BENDIX DRM DRYER RESERVOIR MODULE User manual

1
Air
Connection Function/Connection No.
Port ID
DESCRIPTION
The function of the dryer reservoir module (DRM™) is to
provideheavyvehicleswithanintegratedvehicleairdryer,
secondaryreservoir,purgereservoir,governorandanumber
ofthechargingvalvecomponentsinamodule. TheDRM™
dryer module model covered in this Service Data Sheet is
the first to be released, see updates to this Service Data
Sheetforother models.
TheDRM™dryermoduleincludesanintegrated solution air
dryer (AD-IS®), a reservoir (including a separate purge
reservoir section) a governor and four pressure protection
valves. Thesehavebeendesignedasanintegratedairsupply
system.
ThefunctionoftheAD-IS®airdryeristo collect and remove
air system contaminants in solid, liquid and vapor form
before they enter the brake system. It provides clean, dry
airtothecomponentsofthebrakesystemwhichincreases
thelifeof thesystemandreduces maintenancecosts. Daily
manual draining of the reservoirs is eliminated.
The function of the pressure protection valves is to both
controlthe order in which the components receive airfrom
theAD-IS®airdryer,andalsotoprotecteach reservoir from
a pressure loss in the other reservoir or a pressure loss in
an air accessory.
FIGURE 1 - DRYER RESERVOIR MODULE
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
thepurgevalveassembly.
Bendix®Dryer Reservoir Module with AD-IS®Air Dryer
SD-98-9808
1
IN
21
PRI
22
AUX1
23
AUX2
UNL UnloaderControlAir(D-2A™Governor) 2
RES CommonReservoirPressure(D-2A™Governor) 2
EXH GovernorExhaust 1
TABLE 1 - DRM™DRYER MODULE AIR CONNECTIONS
Inlet Port (air in). 1
Delivery Port out (to Primary reservoir) 1
Auxiliary Delivery Port (air out). 4
Auxiliary Delivery Port (air out). 1
DESICCANT
CARTRIDGE
SECONDARY
RESERVOIR AD-IS®
Air Dryer
INTEGRATED
PURGE RESERVOIR
GOVERNOR
PRESSURE PROTECTION
VALVES (4)
AUXILIARY
DELIVERY PORTS
(5)
HEATER/
THERMOSTAT
SAFETY VALVE
AD-IS®AIRDRYER PART NUMBERSTAMPED HERE
MOUNTING
BOLTS (3)

2
FIGURE 2 - AD-IS
®
AIR DRYER CHARGE CYCLE. DIAGRAM SHOWS PRESSURE PROTECTION VALVES A AND B OPEN, C & D CLOSED.
COMPRESSOR
GOVERNOR
PURGE
CONTROL
CHANNEL
DESICCANT
BED
DELIVERY
CHECK
VALVE
(OPEN) PURGE RESERVOIR
PRIMARY
PORT
(PRI)
PURGE
VALVE
(CLOSED)
TURBO
CUTOFF
VALVE
(OPEN)
ENGINE
TURBO
UNLOADER
PORT
INLET
PORT
(IN)
OIL
SEPARATOR
PURGE
ORIFICE
PRIMARY
RESERVOIR
SECONDARY
RESERVOIR
PRESSURE PROTECTION
VALVES
AUXILIARY PORTS
(TO ACCESSORIES)
SEE
NOTE 1
Note 1:
TheAD-IS®air dryer purgepistonhasa
purgecontrolchanneldrain.Thisallows
any condensation in this area to flow
pastadiaphragm inthetopofthepurge
pistonandoutthroughachannelinthe
middle of the central bolt of the purge
assembly to be drained. During the
purge cycle this drain is closed.
SAFETY
VALVE
PURGE
RESERVOIR
DRAIN VALVE
Theremovablepurgevalveassemblyincorporatesthepurge
valve mechanism and a turbocharger cutoff feature that is
designed to prevent loss of engine “turbo” boost pressure
during the purge cycle of theAD-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. RefertoPreventiveMaintenancesection.
DRM™DRYER MODULE OPERATION:
GENERAL (Refer to Figure 2)
TheDRM™dryermoduleisdesignedtoreceivecompressed
air from the vehicle air compressor, clean and dry the air
using theAD-IS®airdryer,deliverairtothevehicle’sprimary
reservoir,secondaryreservoir and accessories,andcontrol
thecompressor/dryer charge cycle.
AIR DRYER OPERATION: GENERAL
The AD-IS®air dryer alternates between two operational
modes or “cycles”duringoperation: the ChargeCycle and
thePurgeCycle. The following descriptions are 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
A
D
CB

3
FIGURE 3 - AD-IS®AIR DRYER PURGE CYCLE.
COMPRESSOR
GOVERNOR
PURGE
CONTROL
CHANNEL
DESICCANT
BED
DELIVERY
CHECK
VALVE
(CLOSED) PURGE
RESERVOIR
PURGE
VALVE
(OPEN)
TURBO
CUTOFF
VALVE
(CLOSED)
ENGINE
TURBO
OIL
SEPARATOR
PURGE
ORIFICE
PRIMARY
RESERVOIR
SECONDARY
RESERVOIR
GOVERNOR SIGNALS AIR
COMPRESSOR TO SUSPEND
COMPRESSED AIR SUPPLY
TOAD-IS®AIRDRYER
EXHAUST
PRIMARY
PORT
(PRI)
UNLOADER
PORT
INLET
PORT
(IN)
SAFETY
VALVE AUXILIARY PORTS
(TO ACCESSORIES) PURGE
RESERVOIR
DRAIN VALVE
vapor flows through the compressor discharge line to the
inlet (1 IN) port of the air dryer body.
As air travels through theAD-IS®air dryer, its 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
flowsintothedesiccantcartridge,where it flows throughan
oilseparatorwhichremovesliquidoilandsolidcontaminants.
Air then flows into the desiccant drying bed and becomes
progressivelydrieraswatervapor adheres tothedesiccant
material in a process known as “ADSORPTION.”
Dry air exits the desiccant cartridge through the center of
thebaseassembly. Theairthen flows to thedeliverycheck
valve and also through an orifice into the purge reservoir.
Thedeliverycheckvalveopens,supplyingairtothepressure
protection valves (A) and (B), the safety valve, and also to
thereservoirportoftheattachedgovernor. Thepurgereservoir
fills,storing air that will be usedto reactivate the desiccant
duringthe purge cycle.
When the air pressure reaches approximately 103 p.s.i.,
the first pressure protection valve (A) will open and air will
besuppliedtotheprimary reservoir. When theairpressure
in the primary reservoir reaches approximately 109 p.s.i.,
PRESSURE PROTECTION
VALVES
A
D
CB

4
thesecondpressureprotectionvalve(B)opensandairwill
besuppliedto the secondaryreservoirandto theaccessory
pressure protection valves (C & D). (Note: there is no
external air hose feeding the secondary reservoir, instead
airissuppliedby a connectorpassingthroughthebulkhead
ofthepurge reservoirsectionofthereservoir.) Whentheair
pressureinthesecondaryreservoir reaches approximately
55 p.s.i. and 85 p.s.i. respectively, the two remaining
pressureprotectionvalves(C&D)willopenandsupply air
to the vehicle accessories.
The air dryer will remain in the charge cycle until the air
brakesystempressurebuilds to thegovernorcutoutsetting
of approximately 130 p.s.i.
PURGE CYCLE (Refer to Figure 3.)
Whenairbrakesystempressure reaches the cutoutsetting
ofthegovernor,thegovernorunloads the compressor and
the purge cycle of the air dryer begins.
The governor unloads the compressor by allowing air
pressureto fill the line leading to the compressor unloader
mechanism - causing the delivery of compressed air to
theAD-IS®air dryer to be suspended.
Similarly, the governor also supplies air pressure to the
AD-IS®airdryerpurge controlchannel. TheAD-IS®airdryer
purgepiston moves down in response to this air pressure,
causingthepurgevalvetoopentotheatmosphere 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
wasflowingthroughthedesiccantcartridgechangesdirection
and begins to flow toward the open purge valve. Oil and
solidcontaminantscollectedbytheoilseparatorareremoved
byairflowing fromthepurgereservoirthroughthedesiccant
dryingbedtotheopenpurgevalve.
The initial purge and desiccant cartridge decompression
lasts only a few seconds and is evidenced by an audible
burst of air at theAD-IS®air dryer exhaust.
The actual reactivation of the desiccant drying bed begins
asdry air from the purge reservoir flows throughthe 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
toit. Approximately 30 seconds are required forthe entire
contentsofthepurge reservoirofa standardAD-IS®airdryer
to flow through the desiccant drying bed.
Thedeliverycheckvalveassembly prevents airpressurein
the brake system from returning to the air dryer during the
purgecycle.Afterthepurgecycleiscomplete,theairdryer
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
isconnected to the engine turbocharger.
Atthe onset of the purge cycle, the downward travel of the
purge piston is stopped when the turbo cutoff valve
(taperedportion of purge piston) contacts its mating metal
seatinthepurgevalvehousing. Withtheturbo cutoff valve
seated (closed position), air in the compressor discharge
lineandAD-IS®airdryerinletport cannot entertheairdryer.
In this manner the turbo cutoff effectively maintains turbo
chargerboost pressure to the engine.
PREVENTIVE MAINTENANCE
Important: Reviewthe 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
bestmaintenanceintervalforanyoneparticularoperation.
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
desiccantcartridge. Someoilatthedryerexhaustisnormal.
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-torqueto360-420inch pounds.

5
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
dryerforleakageandintegrity. Repairany leaks found.
2. Build up system pressure to governor cutout and note
thattheAD-IS®airdryerpurgeswithanaudibleescape
ofair. Watchthesystempressure and notethepressure
fall-offfora tenminuteperiod. Ifpressuredropexceeds,
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"
bubblein1second. Iftheleakageexceedsthemaximum
specified, refer to section entitled Troubleshooting,
Symptom 4.
4. Build up system pressure to governor cutout and note
thattheAD-IS®airdryerpurgeswithanaudibleburstof
air,followedimmediatelybyapproximately30seconds
of air flowing out of the purge valve. “Fan” the service
brakes to reduce system air pressure to governor cut-
in. Notethatthesystemonceagainbuildstofullpressure
and is followed by anAD-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.
B. ThermostatandHeater Operation
Note: These tests are not possible except in cold
weather operation.
Turnofftheignitionswitchandcool the thermostat and
heater assembly to below 40 degrees Fahrenheit.
Usinganohmmeter,checkthe 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
approximately90degreesFahrenheitandagaincheck
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. Pressureprotectionvalves. Observethepressuregauges
ofthevehicleas system pressurebuildsfromzero. The
primarygaugeshould riseuntilitreachesapproximately
109 psi (±5 psi), then level off (or a momentary slight
fall) as the second pressure protection valve opens
supplyingthesecondaryreservoir. When thesecondary
pressure gauge passes through approximately 55 (±5
psi)andthen85psi(±5psi)thereshouldbeanassociated
levelingoff(ormomentaryslightfall)ofpressureasthe
thirdandfourth pressureprotectionvalvesopen. Finally
both the primary and secondary gauges should reach
theirfull 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
FIGURE 4 - AD-IS®AIR DRYER HEATER AND
THERMOSTAT CONNECTOR
HEATER & THERMOSTAT
CONNECTOR