BENDIX FD-1 CLUTCH TYPE FAN DRIVE User manual

1
®
Bendix®FD-1™Clutch Type Fan Drive
SD-09-8501
FIGURE 1
PRESSURE
PLATE
BEARINGS
BRACKET
O-RING
FIGURE 2
DESCRIPTION
TheBendix®FD-1™fanclutchisa pneumatically operated,
thermostaticallycontrolledclutchfortheengine cooling fan.
Itspurposeisto maintain engine temperature by engaging
or disengaging the cooling fan, thereby providing better
fueleconomy,greaterengineefficiency,fasterwarm-upsand
aquieter vehicle.
TheFD-1™clutchis produced in severaldifferentmodelsto
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 or component or air line failure.
OPERATION
GENERAL
TheFD-1™fanclutchreplaces the standard fan hub on the
engineand iscontrolled byatemperature sensitiveairvalve
(see Fig. 5). The same valves used to control radiator
shutters are used to control the FD-1™clutch. Installed in
the engine block, the control valve directly senses coolant
temperature.Provided coolant temperature remains below
the setting of the valve, air passes through it to disengage
thefan clutch. When coolant temperature rises to the valve
setting, it closes and exhausts air pressure from the fan
clutchwhich engages the fan.
TEFLON
BACK-UP
RING
AIRPASSAGE
SHAFT
GREASE
PASSAGE
GREASE
FITTING
SPACER RETAINER NUT
PISTON FRICTION
MATERIAL
FAN
SPRING
SPRING
CAGE
FAN PILOT
DOUBLE ROW
BALLBEARING
BEARING
RETAINER
PULLEY
AIRINLET

2
FIGURE 3
FAN DISENGAGED
FIGURE 4
FANENGAGED
Dependinguponoptionalequipment installedon thevehicle
such as radiator shutters and radiator mounted air
conditioning condenser, different piping arrangements are
necessary. These will be explained in the paragraph on
controlsystems.
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
shaft moving the pressure plate assembly and fan to the
disengaged position. In this position the clutch lining is out
ofcontact with the pulley and thefan is no longer driven by
the engine (see Fig. 3).
ENGAGED
As the engine coolant rises in temperature, the engine
thermostat opens to circulate radiator coolant through the
engine. With further increase in coolant temperature, the
fan drive control valve closes and exhausts air from the
pistoncavity when theenginecoolanttemperature reaches
thesettingof the control valve. The fan clutch spring forces
the piston and pressure plate back on the shaft. When the
pressureplate lining contactsthe pulley, the fanisengaged
and is driven by the engine (see Fig. 4).
CONTROL SYSTEMS
Thefanclutch,in additiontoitsprimaryfunction ofoperating
the fan as needed to maintain the cooling liquid within a
certaintemperaturerange,mustbe coordinated with other
deviceswheninstalled on the vehicle.
Theseareradiatorshuttersandradiatormountedcondenser
for air conditioning. Four basic configurations are possible
asfollows:
Figure 5. Fan Clutch only
Figure 6. FanClutchwithshutters
Figure 7. Fan Clutch with radiator mounted air
conditioningcondenser
Figure 8. Fan Clutch, shutters and condenser
Theobjective inthe caseofFigure 5isto notengagethefan
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
temperatureisatleast 10°F.higher than the full open point
oftheenginethermostat.
The objective in the case of Figure 6 is to not engage the
fan until the shutters are fully open. The fan control valve
should,therefore,engagethefanatacoolanttemperature
10°F. higher than the shutter opening point. If the shutters
are the modulating type, the fan engagement should be at
least 10°F. higher than the full-open temperature of the
shutter.
Inthe case ofFigure7 the fanmustbe controlled toperform
the supplementary function of pulling cooling air through
theair conditioning condenser when required,althoughthe
engine coolant may be below the fan cut-in temperature.
This is most likely to occur at high ambient temperatures
and low road speed or idling. If the condenser is
inadequately cooled, 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, as shown in Figure 7. When
thispressureswitchsensesahigherthannormalpressure
in the air conditioning system (approximately 250 P.S.I.), it
closesanelectricalcircuit whichin turnenergizesasolenoid
operatedairsupplyvalvewhichexhauststhe air supply for

3
FIGURE 5 FIGURE 7
FIGURE 8FIGURE 6
the fan control, causing the fan to engage. Most vehicles
also have an additional dual function pressure switch
connected in series with the air conditioner clutch. This
switch is normally open, closes at approximately 30 P.S.I.
and opens again at approximately 400 P.S.I. Its purpose is
to prevent operation of the air conditioning compressor if
the refrigerant is lost or to shut off the compressor if the
system pressure reaches a dangerously high pressure
(approximately 400 P.S.I.). This switch does not normally
have anything to do with fan operation; however, it is
sometimescombinedwiththepreviouslymentionedoverride
switch.
Figure 8 depicts a combination of shutters, fan clutch and
airconditioning. This combination requires the two thermo-
pneumatic controls for fan and shutters, as well as the
electro-pneumatic override for the air conditioning. With
thiscombinationthe samerequirementsforfancontrolapply
asin Figure 6 and 7withtheadditional requirement thatthe
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
otherinfrontof the remaining portion of the radiator.In this
combinationonlythesectioninfront ofthe condenserneeds
to open when the air conditioner engages.
PREVENTIVE MAINTENANCE
Thedurability of the Bendix®FD-1™fan clutchmatchesthat
of the vehicle’s engine when proper maintenance is
performed. Maintenance intervals for the FD-1™clutch will
vary in relation to the type of service the vehicle performs.
Thefollowing is a guide:
THERMO-PNEUMATIC
VALVE
THERMO-PNEUMATIC
VALVES
BLOCK
FAN
CLUTCH
RADIATOR
RADIATOR
FAN
CLUTCH
BLOCK
SHUTTER
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

4
FIGURE 9
LINEHAUL VEHICLES:
Every25,000 miles,900hours, orthreemonths -whichever
occurs first-lubricate the FD-1™clutch (SEE NOTE).
Every 50,000 miles, 1,800 hours, or every six months
whicheveroccursfirst-performtheservice checks outlined
inthismanual.
CITYDELIVERY
Every 15,000 miles, 300 hours or two months - whichever
occurs first:
1. Perform the service checks outlined in this manual.
2. Lubricate the FD-1™clutch (SEE NOTE).
NOTE: Prior to July, 1980,agreaseprovision wasoptional.
When this option was not included, permanently
lubricated components were installed. Most fan
clutches produced after July, 1980, include the
greaseprovision as a standardfeature.
Lubricate the FD-1™clutch with approximately 10 cubic
centimetersof CHEVRON SRI #2 or anequivalentgrease.
SERVICE CHECKS
Before performing the operational 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
disengagedfrom the pulley and can be turned by hand.
If the fan can be turned, proceed to 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
andmust be repaired or replaced (see appropriate
section of this manual).
C. If the fan can now be turned; check the air lines
leading to and from the thermostatic control valve
for “kinks” or obstructions, and check the control
valve itself according to the manufacturer’s
instructions.
2. Afterperforming check#1,drainallair pressurefromthe
brake system. Note that the fan is now engaged and
cannotbeturnedbyhand.Ifitcannotbeturned,proceed
totest#3. If it can be turned, the clutch is defective and
mustberepaired or replaced.
3. Checkthe operation ofthethermostatic control valveby
running the engine up to operating temperature. 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 check #4. If
engagementtimedoesexceed two minutes:
A. Ifthistestis being performed for the first time after
installationof the fan clutch, recheck the setting of
the thermostatic control valve and compare it with
the setting of the engine coolant thermostat or in
thecaseof vehicles with radiator shutters, with the
settingof the shutter control. The fanclutchcontrol
shouldalwaysbe10°higherthanthehighestsetting.
B. Ifthefanclutchinstallationhassuccessfully passed
this test before, but does not do so now, the
thermostatic control valve is defective and should
bereplaced.
4. Check the condition of the rear main bearings during
operationand note any excessive wobble ornoise.The
pressure plate ball bearing and sliding piston can be
checked while the engine is off and the fan is
disengaged. “Rock” the fan from front to back at the
outertipof the blade. If movement of the blade tip, front
to back, exceeds 3/8" (See fig. 5) the fan clutch must
be repaired or replaced.
5. Check thepressureplatelining thickness by measuring
thegap between thepressureplate edge andthepulley
face with the clutch engaged. The gap should not be
less than .120 inch or approximately 1/8 inch.
LEAKAGECHECKS
In order to check for air leakage past the only two sliding
o-ringsinthe FD-1™fan clutch,itis necessary todisconnect
the single air control line.
Checkforleakagebyconnectinga90cu.in.reservoir(Bendix
part number 225000) with a gauge installed to the control
(9) (8) (13)
(11)
(10)
(3) (2)
(1)
(4)
(5)
(15)
(14)
(12)
(7)
(6)
(15)
(14)

5
FIGURE 10
portof the fan clutch.After fillingthe90cu. in. reservoirwith
100psi, allowthepressure tostabilizeand observe thetime
required for the reservoir pressure to drop to 90 psi. If the
time required is less than 1 minute, leakage is excessive
andrepairor replacement is necessary.
If the FD-1™fan clutch fails to operate as described or
leakageisexcessive,it is recommended that it be returned
to the nearest authorized Bendix outlet for a factory
remanufacturedunit under the exchange plan. If this is not
possible, the FD-1™clutch can be repaired with genuine
Bendixparts,in which case the following should be helpful.
NOTE: Apressure platemaintenancekitincludingpressure
plateand o-ringsisavailable underpc.no. 288907.
O-ring kit only is pc. no. 289319.
REMOVAL
Itisrecommended forease ofrepairthattheentirefanclutch
assemblyberemovedfromthe vehicle.Before removingthe
fan clutch apply the vehicle parking brakes or check the
wheels and drain all brake system air pressure.
1. Remove the six cap screws which hold the fan clutch
pressureplate and remove thefan.
2. Loosenthefanbeltsandremovethefanclutchassembly.
DISASSEMBLY
1. Removethe3/8inch cap screw (1) and washer (2) from
the radiator end of the fan hub shaft (see Fig. 9).
2. Removespring cover (3),spring(4),andthrust washer
(5).
3. Remove pressure plate assembly complete and set
aside.
4. Disengage lock tab on lock washer (6) (see Fig. 9) and
remove bearing nut (7), using a spanner tool as shown
in Fig. 10.
5. Remove lockwasher, piston housing (8) and o-ring (9)
(see Fig. 9).
6. Support the back side 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, a force as high as 5000 lbs. may be required
toremovethepulleyassembly.Iftheshaftistobereused,
acap screw should be screwed intotheendof the shaft
to protect the end of the shaft from damage.
PRESSUREPLATE DISASSEMBLY
1. RemovethreePhillipsscrews(10)(Fig.9).
2. Removepressure plate(11).
3. Removethe large o-ring(12)from the O.D.ofthe piston
(13) and the small o-ring (14) and Teflon backup ring
(15) from the internal groove in the bore of the piston.
(Seeenlargedviewin circle)NOTE:Fansmanufactured
prior to Jan. 1979 do not have the Teflon back-up ring
andthe groove is not wide enough to acceptone.
4. Infan assembliesmanufactured priorto December1976
the piston in the bearing retainer/piston sub-assembly
is die cast aluminum and is retained in the bearing by
Locktite and lock ring.
After December 1976 the piston is of cast iron retained
in the bearing by a lock nut. In any case, the bearing
retainer,bearing,piston, lockringand lock nutcomprise
a sub-assembly and must be serviced as such. The
aluminumpistonversionshouldalwaysbereplacedwith
the later version with the cast iron piston. Refer to the
Bendix Parts Catalog for part identification.
PULLEY DISASSEMBLY (See Fig. 11)
1. Support pulley on front (tapered) end. Displace spacer
(1) eccentrically as far as possible. With a round
pressing tool which fits loosely through the I.D. of the
top bearing, press the bottom bearing out (3) pressing
on the eccentrically positioned spacer.
2. Remove the tapered snap ring (2), using Waldes Tool
#6500.Theremaining bearing (4) may now be pressed
out towards the rear of the pulley, leaving snap ring (5)
in pulley if pulley is to be reused.
3. In the case of closely spaced matched bearings such
as shown in Fig. 12, remove the snap ring and press
both bearings out the rear of the pulley.
This completes normal disassembly of the fan clutch.
Thebracket-shaftassemblyis normally recommended
to be serviced as an assembly.
27/32” DRILL THRU (2
HOLESFOR 3/4 BAR) MAT’L O.H.T.S. TUBING
HDN&DRAWRC40-45
.235 + .002 CENTERED
(4 LUGS)
I< 2.080+.005 >I
2.75”
1/32” FLAT
4.25”
4.62”
5.38”

6
FIGURE 11
FIGURE 12
CLEANINGAND INSPECTION
After disassembly is complete:
1. Washall metal parts, with the exceptionofthepressure
plate and lining, in a cleaning solvent and dry them.
2. Inspect parts not included in the maintenance kit for
nicks, burrs, corrosion and/or excessive wear.
3. Replace any part not considered reusable, after
inspection,with genuineBendixreplacement partsonly.
REASSEMBLY
ASSEMBLYOFPULLEY-BEARINGSUB-ASSEMBLY
1. (Spacedbearingassembly)(Fig.11)Installsnapring(5)
usingWaIdes Truarc snap ringplier6500 or equivalent.
2. Supportthe pulley onthefront or tapered end. Press in
bearing(4),sealside 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, tapered end up. Position spacer (1)
concentricwithinnerraceof previouslyinstalled bearing.
Pack grease (Chevron SRI #2) around spacer. Press
in second bearing (3), seal side up, until inner race
contactsspacer.Pressingfixturemustcontactbothinner
and outer races.
5. (Matched Bearings) To install the closely spaced
bearingsasshownin Fig.12,matchedbearings291458
mustbe used. Supportthepulley on thefrontor tapered
end and press in the first bearing, seal side down, until
bearing bottoms on shoulder in pulley. Press on outer
race of bearing. Press in second bearing, seal side up,
bottoming on first bearing.
6. Install tapered snap ring.
ASSEMBLY OF PULLEY ASSEMBLY ON BRACKET
SHAFT
1. Support bracket with shaft pointing up. Apply one band
of Loctite RC 601 around shaft for each bearing as
shown in Fig. 9. Apply one band of Loctite RC 601 on
each race.
NOTE: When using Loctite, parts must be clean and free
ofoilandgrease.Allow24hoursforcompletecuring.
2. Slidepulley assembly on shaft, making sure thebottom
bearing inner race bottoms against bracket.
3. Position o-ring (9) as shown in Fig. 9. Install piston cup
(8),lockwasher(6)withsingle tang located in groove in
shaft,andbearingnut(7).Atool similar to that shownin
Fig. 10 may be fabricated to tighten the bearing nut to
100-150 ft. lbs. One tang on the lockwasher must then
bebent upintothe appropriateslotin thenut.Care must
be taken not to injure the finish on the I.D. of the piston
cup.
FINALASSEMBLY (Ref. Fig. 9)
1. Supportbracket-shaftpulleyassemblywithshaftpointing
up.Lubricateinnersurfaceofpistonhousingandlower
half of shaft with lubricant BW 655M.
2. Lubricatethelargeo-ring(12) andinstallonpiston.Install
theTeflonback-upring(15)(ifused)intheinternalgroove
in the piston (13), then lubricate and install the smaller
O.D.REF.
PULLEY
(2)
(4)
SEAL
(3)
(1)
(5)
SEAL
PULLEY
SEAL SEAL
MATCHED
BEARINGS TO BE
ASSEMBLEDWITH
SEALSASSHOWN
TAPERED
SNAPRING

7
o-ring (14). Slide bearing retainer/piston assembly in
placeovershaft.Makesuretheindexingfinger onpiston
(13) is aligned with the corresponding gap in the side
wallof pistoncup(8). Push thepressureplate assembly
all the way home until the piston bottoms in the piston
housing.
3. Installspacer(5), spring (4), spring retainer (3), washer
(2) and cap screw (6). A new cap screw should always
beused (becauseofthe coatingonthe threads).Torque
the cap screw to 300 inch pounds.
4. Apply air pressure in control port of bracket or shaft
(80-120psi). Thiswill extendthebearing retainer/piston
assembly so the pressure plate can be positioned and
thethreePhillipsheadscrews(10)startedandtorqued
to 40 in. lbs. (It may be easier to torque the Phillips
headscrewsifthe air pressure in the clutch is released
after the screws are started.)
TEST
1. With no air pressure applied, the gap between the
pressure plate edge and the pulley face line should be
.375in. ± .04.With120psi air pressureapplied,thegap
may be .526 in. maximum (see Fig. 9).
2. Withnoairpressureapplied,thetorquerequired torotate
the clutch must not exceed 150 in. oz.
3. With 70-75 psi applied, the pressure plate must rotate
freely, separate from the pulley.
4. Perform the leakage checks outlined in the manual.
5. Do not overtighten engine fan belts.
RETROFIT INSTALLATION INFORMATION
To determine which fan clutch piece number should be
purchasedwhen retrofitting existingequipment,consultthe
nearestauthorizedBendixpartsoutlet for assistance.
Completeinstallation instructions and piping diagrams are
packed with each FD-1™fan clutch.
It is recommended that only cooling fans approved by the
vehicle or fan manufacturer be installed on the FD-1™fan
clutch.
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 inoperation, 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 propertools and observe
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 certain todrain theair pressure 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, deactivatethe electrical
system in a manner that safely removes all
electrical power from the vehicle.
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.

8BW1451 © 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 4/2004 Printed in U.S.A.