BENDIX D-2 GOVERNOR User manual

1
®
SD-01-503
DESCRIPTION
TheD-2™governor,operatinginconjunctionwiththeunloading
mechanism, automatically controls the air pressure in the
air brake or air supply system between a maximum (cut-
out) pressure and a minimum (cut-in) pressure. The
compressorrunscontinuallywhiletheengineruns,butthe
actual compression of air is controlled by the governor
actuatingthecompressorunloadingmechanismwhichstops
or starts the compression of air when the maximum or
minimumreservoirpressures arereached.
D-2™governorsareprovidedwithmountingholeswhichallow
directmountingtothecompressororremotemounting.
Porting consists of three reservoir ports (1/8 inch P.T.),
three unloader ports (1/8 inch P.T.) and one exhaust port
(1/8 inch P.T.).
Bendix®D-2™Governor
EXHAUST
PORT
RESERVOIR
PORTS(3)
14
RETAINING
RING
11
PISTON
4
ADJUSTING
SCREW
2
BODY
6
EXHAUST
STEM
FIGURE 1 - D-2™GOVERNOR
5
15
11
5
11
20
O-RING
CLEAR/BLACK
NONMETALLIC
WITH O-RING BLACK
RUBBER
BLUE
NONMETALLIC
FIGURE 2 - TYPES OF COVERS FIGURE 3 - TYPES OF PISTONS
16
UPPERSPRING
SEAT
1
RETAINING
RING
15
RETAINING
RING
10
INLET/
EXHAUST
VALVE
12
O-RING
13
WASHER
MOUNTING
HOLES
(2)
15
RETAINING
RING
7
FILTERS
9
INLET/EXHAUST
VALVESPRING
5
EXHAUST
STEM
8
O-RING
12 O-RING
8 O-RING
19LOWER
SPRINGSEAT
19LOWER
SPRINGSEAT
10
INLET/EXHAUST
VALVE 11
PISTON
18
SPRING GUIDE
17
PRESSURE SETTING
SPRING
3
LOCKNUT
UNLOADER
PORTS(3)
COVER
9
INLET/EXHAUST
COVERVALVE
SPRING
NONMETALLIC METALLIC

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OPERATION
Reservoirair pressureenterstheD-2™governorat oneofits
reservoirportsandactsonthepistonandinlet/exhaustvalve.
As the air pressure builds up, the piston and valve move
togetheragainsttheresistanceofthepressuresettingspring.
Whenthereservoir air pressure reaches thecut-outsetting
ofthe governor, theexhauststem seatson theinlet/exhaust
valve, closing the exhaust passage, and then opens the
inletpassage.Reservoir air pressure thenflowsaroundthe
inlet valve, through the passage in the piston and out the
unloaderporttothe compressor unloading mechanism.Air
also flows around the piston which is slightly larger at the
upper end. The added force resulting from this larger area
assuresapositiveactionandfullyopenstheinletvalve.
As the system reservoir air pressure drops to the cut-in
settingof the governor,theforce exertedbythe airpressure
on the piston will be reduced so that the pressure setting
spring will move the piston down. The inlet valve will close
andtheexhaustwill open. With the exhaust open, theairin
theunloaderlinewillescapebackthroughthepiston,through
the exhaust stem and out the exhaust port.
PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performinganyintrusivemaintenanceprocedures.Awarranty
maybevoided if intrusivemaintenanceisperformed during
thewarrantyperiod.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuableguide indeterminingthe bestmaintenanceinterval
for air brake system components.At a minimum, the D-2™
governor should be inspected every 6 months or 1500
operatinghours,whichevercomesfirst,forproperoperation.
Should the D-2™governor not meet the elements of the
operationaltestsnotedinthisdocument,furtherinvestigation
andserviceof thegovernormaybe required.
SERVICE TESTS
OPERATING TESTS
Start the vehicle engine and build up air pressure in the air
brakesystemandcheckthepressure registered by a dash
ortest gauge atthetime thegovernorcuts-out, stoppingthe
compressionof airbythecompressor.Thecut-out pressure
should be in accordance with the pressure setting of the
piecenumberbeingused. (Common cut-out pressures are
between105-125psi.) Withtheenginestill running, makea
series of brake applications to reduce the air pressure and
observe at what pressure the governor cuts-in the
compressor.Asin the case of the cut-out pressure,thecut-
inpressureshouldbeinaccordancewiththepressuresetting
of thepiecenumberbeingused.(Commoncuttingpressures
arebetween90-105 psi.)
Never condemn or adjust the governor pressure settings
unless they are checked with an accurate test gauge or a
dash gauge that is registering accurately. If the pressure
settingsoftheD-2™governorareinaccurateoritisnecessary
that they be changed, the adjustment procedure follows.
Note:If thegovernorcoverismarkednonadjustableand the
adjustingstemhasbeenshearedoff,thisisanonserviceable
governorandmustbereplacedwithaneworremanufactured
unit.
A. Removethe topcoverfromthegovernor.
B. Loosen the adjusting screw locknut.
C. Toraisethe pressuresettings, turntheadjustingscrew
counter-clockwise. To lower the pressure settings,
turn the adjusting screw clockwise. Note: Be careful
not to overadjust. Each 1/4 turn of the adjusting screw
raises or lowers the pressure setting approximately 4
psi.
D. When proper adjustment is obtained, tighten the
adjustingscrewlocknutandreplacethecover.
(Note:Thepressurerange betweencut-inand cut-outisnot
adjustable.)
LEAKAGE TEST
Leakagetests ontheD-2™governorshouldbe madeinboth
cut-in and cut-out positions.
CUT-IN POSITION
Apply soap solution around the cover and to the exhaust
port. Slight bubble leakage permitted. Excessive leakage
indicatesafaultyinletvalveor lower piston o-ring.
CUT-OUT POSITION
Apply soap solution around the cover and to the exhaust
port. Slight bubble leakage permitted. Excessive leakage
indicates a faulty exhaust valve seat, exhaust stem o-ring,
or o-ring at the top of the piston.
Ifthegovernor does not functionasdescribedorleakage is
excessive,itis recommended thatitbe replaced withanew
orremanufacturedunit,orrepairedwithgenuineBendixparts
availableatauthorizedBendixpartsoutlets.
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

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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 CAUTIONshould
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 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, 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.
REMOVING AND INSTALLING
REMOVING
1. Blockandholdvehiclebymeansotherthanairbrakes.
2. Drain air brake system.
3. Ifthegovernor iscompressor-mountedtype, disconnect
reservoir air line. If the governor is remote-mounted,
disconnectboththeunloader and reservoir air lines.
4. Removegovernormountingbolts,thengovernor.
Caution: Priortodisassembly,it is required tohavethe
proper maintenance kit available to replace parts to be
discardedduringdisassembly.
DISASSEMBLY
1. Cleanthegovernor exterior ofdirtandgrease.
2. If the governor cover is marked nonadjustable and the
adjusting screw has been sheared off, this is a
nonserviceable governor and must be replaced with a
neworremanufactured unit.
3. If the governor has a blue nonmetallic cover, (refer to
Figure 2) hold governor with one hand, with the other
handgripcover fromthetop and pullupwith thumb until
coverdisengagesfromthegovernorbody.Iftopcoveron
governoris madeofrubberorclearnonmetallicmaterial
unscrewcoveruntil it releases from theadjustingscrew
(4)ofgovernor.Removeo-ring(20, Figure 2) ifpresent.
Note: O-ring (20) is used on Hi-Temp and waterproof
governorsonly.
4. With a pair of retaining ring pliers, remove the spring
assemblyretainingring(1) and save.
5. Pulltheadjustingscrew (4) and spring assembly out of
thegovernor body(2).
Note: Disassembly of the spring assembly normally is
not required. (Reuse and do not wash the assembly
because lubrication may be removed.) If Disassembly
of the spring assembly is necessary, the following in-
structions apply; otherwise, proceed to Step 6.
Remove the lock nut (3), then the hex-shaped upper
spring seat (16) from the adjusting screw (4). Remove
thepressuresettingspring(17),lowerspring seat (19),
spring guide (18) and the other lower spring seat (19)
fromtheadjustingscrew(4).
6. Gently tap the open end of the valve body on a flat sur-
face to remove the exhaust stem (5), the exhaust stem
spring (6), and piston assembly (11). Items 5 and 11
may be made of metal or nonmetallic material.
7. Remove and discard the two o-rings (8) on the piston
O.D. and with a hooked wire remove and discard the
o-ring (12) from the piston l.D. On nonmetallic piston,
washer (13) and retaining ring (14) may be removed to
facilitateremovalof o-ring(12).
8. Ifpistonassembly is nonmetallic (Figure3),useasmall
screwdriverand carefullyinsertbladeofscrewdriverbe-
tweentwo oftheearsof theretainerring inthebottom of
thepiston (11)andpry retainerring (15)outofthe piston
anddiscard.Remove inlet/exhaust valve spring(9)and
the inlet/exhaust valve (10) and discard. If piston as-
semblyismetallic, disengageinlet/exhaustvalvespring
(9) from recess in bottom of piston (11), remove inlet/
exhaustvalve spring(9),andtheinletexhaustvalve (10)
anddiscard.
9. Remove and discard filters (7) from unloader and
reservoirportsingovernor body.

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CLEANING AND INSPECTION
1. Clean all remaining parts in mineral spirits.
2. Inspect body for cracks or other damage. Be particu-
larly careful that all air passages in the body, exhaust
stem, and piston are not obstructed.
3. Check springs for cracks, distortion, or corrosion.
4. Replaceallpartswhichare worn or damaged.
ASSEMBLY
Prior to assembly, lubricate the two lower body bores, all
o-ringsando-ringgrooveswithlubricantprovided.Note:Also
springguideandadjustingscrew(if disassembled).
1. Install o-ring (12) in piston (11). Replace washer (13)
andretainingring(14) on nonmetallic piston if removed
duringdisassembly.
2. Drop the inlet/exhaust valve (10) into place at the
bottom of the piston (11).
3. NonmetallicPiston:Installtheinlet/exhaustvalvespring
(9)with thesmallend againstthevalve, placetheretain-
ingring(15)ontopof thelarge endofthevalvespring(9)
[concaveside ofretainingring(15)facingawayfrom pis-
ton(11)], pressintopiston withthumb,making sureears
ofretainingring(15)are seated into piston(11)as faras
possible.
Note: Donotuseapressorhammertoinstallretaining
ring. Excessive force may damage the piston.
Metallic Piston: Install the inlet/exhaust valve spring
(9)with thesmallendagainstthevalve.Pressthe spring
down until the larger coiled end snaps into the recess
inside the piston (11).
4. Install the piston o-rings (8) on the piston (11).
5. Installthe exhaust stemspring(6)inthe piston (11)with
the large coil end next to the piston.
6. Install the exhaust stem (5) through spring (6) and into
piston(11).
7. Installassembledpiston (11)intothe governorbody(2).
8. If the spring assembly was not disassembled, proceed
to Step 9. If the spring assembly was disassembled,
the following instructions apply: install on the adjusting
screw (4) in this order; lower spring seat (19), spring
guide(18), springseat(19),pressuresettingspring(17),
hex-shaped upper spring seat (16). Screw the upper
spring seat onto the adjusting screw until the distance
from the top of the seat to the bottom of the adjusting
screw head is approximately 1-7/8 inches. Install the
lock nut (3).
9. Installtheadjustingscrew(4)andspringassembly into
thegovernor body(2).
10. Installretainingring (1)makingcertainthat itseatscom-
pletelyintothegroove in the governor body(2).
Ifcoverprovided in kitisblackrubber,(referto Figure 2)
install by pushing it onto the adjusting screw.
Ifcoverprovidedinkit is clear nonmetallic, install o-ring
(20)andscrewcoverontotheadjustingscrew.Tighten
untilcoverbottoms on governorbody.Note: O-ring(20)
is used only on Hi-Temp and waterproof governors. If
coverprovided inkitisbluenonmetallic placecoverover
oneedgeoftop ofgovernor;withindexfingercatchknob
ontop of cover and pull untilcover snaps into place.
Note: Nonmetalliccover shouldbeat roomtemperature
for ease of assembly. Do not attempt to force cover on
squaretothe governor body.
11. Install filters (7) in governor body. The head of a pencil
makes a satisfactory installation tool.
INSTALLATION
1. Ifthegovernoris compressor-mounted,cleanthemount-
ing pad on both the compressor and governor. Clean
connecting line, or lines. Be certain the unloading port
isclearandclean.Ifthegovernorismountedremotely,
it should be positioned so that its exhaust port points
down.It shouldbemountedhigher thanthecompressor
so that its connecting lines will drain away from the
governor.
2. Installgovernor.
3. Ifcompressor-mountedtype,usethegovernormounting
gasketprovided.
4. Connectairlines to governor.
5. Perform operating and leakage tests as outlined under
Service Tests section.
BW1425 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2004 Printed in U.S.A.