Specifications

Pneumatic Tie Rod Cylinders
Series VE
Parker Hannifin Corporation
Cylinder Division
Des Plaines, Illinois USA
www.parker.com/cylinder
16
Catalog HY08-0948-3/NA
Cylinder Safety Guide
3.1.2 –Cylindersoperatinginanenvironmentwhereairdryingmaterials
are present such as fast-drying chemicals, paint, or weld splatter, or
other hazardous conditions such as excessive heat, should have shields
installed to prevent damage to the piston rod and piston rod seals.
3.1.3 –Properalignmentofthecylinderpistonrodanditsmating
component on the machine should be checked in both the extended and
retracted positions. Improper alignment will result in excessive rod gland
and/or cylinder bore wear. On fixed mounting cylinders attaching the pis-
ton rod while the rod is retracted will help in achieving proper alignment.
3.1.4 –Sometimesitmaybenecessarytorotatethepistonrodinorder
to thread the piston rod into the machine member. This operation must
always be done with zero pressure being applied to either side of the
piston. Failure to follow this procedure may result in loosening the piston
to rod-threaded connection. In some rare cases the turning of the piston
rod may rotate a threaded piston rod gland and loosen it from the
cylinder head. Confirm that this condition is not occurring. If it does,
re-tighten the piston rod gland firmly against the cylinder head.
For double rod cylinders it is also important that when attaching or
detaching the piston rod from the machine member that the torque be
applied to the piston rod end of the cylinder that is directly attaching to
the machine member with the opposite end unrestrained. If the design
of the machine is such that only the rod end of the cylinder opposite to
where the rod attaches to the machine member can be rotated, consult
the factory for further instructions.
3.2 Mounting Recommendations
3.2.1 –Alwaysmountcylindersusingthelargestpossiblehightensile
alloy steel socket head screws that can fit in the cylinder mounting holes
and torque them to the manufacturer’s recommendations for their size.
3.2.2 –Side-MountedCylinders–Inadditiontothemountingbolts,
cylinders of this type should be equipped with thrust keys or dowel pins
located so as to resist the major load.
3.2.3 –TieRodMounting–Cylinderswithtierodmountingsarerecom-
mended for applications where mounting space is limited. The standard
tie rod extension is shown as BB in dimension tables. Longer or shorter
extensions can be supplied. Nuts used for this mounting style should be
torqued to the same value as the tie rods for that bore size.
3.2.4 –FlangeMountCylinders–Thecontrolleddiameteroftherod
gland extension on head end flange mount cylinders can be used
as a pilot to locate the cylinders in relation to the machine. After align-
ment has been obtained, the flanges may be drilled for pins or dowels to
prevent shifting.
3.2.5 –TrunnionMountings–Cylindersrequirelubricatedbearingblocks
with minimum bearing clearances. Bearing blocks should be carefully
aligned and rigidly mounted so the trunnions will not be subjected to
bending moments. The rod end should also be pivoted with the pivot pin
in line and parallel to axis of the trunnion pins.
3.2.6 –ClevisMountings–Cylindersshouldbepivotedatbothends
with centerline of pins parallel to each other. After cylinder is mounted,
be sure to check to assure that the cylinder is free to swing through its
working arc without interference from other machine parts.
4.0 Cylinder and Accessories Maintenance, Troubleshooting
and Replacement
4.1 Storage–Attimescylindersaredeliveredbeforeacustomerisreadyto
install them and must be stored for a period of time. When storage is required
the following procedures are recommended.
4.1.1 –Storethecylindersinanindoorareawhichhasadry,cleanand
noncorrosive atmosphere. Take care to protect the cylinder from both
internal corrosion and external damage.
4.1.2 –Wheneverpossiblecylindersshouldbestoredinaverticalposi-
tion (piston rod up). This will minimize corrosion due to possible conden-
sation which could occur inside the cylinder. This will also minimize seal
damage.
4.1.3 –Portprotectorplugsshouldbeleftinthecylinderuntilthetimeof
installation.
4.1.4 –Ifacylinderisstoredfullofhydraulicfluid,expansionofthefluid
due to temperature changes must be considered. Installing a check
valve with free flow out of the cylinder is one method.
4.1.5 –Whencylindersaremountedonequipmentthatisstoredoutside
for extended periods, exposed unpainted surfaces, e.g. piston rod, must
be coated with a rust-inhibiting compound to prevent corrosion.
4.2 Cylinder Trouble Shooting
4.2.1 –External Leakage
4.2.1.1 –Rodsealleakagecangenerallybetracedtowornor
damagedseals.Examinethepistonrodfordents,gougesorscore
marks, and replace piston rod if surface is rough.
Rod seal leakage could also be traced to gland wear. If clearance
is excessive, replace rod bushing and seal. Rod seal leakage can
also be traced to seal deterioration. If seals are soft or gummy or
brittle, check compatibility of seal material with lubricant used if air
cylinder, or operating fluid if hydraulic cylinder. Replace with seal
material, which is compatible with these fluids. If the seals are hard
or have lost elasticity, it is usually due to exposure to temperatures
in excess of 165°F. (+74°C). Shield the cylinder from the heat
source to limit temperature to 350°F. (+177°C.) and replace with
fluorocarbon seals.
4.2.1.2 –Cylinderbodysealleakcangenerallybetracedtoloose
tie rods. Torque the tie rods to manufacturer’s recommendation for
that bore size.
  Excessivepressurecanalsoresultincylinderbodysealleak.
Determine maximum pressure to rated limits. Replace seals and
retorquetierodsasinparagraphabove.Excessivepressurecan
also result in cylinder body seal leak. Determine if the pressure
rating of the cylinder has been exceeded. If so, bring the operating
pressure down to the rating of the cylinder and have the tie rods
replaced.
Pinched or extruded cylinder body seal will also result in a leak.
Replace cylinder body seal and retorque as in paragraph above.
Cylinder body seal leakage due to loss of radial squeeze which
shows up in the form of flat spots or due to wear on the O.D. or I.D.
–Eitherofthesearesymptomsofnormalwearduetohighcycle
rate or length of service. Replace seals as per paragraph above.
4.2.2 –Internal Leakage
4.2.2.1 –Pistonsealleak(by-pass)1to3cubicinchesperminute
leakage is considered normal for piston ring construction. Virtually
no static leak with lipseal type seals on piston should be expected.
Piston seal wear is a usual cause of piston seal leakage. Replace
seals as required.
4.2.2.2 –Withlipsealtypepistonsealsexcessivebackpressure
due to over-adjustment of speed control valves could be a direct
cause of rapid seal wear. Contamination in a hydraulic system
can result in a scored cylinder bore, resulting in rapid seal wear.
In either case, replace piston seals as required.
4.2.2.3 –Whatappearstobepistonsealleak,evidencedbythe
fact that the cylinder drifts, is not always traceable to the piston. To
make sure, it is suggested that one side of the cylinder piston be
pressurized and the fluid line at the opposite port be disconnected.
Observe leakage. If none is evident, seek the cause of cylinder drift
in other component parts in the circuit.
4.2.3 –Cylinder Fails to Move the Load
4.2.3.1 –Pneumaticorhydraulicpressureistoolow.Checkthe
pressure at the cylinder to make sure it is to circuit requirements.
4.2.3.2 –PistonSealLeak–Operatethevalvetocyclethecylinder
and observe fluid flow at valve exhaust ports at end of cylinder
stroke. Replace piston seals if flow is excessive.
4.2.3.3 –Cylinderisundersizedfortheload–Replacecylinderwith
one of a larger bore size.
4.3 Erratic or Chatter Operation
4.3.1 –Excessivefrictionatrodglandorpistonbearingduetoload
misalignment–Correctcylinder-to-loadalignment.
4.3.2 –Cylindersizedtooclosetoloadrequirements–Reduceloador
install larger cylinder.
4.3.3 –Erraticoperationcouldbetracedtothedifferencebetweenstatic
and kinetic friction. Install speed control valves to provide a back pres-
sure to control the stroke.
4.4 Cylinder Modifications, Repairs, or Failed Component–Cylinders
as shipped from the factory are not to be disassembled and or modified.
If cylinders require modifications, these modifications must be done at
company locations or by the Company’s certified facilities. The Cylinder
DivisionEngineeringDepartmentmustbenotifiedintheeventofamechani-
cal fracture or permanent deformation of any cylinder component (excluding
seals). This includes a broken piston rod, tie rod, mounting accessory or any
other cylinder component. The notification should include all operation and
application details. This information will be used to provide an engineered
repair that will prevent recurrence of the failure.
It is allowed to disassemble cylinders for the purpose of replacing seals or
seal assemblies. However, this work must be done by strictly following all the
instructions provided with the seal kits.