Bendix DRM DRYER RESERVOIR MODULE User Manual

Bendix® Dryer Reservoir Module with AD-IS® Air Dryer

SD-98-9808

INTEGRATED

PURGE RESERVOIR

SECONDARY

RESERVOIR

AD-IS® AIR DRYER PART NUMBER STAMPED HERE

GOVERNOR

MOUNTING

DESCRIPTION

The function of the dryer reservoir module (DRM™) is to provide heavy vehicles with an integrated vehicle air dryer, secondary reservoir, purge reservoir , governor and a number of the charging valve components in a module. The DRM dryer module model covered in this Service Data Sheet is the first to be released, see updates to this Service Data Sheet for other models.

DESICCANT CARTRIDGE

BOLTS (3)

AUXILIARY

DELIVERY PORTS

(5)

SAFETY VALVE

AD-IS

Air Dryer

PRESSURE PROTECTION

VALVES (4)

FIGURE 1 - DRYER RESERVOIR MODULE

HEATER/

THERMOSTAT

The air dryer consists of a “spin on” desiccant cartridge secured to a base assembly.

The base assembly contains a delivery check valve

™

assembly , safety valve, heater and thermostat assembly , pressure protection valves, threaded air connections and the purge valve assembly .

The DRM™ dryer module includes an integrated solution air dryer (AD-IS®), a reservoir (including a separate purge reservoir section) a governor and four pressure protection valves. These have been designed as an integrated air supply system.

The function of the AD-IS® air dryer is to collect and remove air system contaminants in solid, liquid and vapor form before they enter the brake system. It provides 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 function of the pressure protection valves is to both control the order in which the components receive air from the AD-IS® air dryer, and also to protect each reservoir from a pressure loss in the other reservoir or a pressure loss in an air accessory.

Air

Connection Function/Connection No.

Port ID

IN 21

PRI

AUX 1

AUX 2

Inlet Port (air in). 1

Delivery Port out (to Primary reservoir) 1

Auxiliary Delivery Port (air out). 4

Auxiliary Delivery Port (air out). 1

UNL Unloader Control Air (D-2A™ Governor) 2 RES Common Reservoir Pressure (D-2A™ Governor) 2 EXH Governor Exhaust 1

TABLE 1 - DRM™ DRYER MODULE AIR CONNECTIONS

DESICCANT

BED

OIL

SEPARATOR

GOVERNOR

UNLOADER

PORT

INLET PORT

(IN)

DELIVERY

CHECK

VALVE

(OPEN)

CONTROL CHANNEL

TURBO

CUTOFF

VALVE

(OPEN)

PURGE

VALVE

(CLOSED)

SEE

NOTE 1

ENGINE

TURBO

COMPRESSOR

SAFETY

VALVE

PRIMARY

PORT

(PRI)

PRIMARY

RESERVOIR

PRESSURE PROTECTION

VALVES

AUXILIARY PORTS

(TO ACCESSORIES)

PURGE

ORIFICE

PURGE

RESERVOIR

DRAIN VALVE

PURGE

RESERVOIR

SECONDARY

RESERVOIR

Note 1:

The AD-IS® air dryer purge piston has a purge control channel drain. This allows any condensation in this area to flow past a diaphragm in the top of the purge piston and out through a channel in the middle of the central bolt of the purge assembly to be drained. During the purge cycle this drain is closed.

FIGURE 2 - AD-IS® AIR DRYER CHARGE CYCLE. DIAGRAM SHOWS PRESSURE PROTECTION VALVES A AND B OPEN, C & D CLOSED.

The removable purge valve assembly incorporates the purge valve mechanism and a turbocharger cutoff feature that is

reservoir, secondary reservoir and accessories, and control

the compressor/dryer charge cycle. designed to prevent loss of engine “turbo” boost pressure during the purge cycle of the AD-IS® air dryer. For ease of serviceability , all replaceable assemblies can be replaced without removal of the air dryer from its mounting on the vehicle. Refer to Preventive Maintenance section.

AIR DRYER OPERATION: GENERAL

The AD-IS® air dryer alternates between two operational

modes or “cycles” during operation: the Charge Cycle and

the Purge Cycle. The following descriptions are separated

into these “cycles” of operation.

DRM™ DRYER MODULE OPERATION: GENERAL

(Refer to Figure 2)

The DRM™ dryer module is designed to receive compressed air from the vehicle air compressor, clean and dry the air using the AD-IS® air dryer, deliver air to the vehicle’ s primary

CHARGE CYCLE (Refer to Figure 2)

When the compressor is loaded (compressing air)

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

GOVERNOR

UNLOADER

PORT

DELIVERY

CHECK

VALVE

(CLOSED)

DESICCANT

BED

OIL

SEPARATOR

PURGE

ORIFICE

PURGE

RESERVOIR

INLET PORT

(IN)

CONTROL CHANNEL

TURBO

CUTOFF

VALVE

(CLOSED)

PURGE

EXHAUST

PURGE

VALVE

(OPEN)

COMPRESSOR

ENGINE

TURBO

SAFETY

VALVE

PRESSURE PROTECTION

VALVES

PRIMARY

PORT

(PRI)

AUXILIARY PORTS

(TO ACCESSORIES)

PRIMARY

RESERVOIR

SECONDARY

RESERVOIR

PURGE

RESERVOIR

DRAIN VALVE

GOVERNOR SIGNALS AIR

COMPRESSOR TO SUSPEND

COMPRESSED AIR SUPPLY

TO AD-IS

AIR DRYER

FIGURE 3 - AD-IS® AIR DRYER PURGE CYCLE.

vapor flows through the compressor discharge line to the inlet (1 IN) port of the air dryer body .

As air travels through the AD-IS® air dryer, it s temperature falls, causing some of the contaminants to condense and drop to the bottom of the air dryer purge valve assembly, ready to be expelled at the next purge cycle. The air then flows into the desiccant cartridge, where it flows through an oil separator which removes liquid oil and solid contaminants.

Air then flows into the desiccant drying bed and becomes progressively drier as water vapor adheres to the desiccant material in a process known as “ADSORPTION.”

Dry air exits the desiccant cartridge through the center of the base assembly . The air then flows to the delivery check valve and also through an orifice into the purge reservoir. The delivery check valve opens, supplying air to the pressure protection valves (A) and (B), the safety valve, and also to the reservoir port of the attached governor . The purge reservoir fills, storing air that will be used to reactivate the desiccant during the purge cycle.

When the air pressure reaches approximately 103 p.s.i., the first pressure protection valve (A) will open and air will be supplied to the primary reservoir. When the air pressure in the primary reservoir reaches approximately 109 p.s.i.,

the second pressure protection valve (B) opens and air will be supplied to the secondary reservoir and to the accessory pressure protection valves (C & D). (Note: there is no external air hose feeding the secondary reservoir, instead air is supplied by a connector passing through the bulkhead of the purge reservoir section of the reservoir.) When the air pressure in the secondary reservoir reaches approximately 55 p.s.i. and 85 p.s.i. respectively, the two remaining pressure protection valves (C & D) will open and supply air to the vehicle accessories.

The air dryer will remain in the charge cycle until the air brake system pressure builds to the governor cutout setting of approximately 130 p.s.i.

PURGE CYCLE (Refer to Figure 3.)

When air brake system pressure reaches the cutout setting of the governor, the governor unloads the compressor and the purge cycle of the air dryer begins.

The governor unloads the compressor by allowing air pressure to fill the line leading to the compressor unloader mechanism - causing the delivery of compressed air to the AD-IS® air dryer to be suspended.

Similarly, the governor also supplies air pressure to the AD-IS® air dryer purge control channel. The AD-IS® air dryer purge piston moves down in response to this air pressure, causing the purge valve to open to the atmosphere and the turbo cutoff valve to close off the supply of air from the compressor (this will be further discussed in the Turbo Cutoff Feature section). Water and contaminants which have collected in the purge valve base are expelled immediately when the purge valve opens. Also, air which was flowing through the desiccant cartridge changes direction and begins to flow toward the open purge valve. Oil and solid contaminants collected by the oil separator are removed by air flowing from the purge reservoir through the desiccant drying bed to the open purge valve.

The initial purge and desiccant cartridge decompression lasts only a few seconds and is evidenced by an audible burst of air at the AD-IS® air dryer exhaust.

The actual reactivation of the desiccant drying bed begins as dry air from the purge reservoir flows through the purge orifice into the desiccant bed. Pressurized air from the purge reservoir expands after passing through the purge orifice; its pressure is lowered and its volume increased. The flow of dry air through the drying bed reactivates the desiccant material by removing the water vapor adhering to it. Approximately 30 seconds are required for the entire contents of the purge reservoir of a standard AD-IS® air dryer to flow through the desiccant drying bed.

The delivery check valve assembly prevents air pressure in the brake system from returning to the air dryer during the purge cycle. Af ter the purge cycle is complete, the air dryer is ready for the next charge cycle to begin.

TURBO CUTOFF FEATURE (Refer to Figure 3.)

The primary function of the turbo cutoff valve is to prevent

loss of engine turbocharger air pressure through the

AD-IS

air dryer in systems where the compressor intake

is connected to the engine turbocharger.

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

purge piston is stopped when the turbo cutoff valve

(tapered portion of purge piston) contacts its mating metal

seat in the purge valve housing. With the turbo cutoff valve

seated (closed position), air in the compressor discharge

line and AD-IS

air dryer inlet port cannot enter the air dryer. In this manner the turbo cutoff effectively maintains turbo charger boost pressure to the engine.

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.

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.

Every 900 operating hours, or 25,000 miles or three (3) months:

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

reservoir drain valves and checking for presence of water. If moisture is present, the desiccant cartridge may require replacement; however, the following conditions can also cause water accumulation and should be considered before replacing the desiccant:

A. An outside air source has been used to charge the

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

B. Air usage is exceptionally high and not normal.

This may be due to high air system leakage.

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

temperature occurs in one day, small amounts of water can temporarily accumulate in the air brake system due to condensation. Under these conditions, the presence of small amounts of moisture is normal.

Note: A small amount of oil in the system is normal and should not be considered as a reason to replace the desiccant cartridge. Some oil at the dryer exhaust is normal.

2. Visually check for physical damage such as chaffed or

broken air and electrical lines and broken or missing parts.

3. Check mounting bolts for tightness. See Figure 1.

Re-torque to 360-420 inch pounds.

4. Perform the Operation & Leakage Tests listed in this publication.

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 (ALSO SEE VIDEO BW2327)

1. Check all lines and fittings leading to and from the air dryer for leakage and integrity. Repair any leaks found.

2. Build up system pressure to governor cutout and note that the AD-IS® air dryer purges with an audible escape of air. W atch the system pressure and note the pressure fall-off for a ten minute period. If pressure drop exceeds, for a single vehicle - 1 psi/minute from either service reservoir; or for tractor trailer - 3 psi/minute from either service reservoir, inspect the vehicle air systems for sources of leakage and repair them. Refer to section entitled Troubleshooting, Symptoms 1 and 4.

3. Check for excessive leakage around the purge valve with the compressor in the loaded mode (compressing air). Apply a soap solution to the purge valve exhaust port and observe that leakage does not exceed a 1" bubble in 1 second. If the leakage exceeds the maximum specified, refer to section entitled Troubleshooting, Symptom 4.

4. Build up system pressure to governor cutout and note that the AD-IS® air dryer purges with an audible burst of air, followed immediately by approximately 30 seconds of air flowing out of the purge valve. “Fan” the service brakes to reduce system air pressure to governor cutin. Note that the system once again builds to full pressure and is followed by an AD-IS® air dryer purge. If system does not follow this pattern, refer to section entitled Troubleshooting, Symptoms 5 and 6.

5. 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 RUN position, check for voltage to the heater and thermostat assembly using a voltmeter or testlight. Unplug the electrical connector at the air dryer and place the test leads on each of the connections of the female connector on the vehicle power lead. 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.

HEATER & THERMOSTAT

CONNECTOR

FIGURE 4 - AD-IS® AIR DRYER HEATER AND THERMOSTAT CONNECTOR

B. Thermostat and Heater Operation

Note: These tests are not possible except in cold weather operation.

Turn off the ignition switch and cool the thermostat and heater assembly to below 40 degrees Fahrenheit. Using an ohmmeter, check the resistance between the electrical pins in the air dryer connector half. The resistance should be 1.5 to 3.0 ohms for the 12 volt heater assembly and 6.0 to 9.0 ohms for the 24 volt heater assembly.

Warm the thermostat and heater assembly to approximately 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 heater and thermostat assembly.

6. Pressure protection valves. Observe the pressure gauges of the vehicle as system pressure builds from zero. The primary gauge should rise until it reaches approximately 109 psi (±5 psi), then level off (or a momentary slight fall) as the second pressure protection valve opens supplying the secondary reservoir. When the secondary pressure gauge passes through approximately 55 (±5 psi) and then 85 psi (±5 psi) there should be an associated leveling off (or momentary slight fall) of pressure as the third and fourth pressure protection valves open. Finally both the primary and secondary gauges should reach their full pressure of approximately 130 psi (±5 psi).

If the AD-IS® air dryer does not perform within the pressure ranges as described above recheck using gauges known to be accurate. If the readings remain outside of the ranges outlined above, replace the AD-IS® air dryer. NOTE: There are no kits available for

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