proceed to step #2) on
the vehicle by sliding it into mounting brackets until
mounting bracket hook catches under the lip of the cover.
Proceed to step #3.
2. Install the assembled AD-4 ™ air dryer back onto the
vehicle by slipping it into the upper mounting bracket.
Align the two unused holes in the end cover with the
bottom mounting bracket such that the bottom bracket
supports air dryer. The AD-4
™ air dryer end cover should
rest on the bracket. Using the remaining two 3/8" cap
screws, four special washers, and two locknuts, secure
the air dryer to the lower bracket. Tighten, then torque
the two remaining cap screws to 270-385 in. Ibs.
3. Tighten the 5/16" x 4-1/2" bolt and nut on the upper
mounting bracket. Torque to 80-120 in Ibs.
4. Reconnect the three airlines to the proper ports on the
end cover (identified during disassembly).
5. Reconnect the thermostat and heater wire and place
boot in position to protect connection by forcing it over
knob on plastic cover.
6. Before placing vehicle back into service, perform the
Operation and Leakage Tests stated elsewhere in this
manual.
RETROFITTING THE AD-4 ™ AIR DRYER
GENERAL
The following retrofit instructions are presented for reference
purposes only since Bendix aftermarket retrofit and
replacement air dryers are packaged with the most up-to-
date installation instructions. The instructions packaged with
the AD-4
™ air dryer should be followed in lieu of those
presented here.
The preceding portion of this manual deals with “in-service”
repair and or replacement of the AD-4
™ air dryer. The portion
of the manual that follows is concerned with installing an
AD-4
™ air dryer on a vehicle not previously equipped with
one.
VEHICLE APPLICATION REQUIREMENTS
The basic application requirements presented here apply to
a standard air dryer installation. The majority of highway
vehicles in use today will meet these basic requirements
however, some may not. Examples of vehicles that may not
meet the requirements include bulk trailer unloading
operations and other high air consumption/continuous flow
systems. While the AD-4
™ air dryer can be used on these
vehicles the standard installation procedure presented in
this manual may require modification to assure proper
operation and service life. Consult your local authorized