BENDIX ROTO CHAMBERS User manual

1
®
Rotochambers
SD-02-1336
OUTER
DIAPHRAGM
CLAMP
PUSH ROD
ASSY.
INNER
DIAPHRAGM
CLAMP
BODY
BOOT
SPRING
COVER
MOUNTING STUD
DIAPHRAGM
LOCK NUT
YOKEASSY.
DIAPHRAGM
GUIDE
DESCRIPTION
Therotochamberisanactuatorwhichconvertstheenergy
of air pressure into mechanical force. The type number of
therotochamberindicatestheactuator’sdiaphragmeffective
area (Type 30 - 30 sq. in. of diaphragm) and the various
sizesavailablegivea wide range ofoutputforceandlength
ofstroke.Therollingtypediaphragmprovideslonglifeand
givesaconstantoutputforcethroughouttheentirestroke.
One end of the diaphragm is clamped to the inside wall of
thebody bytheouterclamp.The otherendofthediaphragm
is clamped between the diaphragm guide and inner
diaphragm clamp. The cover is fastened to the outer body
by cap screws. Mounting studs are used to mount the
chambers. A boot retained by a boot retainer is used to
prevententranceofmoisturethroughtheholeinthecover.
A lock nut and yoke with pin are screwed on the threaded
push rod. Most rotochambers now have 3/8 in. NPTF inlet
ports.The long stroke Type 50 employ a 1/2 in. NPTF inlet
port.
OPERATION
Controlledairpressureenters the rotochamberthroughthe
inletportandactsuponthediaphragm,movingthediaphragm
guideanddiaphragm forward.Thediaphragmmoves along
the inside wall of the cylinder body with a smooth rolling
motion. The forward motion of the diaphragm guide and
diaphragmforcesthepushplate and push rodforward.
Whentherotochamberisusedtoactuatecamtypefoundation
brakeassemblies,the yoke isconnectedtoa slackadjuster
which in turn is connected to the brake cam shaft. This
forward motion of the push rod rotates the slack adjuster,
cam shaft and cam applying the vehicle brakes.
Therotochamberisalsoused in industrial applications and
in such cases may be used in clamping or holding
operations.
The greater air pressure admitted to the rotochamber, the
greater the force applied by the push rod and, conversely,
the less air pressure applied to the rotochamber, the less
forceappliedbythe push rod. Pushrodforceisdetermined
by multiplying the air pressure delivered by the effective
diaphragm area. For example, if 60 psi is admitted to the
Type 30 rotochamberthelinealforce on theendofthe push
rod is approximately 1800 lbs.
When air pressure is released from the rotochamber the
rotochamberspring returnstheslack adjuster(ifapplicable),
pushrod, diaphragm guide and diaphragm to thereleased
position.

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PREVENTIVE MAINTENANCE
A. Everymonth,8,000miles,or after 300 operating hours,
dependingontypeof operation:
1. Checkpushrodtravelandadjusttravelattheslack
adjusterifneeded.Pushrodtravelshouldbe asshort
aspossiblewithoutbrakesdragging.Excessive push
rod travel reduces braking efficiency, shortens
diaphragm life, gives slow braking response and
wastesair.
2. Check push rod to slack adjuster alignment from
release to full stroke position to be sure push rod
moves out and returns properly without binding at
the cover hole or with other structures. Also check
theangleformedbytheslack adjusterarmand push
rod.Itshouldbe 90° orgreaterwhenthechamber is
intheappliedorreleased positions.
3. Checktightnessof mountingnuts.Checkcotterpins
to make sure they are in place.
4. Check all hoses and lines. They should be secure
andingoodcondition.
B. Everyyearoraftereach100,000milesor3,600operating
hours,dependingontype of operation.
1. Disassemble and clean all parts.
2. Install new diaphragm or any other parts if they are
wornordeteriorated.
Whenthediaphragm,spring,orbotharereplacedtheyshould
bereplacedinthecorrespondingchamber onthesameaxle.
OPERATING AND LEAKAGE TESTS
A. OperatingTest
1. Applybrakesandobserve that the push rods move
outpromptlyandwithoutbinding.
2. Releasebrakesandobservethatthepushrodsreturn
tothereleasedpositionpromptlyandwithoutbinding.
3. Checkpushrodtravel. Push rod travelshouldbeas
short as possible without brakes dragging. Adjust
travel of push rod at slack adjuster if necessary.
B. LeakageTest
1. Loosen rubber boot from around push rod hole in
cover.Makeandholdafullbrakeapplication.
Coatareawithsoap sudsandcheckforleakage.Noleakage
is permissible. If leakage is detected, the diaphragm must
be replaced.
REMOVING
1. Block vehiclewheels.
2. Disconnectlinetorotochamber.
3. Removetheyokepin.
4. Removetherotochamber.
INSTALLING
1. Before installing chamber, check bracket for distortion,
cracks or any condition which might cause chamber
misalignmentormalfunction.
2. Re-install the chamber on the bracket. Tighten the
mountingnutssecurelyandevenly.
3. Connect the air lines to the rotochamber and check for
leakage.
4. Insertthepush rodyokepinthrough theholeinthe yoke
andslackadjuster.Makesurethesamehole location in
the slack adjuster on each side of the axle is used.
5. The yoke should be adjusted on the push rod so that
with brakes released the angle formed by the push rod
andslackadjusterwillbegreaterthan90°andallslack
adjusters should be at the same angle. With properly
adjustedbrakes applied,theangle shouldstillbegreater
than90°.
DISASSEMBLY
For ease in disassembly, if the rotochamber has been in
service and shows signs of rust accumulation, it is
recommendedthatthechamber be immersed and soaked
in the cleaning or rust dissolving solvent for 24 hours.
1. Remove yoke and lock nut from push rod.
2. Remove rubberboot.
3. Remove cap screws from cover.
4. Remove cover, springs and spring guides (if so
equipped).
5. Remove nuts from body. These nuts secure the outer
clampto the body and are locatedat the air inlet end of
therotochamber.
6. Grasp the push rod and by pulling and wiggling the
entire assembly consisting of push rod and plate,
diaphragm guide, diaphragm, inner and outer clamps
should ease out of the body.
7. Straighten therolleddiaphragm.
8. Remove outerdiaphragmclamp.
9. Remove nuts from inside of diaphragm guide.
10.Disassemble inner diaphragm clamp, diaphragm and
push plate rod assembly from the diaphragm guide.
CLEANING AND INSPECTION
1. Clean all metal parts in a good cleaning solvent.
2. Carefully inspect allmetalpartsforcracks,distortionor
damage.Replaceanypartsnotconsidered serviceable.
3. Replace diaphragm and rubber boot.

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ASSEMBLY
1. Position the diaphragm on end in the inner diaphragm
clamp.Thesmallerdiameterendofthediaphragmshould
beagainstthediaphragmclamp.
2. Place and install the diaphragm guide within the
diaphragm and over the inner diaphragm clamp studs.
3. Install the push plate push rod assembly within the
diaphragm guide and over the inner diaphragm clamp
studs.
4. Install nuts on the inner diaphragm clamp studs and
tighten securely.
5. Place the assembly consisting of the push rod, push
plate, diaphragm guide, diaphragm and inner clamp
inside of the outer clamp.
6. Roll the free end of the diaphragm back and over the
end of the outer diaphragm clamp.
7. Lubricate the inside wall of the body and the rolled
surfaceofthediaphragmwithMurphy’soilsoap.
8. Slide the above assembly into the body.The endofthe
diaphragmshouldfitsnuglyagainst the shoulder in the
body.Positiontheouter diaphragmclampstuds through
theholesattheendofthebody, installnutsand tighten
securely.
9. Install spring guide (if so equipped) and install spring
over push rod, and install spring guide on spring (if so
equipped).
10. Install coveroverpush rodandinto body.Attach cover to
body with cap screws, tightening securely.
11. Install boot over push rod attaching to cover.
12.Install lock nut and yoke on push rod.
TESTING OF REBUILT ROTOCHAMBER
Perform“OperatingandLeakage” checks.
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
enginebein operation,EXTREMECAUTION 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. Useonlythe proper toolsand 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 draintheairpressurefrom
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.
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.

4BW1561 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2004 Printed in U.S.A.