12
with governors which have a 120 to 130 psi nominal cut-
out pressure. If a governor is used that is not within this
limitation contact your Bendix parts outlet or sales
representative for additional information. If the recovery
time consistently exceeds this limit, it may be
necessary to "by-pass" 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
30 seconds. This minimum purge time is 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 - The AD-SP
™
air dryer
must not be installed in brake systems that
incorporate compressors without integral unloading
mechanisms and/or utilize a compressor discharge
line unloader valve. When vehicles of this type are
encountered other Bendix air dryer models must be used.
Consult your local authorized Bendix parts outlet or sales
representative for additional information.
4. Air Compressor Size - The AD-SP
™
air dryer was
designed primarily for use with compressors rated up to
30 CFM. It is recommended that when using the
AD-SP
™
air dryer with a compressor which has a rated
displacement exceeding 30 CFM that an authorized
Bendix parts outlet or Bendix marketing representative
be contacted for assistance.
5. Holset "E or QE" Type Air Compressors - The AD-SP
™
air dryer can be installed with the Holset Type "E or QE"
compressor. When the AD-SP
™
air dryer is used in this
installation, the Holset ECON valve should be removed
and the special orifice check valve in the "make-up" line
should be removed and replaced with a conventional
single check valve. This is most easily done using a
special 45 deg. supply port fitting, 112864, and single
check valve 109710.
6. Use the following guidelines to determine the vehicle
application suitable for the AD-SP
™
air dryer:
Total Vehicle Res.
Air Dryer Model
Volume (Cu. In.)
Less than 9,000 ........................... AD-SP
™
Air Dryer
Less than 9,000 w/several ........... AD-9
™
Extended Purge
air accessories or high air
Volume Air Dryer
usage (e.g. transit coaches
& refuse haulers)
Greater than 9,000 ....................... AD-9
™
Extended Purge
Volume Air Dryer or
Contact Bendix Commercial
Vehicle Systems LLC
VEHICLE PREPARATION
1. Park the vehicle on a level surface and prevent movement
by means other than the brakes.
2. Locate the front axle service (secondary) reservoir in
preparation for installing the SC-PR
™
single check
protection valve included with AD-SP
™
air dryer retro-fit
kits.
A. With full system pressure in all reservoirs, drain any
single reservoir and observe the reaction of the dash
gauges. If the supply reservoir was drained, no
reaction will be noted on the dash gauges. Drain air
from another reservoir. When the front axle service
reservoir gauge displays a pressure loss mark the
reservoir that was drained. Confirm that the front axle
service (secondary) reservoir has been found by
building system pressure to governor cut-out and
draining the marked reservoir. After the reservoir is
completely drained make a service brake application
and have an assistant observe the front axle service
brakes. The front axle brakes should be inoperative.
B. Some vehicles may be equipped with multi-
compartment reservoirs. This type of reservoir is eas-
ily identified by the presence of more than one drain
cock in the reservoir shell. The most common is a
two compartment reservoir with a "built-in" single
check valve between the two compartments. In most
instances when this type of reservoir is in use, one
of the two compartments (usually the smallest) will
be the supply reservoir and the second compart-
ment will be either the front or rear service reservoir.
Drain air from either of the two compartments and
observe the dash gauges. If the supply reservoir com-
partment was drained, no reaction will be noted on
the dash gauges. If one dash gauge displays pres-
sure loss note whether it is the front axle (secondary)
or rear axle (primary) reservoir. Mark the front axle
service (secondary) reservoir or compartment. Con-
firm that the correct reservoir has been found in the
same manner described in 2A.
3. Locate the supply reservoir ("wet tank") and note if a
single check valve is installed in the discharge line
connected to the reservoir. If a single check valve is found
it should be removed before proceeding with the
installation.
4. Locate and mark the single check valve that is used to
protect and isolate the front axle service reservoir.
5. Drain all reservoirs to 0 p.s.i. (0 kPa).
LOCATING AD-SP
™
AIR DRYER ON VEHICLE
1. The AD-SP
™
air dryer must be mounted vertically (purge
exhaust port toward road surface) outside the engine
compartment in an area of air flow while the vehicle is in
motion. The AD-SP
™
air dryer must not be exposed to
direct wheel splash (located behind axle mud flap is
acceptable).
2. Locate the AD-SP
™
air dryer as close to the first (supply)
reservoir as possible.
