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Ever greater demands are placed on modern sealing ele-ments in terms of their sealing capability and service life.Rod seals in particular have to fulfil the requirements ofenvironmental protection with the lowest possible leakagerate.Besides the leakage rate, the positioning accuracy of thecylinder also plays a significant role in the design of amodern hydraulic seal. Properties such as stick-slip-freerunning have become standard today. Modern sealing andbearing elements can guarantee this smooth, quiet move-ment even at lowest speeds.

TDI Rod SealIn order to meet these requirements, the "TDI" rod seal(see illustration 1) was developed. One of the outstandingfeatures of this patented seal is its high sealing capacity.Minimum leakage rates and a long service life have beenharmonised to produce smooth cylinder operation overseveral million strokes. This seal consists of the two com-ponents, the elastic body and the slide ring:• In the standard material design the elastic body con-

sists of highly wear-resistant polyurethane (PUR). In theTDI sealing system this fulfils two tasks. On the onehand its geometry forms an elastic sealing lip as aprimary seal. On the other hand it acts as an elasticpre-stressing element for the second sealing com-ponent, the integrated slide ring.

• The slide ring consists of a wear-resistant and low-friction PTFE bronze compound. Due to its shape thisforms a secondary sealing edge. Any seepage oil thathas passed the primary lip is held back by the secon-dary sealing edge, and during the return stroke of therod is forced under the primary lip back to the oilchamber.

The TDI offers the following advantages:• full functionality in an unpressurised state due to the

pretension of the sealing lips• long service life of the sealing system• permanent stick-slip-free running.The operating temperature is between -35 and +100°C.Through the use of special rubbers it is possible to modifythe TDI for use between -60 and +200°C and resistance toalmost all types of media.

GD1000K Piston SealIn contrast to the rod seal, the piston seal's qualities arewell hidden. The GD1000K (see illustration 2), which isalso patented, is suitable even for exceptional stresses.For the standard seal, temperatures of -45 to +120°C arepermitted. When modified it may be used for tempera-tures of between -60 and +200°C, as well as at high pres-sures or running speeds. It is therefore a sealing elementthat can be used for all hydraulic and pneumatic applica-tions.

The standard version of the GD1000K consists of the fol-lowing:• a rectangular, elastic body of modified NBR,• a slide ring made of abrasion-proof and low-friction

PTFE bronze compound as the actual sealing ring,• two lateral support rings made of modified polyurethane

(PUR) which protect against gap extrusion, and• two bearing rings made of pressure-proof and low-

wearing POM-PTFE bronze compound.

Decades of experience and continuous development have led to the creation by the firmHunger DFE of a complete range of sealing and bearing elements. In several fields ofapplication the knowledge gained from practical experience has been translated intomodern sealing concepts which offer not only many advantages, but have proved theirworth on millions of occasions.

The Hunger DFE Concept

Illustration 1: TDI

elastic body

slide ring

Composition:

Standard Installation:

Illustration 2: GD 1000 K

2 bearing rings

2 support ringsslide ringelasticbody

Composition:

Standard Installation:

3

The GD1000K offers numerous advantages:• The bearing rings positioned on the support rings

prevent any metal to metal contact between the pistonand the cylinder tube, while also guaranteeing exactguidance.

• The piston seal fulfils the requirements for a high level ofsealing as well as for stick-slip-free smooth running move-ment.

• Due to its structure it does not require any coveredinstallation space, thus simplifying the design of thepiston.

• Its combined bearing and sealing function in conjunctionwith its very narrow overall width provide structuraladvantages for the double-acting cylinder.

FA / FI / FAI Bearing ElementsThe bearing rings (see illustration 3) represent the bearingand guiding surface between the moving parts of the hy-draulic cylinder. These prevent metal to metal contact whileat the same time ensuring a high degree of pressureresistance. The bearing rings consist of a highly wear-resistant, low-friction polyoxymethylene (POM) modifiedwith bronze and PTFE. They are grooved for easy assem-bly and can be inserted using their patented U-shapedprofile without metal chambering. This makes it possibleto fully screen the sliding surfaces from one another. Fur-thermore, due to their almost constant friction magnitudeover the entire permitted speed range, they contribute tothe stick-slip-free operation of the cylinder.

OBVD Static SealOne seal that has been specially developed for staticsealing purposes fits into the existing O-ring installationspaces while preventing the undesired gap extrusion ofthe O-rings.The composite O-ring back ring seal "OBVD" (see illu-stration 4) is an 80° Shore A hard NBR O ring with a coldwelded and therefore permanently connected back ringmade of 95° Shore A hard polyurethane (PUR) which ishighly resistant to gap extrusion.

The OBVD can be inserted into the existing O-ring instal-lation spaces without the need to make any structuralchanges. The standard insertion spaces of the O-ringsare also sufficient for the OBVD in the case of new de-signs. The geometry of the polyurethane back ring sup-ports the sealing function and, in contrast to hard backrings, does not have any sharp edges, thus preventingany peeling of the O-ring.The one-part OBVD also has the advantage of simple in-stallation and reduced storage.

Modern AspectsWhen selecting a design element, several aspects haveto be considered:Besides its basic function, it should be possible to combi-ne the element with guide mechanisms and seals to forma sealing system.The complexity of the design should be kept as low aspossible.The sealing and bearing elements play a decisive role inthe serviceable life of the hydraulic cylinder.

That is why quality, sealing capability, guide functions andservice life are the most important factors when selectingthe sealing and guide elements.

Illustration 3: FI / FA / FAI

FI:

FA:

FAI:

Situation so far:

Solution:

Illustration 4: OBVD

p

p

Gap Extrusion

O - Ring

O - Ringincl.

Backring

Composition:

Function:

4

Material SelectionThe target of making a material ready for series produc-tion which was not only able to fulfil the bearing functionbut was also better in terms of its properties than thepolyoxymethylene (POM) predestined for this task resul-ted in the creation of the POM-PTFE bronze compoundthat is enriched with PTFE and bronze particles.

This material and the optimised geometry of the bearingelements open up numerous opportunities for improvingcylinder design.

The improved characteristics of the compound essentiallyresult from the positive values of its individual compon-ents:

• POM is a classical material for high-strength bearingsand accurate guide mechanisms. Even the basicmaterial stands out not only due to its low coefficient offriction and minimum wear, but also high thermal andchemical resistance.

• PTFE is the plastic with the lowest level of friction againststeel. Its dynamic and static coefficients are practicallythe same and allow stick-slip-free running even at thelowest speeds.

• Bronze increases the pressure resistance of the ma-terial and reduces the tendency to creep to a minimum.

Not only the combination of these materials, but ratherthe correct ratio in which the components were mixedproduced a material which opened up new possibilitiesbecause of its capabilities and broad range of applica-tions.

Laboratory TestsAn independent testing institute was commissioned todirectly compare the new material with traditional ones. Itwas shown that the excellent properties of the POM wereeven further improved by the compounding.

The coefficient of friction of the compound is markedlylower than that of the starting material (see diagram 2).The main effect of this is the reduced wear on the guidemechanisms and sliding surface (see diagram 1).

The mechanical loss factor of the compound is higher,resulting in improved damping characteristics and a high-er level of recovery after mechanical deformation.

The dynamic modulus of elasticity is lower than for thepure POM (see diagram 3). However, this is still within therange which is required for practical applications. Aftercompletion of the trials it was possible to get even closerto the modulus of elasticity using a new type of compoun-ding process.

The positive properties of the material compound have beenconfirmed by all types of practical applications. Mainte-nance-free and reliable hydraulic components in produc-tion lines, casting plant, dams or in mobile hydraulics takeadvantage of these properties on a permanent basis.

Note:The values stated here refer only to the samples used inthese trials and do not represent a guaranteed property.

Since the foundation of Hunger DFE GmbH the company has been constantly involved inthe development and processing of high-quality thermoplastics for the manufacture of theproducts.

Diagram 1 and 2: Wear and Coefficient of friction Diagram 3: Comparison of the dynamic modulus of elasticity

Modern Materials for Bearing Elements

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"Wet" cylinder rods caused by leaking seals are thereforeabsolutely taboo!

What is required is a maximum sealing effect and reliabi-lity with a minimum of friction and stick-slip-free move-ment.

Particularly during the soft start on the way down after thelift has stopped at a floor, and again when coming to astop at another floor, there must be no "jolting".

Passengers in the lift would be made to feel uneasy oreven placed in danger.

Hydraulic panorama lifts such as those to be found in shopping centres and furniture housesprovide not only an insight into the multitude of items on sale, but also a direct insight intothe technology of the lift.

Lift Hydraulics

Illustration 2: Seals and bearing elements of the guiding head

Tandem Seal TDI

Bearing Element FI

Wiper AI

Illustration 1: Bearing elements of the damping bush

Bearing Element FI

Here the sealing and bearing elements are required toensure that the desired properties remain constant fromthe very beginning while the lift is travelling up and down.

A number of lift manufacturers therefore use HUNGER pro-ducts with which the requirements of easy running andabsence of leaks are easily fulfilled under all operatingconditions (pressure, speed, temperature, etc.).

An interesting insight isprovided by open steel-glass constructions.And there, visible to eve-ryone, laterally placed liftcylinders (plungers ormultistage telescopiccylinders) confirm thereliability of the Hungersystem solutions consi-sting of sealing and bea-ring elements that are inuse there.

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The ratio of modern timber harvesting machines used for the thinning out or large-scalefelling of trees is constantly increasing. Harvesting machines are used all over the world,from Indonesia to Siberia, and in the most difficult of terrains.

Highest DemandsOne of the world's leading manufacturers of forestry ma-chines is the Finnish company Ponsse. The timber com-panies expect their machines to be fast and highly pro-ductive during the harvesting process. In order to be ableto fulfil these requirements Ponsse demands the highestlevels of quality from their suppliers. After extensive te-sting - and due to the outstanding quality shown by prac-tical experience - for approximately the last five years thehydraulic cylinders have been equipped almost exclusive-ly with HUNGER sealing and bearing elements.Depending on the type of machine, 10 to 20 hydrauliccylinders of varying diameter and construction (suppor-ting cylinders, telescopic cylinders, steering cylinders...)are used, making it possible to carry out lifting, lowering,tensioning and swivelling operations. With this considera-ble number of cylinders per vehicle and the high stan-dards required, it becomes clear that also the wearingparts, such as the sealing and bearing elements, are ofparticular significance.

Tailor-Made Sealing SystemsThe decisive factor in the service life of a sealingsystem is harmonisation of the componentsused, taking into account all operating parame-ters and structural aspects.

The sealing systems have been adapted to therespective demands placed on the cylinders. Forexample, in the case of the harvesting aggrega-te a rapidly assembled sealing and guide sy-stem was developed. With this, the tree trunksare cut into lengths, disbranched and depositedon the vehicle for removal in less than a minute.

In order to fulfil the requirements of a rapidassembly sealing and guide system without ha-ving to forfeit any of the sealing effect, the TDItandem seal was chosen as the rod seal in con-junction with the FI bearing element.

Environmental ProtectionBesides the absence of leaks, a further important environ-mental aspect is fulfilled by the possible use of environ-mentally friendly hydraulic fluids. The use of rapidly de-gradable hydraulic media is frequently demanded both bycustomers and strict regional environment legislation. Forall the sealing types used the materials can be adapted tothe environmentally friendly hydraulic fluids approved byPonsse.

Forestry Machines

The harvester fells, measures, disbranches and cuts the treesinto lengths within a few seconds for further processing ofthe trunks.

For the transport of the timber to paved roadways forwarders are usedwhich can transport up to 14 tonnes of material. These are equipped witha telescopic crane which can grip tree trunks from a distance of 10 m.

Illustration 1: Mounting arrangement of the cylinder rod

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The airline Deutsche Lufthansa AG successfully uses areal "master cleaner" for almost the entire Boeing andAirbus family at Frankfurt and Munich Airports. By theuse of state-of-the-art technology, this sensitive washingrobot makes it possible to save time and money whenwashing the aircraft. Computer controlled and regulatedwith extreme accuracy, the washing brush is pressed gent-ly against the body of the aircraft. The frictional resistanceof the brush elements regulates the telescopic movementof the robot arm. This is of course assisted by the sealingsystems of the hydraulic cylinders that are installed, sothat the 33 metre-high, 5-armed mast slides safely andreliably with the washing brush over the surfaces of theaircraft.

Sealing ConceptBesides the leak and stick-slip-free rod sealing concept,consisting of the AI wiper, TDI rod seal and FI bearingrings, the GD 1000 K piston seal also has a decisive roleto play.

The double-acting GD 1000K compact piston seal is com-posed of two bearing rings, two support rings, an elasto-mer section and a PTFE compound slide ring. Through itsstick-slip-free movement this seal also ensures the exactpositionability of the arm, holding it exactly on the sensi-tive skin of the aircraft with its outstanding sealing effect.Its plastic bearing rings fully exclude metal to metal con-tact on the inside of the hydraulic cylinder, thus enablinga low wearing and inexpensive cylinder design.

In order to guarantee reliability, which is absolutely es-sential in the area of the static seals, a composite ele-ment consisting of an O-ring with back ring is used.

This so-called OBVD (O-ring back ring composite seal)can be easily installed in standard installation spaces for

O-rings in accordance with DIN 3771, but is protected bythe back ring against undesired gap extrusion.

Therefore, in this application the sealing and bearing ele-ments used ensure that during the 2-3 hour washing ofthe aircraft, only the "gentle wash" is switched on.

AI

TDISTI-OG

GODI-SP

FI

Illustration 1: Mounting arrangement of the rod seal

GD 1000 K

Illustration 2: Mounting arrangement of the piston seal

Tedious and time-consuming washing by hand is no longer required. Today the washingbrush is rotated by the robot.

Washing Robot

Illustration: Company Putzmeister

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Construction machines lift, hold, transport and move large loads. Behind the scenes thereis usually a sophisticated hydraulic system at work which has to fulfil a number ofrequirements.

For the seal manufacturer these requirements are specifi-cally defined: a long service life, a high level of operatingsafety, short-term availability, replacability with productsof the competitors and easy installation, as the repair ofthe machine often has to be carried out on site using sim-ple equipment.

Fields of ApplicationThe fields of application for seals are as numerous astheir various types. For example, many construction ma-chines have supporting cylinders which give the basicdevice the required stability. Here the seals are subjectednot so much to wear and tear than to high static sealingrequirements. Due to the technical principle used, lip sealsmade of thermoplastics or elastomers are recommendedhere which have sharp-edged sealing lips and which keepthe pressure constant over a long time. Illustration 1 showsan example of the structure of a supporting cylinder com-bined with seals and bearing elements which permitmaximum lateral forces without contact of the metal sli-ding "partners". Complemented by a robust wiping ele-ment which carefully removes any dirt when the support isdrawn in, the system is able to fulfil all requirements.

The next hydraulic station of the equipmentcould, for example, be the rotary actuatorof a boom. In such cases toothed racksare mostly used to transmit a rotary move-ment to a pinion using hydraulic control.This task has to be performed as smooth-ly as possible, often using precise controlmethods; the sealing elements must the-refore have a low coefficient of friction. Thespecific use of PTFE (polytetrafluoroethy-lene) and its compounds has brought manyadvantages in comparison to the some-

what "antiquated" sets of sleeves, especially when thisinvolves elastomer lip seals with PTFE slide ring (tandemconstruction). These combine the sealing power of the lipseal with the excellent sliding properties of a slide ringseal. The moving arm or boom of the crane now has to belifted and lowered. Here too, high standards are requiredof the system and rod seals. Primarily, both elementsmust provide high levels of sealing capability, as a suddendrop as a result of a leak from the piston would be evenmore fatal than oil leaking from the piston rod.

CollaborationMany construction machine manufacturers collaborateintensively with the seal producer, and in the present casethis resulted in the 6-part compact seal "GD 1000 K" (seeillustration 2, page 7), where each element is allocated aspecific task. The heart of this seal is a rectangular ex-pander made of nitrile rubber which is rounded off to thecylinder tube and covered with a slide ring made of PTFEcompound.

In order to resist high pressures for a prolonged period,this element also includes chamber rings made of high-strength TPE. The seal is rounded off by two U-shapedbearing elements consisting of PTFE-enriched POM,which are mounted by simply snapping on into place. Inprinciple the same requirements are placed on the sealingelements with respect to the rod. Therefore only sealswhich are able to withstand high pressures can be used.With the lip seals which are mostly used, a back ring isinserted as extrusion protection for support over the entirearea (illustration 2). For pressures over 360 bar this isrecommended, while from 450 bar and up it is required.Nevertheless, with rod and piston seals it may be neces-sary to insert a back ring even at lower temperatures butgreater gap sizes. These gap sizes need not be basedonly on manufacturing tolerances, as often the fits onlybecome apparent once operation has started, for examp-le through pipe enlargement (high internal pressures,

Construction Machines

Illustration 1: Mounting arrangement of the cylinder

Wiper

Bearing Element

Tandem Seal

Static Seal

Piston Seal

Backring

BearingElement

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lightweight cylinders). Therefore you should consult theapplication engineer of your seal supplier for advice at anearly stage. Even at the design phase it is then possibleto exchange valuable experience or adopt complete in-stallation proposals.

Often it is easier to seal til-ting cylinders with a teles-copic construction. Theseare mostly only single-acting and the return stro-ke is effected by the de-vice's own weight. Here, tan-dem lip seals are the mostsuitable solution, where acompact sealing elementcan have several sealing lipsarranged one behind theother (illustration 3).

Hydraulic MediaParticular attention must be given to the selection of sealingelements of increasing dimensions with respect to theircompatibility with the hydraulic medium. Although in thepast mineral oils were almost exclusively used in mobile

hydraulics which were compatible with almost all widelyused sealing materials, today more and more rapidly bio-degradable media are used which even on the same basishave a different effect on the behaviour of the elastomers.The following fluids are the main ones on offer today:

• HETG fluids on a vegetable oil base• HEPG fluids on a synthetic polyglycol base and• HEES fluids consisting of synthetic carbonic acids.

The consequences of unsuitable material/medium pairingmay be various types of damage. The sealing materialmay swell and become soft, shrink and become hard oreven be dissolved. It is therefore essential for the sealmanufacturer to carry out thorough compatibility trials usingvarious biological media.

The task of a widely used mobile hydraulic applicationshould also be carried out, as it is not always possible toconnect subassemblies moving in opposite directions toone another by hydraulic tubes or pipes. By the use ofrotary transmission leadthroughs or medium rotary distri-butors, pressure, lubricating, cooling or cleaning mediaare transported from the static to the moving subassem-

bly. Here it is not only necessary to avoid leakage to theexterior; the individual channels must be reliably separa-ted from one another, as otherwise the penetration of wa-ter, for example, into the central lubrication channels mayresult in entire aggregates being destroyed before thedamage is detected. This important task should be left tospecially designed slide and O-ring seals. Their geometryis modified with respect to the axial seals to the extentthat the movement has to be specifically placed on thedynamic sealing surface. Rotation of the slide ring on theexpander is generally a cause of premature failure forrotary seals and often results from incorrect installation(overstretching). During initial assembly or employee trai-ning courses you should therefore take note of the instal-lation instructions, recommendations concerning specialinstallation greases or practical tips given by the applica-tion engineers of your seal supplier.

Illustration 3: The residual oil film is forced back via the leadingedge angle a

Secondary Lip

Leakage chamberPrimary Lip

Residual Oil Film

Rod Movement

p

Illustration 2: Backring as extrusion protection as a function of pressure and gap

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10

Scrap Presses

Producing a great deal of noise, unshapely pieces of sheetmetal punched out during production fall down to the lo-wer storeys into the meter-long filler channel of the hy-draulic press, where an initial hydraulic cylinder pushesthem several meters into the pressing chamber. Here, thecylinders press the shapeless pieces of metal into a spa-ce-saving block, which is then transported away for re-cycling.Similar equipment is found in the yards of the scrap cardealers.Common to both applications are the high standards re-quired of the sealing and bearing elements of the hydrau-lic cylinders, which have to work reliably at all times underthe most difficult of conditions. In the past designers the-refore often used rubber-tissue V-shaped seals, which wereconsidered to be robust.

V-Packing ReplacementThe continually increasing requirement for higheroperating pressures in conjunction with fasterspeeds and higher levels of press utilisation canoften not be fulfilled by these V-shaped seals(illustration 1).

In existing plant these inadequate seals havetherefore been replaced by bushes equipped withstate-of-the-art sealing systems (illustration 2).

This saves valuable time which would otherwisehave to be used for corrective measures andmodifications, with the packing presses becomingfully available again after only a short time.

Punchings from bodywork manufacture of the automobile producers are transported byconveyor belt in the respective production shops through the factory to a central packingpress.

Illustration 1: Worn-out V-Packing

In this system the metal guide bush, which is oftenresponsible for damage to the piston rod of the cylinder, isreplaced by a "more flexible" guide bush made of a high-performance thermoplastic. This plastic bush reduces thepunctual pressing peaks and distributes the load evenly,so that the level of pressing is kept at a low level. Damageto the rod is therefore a thing of the past.

The modern sealing elements that are now incorporatedhave a high level of efficiency, allow maximum speeds andcan be positioned exactly. Due to their ideal profile geo-metry and optimum material selection they show the lo-west possible levels of friction, minimising wear and gua-ranteeing a long service life.

Hunger system solutions therefore make an importantcontribution towards guaranteeing plant availability as re-quired by all users in the field of automobile manufactu-ring and recycling.

Illustration 2: Replacement of V-Packings by modern sealing systems

before

afterwards

11

Casting Plants

Intelligent Sealing SystemThe sealing and bearing elements play a decisive role inthe friction and movement behaviour of the casting cylin-der.In addition to a primary sealing ring of type "TDI" or "DMDTandem 2000", the cylinder sealing system contains asecondary seal. This uses a sealing ring of the externallyadjustable sealing system of type EVD.The sealing ring of the EVD has a pressure chamber whichis integrated into the main body of the seal and is insertedinto the installation space without any radial prestressing.If the primary seal is intact the sealing edge of the EVDdoes not have any function and is therefore not subject toany wear and tear. If after a long period a leak occurs as aresult of wear or damage to the primary seal, the external-ly adjustable EVD sealing system can be activated and

can then take over the full sealing function. To this pur-pose gel is pressed via an external pressure source intothe pressure chamber of the EVD sealing ring, with theresult that the sealing edge is pressed against the pistonrod surface. The sealing function is therefore provided witha sealing edge that is not worn. There are several ways ofbuilding up pressure for the EVD, from manual delivery toan intelligent sealing system which offers automatic leakdetection and activation of a pressure-regulated hydraulicunit. The intelligent sealing system is particularly usefulfor this application, as it is almost impossible for the ope-rator of the plant to detect any external leakage of theplunger seal at an early stage. With the intelligent EVDthe plant operator is informed of the activation of the EVDby means of a signal lamp and can include maintenanceof the casting cylinder in the maintenance schedule of thecasting plant in the long term. The function of the castingcylinder and therefore the entire casting plant is retainedin full.

One example of how the functional properties of a hydraulic component can be optimisedby the specific coordination of cylinder design and selection of the sealing elements isshown by the use of Hunger hydraulic cylinders with Hunger DFE sealing elements in castingcylinders. These ensure consistent casting quality in over 50 vertical casting plantsworldwide.

The Casting Cylinder System SolutionThe casting process of aluminium bars is shown inillustration 1. Molten aluminium passes via channels fromthe casting furnace to a mould, in which several bars canbe depicted at the same time. Initially the mould is closedat the bottom by the casting platform, which is mountedon the casting cylinder plunger. The casting platform isslowly lowered into the casting pit by drawing in thecasting cylinder, while at the same time further moltenaluminium is added from above. The bars "grow" so tospeak from the bottom of the casting mould.In order to achieve perfect aluminium casting it is essen-tial that the stroke of the casting cylinder is absolutelystick-slip-free. Any jerky movement or changes to the strokespeed result in the aluminium material losing its homo-geneity.For this reason Hunger DFE sealing and bearing elementsthat have been specially adapted for this application areused in the casting.

Illustration 2: Sealing system of a vertical casting cylinderwith EVD

Gel feed ofmedia separator

Measuring port forEVD activation

Wiper AI EVD Seal ring DMD-Tandem 2000 Bearing element

Illustration 1: Prinziple of a vertical casting plant

Hunger DFE GmbHDichtungs- und FührungselementeAlfred-Nobel-Str. 26 • DE-97080 WürzburgTel. 0931-90097-0 • Fax 0931-90097-30Internet: www.hunger-dichtungen.deEmail: info@hunger-dichtungen.de

HydraulicsWalter Hunger KG, HydraulikzylinderwerkRodenbacher Straße 50DE-97816 Lohr am MainTel. 09352-501-0 • Fax 09352-501-106Internet: www.hunger-hydraulik.deEmail: info@hunger-hydraulik.de

MachinesHunger Maschinen GmbHAlfred-Nobel-Str. 26 • DE-97080 WürzburgTel. 0931-90097-0 • Fax 0931-90097-30Internet: www.hunger-maschinen-gmbh.deEmail: info@hunger-maschinen-gmbh.de

AbrasivesHunger Schleifmittel GmbHAlfred-Nobel-Str. 26 • DE-97080 WürzburgTel. 0931-90097-0 • Fax 0931-90097-30Internet: www.hunger-group.comEmail: abrasives@hunger-group.com

Mobile/Vehicle HydraulicsHunger GmbH & Co.Werke für Fahrzeugbau und MobilhydraulikChemnitzer Strasse 61a • DE-09669 FrankenbergTel. 037206-60080 • Fax 037206-600860Internet: www.hunger-group.comEmail: hunger-fahrzeugbau@arcor.de

Hydraulics USAHunger Hydraulics C.C., Ltd.63, Dixie Highway • Rossford (Toledo), OH 43460Tel. +1-419-666-4510 • Fax +1-419-666-9834Internet: www.hunger-group.comEmail: hungercc@glasscity.net

Hunger DFE GmbHDichtungs- und FührungselementeP.O. Box 5860 · DE-97008 WürzburgTel. 0931/90097-0 · Fax 0931/90097-30Internet: www.hunger-dichtungen.deEmail: info@hunger-dichtungen.de

Further products on request.

Seals

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