Bendix Sd 08 2412 Users Manual

2015-04-02

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SD-08-2412

Bendix® AD-9® and AD-9® IPC (Integrated PuraGuard® Coalescing) Air Dryers

EXTENDED

PURGE STANDARD

DESCRIPTION

The function of the Bendix® AD-9® and AD-9® IPC Integrated

PuraGuard® Coalescing air dryers is to collect and remove

air system contaminants in solid, liquid, and vapor form

before they enter the brake system. They provide clean, dry

air to the components of the brake system which increases

the life of the system and reduces maintenance costs. Daily

manual draining of the reservoirs is eliminated.

The Bendix AD-9 and AD-9 IPC Integrated PuraGuard

Coalescing air dryers consists of a desiccant cartridge

and a die cast aluminum end cover secured to a cylindrical

steel outer shell with eight cap screws and nuts. The end

cover contains a check valve assembly, a safety valve,

three threaded air connections, and the purge valve

housing assembly. The removable purge valve housing

assembly incorporates a purge valve mechanism and a

turbocharger cut-off feature that is designed to prevent loss

OUTER

SHELL

SUPPLY

PORT

WIRING HARNESS

CONNECTION

DELIVERY PORT

CHECK

VALVE

ASSEMBLY

END COVER

CONTROL

PORT

FIGURE 1 - BENDIX® AD-9® AND AD-9® IPC AIR DRYER MODELS

IPC AIR DRYER LABEL

SAFETY VALVE

PURGE VALVE

END COVER

of engine “turbo” boost pressure during the purge cycle of

the Bendix® AD-9® and AD-9® IPC air dryers. For ease of

serviceability, the desiccant cartridge and discharge check

valve assembly are screw-in type. The purge valve housing

assembly – which includes the heater and thermostat

assembly – and the discharge check valve assembly are

serviceable from the exterior of the air dryer, while servicing

the screw-in desiccant cartridge requires removal of the air

dryer assembly from the vehicle.

The AD-9 IPC air dryer appears identical to the standard

AD-9 air dryer, but contains a coalescing media at

the inlet of the desiccant bed. This coalescing media

provides a higher level of oil removal over the standard

AD-9 air dryer. The AD-9 IPC air dryer has all the same

functions of the standard AD-9 air dryer, and is used

where oil is contaminating downstream components.

The Bendix AD-9 IPC air dryer can be identiﬁ ed by the

IPC label (shown in Figure 1), located on the air dryer

housing.

The Bendix AD-9 and AD-9 IPC air dryers have three

female pipe thread air connections and each is identiﬁ ed

as follows:

Port l.D. Function/Connection

CON 4................Control Port

(purge valve control and turbo cut-off)

SUP 11 .............Supply Port (air in)

DEL 2 ...............Delivery Port (air out)

OPERATION OF THE BENDIX AD-9 AIR

DRYER

The AD-9 and AD-9 IPC air dryers alternate between two

operational modes, or “cycles”, during operation: the charge

cycle and the purge cycle. The following description of

operation is separated into these “cycles” of operation.

CHARGE CYCLE (Refer to Figure 2)

When the compressor is loaded (compressing air)

compressed air – along with oil, oil vapor, water and water

vapor – ﬂ ows through the compressor discharge line to

the supply port of the air dryer end cover. As air travels

through the end cover assembly, its direction of flow

ORIFICE

PURGE

VOLUME

DELIVERY

PORT

HEATER

ELEMENT

SUMP

EXHAUST

PURGE

VALVE

RESERVOIR

SUPPLY

PORT

COMPRESSOR

GOVERNOR

ENGINE

TURBO

CONTROL

PORT

OIL

SEPARATOR

DESICCANT

BED

DESICCANT

CARTRIDGE

















CHECK

VALVE

FIGURE 2 - BENDIX® AD-9® AND AD-9® IPC AIR DRYER CHARGE CYCLE









CHECK

VALVE

ASSEMBLY



CHECK

VALVE ORIFICE

PURGE

VOLUME

DELIVERY

PORT

HEATER

ELEMENT

SUMP

EXHAUST

PURGE

VALVE

RESERVOIR

SUPPLY

PORT

COMPRESSOR

GOVERNOR

ENGINE

TURBO

CONTROL

PORT

OIL

SEPARATOR

DESICCANT

BED

DESICCANT

CARTRIDGE















TURBO

CUT-OFF

PISTON



CHECK

VALVE

ASSEMBLY

FIGURE 3 - BENDIX®AD-9® AND AD-9® IPC AIR DRYER PURGE CYCLE



changes several times, reducing the temperature, causing

contaminants to condense and drop to the bottom, or sump,

of the air dryer end cover.

After exiting the end cover, the air ﬂ ows into the desiccant

cartridge. Once in the desiccant cartridge, air ﬁ rst ﬂ ows

through an oil separator which removes water in liquid form

as well as oil and solid contaminants.

Air exits the oil separator and enters the desiccant drying

bed. Air ﬂ owing through the column of desiccant becomes

progressively drier as water vapor adheres to the desiccant

material in a process known as “adsorption”. The desiccant

cartridge using the adsorption process typically removes

95% of the water vapor from the pressurized air.

The majority of dry air exits the desiccant cartridge through

its integral single check valve to ﬁ ll the purge volume

between the desiccant cartridge and outer shell. Some

air will also exit the desiccant cartridge through the purge

oriﬁ ce adjacent to the check valve.

Dry air ﬂ ows out of the purge volume through the single

check valve assembly and out the delivery port to the ﬁ rst

(supply) reservoir of the air system.

The air dryer will remain in the charge cycle until air brake

system pressure builds to the governor cut-out setting.

PURGE CYCLE (Refer to Figure 3)

When air brake system pressure reaches the cut-out setting

of the governor, the compressor unloads (air compression

stopped), and the purge cycle of the air dryer begins. When

the governor unloads the compressor, it pressurizes the

compressor unloader mechanism and line connecting the

governor unloader port to the air dryer end cover control

port. The purge piston moves in response to air pressure,

causing the purge valve to open to atmosphere and

(partially) closing off the supply of air from the compressor.

(This will be further discussed in the section covering

the turbo cut-off feature.) Contaminants in the end cover

sump are expelled immediately when the purge valve

opens. Also, air – which was ﬂ owing through the desiccant

cartridge – changes direction and begins to ﬂ ow toward

the open purge valve. Oil and solid contaminants collected

by the oil separator are removed by air ﬂ owing from the

desiccant drying bed to the open purge valve.

AD-9 CHARGE MODE

The initial purge and desiccant cartridge decompression

lasts only a few seconds and is evidenced by an audible

burst of air at the Bendix® AD-9® or AD-9® IPC air dryer

exhaust.

The actual reactivation of the desiccant drying bed begins

as dry air ﬂ ows from the purge volume through the desiccant

cartridge purge oriﬁ ce and into the desiccant drying bed.

Pressurized air from the purge volume expands after

passing through the purge oriﬁ ce; its pressure is lowered

and its volume increased. The ﬂ ow of dry air through the

drying bed reactivates the desiccant material by removing

the water vapor adhering to it. Generally 15–30 seconds are

required for the entire purge volume of a standard Bendix

AD-9 or AD-9 IPC air dryer to ﬂ ow through the desiccant

drying bed.

The end cover single check valve assembly prevents air

pressure in the brake system from returning to the air dryer

during the purge cycle. After the 30 second purge cycle is

complete, the air dryer is ready for the next charge cycle

to begin.

The purge valve will remain open after the purge cycle is

complete, and will not close until air brake system pressure

is reduced and the governor signals the compressor to

charge.

TURBO CUT-OFF FEATURE (Refer to Figure 4)

The primary function of the turbo cut-off valve is to prevent

loss of engine turbocharger air pressure through the

Bendix AD-9 and AD-9 IPC air dryers in systems where the

compressor intake is connected to the engine turbocharger.

The turbo cut-off valve also reduces the “pufﬁ ng” of air out

the open exhaust when a naturally aspirated, single cylinder

compressor equipped with an inlet check valve is in use.

At the onset of the purge cycle, the downward travel of

the purge piston is stopped when the turbo cut-off valve

(tapered portion of purge piston) contacts its mating metal

seat in the purge valve housing. With the turbo cut-off valve

seated (closed position), air in the discharge line and air

dryer inlet port is restricted from entering the air dryer. While

the turbo cut-off effectively prevents loss of turbocharger

boost pressure to the engine, some “seepage” of air may

be detected under certain conditions of compressor engine

and turbocharger operation. Even so, there will always be

low pressure trapped in the discharge line.

PREVENTIVE MAINTENANCE

Important: Review the warranty policy before performing

any intrusive maintenance procedures. An extended

warranty may be voided if intrusive maintenance is

performed during this period. Note: It is acceptable for

the purge valve to be maintained as necessary, (i.e., the

installation of a purge valve maintenance kit), without

voiding the warranty.

Because no two vehicles operate under identical

conditions, maintenance and maintenance intervals will

vary. Experience is a valuable guide in determining the

best maintenance interval for any one particular operation.

FIGURE 4 - BENDIX® AD-9® AND AD-9® IPC AIR DRYER

TURBO CUT-OFF

UPPER

BRACKET

CHECK

VALVE

ASSEMBLY

SUPPLY

PORT



UPPER

BRACKET

STRAP

DESICCANT

CARTRIDGE

LOWER

BRACKET

HOUSING

CHECK

VALVE

ASSEMBLY



DISCHARGE

LINE

TURBO

CUT-OFF

PISTON

EXHAUST

PURGE

VALVE

TURBO

CUT-OFF

PISTON PURGE VALVE

HOUSING

ASSEMBLY

PURGE

VALVE DISCHARGE

PORT

FIGURE 5 - BENDIX® AD-9® AND AD-9® IPC AIR DRYER

CROSS SECTION

DESICCANT

BED

OIL

SEPARATOR

CONTROL

PORT

SUPPLY

PORT

LOWER

MOUNTING

BRACKET

AD-9® / AD-9® IPC

AIR DRYER

END COVER FEMALE

CONNECTOR

MALE

CONNECTOR

LATCH MUST BE

INSERTED UNTIL

IT SNAPS OVER

TAB ON MATING

CONNECTOR

SIDE VIEW END VIEW

A two lead, 12 inch, wire harness with attached weather

resistant connector is supplied with all retroﬁ t and

replacement Bendix® AD-9® and AD-9® IPC air dryers.

Connect one of the two leads of the wire harness to

the engine kill or ignition switch. The remaining lead of

the wire harness must be connected to a good vehicle

ground. A fuse should be installed in the power carrying

wire; install a 10 amp fuse for 12 volt heaters and a 5

amp fuse for a 24 volt heater. Use 14 AWG wire if it

is necessary to lengthen the wire harness provided.

Make certain all wire splices are waterproofed. Tie

wrap or support all electrical wire leading to the

AD-9® or AD-9® IPC air dryer.

FIGURE 6 - HEATER AND THERMOSTAT CONNECTOR

Every 900 operating hours or 25,000 miles or every

three (3) months:

1. Check for moisture in the air brake system by opening

reservoirs, drain cocks, or valves and checking for

presence of water. If moisture is present, the desiccant

may require replacement; however, the following

conditions can also cause water accumulation and

should be considered before replacing the desiccant:

An outside air source has been used to charge the

system. This air did not pass through the drying bed.

B. Air usage is exceptionally high and not normal for

a highway vehicle. This may be due to accessory

air demands or some unusual air requirement that

does not allow the compressor to load and unload

(compressing and non-compressing cycle) in

a normal fashion. Check for high air system

leakage. If the vehicle vocation has changed it may

be necessary to upgrade the compressor size.

Refer to Appendix A, Table A and the column titled

Vehicle Vocation.

C. The air dryer has been installed in a system that

has been previously used without an air dryer. This

type of system will be saturated with moisture and

several weeks of operation may be required to dry

it out.

D. Location of the air dryer is too close to the air

compressor. Refer to the Locating Bendix® AD-9®

and AD-9® IPC Air Dryer On Vehicle section and

Appendix A, Table A, column 2 for discharge line

length; or

E. In areas where more than a 30 degree range of

temperature occurs in one day, small amounts

of water can accumulate in the air brake system

due to condensation. Under these conditions, the

presence of small amounts of moisture is normal

and should not be considered as an indication that

the dryer is not performing properly.

Note: A small amount of oil in the system may be normal

and should not, in itself, be considered a reason to

replace the desiccant; oil stained desiccant can function

adequately.

2. Check mounting bolts for tightness. Re-torque to

270–385 inch pounds.

3. Perform the Operation & Leakage Tests listed in this

publication.

Oil removal requirements for air brake quality vary by

vehicle manufacturer. Because vehicle vocation and

maintenance can inﬂ uence when the AD-9® IPC air dryer

cartridge requires replacement, each ﬂ eet should modify

their replacement schedule based on experience. The

change out interval will be extended if the compressor

passes a low level of particles, and the interval will be

reduced if excessive carbon particles are delivered to the

dryer inlet. Higher compressor build up times at idle and

water or oil in downstream reservoirs indicate an AD-9®

IPC air dryer desiccant cartridge may need to be replaced.

Every 10,800 hours; 300,000 miles or 36 months:

1. Rebuild the air dryer including the desiccant cartridge.

Note: The desiccant change interval may vary from vehicle

to vehicle. Although typical desiccant cartridge life is three

years, many will perform adequately for a longer period of

time. In order to take maximum advantage of desiccant life

and assure that replacement occurs only when necessary, it

is important that Operation & Leakage Tests be performed.

WARNING!

This air dryer is intended to remove moisture and other

contaminants normally found in the air brake system.

Do not inject alcohol, anti-freeze, or other de-icing

substances into or upstream of the air dryer. Alcohol

is removed by the dryer, but reduces the effectiveness

of the device to dry air. Use of other substances can

damage the air dryer and may void the warranty.

OPERATION & LEAKAGE TESTS

1. Test the outlet port check valve assembly by building

the air system to governor cut-out and observing a test

air gauge installed in the #1 reservoir. A rapid loss of

pressure could indicate a failed outlet port check valve.

This can be conﬁ rmed by bleeding the system down and

removing the check valve assembly from the end cover.

Once this has been done, subject air pressure to the

unit and apply a soap solution to the check valve side.

Leakage should not exceed a 1” bubble in 1 second.

2. Check for excessive leakage around the purge valve.

With the compressor in loaded mode (compressing

air), apply a soap solution to the purge valve housing

assembly exhaust port and observe that leakage does

not exceed a 1” bubble in 1 second. If the leakage

exceeds the maximum speciﬁ ed, service the purge

valve housing assembly.

3. Close all reservoir drain cocks. Build up system

pressure to governor cut-out and note that the air dryer

purges with an audible escape of air. “Fan” the service

brakes to reduce system air pressure to governor

cut-in. Note that the system once again builds to full

pressure and is followed by an air dryer purge.

4. Check the operation of the safety valve by pulling

the exposed stem while the compressor is loaded

(compressing air). There must be an exhaust of air while

the stem is held and the valve should re-seat when the

stem is released.

5. Check all lines and ﬁ ttings leading to and from the air

dryer for leakage and integrity.

6. Check the operation of the end cover heater and

thermostat assembly during cold weather operation as

follows:

A. Electric Power to the Dryer

With the ignition or engine kill switch in the ON

position, check for voltage to the heater and thermostat

assembly using a voltmeter or test light. Unplug the

electrical connector at the air dryer and place the test

leads on each of the pins of the male connector. If there

is no voltage, look for a blown fuse, broken wires, or

corrosion in the vehicle wiring harness. Check to see

if a good ground path exists.

B. Thermostat and Heater Operation

Turn off the ignition switch and cool the end cover

assembly to below 40 degrees Fahrenheit. Using

an ohmmeter, check the resistance between the

electrical pins in the female connector. The resistance

should be 1.5 to 3.0 ohms for the 12 volt heater

assembly and 6.8 to 9.0 ohms for the 24 volt heater

assembly.

Some early models of the Bendix® AD-9® air dryer will

have resistance readings of 1.0 to 2.5 ohms for the 12

volt heater assembly and 4.8 to 7.2 ohms for the 24

volt heater assembly. If the resistance is higher than

the maximum stated, replace the purge valve housing

assembly, which includes the heater and thermostat

assembly.

Warm the end cover assembly to over 90 degrees

Fahrenheit and again check the resistance. The

resistance should exceed 1000 ohms. If the

resistance values obtained are within the stated

limits, the thermostat and heater assembly is

operating properly. If the resistance values obtained

are outside the stated limits, replace the purge valve

housing assembly, which includes the heater and

thermostat assembly.

REBUILDING THE BENDIX® AD-9® AND

AD-9® IPC AIR DRYERS

GENERAL

If, after completing the routine operation and leakage tests,

it has been determined that one or more components of the

air dryer requires replacement or maintenance, refer to the

maintenance kit listing in this manual or the Bendix® Quick

Reference Catalog (BW1114) for complete kit information.

When rebuilding or replacing components of the air dryer,

use only genuine Bendix parts. For ease in servicing

the Bendix® AD-9® and AD-9® IPC air dryer desiccant

cartridge assemblies, it is recommended that the air dryer

be removed from the vehicle.

The kit illustrations on the following pages show the

kit contents and will be referenced throughout the

rebuilding procedures.

BENDIX® AD-9® AND AD-9® IPC AIR DRYER

REMOVAL

1. Park the vehicle on a level surface and prevent

movement by means other than the brakes.

2. Drain all reservoirs to 0 psi (0 kPa). — Caution:

compressor discharge line may still contain residual

pressure.

3. Identify and disconnect the three air lines from the end

cover and note the position of end cover ports relative

to the vehicle. See Figure 1.

4. Unplug the vehicle wiring harness from the heater and

thermostat assembly connector on the purge valve

housing assembly. See Figure 6.

5. Loosen the 5/16" hex cap screw and sleeve nut

securing the upper mounting strap to the upper

mounting bracket. See Figure 7, illustration A.

Some air dryers may contain a one piece upper

mounting strap as shown in Figure 7, illustration B. If

this is type of strap is present, loosen the adjustment

locknut and remove the strap and isolator from the

upper bracket.

6. Mark and remove the two 3/8" end cover cap screws,

locknuts, and four special washers that secure the

lower mounting bracket to the end cover. Also be sure

to mark these two holes of the end cover. (These bolts

are longer than the other 6 bolts.) Retain the mounting

hardware. See Figure 7, illustrations A and B.

7. Remove the air dryer from the vehicle.

MAINTENANCE KITS

Kit Part

Number

Service New (S)

or Reman

Exchange (RX)

Purge

Valve Type Heater

Connector

Color Kit Description Illustration

107695 S – – – Complete Mounting Bracket Kit - Contains the

upper and lower brackets as well as the necessary

mounting hardware. A

5002080 S – – – Mounting Kit B

5009610 S – – –

107799 S – – – End Cover Check Valve Assembly Replacement -

3/4 inch thread size. C

107800N S – – –

End Cover Check Valve Assembly Replacement -

1/2 inch thread size.

5005037 S Hard Seat – – Purge Valve Housing Maintenance Kit - Contains

the parts necessary to rebuild the air portion of

the purge valve housing and does not include the

heater and thermostat.

5005893 S Soft Seat – –

K041395 S – – – Universal Check Valve Kit E

5003838 S – – – Exhaust Cover Kit F

5004224N S – – – Silencer Kit G

107796 S – – – Desiccant Cartridge Replacement Kit - Contains

the parts necessary to change the desiccant

cartridge only. Non-IPC Air Dryer H

107794X RX – – –

K028830 S – – – Desiccant Cartridge Replacement Kit - Contains

the parts necessary to change the desiccant

cartridge only. IPC Air Dryer

109960 S – – – Makeup Line Kit I5000457 S – – –

109961 S – – – Adaptor Kit

800405 S Soft Seat 12V-75W White

Purge Valve Housing Assembly

(w/heater and thermostat) J

5004338 S Soft Seat 24V-75W Gray

5004341X RX Soft Seat 12V-75W White

5004342X RX Soft Seat 24V-75W Gray

5004479 S Hard Seat 12V-75W White

5004480 S Hard Seat 24V-75W Gray

5004381 S Hard Seat 24V-100W Yellow

5004339 S DLU 12V-75W White

5004340 S DLU 24V-75W Gray

5006580 S DLU 24V-100W Yellow

See Catalog

BW1114 S and RX – – – End Cover Replacement K

109578 S – 12V-75W White

Heater and Thermostat Kit L

109579 S – 24V-75W Gray

5002595 S – 24V-100W Yellow

109871N S – – – Heater Electrical Splicing Kit M

113209 S – – – Universal Mounting Plate N

CHECK VALVE

MAINTENANCE KIT

STANDARD MOUNTING BRACKET KIT MOUNTING BRACKET KIT

MOUNTING

STRAP MOUNTING STRAP

ISOLATOR

UPPER BRACKET

SPECIAL

WASHER

LOWER

MOUNTING

BRACKET

3/8" END COVER

CAP SCREW

SPECIAL

WASHER

LOCKNUT

MOUNTING

SADDLE

SPECIAL

WASHER

LOWER

MOUNTING

BRACKET

3/8" END

COVER CAP

SCREW

SPECIAL

WASHER

5/16" HEX

HEAD SCREW

SLEEVE

NUT

LOCKNUT

O-RING

CHECK

VALVE

DELIVERY CHECK VALVE KIT

O-RING

CHECK VALVE

SPRING

RETAINER

O-RING

CHECK VALVE

SPRING

PURGE VALVE HOUSING MAINTENANCE KIT

SMALL O-RING

PURGE

VALVE

RETURN

SPRING

MEDIUM O-RING

LARGE O-RING

QUAD RING

PISTON

ASSEMBLY

EXHAUST

GUIDE

SHOULDER

BOLT

WASHER

SCREW

ABC

FIGURE 7 - MAINTENANCE KIT CONTENTS (ILLUSTRATIONS A THROUGH E)

PURGE VALVE

ASSEMBLY

(NOT

INCLUDED

IN KIT)

ADJUSTING NUT

DELIVERY CHECK

VALVE PLUG

(NOT INCLUDED

IN KIT)

DELIVERY CHECK

VALVE HOUSING

(NOT INCLUDED

IN KIT)

HORIZONTAL

VERTICAL

DESICCANT CARTRIDGE KIT H

SILENCER KIT

GASKET

EXHAUST COVER

EXHAUST

COVER

SCREWS

ADAPTER

SILENCER

GASKET

ADAPTER

SCREWS

ADAPTER

SILENCER

BODY

FILTER

SILENCER

COVER

EXHAUST

COVER

EXHAUST

COVER SCREWS

DESICCANT

CARTRIDGE

DESICCANT

CARTRIDGE

O-RING

OUTER

HOUSING

O-RING

LETTER "U" STAMPED HERE

TO IDENTIFY DLU ASSEMBLY

SMALL

O-RING

LARGE

O-RING

MEDIUM

O-RING

STANDARD PURGE VALVE

SMALL

O-RING

LARGE

O-RING

STANDARD

PURGE VALVE

ASSEMBLY

DISCHARGE

LINE

UNLOADER

PURGE VALVE

ASSEMBLY

WASHER

SCREWS

MAKEUP AIR LINE

ADAPTER

CHECK VALVE

ADAPTER CHECK

VALVE

MAKEUP LINE KIT I

FIGURE 8 - MAINTENANCE KIT CONTENTS (ILLUSTRATIONS F THROUGH J)

DISCHARGE LINE UNLOADER PURGE VALVE

EXHAUST COVER

KIT

ADHESIVE LINED

HEAT SHRINK TUBING

EYELET

W/HEAT SHRINK

INSULATOR

UNINSULATED

BUTT SPLICE

CONNECTOR

WIRE HARNESS

ASSEMBLY

HEATER ELECTRICAL SPLICING KIT M

SMALL

O-RING

LARGE

O-RING

MEDIUM

O-RING SCREW

HEATER &

THERMOSTAT

SEALING

RING

HEATER & THERMOSTAT KIT

END COVER REPLACEMENT KIT

DESICCANT

CARTRIDGE O-RING

OUTER HOUSING

O-RING

END COVER

FIGURE 9 - MAINTENANCE KIT CONTENTS (ILLUSTRATIONS K THROUGH M)

DISASSEMBLY

The following disassembly procedure is presented for

reference purposes and presupposes that a major rebuild

of the Bendix® AD-9® or AD-9® IPC air dryer is being

undertaken. Several replacement parts and maintenance

kits are available which do not require full disassembly. The

instructions provided with these parts and kits should be

followed in lieu of the instructions presented here. Refer

to Figures 7, 8 and 9 during disassembly.

Caution: While performing service on the AD-9® and

AD-9® IPC air dryers, it is not recommended that a

clamping device (vise, C-clamp, etc.) be used to hold

any die cast aluminum component, as damage may

result. To hold the end cover, install a pipe nipple in

the supply port and clamp the nipple into a vise.

Delivery Check Valve Removal

The current style AD-9 ® air dryer end cover has a horizontal

delivery check valve while earlier styles contained a vertical

design. Identify the style of AD-9® air dryer end cover and

proceed to the appropriate step for removal. See Figure

7, illustration E.

1. Vertical Delivery Check Valve Removal – Using an

adjustable wrench or a 1-3/4" socket, remove the

delivery check valve assembly and o-ring. Remove

the o-ring from the check valve assembly.

Horizontal Delivery Check Valve Removal – Remove

the delivery check valve plug from the air dryer end

cover.

2. Remove the spring, check valve body, and o-ring.

UNIVERSAL

MOUNTING PLATE

Silencer Removal

If the air dryer purge valve has a silencer attached to it,

identify the style of silencer before attempting to remove

it. There are two different styles of silencers that have

been used with the Bendix® AD-9® air dryer. One design

is secured to the air dryer purge valve adapter with four

cap screws that are visible from the bottom. The other is

a snap-on design. See Figure 8, illustration G.

Screw Mounted Silencer

1. Remove the four screws that secure the exhaust cover,

silencer cover, ﬁ lter and silencer body to the adapter.

2. Remove the three screws that secure the adapter to

the purge valve. Remove the adapter and gasket.

Snap-on Silencer

1. Firmly grip the silencer and pull it away from the air

dryer end cover.

2. Slide the adapter off of the exhaust cover.

3. Remove the three screws that secure the exhaust cover

to the purge valve housing assembly of the end cover.

Remove the exhaust cover and gasket.

Purge Valve Removal

1. Remove the three 1/4" screws that secure the purge

valve housing assembly to the end cover assembly. Pull

the purge valve housing assembly out of the end cover

assembly. Remove the three o-rings from the exterior

of the purge valve housing assembly. (The medium

o-ring is not included in DLU models.) The o-rings may

be lodged in the end cover bores, if so, they must be

removed. Refer to Figure 8, illustration J.

2. Purge Valve Disassembly:

Note: In some cases a ﬂ at (non-extended) exhaust

cover is used. If an extended type exhaust cover is in

use, (to accommodate the attachment of an exhaust

hose), the exhaust cover must be carefully peeled off of

the purge valve housing. Use a thin ﬂ at blade to pry

the exhaust cover off, taking care not to damage

the potting material (RTV sealant) under the cover.

Removal of the piston from the purge valve housing

assembly requires a tool to hold the head of the purge

piston while unscrewing the purge valve shoulder

bolt. Remove the piston from the purge valve housing

assembly using a twelve point 1/4" socket to hold the

head of the purge valve shoulder bolt. See Figure 7,

illustration D.

A. Secure the top of the purge piston assembly using

the two opposing cast indentations and a removal

tool. Remove the purge valve shoulder bolt from

the bottom of the purge valve housing assembly.

Remove the exhaust guide and purge valve from

the purge valve housing.

B. Remove the purge piston assembly and return

spring from the opposite end of the purge valve

housing assembly. Remove the quad ring from the

purge piston assembly.

FIGURE 10 - HEATER & THERMOSTAT REMOVAL & INSTALLATION

RUBBER CUSHION

PURGE VALVE

W/HEATER & THERMOSTAT INSTALLED

(SECTIONAL VIEW FROM BOTTOM)

THERMOSTAT

HEATER

ELEMENT

RUBBER CUSHION

THERMOSTAT

HEATER

ELEMENT

Step B

Step A

PURGE VALVE HOUSING W/HEATER & THERMOSTAT

(SECTIONAL VIEW FROM BOTTOM)

PURGE

VALVE

ASSEMBLY

SMALL

O-RING

LARGE

O-RING

MEDIUM

O-RING SCREW

HEATER &

THERMOSTAT

SEALING

RING

HEATER &

THERMOSTAT

SEALING RING

HEATER &

THERMOSTAT

SEALING RING

PURGE VALVE

ASSEMBLY

Heater and Thermostat Assembly Removal

1. Remove the two screws that secure the heater and

thermostat assembly to the purge valve assembly. See

Figure 9, illustration L for kit contents.

CAUTION

DO NOT PULL THE HEATER & THERMOSTAT

ASSEMBLY STRAIGHT OUT OF THE PURGE VALVE

BODY! READ STEP 2 COMPLETELY BEFORE

ATTEMPTING REMOVAL.

2. Study Figure 10 closely and note the "Y" shape of the

Heater & Thermostat assembly in its installed position

in the purge valve housing. As illustrated, remove the

heater & thermostat assembly by gently "rotating" the

connector to the left (Step A) until the thermostat clears

the purge valve housing, then slide the heater element

out, to the right and up (Step B).

End Cover Removal

1. Remove the remaining six 3/8" cap screws, locknuts

and twelve special washers that secure the end cover to

the housing air dryer housing. Separate the end cover

and desiccant cartridge from the housing. See Figure

9, illustration K.

2. Remove the end cover to outer housing o-ring.

3. Do not remove the safety valve from the end cover

unless it has been proven defective. If replacement

is required, apply thread sealant or Teflon® tape on

the threads of the replacement valve and torque

to 120–400 in. lbs. See Figure 1 for safety valve

location.

4. Place a strap or chain wrench around the desiccant

cartridge so that it is approximately 2–3 inches

away from the end cover. Rotate the cartridge

counterclockwise until it completely separates from the

end cover.

Note: A substantial torque (up to 50 lb. ft.) may be

required to perform this disassembly.

5. Remove the desiccant cartridge o-ring from the end

cover.

Drop In Air Dryer Makeup Line Removal

1. Before beginning, note the approximate angle of

the fittings, check valve and the general routing of

the makeup line on the air dryer. It is important that

the same approximate routing be duplicated during

re-installation. See Figure 11.

2. Disconnect the makeup line from the 90 degree ﬁ tting

on the check valve.

3. Disconnect the makeup line from the 90 degree ﬁ tting

on the port adapter itself or the check valve. Remove

the adapter along with the attached 90 degree ﬁ tting.

CLEANING & INSPECTION

1. Using mineral spirits or an equivalent solvent, clean

and thoroughly dry all metal parts.

2. Inspect the interior and exterior of all metal parts

that will be reused for severe corrosion, pitting and

cracks. Superficial corrosion and/or pitting on the

exterior portion of the upper and lower body halves is

acceptable.

3. Inspect the bores of both the end cover and the purge

valve housing for deep scufﬁ ng or gouges.

DELIVERY PORT

ADAPTER

(WITH 90° FITTING)

DELIVERY PORT

ADAPTER

(WITH 90° FITTING)

MAKEUP AIR LINE

CHECK VALVE

(WITH 90° FITTING)

SPECIAL ASSEMBLY,

MUST BE REPLACED BY

AD-9 SOFT SEAT

AIR DRYER ASSY.

SPECIAL ASSEMBLY,

MUST BE REPLACED BY

AD-9 SOFT SEAT

AIR DRYER ASSY.

FIGURE 11 - BENDIX® AD-9® DROP IN AIR DRYER

MAKEUP AIR LINE

4. Make certain that all purge valve housing and end cover

passages are open and free of obstructions.

5. Inspect the pipe threads in the end cover. Make certain

they are clean and free of thread sealant.

6. Inspect the purge valve housing bore and seats for

excessive wear and scufﬁ ng.

7. Inspect the purge valve piston seat for excessive wear.

8. Inspect all air line ﬁ ttings for corrosion. Clean all old

thread sealant from the pipe threads.

9. All o-rings removed should be discarded and replaced

with new o-rings provided in appropriate kit(s).

Any component exhibiting a condition described in step 1

to 8 should be replaced.

ASSEMBLY

The following assembly procedure is presented for

reference purposes and presupposes that a major rebuild

of the Bendix® AD-9® or AD-9® IPC air dryer is being

undertaken. Several replacement parts and maintenance

kits are available which do not require full disassembly. The

instructions provided with these parts and kits should be

followed in lieu of the instructions presented here. Refer

to Figures 7, 8 and 9 during assembly.

Purge Valve Housing Assembly

1. Prior to assembly, coat all o-rings, o-ring grooves, and

bores with a generous amount of the lubricant included

in the maintenance kit. See Figure 7, illustration D.

A. Install the quad-ring in its groove on the O.D. of the

purge piston. Place the return spring in the bore of

the purge valve housing. Insert the purge piston into

the I.D. of the return spring. Place the purge valve

guide onto the shoulder bolt followed by the purge

valve. Using a ratchet or wrench, screw the purge

valve, purge valve guide and shoulder bolt into the

purge housing until it bottoms. This will require a tool

to hold the top of the purge piston from rotating as the

shoulder bolt is screwed into the bottom of the purge

piston to complete the purge valve assembly. Torque

the shoulder bolt to 60–90 in. lbs.

B. Install the o-rings on the purge valve housing, placing

each in its appropriate location. Note the medium

o-ring is not used on Discharge Line Unloaded

(DLU) models. If the exhaust cover was removed

during disassembly, install it on the purge valve

assembly making certain the “bubble” portion is

positioned over the thermostat. Install the assembled

purge valve housing in the end cover. Make certain

to orient both parts such that the connector is

approximately 10 degrees clockwise from the supply

port, while making certain the purge valve housing is

fully seated against the end cover. Secure the purge

valve housing to the end cover using the three 1/4"

self-tapping screws. Start all three screws by hand

then torque to 50–80 in. lbs.

Delivery Check Valve Assembly

The current style AD-9® air dryer end cover has a

horizontal delivery check valve while earlier styles

contained a vertical design. Identify the style of AD-9®

air dryer end cover and proceed to the appropriate step

for installation. See Figure 7, illustration E.

Vertical Delivery Check Valve –

1. Assemble the spring to the retainer and check valve.

Ensure the spring is fully seated on the retainer and

the check valve.

2. Lubricate the entire spherical surface of the check valve

and bore chamfer of the check valve housing with the

lubricant provided in the kit.

3. Place the retainer, spring and check valve sub-

assembly into the check valve housing. Press the

retainer using a 7/16" deep socket with a 3/8" drive,

and a vise as shown in Figure 12.

4. Inspect the bore of the end cover. Make certain that the

end cover passage is open and free of obstructions.

5. Install the o-ring on the outer body of the delivery check

valve assembly. Ensure the o-ring is seated properly

and not twisted. Lubricate the o-ring.

6. Install the delivery check valve assembly into the end

cover. Torque to 200–250 in. lbs.

Horizontal Delivery Check Valve –

1. Lubricate the o-ring and the long check valve body with

the lubricant provided. Use only the lubricant contained

in the kit.

2. Install the o-ring on the long check valve body. Push

the o-ring down, over the 3 guide lands until it is in the

o-ring groove. Ensure the o-ring is seated properly

and not twisted.

3. Install the spring on the white check valve body so that

the small coils of the spring slip over the check valve

body.

DELIVERY CHECK

VALVE BODY

7/16" DEEP

SOCKET WITH A

3/8" DRIVE

APPLY LUBRICANT

BENCH VISE

CHECK

VALVE

SPRING

RETAINER

FIGURE 12 - VERTICAL DELIVERY CHECK VALVE

FIGURE 13 - END COVER TO HOUSING TORQUE PATTERN

1&9

4. Install the assembled long check valve body, o-ring,

and spring in the end cover delivery check valve port

so that the o-ring rests on its seat in the end cover and

the spring is visible.

5. Install the delivery check valve plug that was removed

during the disassembly, into the air dryer end cover.

See Figure 5. Torque the plug to 130–170 inch pounds.

Drop In Air Dryer Makeup Line Assembly

1. Install the adapter and the attached 90 degree ﬁ tting in

the air dryer. Take care that the replacement adapter

and attached ﬁ tting is in the same approximate position

as the original. See Figure 11.

2. Install the check valve and ﬁ tting, taking care that the

replacement is in the same approximate position as the

original.

3. Install the makeup line and tighten the tubing nuts at

both ends while preventing the 90 degree ﬁ ttings from

turning. Tighten the nuts sufﬁ ciently to prevent air

leakage, but do not over tighten.

Air Dryer Assembly

1. Install the desiccant cartridge o-ring in its groove in

the end cover. Using a light coat of lubricant (included

in kit), lubricate the bottom of the desiccant cartridge

in the area that will contact the o-ring and end cover.

Screw the desiccant cartridge into the end cover until

contact is made between it and the o-ring. Using a strap

or chain wrench positioned 2–3 inches from the bottom

of the cartridge, turn the desiccant cartridge clockwise

180–225 degrees beyond the position where initial

contact was made between the cartridge and end cover

o-ring. Torque should not exceed 50 ft. lbs.

2. Install the end cover outer housing o-ring on the

shoulder in the end cover. Place the housing over the

desiccant cartridge and align the holes. Install the six

3/8" cap screws, locknuts and twelve special washers,

making certain they are in the proper position as marked

during disassembly. The two longer 3/8" cap screws will

be used to secure the air dryer to its mounting bracket.

Tighten the six cap screws and nuts in a star pattern

in a fashion similar to Figure 13; depending on lower

bracket location. Torque to 270–385 in. lbs.

Note: The two remaining bolt holes in the end cover and

two 3/8" cap screws must be the ones marked during

disassembly to assure proper orientation of the ports

and adequate length of the cap screws.

INSTALLATION

1. Install the assembled Bendix® AD-9® or AD-9® IPC 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 the air dryer. The 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. lbs. See Figure 14.

2. See Figure 7, illustrations A and B, to determine the

mounting bracket type.

Illustration A Style - Attach the mounting strap to the

air dryer and secure it to the mounting saddle with

the 5 /16" X 4-1/2" hex cap screw and nut. Torque to

80–120 in. lbs.

Illustration B Style - Place the isolator between the

upper bracket and air dryer. Secure the air dryer to

the upper bracket with the mounting strap. Tighten the

adjusting nut to 50–60 in. lbs.

2-1/8"

END

COVER

LOWER

BRACKET

EXTRA

LONG

BRACKET

CAP SCREW



SPECIAL

WASHER

FIGURE 14 - LOWER BRACKET INSTALLATION

3. Reconnect the three air lines to the proper ports on the

end cover (identiﬁ ed during disassembly).

4. Reconnect the vehicle wiring harness to the air dryer

heater and thermostat assembly connector by plugging

it into the air dryer connector until its lock tab snaps in

place.

5. Before placing vehicle back into service, perform the

Operation and Leakage Tests stated earlier in this

manual.

RETROFITTING THE BENDIX® AD-9® AIR

DRYER

GENERAL

The following retrofit instructions are presented for

reference purposes only since Bendix aftermarket retroﬁ t

and replacement air dryers are packaged with the most up-

to-date installation instructions. The instructions packaged

with the Bendix® AD-9® and AD-9® IPC air dryers 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-9® and AD-9® IPC air

dryers. The portion of the manual that follows is concerned

with installing an AD-9® or AD-9® IPC 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 ﬂ ow

systems. While the AD-9® or AD-9® IPC air dryer can be

used on these vehicles, the standard installation procedure

presented in this manual may require modiﬁ cation to

assure proper operation and service life. Consult your local

authorized Bendix parts outlet or sales representative for

additional information.

1. Charge Cycle Time - The Bendix® AD-9® and AD-9® IPC

air dryers are 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.

FIGURE 11 - AD-9® AIR DRYER CHARGE CYCLE

COMPRESSOR

10 AMP - 12V

5 AMP - 24V

SUP

CON

14 GA WIRE

TO IGNITION

& GROUND

SAFETY VALVE

DEL TO RESERVOIR

RESERVOIR

GOVERNOR

UNLOADER

PORT DELIVERY

SUPPLY

CONTROL

(HIDDEN)

FUSE

2. Purge Cycle Time - During normal vehicle operation,

the air compressor must remain unloaded for a

minimum of 20 seconds for the standard 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 speciﬁ ed,

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 Bendix® AD-9® and

AD-9® IPC air dryer installation requirements. Consult

your local authorized Bendix parts outlet or sales

representative for additional information.

4. Holset “E or QE” Type Air Compressors - In order for the

AD-9 or AD-9 IPC 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.

5. Use of Standard or Extended Purge AD-9 or AD-9 IPC

Air Dryer - Use the following guidelines:

Total Vehicle

Reservoir Volume Bendix® AD-9® or

AD-9® IPC Air Dryer

Requirement

Less than 9,000 cu. in. Standard Air Dryer

9,000 - 12,500 cu. in. Extended Purge Air Dryer

Greater than 12,500 cu. in. Contact Bendix Rep. or Bendix

Engineering

VEHICLE PREPARATION

1. Park the vehicle on a level surface and prevent

movement by means other than the brakes.

2. Drain all reservoirs to 0 psi (0 kPa).

LOCATING THE BENDIX® AD-9® AIR DRYER ON

VEHICLE

1. The AD-9 or AD-9 IPC air dryer must be mounted

vertically (purge exhaust toward road surface) outside

the engine compartment in an area of air ﬂ ow while the

vehicle is in motion. The air dryer must not be exposed

to direct wheel splash (located behind axle mud ﬂ ap is

acceptable).

2. Locate the AD-9 or AD-9 IPC air dryer as close to the

ﬁ rst (supply) reservoir as possible.

3. Do not locate the AD-9 or AD-9 IPC air dryer near heat

producing components, such as the vehicle exhaust,

and make certain adequate clearance from moving

components (e.g. drive shaft, suspension, pitman arm,

etc.) is provided.

4. Locate the AD-9 or AD-9 IPC air dryer on the vehicle

so that a minimum of 11 inches (28 cm) clearance

below the end cover is available to allow servicing.

Alternatively, provide access to the bracket bolts so

the unit may be removed for servicing.

5. When choosing the mounting location for the AD-9

or AD-9 IPC air dryer, note the discharge line length

requirements stated under the heading Connecting the

Air Lines, elsewhere in this instruction sheet.

Important Note: Under normal operating conditions,

the maximum inlet air temperature for the AD-9 and

AD-9 IPC air dryers is 160 degrees Fahrenheit.

MOUNTING THE BENDIX® AD-9® AND AD-9® IPC

AIR DRYER

1. To install the lower mounting bracket on the AD-9 or

AD-9 IPC air dryer, it will be necessary to remove and

discard two of the end cover bolts and locknuts. To

determine which end cover bolts to utilize to attach

the lower bracket, take into consideration the piping

connections required to install the air dryer and

use those that will best position the unit for ease of

installation. Locate the bracket such that it cradles

the end cover as shown in Figure 9. Utilizing the two

2-3/8" long cap screws, locknuts and special washers

provided with the AD-9 or AD-9 IPC air dryer retroﬁ t

unit, attach the lower mounting bracket and torque to

270–385 in. lbs.

2. Assemble the mounting strap and upper mounting

bracket as illustrated in Figure 10, by utilizing the 5/16"

cap screw and sleeve nut.

3. Place the upper bracket assembly onto the shell of

the AD-9 or AD-9 IPC air dryer and orient it so that it

bears entirely on the cylindrical surface and does not

extend onto the domed top. The slot spacing between

the upper and lower bracket should be a minimum of

5.5 inches apart. Do not tighten strap onto the shell at

this time.

4. Mount the air dryer on the vehicle using 3/8" bolts

(grade 5 min.) and washers. Torque to 25 ft. lbs. (300

inch pounds.) After positioning and mounting the

upper bracket assembly according to the installation

requirements, torque the 5/16" nut to 80–120 in. lbs.

to tighten strap onto the shell.

CONNECTING THE AIR LINES

PURGE CONTROL LINE

1. Install a purge control air line having a minimum inside

diameter of 3/16 inches between the Bendix® AD-9®

or AD-9® IPC air dryer end cover control port and an

unused unloader port on the governor. The control line

must be plumbed direct to the governor and not in series

with automatic drain valves, lubrication systems, etc.

2. The control line should slope downward to the end

cover without forming potential water traps.

DISCHARGE LINE

General:

Refer to Appendix A, Table A for recommended discharge

line lengths and sizes for various vehicle applications and

vocations.

PURGE EXHAUST LINE

1. If it is necessary to direct AD-9 or AD-9 IPC air dryer

discharge contaminants away from vehicle components

it may be necessary to purchase a special exhaust

cover for the AD-9 or AD-9 IPC air dryer (Pc. No.

5003838). A one inch (25.4 mm) I.D. hose can be

clamped on the special air dryer exhaust cover.

WIRING THE HEATER/THERMOSTAT

1. Determine the vehicle’s electrical system voltage and

make certain that the AD-9 or AD-9 IPC air dryer that is

to be installed contains the same voltage heater. Use the

AD-9 or AD-9 IPC air dryer part number to conﬁ rm the

proper voltage. The AD-9 and AD-9 IPC air dryers are

available with either a 12 or 24 volt heater which uses

75 watts of power.

2. A two lead, 12 inch, wire harness with attached weather

resistant connector is supplied with all retroﬁ t and

replacement AD-9 and or AD-9 IPC air dryers. Connect

one of the two leads of the wire harness to the engine

kill or ignition switch. The remaining lead of the wire

harness must be connected to a good vehicle ground

(not to the air dryer or its mounting bracket). A fuse

should be installed in the power carrying wire; install a

10 amp fuse for 12 volt heaters and a 5 amp fuse for

a 24 volt heater.

3. Use 14 GA wire if it is necessary to lengthen the wire

harness provided with the AD-9 or AD-9 IPC air dryer.

Make certain all wire splices are waterproofed.

4. Tie wrap or support all electrical wire leading to the

AD-9 or AD-9 IPC air dryer at 6–8 inch intervals.

Note: Wires should have sufﬁ cient slack and not be

completely taught.

TESTING THE BENDIX® AD-9® AND AD-9® IPC

AIR DRYER

Before placing the vehicle in service, perform the following

tests:

1. Close all reservoir drain cocks.

2. Build up system pressure to governor cut-out and note

that the air dryer purges with an audible escape of air.

3. “Fan” the service brakes to reduce system air pressure

to governor cut-in. Note that the system once again

builds to full pressure and is followed by a purge at the

air dryer exhaust.

4. It is recommended that the following items be tested for

leakage to assure that the AD-9 or AD-9 IPC air dryer

will not cycle excessively.

(A) Total air system leakage (See Bendix® Air Brake

Handbook, BW5057).

(B) Compressor unloader mechanism.

(D) Drain cock and safety valve in first (supply)

reservoir.

(E) All air connections leading to and from the ﬁ rst

(supply) reservoir.

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

1. Dryer is constantly “cycling”

or purging. Dryer purges

frequently (every 4 minutes

or less while vehicle is idling).

A. Excessive system leakage.

IMPORTANT: Note whether air

pressure loss is shown on dash

gauge(s). Pressure loss shown on

gauges is caused by service brake

system or component leakage.

Pressure loss NOT SHOWN

on gauges is caused by supply

system or component leakage.

A. If leakage IS SHOWN on gauges, test for excessive service

brake system leakage.

Allowable leakage:

Pre-121 vehicles, single vehicles - 2 psi / minute.

Tractor trailer - 3 psi / minute.

121 vehicles, single vehicle - 1 psi / minute per service reservoir.

Tractor trailer - 3 psi / minute per service reservoir. Repair and

retest as required.

If leakage is NOT SHOWN on gauges test for excessive supply

system leakage.

Remove drain cock or valve in supply reservoir (wet tank) and

install air gauge. Build system pressure, allow air dryer to purge

and observe air gauge in supply reservoir. Pressure drop should

not exceed 1 psi per minute.

Perform tests 1 to 6 in the order presented.

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

1. Dryer is constantly “cycling”

or purging. Dryer purges

frequently (every 4 minutes

or less while vehicle is idling)

(continued).

A. Excessive system leakage.

IMPORTANT: Note whether air

pressure loss is shown on dash

gauge(s). Pressure loss shown on

gauges is caused by service brake

system or component leakage.

Pressure loss NOT SHOWN

on gauges is caused by supply

system or component leakage.

(continued)

1. Test ﬁ ttings, hoses, lines and connections. Apply soap solution

to detect excessive leakage. Tighten or replace as needed

then repeat the air dryer charge-purge cycle and observe the

gauge installed in the supply reservoir. If leakage is within limits,

remove gauge from reservoir and replace drain cock or valve. If

excessive leakage is detected, continue testing.

2. Test accessories connected to supply reservoir. Drain all

air pressure from system, disconnect all air lines leading to

accessories (fan clutch, wipers, air seats, etc.) and plug the

reservoir at disconnection point. Build air system pressure until

air dryer purges and observe supply reservoir gauge. If leakage

is no longer excessive, repair or replace leaking accessory. If

excessive leakage is detected, continue testing.

3. Test governor leakage. Build system pressure to governor cut-

out, turn off engine and apply soap solution to governor exhaust

port and around cap. Leakage should not exceed a 1 in. bubble

in 5 seconds. Reduce system pressure to 80 psi or less, and re-

apply soap solution. Leakage should not exceed a 1 in. bubble in

5 seconds. If excessive leakage is detected in either test, repair

or replace governor.

4. Test compressor unloader leakage. Drain all air pressure

from system and remove the governor from the compressor.

Temporarily plug the governor unloader port or air line that

mated with, or connected to, the compressor. Build air system

pressure until air dryer purges then IMMEDIATELY SHUT OFF

THE ENGINE. Observe the air gauge in the supply reservoir. If

leakage is within limits, replace the compressor unloaders. Re-

connect the governor to the compressor (after removing plug

installed in governor) and retest while observing supply reservoir

gauge. If excessive leakage is detected, continue testing.

5. Test air dryer purge valve and outlet (delivery) check valve. Drain

all air pressure from system, remove the control line connection

at the air dryer and plug the end of the air line leading to the

governor (not the air dryer control port). Build system pressure

to governor cut-out and observe air gauge. If little or no pressure

drop is observed replace the air dryer check valve. If pressure

drop continues, apply soap solution to air dryer purge exhaust

and purge control port (where the control line was removed).

Leakage should not exceed a 1 in. bubble in 5 seconds. If

leakage is excessive, repair or replace purge valve assembly.

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

1. Dryer is constantly “cycling”

or purging. Dryer purges

frequently (every 4 minutes

or less while vehicle is idling)

(continued).

A. Excessive system leakage.

IMPORTANT: Note whether air

pressure loss is shown on dash

gauge(s). Pressure loss shown on

gauges is caused by service brake

system or component leakage.

Pressure loss NOT SHOWN

on gauges is caused by supply

system or component leakage.

(continued)

6. With gauge installed at RES port of governor, pressure should

not drop below ”Cut-In” pressure at the onset of the compressor

“Unloaded” cycle. If pressure drops, check for “kinks” or

restrictions in line connected to RES port. Line connected to

RES port on governor must be same diameter, or preferably

larger than, lines connected to UNL port(s) on governor.

B. Leaking purge valve housing

assembly and/or o-rings in air

dryer end cover.

B. With the supply port open to atmosphere, apply 120 psi at the

control port. Apply a soap solution to the supply port and exhaust

port (purge valve seat area). Permissible leakage - 1" bubble in

5 seconds.

C. Holset® “E” type compressor. C. Test the Holset® E Compressor unloader system with feedback

line and check valve for proper operation. Make certain Holset

ECON is not in use with the drop-in version of the air dryer, if

so, remove and retest.

When installing a Bendix Drop-In air dryer in a system equipped

with a Holset E or QE compressor, remove the Holset ECON valve

along with its feedback and governor control line.

Typical Drop-In Air Dryer End Cover

Check Valve

Feedback Line

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

2. Water and/or Oil in Supply or

Service Reservoir. A. Desiccant requires replacement

- excessive contaminants in

desiccant cartridge assembly.

A. Replace desiccant cartridge.

B. Improper discharge line length or

improper line material. Maximum

air dryer inlet temperature is

exceeded.

B. Refer to section entitled Connecting the Air Lines as well as

Appendix A, Table A columns 1 & 2 then check line size and

length.

C. Air system charged from outside

air source (outside air not passing

through air dryer)

C. If system must have outside air ﬁ ll provision, outside air should

pass through the air dryer. This practice should be minimized.

D. Air dryer not purging (see

Symptom #5). D. See Symptom #5.

E. Purge (air exhaust) time insufﬁ cient

due to excessive system leakage

(see causes for Symptom #1).

E. Check causes and remedies for Symptom #1.

F. Excessive air usage, duty cycle

too high - Air dryer not compatible

with vehicle air system requirement

(Improper air dryer/vehicle

application).

NOTE: Duty Cycle is the ratio of

time the compressor spends building

air to total engine running time. Air

compressors are designed to build air

(run “loaded”) up to 25% of the time.

Higher duty cycles cause conditions

that affect air brake charging system

performance which may require

additional maintenance. Factors

that add to the duty cycle are: air

suspension, additional air accessories,

use of an undersized compressor,

frequent stops, excessive leakage from

ﬁ ttings, connections, lines, chambers or

valves, etc.

F. See Appendix A, Table A, column 1, for recommended

compressor sizes. If the compressor is “too small” for the

vehicle vocation (for example, where a vehicle’s vocation has

changed or service conditions exceed the original vehicle or

engine OE spec’s) then upgrade the compressor. Note: The

costs incurred (e.g. installing a larger capacity compressor,

etc.) are not covered under original compressor warranty.

Charge Cycle Time - Bendix® AD-9® and AD-9® IPC air dryers

are 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 RPM’s 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. An example of where a

by-pass system would be required is when the compressor

is used to pressurize a tank trailer for purposes of off-loading

product. Consult your local authorized Bendix parts outlet or

sales representative for additional information.

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

2. Water and/or Oil in Supply

or Service Reservoir

(continued).

(Continued) Purge Cycle Time - During normal vehicle operation, the

air compressor must remain unloaded for a minimum of 20

seconds for the standard Bendix® AD-9® and AD-9® IPC 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

consistently less than the minimum, an accessory by-pass

system must be installed. Consult your local authorized Bendix

parts outlet or sales representative for additional information.

European Air Brake Systems - Brake systems that incorporate

compressors without integral unloading mechanisms and/

or utilize a compressor discharge line unloader valve have

special air dryer installation requirements. Consult your local

authorized Bendix parts outlet or sales representative for

additional information.

Air Compressor Size - Although the AD-9 and AD-9

IPC air dryers 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-9 or AD-9 IPC 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.

G. Air compressor discharge and/or

air dryer inlet temperature too high. G. Restricted discharge line. See Appendix A, Table A, column 1

& 2 for recommended sizes. If discharge line is restricted or

more than 1/16” carbon build up is found, replace the discharge

line. Replace as necessary.

Discharge Line Freeze-Up. The discharge line must maintain a

constant slope down from the compressor to the air dryer inlet

ﬁ tting to avoid low points where ice may form and block the ﬂ ow.

If, instead, ice blockages occur at the air dryer inlet, insulation

may be added here, or if the inlet ﬁ tting is a typical 90 degree

ﬁ tting, it may be changed to a straight or 45 degree ﬁ tting. For

more information on how to help prevent discharge line freeze-

ups, see Bendix Bulletins TCH-008-021 and TCH-008-022.

Shorter discharge line lengths or insulation may be required in

cold climates.

Insufﬁ cient coolant ﬂ ow through compressor. Inspect coolant line.

Replace as necessary (I.D. is 1/2” min.). Inspect the coolant lines

for kinks and restrictions and ﬁ ttings for restrictions. Replace as

necessary. Verify coolant lines go from engine block to compressor

and back to the water pump. Repair as necessary.

Restricted air inlet (not enough air to compressor). Check

compressor air inlet line for restrictions, brittleness, soft or sagging

hose conditions, etc. Repair as necessary. Inlet line size is 3/4 ID.

Maximum restriction requirement for compressors is 25 inches

of water. Check the engine air ﬁ lter and service if necessary (if

possible, check the air ﬁ lter usage indicator).

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

2. Water and/or Oil in Supply

or Service Reservoir

(continued).

(Continued) Poorly ﬁ ltered inlet air (poor air quality to compressor). Check

for leaking, damaged or malfunctioning compressor air inlet

components (e.g. induction line, ﬁ ttings, gaskets, ﬁ lter bodies,

etc.). Repair inlet components as needed. Note: Dirt ingestion will

damage compressor and is not covered under warranty.

If you found excessive oil present in the service reservoir and you

did not ﬁ nd any issues above, the compressor may be passing oil.

Replace compressor. If still under warranty, follow normal warranty

process.

H. Compressor malfunction. H. If excessive oil is present in the service reservoir and no other

issues (from above) were found, the compressor may be

passing oil. Test the compressor using the Bendix® BASIC™

cup method as described in the Bendix compressor service

manual and referred to in Appendix A, Table A, column 5.

Replace compressor. If still under warranty, follow normal warranty

process.

I. Air by-passes desiccant cartridge

assembly. I. If the vehicle uses a Holset® compressor, inspect the

feedback check valve for proper installation and operation.

When replacing the desiccant cartridge, make sure desiccant

cartridge assembly is properly installed and sealing rings are in

place on mounting surface of desiccant cartridge.

Typical Drop-In Air Dryer End Cover

Feed Back Line

J. Desiccant requires replacement. J. Replace desiccant cartridge assembly. Refer to Appendix A,

Table A columns 3 & 4 for recommended intervals.

3. Oil present at air dryer purge

exhaust or cartridge during

maintenance.

A. Air brake charging system is

functioning normally. A. Air dryers remove water and oil from the air brake charging

system. A small amount of oil is normal. Check that regular

maintenance is being performed and that the amount of oil in

the air tanks (reservoirs) is within the acceptable range shown

on the BASIC cup (see also column 5 of Appendix A, Table

A). Replace the air dryer cartridge as needed and return the

vehicle to service.

Check Valve

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

4. Safety valve on air dryer

“popping off” or exhausting

air.

A. Restriction between air dryer and

supply (ﬁ rst) reservoir. A. Check to determine if air is reaching supply reservoir. Inspect

for kinked tubing or hose. Check for undrilled or restricted hose

or tubing ﬁ ttings and repair or replace as needed.

B. Air dryer safety valve malfunction. B. Verify relief pressure is at vehicle or component manufacturer

speciﬁ cations. Replace if malfunctioning.

C. Desiccant cartridge maintenance

required. C. Refer to Appendix A ,Table A and column 3. Check compressor

for excessive oil passing and/or correct compressor installation.

Repair or replace as necessary. Replace desiccant cartridge.

D. Malfunctioning discharge check

valve in end cover of the Benidix®

AD-IP® air dryer.

D. Test to determine if air is passing through check valve. Repair

or replace.

E. Excessive pressure pulsations

from compressor. (Typical single

cylinder type).

E. Increase volume in discharge line by increasing length or

diameter. Add a ping tank (small reservoir).

F. Governor malfunction. Missing

or restricted governor control line

installation.

F. Test governor operation and/or inspect the control line leading

from the governor UNL (unloader) port to the air dryer control

port.

5. Constant exhaust of air at air

dryer purge valve exhaust.

(Charge mode.)

A. Air dryer purge valve leaking

excessively. A. With compressor loaded, apply soap solution

on purge valve exhaust, to test for excessive leakage. Refer

to Technical Bulletin TCH-008-040. Repair purge valve as

necessary.

B. Compressor fails to unload (stop

compressing air) and air dryer

purge exhaust makes “sputtering”

or “popping” sound.

B. Conﬁ rm failure to unload by increasing & decreasing engine

RPM and noting change in the rate of leakage and intensity

of accompanying leakage sound. Repair/replace compressor

unloaders.

C. Purge control line connected

to reservoir or exhaust port of

governor.

C. Purge control line must be connected to unloader port of

governor.

D. Purge valve frozen open -

malfunctioning heater and

thermostat, wiring, blown fuse.

D. Test heater and thermostat as described in Preventive

Maintenance Section.

E. Excessive system leakage. E. See Symptom #1.

F. Purge valve stays open - supply air

leaks to control side. F. Repair purge valve and housing.

6. Can not build system air

pressure. A. Inlet and outlet air connections

reversed. A. Connect compressor discharge to air dryer supply port.

Reconnect lines properly.

B. Check valve between air dryer and

ﬁ rst reservoir. B. Test check valve for proper operation. Repair or replace as

necessary.

C. Kinked or blocked (plugged)

discharge line. C. Check to determine if air passes through discharge line. Check

for kinks, bends, excessive carbon deposits, or ice blockage.

D. Excessive bends in discharge line

(water collects and freezes) D. Discharge line should be constantly sloping from compressor

to air dryer with as few bends as possible.

E. Refer to Symptom 4, Causes E &

F. E. Refer to Symptom #4, Remedies E & F.

Bendix® AD-9® AND AD-9® IPC AIR DRYER TROUBLESHOOTING CHART

SYMPTOMS CAUSE REMEDY

7. Air dryer does not purge or

exhaust air. A. Missing, broken, kinked, frozen,

plugged or disconnected purge

control line.

A. Inspect control line from governor UNL (unloader) port to control

port of air dryer. Test to determine if air ﬂ ows through purge

control line when compressor unloaded. Check for undrilled

ﬁ ttings. (See Symptom #4, Remedy C.)

B. Faulty air dryer purge valve. B. After determining air reaches purge valve (Remedy A above),

repair purge valve.

C. See Causes, B, E, G for Symptom

#4. C. Refer to Remedies B, E, G for Symptom #4.

8. Desiccant material being

expelled from air dryer purge

valve exhaust (may look like

whitish liquid or paste or

small beads.)

- OR -

Unsatisfactory desiccant life.

A. This symptom is almost always

accompanied by one or more of

Symptoms 1, 2, 3, 4 and 5. See

related causes for these symptoms

above.

A. See Causes and Remedies for Symptoms 1, 2, 3, 4 and 5.

B. Air dryer not securely mounted.

(Excessive vibration.) B. Vibration should be held to minimum. Add bracket supports or

change air dryer mounting location if necessary.

C. Malfunctioning or saturated

desiccant cartridge. C. Replace desiccant cartridge assembly.

D. Compressor passing excessive oil. D. Check for proper compressor installation; if symptoms persist,

replace compressor.

E. Desiccant cartridge not assembled

properly to end cover. (Loose

attachment)

E. Check the torque on the desiccant cartridge

to end cover attachment. Refer to assembly section of this

data sheet.

9. “Pinging” noise excessive

during compressor loaded

cycle.

A. Defective check valve assembly in

air dryer end cover. A. Refer to Remedy C, Symptom #1.

B. Leaking Turbo Cut-off valve. B. Repair or replace purge valve assembly.

C. Leaking purge valve control piston

o-ring. C. Repair or replace purge valve assembly.

10. Constant seepage of air at

air dryer purge valve exhaust

(non-charging mode.)

A. Defective check valve assembly in

air dryer end cover. A. Refer to Remedy C, Symptom #1.

B. Leaking Turbo Cut-off valve. B. Repair or replace purge valve assembly

C. Leaking purge valve control piston

o-ring. C. Repair or replace purge valve assembly.

11. The air dryer purge piston

cycles rapidly in the

compressor unloaded (non-

compressing) mode.

A. Compressor fails to “unload”. A. Faulty governor installation; no air line from governor to

compressor or line is kinked or restricted. Install or repair air

line.

Compressor with up to 25% duty cycle

Footnotes:

1 With increased air demand the air dryer cartridge needs to be replaced more often.

2 Use the drain valves to slowly drain all reservoirs to zero psi.

3 Allow the oil/water mixture to fully settle before measuring oil quantity.

4 To counter above normal temperatures at the air dryer inlet, (and resultant oil-vapor passing

upstream in the air system) replace the discharge line with one of a larger diameter and/

or longer length. This helps reduce the air's temperature. If sufﬁ cient cooling occurs,

the oil-vapor condenses and can be removed by the air dryer. Discharge line upgrades

are not covered under warranty. Note: To help prevent discharge line freeze-ups, shorter

discharge line lengths or insulation may be required in cold climates. (See Bendix Bulletins

TCH-008-021 and TCH-008-022, included in Appendix B, for more information.)

5 For certain vehicles/applications, where turbo-charged inlet air is used, a smaller size

compressor may be permissible.

Recom- Recom- Acceptable

Typical Discharge mended mended Reservoir

Compressors Line Air Dryer Reservoir Oil Contents3

No. of Spec'd Cartridge Drain at Regular

Axles Replacement1 Schedule2 Drain Interval

High Air Use

Low Air Use

e.g. Double/triple trailer,

open highway coach, (most)

pick-up & delivery, yard or

terminal jockey, off-highway,

construction, loggers, concrete

mixer, dump truck, ﬁ re truck.

e.g. Line haul single trailer

w/o air suspension, air over

hydraulic brakes.

e.g. Line haul single trailer

with air suspension, RV,

school bus.

e.g. City transit bus, refuse,

bulk unloaders, low boys,

urban region coach, central tire

inﬂ ation.

less

Table A: Maintenance Schedule and Usage Guidelines

Recom-

mended

Every

Month -

Max of

every 90

days

Every

Month

Every 3

Years

Every 2

Years

Every

Year

I.D.

Vehicle Used for:

Column 1 Column 2 Column 3 Column 4 Column 5

Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system.

Note: Compressor and/or air dryer

upgrades are recommended in

cases where duty cycle is greater

than the normal range (for the

examples above).

For Bendix® Tu-Flo® 550 and 750

compressors, unloader service is

recommended every 250,000 miles.

Length

6 ft.

1/2 in.

9 ft.1/2 in.

12 ft.

1/2 in.

5/8 in. 12 ft.

BASIC™ test

acceptable

range:

5 oil units

per month.

See

appendix

For oil carry-over

control4 suggested

upgrades:

3/4 in. 15 ft.

For oil carry-over

control4 suggested

upgrades:

5/8 in. 15 ft.

For oil carry-over

control4 suggested

upgrades:

5/8 in. 9 ft.

For oil carry-over

control4 suggested

upgrades:

5/8 in. 12 ft.

Compressor with less than 15% duty cycle

Compressor with up to 25% duty cycle

Bendix® BA-921® air compressor

Bendix® Tu-Flo® 550 air compressor

Bendix® Tu-Flo® 750 air compressor

Bendix® BA-922®, or DuraFlo 596™ air compressor

Bendix®

BASIC™ test

acceptable

range:

3 oil units

per month.

See

appendix

For the

BASIC

Test Kit:

Order

Bendix

P/N

5013711

HOLSET TYPE

"E & QE"

COMPRESSOR

W/O ECON

VALVE

DASH

GAUGE

LOW PRESSURE

INDICATOR

Additional Troubleshooting Information

The troubleshooting procedure presented on the following pages has been excerpted from a troubleshooting card entitled:

Troubleshooting Charging and Air Supply Systems. The complete card can be obtained from authorized Bendix parts outlets

under literature number BW1779. It is presented here because of the air dryers connection to the supply air system and

for convenience. The procedure is not all inclusive, but rather represents the most commonly encountered complaints.

CONVENTIONAL

SUPPLY SYSTEM

& INTEGRAL PURGE

AIR DRYER

HOLSET TYPE

"E & QE"

COMPRESSOR

WITH ECON

VALVE

FRONT

REAR

DASH

GAUGE

STANDARD SINGLE

CHECK VALVE

LOW

PRESSURE

INDICATOR

SUPPLY

SAFETY

VALVE

AIR

DRYER

HOLSET

“E OR QE”

COMPRESSOR

SPECIAL

SINGLE CHECK

("CHOKE" IN INLET)

GOVERNOR

HOLSET

ECON VALVE

REAR

FRONT

SUPPLY

DASH

GAUGE

LOW PRESSURE

INDICATOR

STANDARD SINGLE CHECK VALVE

(USED W/INTEGRAL PURGE AIR

DRYERS)

SAFETY

VALVE

AIR DRYER

TWO CYLINDER.

COMPRESSOR

GOVERNOR

STANDARD SINGLE

CHECK VALVE

REAR

FRONT

SUPPLY

HOLSET

“E OR QE”

COMPRESSOR

GOVERNOR

AIR DRYER

SAFETY

VALVE

SPECIAL

SINGLE CHECK

("CHOKE" IN INLET)

SINGLE CHECK -

PROTECTION VALVE

(USED W/SYSTEM

PURGE AIR DRYERS) SINGLE CHECK VALVE (USED

W/INTEGRAL PURGE AIR DRYERS)

DRAIN COCK

Appendix B

Bendix Sd 08 2412 Users Manual

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