BENDIX FD-2 CLUTCH TYPE FAN DRIVE User manual

1
®
Bendix®FD-2™Clutch Type Fan Drive
SD-09-8503
FIGURE 1
FIGURE 2
DESCRIPTION
TheBendix®FD-2™fanclutchisanairoperatedthermostat
controlled clutch for the engine cooling fan. Its purpose is
tomaintainenginetemperaturebyengaging ordisengaging
the cooling fan, thereby providing better fuel economy,
greater engine efficiency, faster warm-ups, and a quieter
vehicle.
TheFD-2™fanclutch isproducedin severaldifferentmodels
to accommodate the variety of installation requirements
resulting from the many engine, vehicle and accessory
combinations. Its fail-safe design prevents overheating in
the event of air loss for any cause.
OPERATION
GENERAL
TheFD-2™fan clutch replaces thestandardfanhubson the
engineand interchanges with other Bendix andcompetitive
fan clutches. It is controlled by a temperature sensitive air
valve(seeFigure5).Thesamevalvesusedtocontrolradiator
shutters are used to control the FD-2™fan clutch. Installed
inthe engineblock,thecontrol valve directlysensescoolant
temperature.Providedcoolanttemperatureremainsbelow
the setting of the valve, air passes through it to disengage
thefanclutch.Whencoolant temperature rises to the valve
setting,the valve closes and exhausts airpressurefromthe
fanclutch which engages the fan.
PRESSUREPLATEBEARINGS
BRACKET
SHAFT
PISTON
DRIVEPIN
DUST
CAP
LOCK
NUT
FANHUB
RETURN SPRING
PULLEY
AIRINLET
BEARINGS
PISTON HOUSING

2
FIGURE 3
FIGURE 5
FANDISENGAGED
FIGURE 4
FANENGAGED
FIGURE 6
THERMO-PNEUMATIC
VALVE
THERMO-PNEUMATIC
VALVES
BLOCK
FAN
CLUTCH
RADIATOR
RADIATOR
FAN
CLUTCH
BLOCK
SHUTTER
Dependingupon optionalequipmentinstalled onthevehicle
such as radiator shutters and radiator mounted air
conditioning condenser, different piping arrangements are
necessary. These will be explained in the paragraph on
control systems.
DISENGAGED
When the vehicle is started with a cold engine the thermo-
pneumatic control valve is open. As brake system air
pressure is built up, air passes through the control valve to
the fan clutch. Air enters the inlet port in the bracket of the
fan clutch and travels through the drilled passage in the
shaft to fill the piston cavity. When air in the piston cavity
reaches a pressure of 70-75 psi, the piston slides on the
shaftmovingthepressure plateassemblytothedisengaged
position. In this position the clutch lining is out of contact
with the fan plate and the fan is no longer driven by the
engine (see Figure 3).
ENGAGED
As the engine coolant rises in temperature, the engine
thermostat opens to circulate radiator coolant through the
engine.Whenthe engine coolant temperature reachesthe
setting of the control valve, the valve exhausts air from the
piston cavity. The fan clutch springs force the piston and
pressure plate forward on the shaft. When the lining
contacts the fan plate, the fan is engaged and is driven by
the engine (see Figure 4).

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FIGURE 7
FIGURE 8
BLOCK
BLOCK
THERMO-PNEUMATIC
VALVE
THERMO-PNEUMATIC
VALVES
FAN
OVERRIDE
SWITCH
AIR
CONDITIONING
SIGNAL
AIRCOND.
COMPRESSOR
SOLENOID
VALVE
FAN
CLUTCH
RADIATOR
CONDENSER
RECEIVER
DRYER
AIR
CONDITIONING
OVERRIDE
SWITCH
FAN
CLUTCH
RADIATOR
SHUTTER
SOLENOIDVALVE
(NORMALLYOPEN)
AIR
CONDITIONING
SIGNAL AIR
CONDITIONING
OVERRIDE
SWITCH
FAN
OVERRIDE
SWITCH
RECEIVER
DRYER
CONDENSER
AIRCOND.
COMPRESSOR
CONTROL SYSTEMS
Thefan clutch,inaddition toitsprimaryfunction ofoperating
the fan as needed to maintain the cooling liquid within a
certaintemperature range, must be coordinatedwithother
deviceswheninstalledon the vehicle.
Theseareradiatorshuttersandradiatormountedcondenser
for air conditioning. Four basic configurations are possible
asfollows:
Figure 5. Fan Clutch only
Figure 6. FanClutchwith shutters
Figure 7. Fan Clutch with radiator mounted air
conditioningcondenser
Figure 8. Fan Clutch, shutters and condenser
Theobjective inthecaseof Figure 5isto not engagethefan
until the engine thermostat is fully open. The thermo-
pneumatic control valve should therefore be calibrated to
release the air from the fan clutch when the coolant
temperatureis atleast10°F.higherthantheshutteropening
point. If the shutters are the modulating type, the fan
engagementshouldbeatleast10°F.higherthanthefull-open
temperatureoftheshutter.
Inthe case of Figure 7 thefanmustbecontrolledto perform
thesupplementary functionofpullingcooling air throughthe
airconditioningcondenserwhenrequired,althoughtheengine
coolant may be below the fan cut-in temperature. This is
most likely to occur at high ambient temperatures and low
roadspeedoridling.Ifthecondenserisinadequatelycooled,
the air conditioning system will start to build up a higher
than normal pressure. Therefore, a pressure switch is
connected into the air conditioning compressor discharge
line(asshowninFigure7).Whenthispressureswitchsenses
ahigher thannormalpressureinthe airconditioningsystem
(approximately250psi), it closes an electrical circuitwhich
inturn energizes asolenoidoperatedairsupply valve which
exhausts the air supply for the fan control, causing the fan
toengage.Mostvehiclesalsohaveanadditionaldualfunction
pressureswitchconnectedinserieswiththeairconditioner
clutch. This switch is normally open, closes at
approximately30 psiandopensagainat approximately400
psi.Its purposeisto preventoperationofthe airconditioning
compressor if the refrigerant is lost or to shut off the
compressorif the system pressurereaches a dangerously
highpressure (approximately 400 psi).Thisswitchdoesnot
normallyhave anything to do with fan operation; however,it
is sometimes combined with the previously mentioned
overrideswitch.
Figure 8 depicts a combination of shutters, fan clutch and
airconditioning.Thiscombinationrequiresthe two thermo-
pneumaticcontrolsforfanandshutters,aswellastheelectro-
pneumatic override for the air conditioning. With this
combinationthe same requirements for fancontrolapplyas
in Figure 6 and 7 with the additional requirement that the
shutters should be controlled in such a manner that they
always open whenever the air conditioning compressor
operates.
A variation of this combination consists of a two section
shutter with one section in front of the condenser and the
otherin front of the remainingportion of the radiator. In this
combinationonlythesectionin frontofthe condenserneeds
toopenwhenthe air conditioner engages.
PREVENTIVE MAINTENANCE
Important: Review the warranty policy before performing
anyintrusivemaintenanceprocedures.Anextendedwarranty
maybe voided if intrusive maintenance is performed during
thisperiod.
Becausenotwovehiclesoperate underidenticalconditions,
maintenanceintervalswillvary.Experienceisavaluableguide
indeterminingthebestmaintenanceinterval for a vehicle.
IGNITION

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ThedurabilityoftheBendix®FD-2™fanclutchmatchesthat
of the vehicle’s engine. There is no need for periodic
maintenance;however,thefollowingservicechecks should
bemade to insureproper function ofthe fan clutch.
LINEHAUL VEHICLES:
Every 50,000 miles, 1,800 hours, or every six months,
whicheveroccursfirst,perform the service checks outlined
in this manual.
CITYDELIVERY
Every 15,000 miles, 300 hours, or every two months,
whicheveroccursfirst,perform the service checks outlined
in this manual.
SERVICE CHECKS
Beforeperforming the operating and leakage checks,apply
the vehicle parking brakes or chock the wheels.
OPERATIONAL
1. With the engine cold, the ignition off and at least 75 psi
air pressure in the brake system, note that the fan is
disengagedfromthepulleyand can be turned by hand.
Ifthefancan be turned, proceedto Step #2. If it cannot
beturned:
A. Drain all reservoirs and disconnect the air control
line leading to the fan clutch and apply at least 75
psi shop air pressure to the fan clutch.
B. If the fan cannot be turned, the clutch is defective
and must be repaired or replaced (see appropriate
section of this manual).
C. If the fan can now be turned; check the air lines
leadingto andfromthe thermostatic controlvalvefor
“kinks” or obstructions, and check the control valve
itselfaccording to the manufacturer’s instructions.
2. Afterperforming Step #1,drainallair pressure from the
brake system. Note that the fan is now engaged and
cannot be turned by hand. If it cannot be turned,
proceed to Step #3. If it can be turned, the clutch is
defectiveandmustberepairedor replaced.
3. Check the operation of the thermostatic control valve
byrunning theengineup tooperatingtemperature.Note
that the fan clutch engages when engine temperature
rises to normal or above and disengages after fan
cooling is accomplished. Normal engagement time
shouldnotexceedtwominutes.Ifengagementtimedoes
not exceed two minutes, proceed to Step #4. If
engagementtimedoesexceedtwo minutes:
A. If this test is being performed for the first time after
installation of the fan clutch, recheck the setting of
the thermostatic control valve and compare it with
thesetting of the engine coolant thermostat or in the
case of vehicles with radiator shutters, with the
setting of the shutter control. The fan clutch control
should always be 10° F. higher than the highest
setting.
B. Ifthefanclutchinstallationhassuccessfullypassed
this test before, but does not do so now, the
thermostaticcontrol valveisdefectiveand shouldbe
replaced.
4. With the clutch in the engaged position (control air
vented),check theconditionof thedrivepinsand mating
holes in the pressure plate by attempting to rotate the
fan clockwise and counter clockwise. If free play
exceeds5/16" (806 MM), fan clutch must be repaired or
replaced.
LEAKAGE CHECKS
In order to check for air leakage past the only two sliding
o-ringsintheFD-2™fanclutch it is necessary to disconnect
the single air control line.
Checkforleakagebyconnectinga90cu.in.reservoir(Bendix
part number 225000) with a gauge installed to the control
portofthefanclutch.Afterfillingthe90cu.in.reservoirwith
100psi, allow thepressuretostabilizeand observe the time
required for the reservoir pressure to drop to 90 psi. If the
time required is less than 1 minute, leakage is excessive
andrepairorreplacement is necessary.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURYOR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
enginebe in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Useonly the proper tools andobserve
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems,make certainto drainthe airpressure from
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS™
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommendedprocedures, deactivate theelectrical
system in a manner that safely removes all
electrical power from the vehicle.

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FIGURE 10
27/32” DRILL THRU
(2HOLES FOR 3/4" BAR) MATERIAL O.H.T.S. TUBING
HDN&DRAWRC40-45
.235 + .002 CENTERED
(4 LUGS)
2.125+.010
2-3/4”
1/32” FLAT
4-7/8”
5-1/8”6”
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix®replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.
REMOVAL
1. Removethesix capscrewsandlockwashers thatattach
the fan to the fan hub.
2. Remove fan. NOTE: Pay particular attention to any
spacersthat maybeinstalledbetween fan andpressure
plate.
3. Loosenfanbelts.
4. Disconnect air line to fan clutch.
5. Remove cap nuts and lockwashers from mounting
bracket and remove unit from vehicle.
DISASSEMBLY (see Figure 9)
1. Removedustcap(1)fromend of fan hub.
2. Removecotterpin (2) and nut (10) from endofshaft.
3. Removefanplate (20) assembly and setaside.
4. Remove piston housing (15), remove piston (16) from
housing,remove twoo-rings(4& 6) frompistonandone
o-ring(3)from shaft.
5. Removepressureplate (7).
6. Removeanti-rotational spring (17) fromshaft.
7. Remove two 1/4 x 20 Phillips screws and lift off spring
pack (8).
8. Disengage lock tab on lockwasher (19) and remove
lock nut (18), using a spanner tool (as shown in Figure
10).Remove lockwasher(19).
9. Support the backside of the pulley so that the shaft
bracket assembly can be pressed down far enough to
remove the pulley assembly. Since the bearings are
originally installed with Locktite between shaft and
bearings,aforce as high as 5,000lbs.may be required
toremove the pulley assembly.
PULLEY DISASSEMBLY (see Figure 11)
1. Support pulley on front end. Displace spacer (1)
eccentrically as far as possible. With a round pressing
toolwhich fits loosely throughtheI.D.ofthe top bearing,
press the bottom bearing out (3) pressing on the
eccentrically positioned spacer.
FIGURE 9
19
584
3
14 2
10
1
12
11
9
6
7
18
17
16
15
13

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FIGURE 11
FIGURE 12
DRIVEPINS
PULLEY
2
4
SEAL
3
1
5
SEAL
BEARINGS THIS END INSTALLED IN
NOTCH IN SHAFT
ANTI-ROTATIONAL
SPRING
2. Remove the tapered snap ring (2), using Waldes Tool
#6500.Theremainingbearing (4) may now be pressed
outtowards therearof the pulley, leavingsnapring(5) in
pulley if pulley is to be reused.
3. Removethetwo drive pins from thepulley.(Only if they
are to be replaced.) Use a stone grinding wheel and
grinda grove into the pinin such a mannerthat a puller
will grip the pin. Remove and discard same.
FAN PLATE DISASSEMBLY
1. Place fanplate(20)onflatsurfacenose down. Displace
spacer (12) between bearing eccentrically as far as
possible. With a round pressing tool which fits loosely
through the I.D. of the top bearing, contact spacer(12)
and force lower bearing (11) out of housing of fan plate
(20).
2. Remove retaining ring (14), using Waldes tool #6500,
turn hub plate over and press out bottom bearing (13).
RE-ASSEMBLY
Assemblyofpulley-bearing sub-assembly (see Figure 11):
1. Installsnap ring (5)usingWaldesTru-arcsnap ring plier
#6500orequivalent.
2. Supportthe pulley onthedrivepinend. Press in bearing
(4) seal side up, until bearing bottoms on snap ring (5).
Pressing fixture should contact outer race.
3. Install tapered snap ring (2), flat side towards bearing
usingWaldes tool#6500.
4. Invert pulley drive pin end up. Position spacer (1)
concentricwithinnerrace ofpreviouslyinstalledbearing.
Pack grease (Chevron SR1 #2) around spacer. Press
in second bearing (3), seal side up, until inner race
contactsspacer.Pressingfixturemustcontactbothinner
andouterraces.
5. If the drive pins were removed (under Step #3 “Pulley
Disassembly”),replace with new pinsby placing pulley
on arbor press (or equivalent piece of equipment) -
drivepin sideofpulley up. Starttaperedendof pin(small
end) into hole and press into place. Drive pins are to
extend 1-1/4 inches from the face of the pulley.
ASSEMBLY OF PULLEYASSEMBLY ON
BRACKET- SHAFT
1. Support bracket with shaft pointingup. Apply one band
of Loctite RC601 around shaft for each bearing (see
Figure 9). Apply one band of Loctite RC601 on each
race. NOTE: When using Loctite, parts must be clean
and free of oil and grease.Allow 24 hours for complete
curing.
2. Slidepulleyassemblyonshaft,makingsurethebottom
bearing inner race bottoms against bracket.
3. Place locking ring (19) on shaft and install locknut(13).
A tool similar to that shown in Figure 10 may be
fabricatedto tighten the lock nutto 100-150 ft. lbs. One
tang on the locking ring (19) must be bent up into the
appropriate slot in the lock nut (13).
ASSEMBLY OF FAN PLATE SUB-ASSEMBLY
1. Place fan plate (20) on flat surface nose up and press
front bearing (11) seal up into housing until it bottoms
against shoulder of fan plate.
THIS END INSTALLED IN
NOTCH IN SPRING COLLAR

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2. Turn fan plate assembly (20) over and install spacer
(12)concentric with inner race of previously installed
bearing.Pack grease (ChevronSR1#2)around spacer.
Press in second bearing (13) seal side up until inner
racecontacts spacer.Pressingfixture must contactboth
innerand outer racer.
3. Install snap ring (14) flat side towards bearing.
FINALASSEMBLY
1. Support bracket, shaft, pulley assembly with the shaft
pointing up.
2. Install spring pack (8) onto pulley assembly and retain
with two 1/4 x 20 Phillips screws. Torque to 50-75 inch
pounds.
3. Install anti-rotational spring (17) making sure one end
of spring is engaged in notch of shaft (see Figure 12).
4. Install pressure plate (7) making sure end of anti-
rotationalspring(17)isengagedinnotchofspringcollar.
Holes in pressure plate must slide over drive pins (9).
5. Press special washer (5) on hub of piston assembly
(16).
6. Lubricate I.D. of piston housing (15) and three o-rings
(3, 4, 6) with BW-655-M.
7. Install o-rings (6 & 4) onto piston (16) and install
o-ring(3)ontoshaft.
8. Install piston (16) into piston housing (15) and install
unitonto shaft.
9. Installfan plate assembly (20) onto shaft andretainwith
lock nut (3). Torque to 75 foot pounds.
10.Install and bend cotter pin (2) and replace cap (1).
INSTALLATION
1. Attach fan clutch unit to vehicle by installing cap nuts
and lockwashers through mounting bracket holes into
mating holes in engine bracket.
2. Reconnect air line to unit.
3. Adjust fan belts per vehicle manufacturer’s
recommendation.
4. Replace fan on pressure plate with six cap screws and
lockwashers.Torque to300-360 inch pounds. (Be sure
to install any spacers that were removed during
Disassembly.)
5. Perform service checks as previously outlined.
TEST
1. With no air pressure applied, the torque required to
rotate the clutch must not exceed 150 inch ounces.
2. With 70-75 psi applied, the fan plate must rotate freely,
separate from the pulley.
3. Perform the leakage checks outlined in the manual.
RETROFIT INSTALLATION INFORMATION
To determine which fan clutch piece number should be
purchasedwhen retrofitting existing equipment, consult the
nearest authorized Bendix distributor for assistance.
Completeinstallation instructions andpiping diagrams are
packed with each FD-2™fan clutch.
It is recommended that only cooling fans approved by the
vehicle or fan manufacturer be installed on the FD-2™fan
clutch.
• Maximum weight of fan blade assembly is 30 lbs.
• Maximum R.P.M. of 28 inch fan is 2700.
• Maximum R.P.M. of 34 inch fan is 2100.
• Maximumthickness of spacers betweenfan and hub
plate is 1-1/2".

8BW1598 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 4/2004 Printed in U.S.A.