Multilobe, Tilting Pad and Combined Bearings

Hydrodynamic Bearings

Excellence in consulting, design, technical support and manufacturing

As part of the global John Crane group, John Crane Bearing Technology GmbH specialises indrive technologies for the power generation, oil, petrochemical and processing industries.

Originally conceived by one of Germany's mostprestigious institutions, John Crane's hydrodynamicbearing business was developed throughout the1940's by Nobel Prize Winner Otto Hahn. It quicklycame to represent precision, reliability andadvanced technology enabling it to satisfy many ofthe world's most demanding applications.

Having first achieved prominence for its multilobebearings for high speed rotating machines, JohnCrane Bearing Technology is now focused on thedevelopment and production of high performance,technically sophisticated tilting pad bearings. Itsupplies to leading manufacturers of turbines,compressors, gearboxes, pumps and turbochargersaround the globe, offering a combination ofestablished standard products and individuallytailored solutions.

A programme of continuous development based oncustomer requirements has resulted in thedevelopment of a range of products from standardbearings through to special designs such asspherically supported tilting pad journal bearingsand self-equalizing tilting pad thrust bearings.

John Crane bearings are able to meet the highesttechnical demands. Designs for specific applicationsare individually tailored with all the relevantcalculations, design, engineering and manufacturingoperations being precisely matched to requirements. Bearings with complete cast-iron housings for

steam turbine applications Customised combined journal thrust bearings for

high perfomance turbo compressors P2 Series spherical bearings for gearbox

applications which offer improved stability to balance edge loading

Global SupportThe wide range of applications supported by John Cranebearings underline the flexibility of these products andare supported by the company's outstanding technicalsupport capabilities, modern production facilities andsophisticated inspection services.

Production of John Crane's hydrodynamic bearingstakes place at the company's new Gttingen-basedplant. Highly advanced CAD based engineeringfacilities ensure consistently high levels of quality,whilst continuous exchange of ideas with technicaluniversities and institutes creates the basis for thesuccessful transformation of a customers technicalrequirements into actual products.

All bearings are supported by John Crane'scomprehensive service and support network. Withover 4,000 staff operating from over 200 sales andservice facilities that network is ideally placed tosupport customers on a truly global basis. Many ofthose facilities provide full engineering, design, manufacture and service capabilities at a local level,and on a round-the-clock basis.

Multilobe BearingsHigh performance hydrodynamic bearings

Multilobe Journal and Thrust Bearings

The outstanding operational performance of John Cranemultilobe bearings allows extreme running precision tobe achieved. A key characteristic of the multilobe journalbearing is the non-cylindrical bearing bore, whichdeviates from conventional, cylindrical hydrodynamicbearings by featuring two or more lobes. The lobe radius(R) is larger than the shaft radius (r) by a specificamount and this results in the formation of a wedge gapin each arc. This gap begins at the oil inlet groove, 'a'axially positioned at the widest point of the respectivearc. As a rule, the narrowest point of the gap lies in thecentre of the lobe.

When the shaft begins rotating the lubricant's adhesiveeffect on the shaft and lobes forces the lubricant intothis gap, which narrows in the direction of rotation. Oncea preset peak pressure has developed between the shaftand the bearing the shaft is lifted off the bearing, as theshaft operates hydrodynamically with no metal-to-metal contact.

John Crane hydrodynamic multilobe(MGF) bearings are the result of provenscientific research. Combined withconsistent efforts to optimise theirmanufacturing quality has made itpossible to achieve high levels ofperformance for high-speed rotatingmachine applications.

Tilting Pad BearingsOptimised stability for high-speed applications

Tilting Pad Journal Bearings

Providing the optimum in rotor stabilityOf all hydrodynamic slide bearing types, tilting padjournal bearings offer the maximum rotor stabilitythanks to their exceptional stiffness and dampingcharacteristics. This makes them ideal for use in high-speed machinery operating under low to high loads, e.g.,turbines, turbo compressors, pumps and high-speedgearboxes.

Tilting Pad Thrust Bearings

Automatic adjustment to suit varying conditionsThese bearings are generally used in high-speedmachinery operating under low to high loads, e.g.turbines, pumps, turbo compressors and high-speedgearboxes. They offer the optimum solution to anyrequirement as they can automatically adjust to suitvarying conditions. John Crane offers different thrustbearing types which can feature a wide range of padsizes in order to suit any given application.

Their load capacity is determined by the oil temperature generated and to maximise this, severalalternatives are offered:

Optimised lubrication systems which reduce power loss and temperature

Offset pivoting of pads to reduce the temperature generated at the sliding surface

A choice of pad material to permit higher operating temperatures

Tilting pad bearings are often chosen overclassical multilobe bearings due to theirimproved stability, particularly on highspeed rotors. John Crane tilting padbearings have excellent stiffness anddamping characteristics which createmaximum stability.

Combined BearingsCustomised solutions for specialist applications

Whether the requirement is for high-speed tilting padjournal bearings with spherical support, high load self-equalizing thrust bearings, or multilobe bearings forlower peripheral speeds and reduced loads, eachcustomer's needs are thoroughly examined with theemphasis on both technical and commercialconsiderations. Close liaison with the customer allowsJohn Crane to provide detailed bearing calculations andtechnical proposals which allow the customer tomaximise the performance of their processes.

John Crane combined bearings provide bespoke solutions for special applications which haverestricted assembly and mounting conditions. They are designed to fulfil the customer'sspecific operational requirements in terms of performance, space and running conditions.

Hydrostatic Jacking

High start-up loads can sometimes induce bearing wearwhich causes poor hydrodynamic behaviour or even abearing failure. John Crane's hydrostatic jackingsystems can be fitted to both new and existing bearingdesigns to eliminate start up torque, therebydramatically cutting the power requirement of the primemover. The necessary hydrostatic pocket parameterssuch as oil flow and pressure are calculated using JohnCrane's specially developed software to ensure that theideal system is provided for each application.

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Self-Equalizing Tilting Pad Thrust Bearings

Ideally, standard thrust bearings need an almost perfectinstallation environment without any shaft or housingmisalignment. The maximum allowed variations aregiven in DIN standard 31699 WELLEN, BUNDE,SPURSCHEIBEN. Maximum load capacity can only beachieved by a perfectly aligned bearing as even smallshaft misalignment can cause abrasion and consequentdamage.

Self-equalizing tilting pad thrust bearings canautomatically adjust to accommodate geometricalmisalignments up to 0.1.This self-equalizing functioncreates an even load and therefore an equal minimumoil film thickness on each pad. As all tilting pads areloaded equally, they offer greater operational safetythan standard thrust bearings.

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Self-Aligning Tilting Pad Journal Bearings

As operators of high speed rotating machinery havedemanded more performance, so the demands placedon hydrodynamic bearings have increased. Bearingmaterials and lubricants must provide better load, speedand thermal performance as today's high powertransfer levels result in large mechanical and thermaldeformations of such parts as shafts and gear-boxes.

John Crane offers Standard P1 (ball and socket contact)and Standard P2 (point contact) journal tilting padbearings which provide:

Interchangeability with the S6 series A maximum deflection angle of 0,15 The ability to avoid hot spots at the loaded edge

The Standard P2 also provides a friction-free contactarea which improves rotor behaviour.

Quality Control

To meet today's stringent quality control and associatedcertification requirements John Crane bearings mustpass inspection. All functional dimensions are recorded,and material certificates are issued where required.

Ultra-sonic inspection guarantees a perfect bond betweensteel and white metal and the bearings undergo a dyepenetration test to ensure that no defects are present. All quality control procedures are reported on individual

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certificates, and if required, bearings can be markedwith the relevant customer identification codes.

John Crane can also reproduce the bearing geometry bymeans of a form tester. This quality device is mainlyused on orders in process or undergoing finalinspection, and especially on high-value and complexgas turbine bearings to ensure that they conformgeometrically to the original drawings.

Production Process Management

In addition to developing its products, bearing conceptsand technical consultation procedures, John Crane'sproduction and quality management functions undergocontinuous improvement and this is reflected in the useof the latest machining centres which have expanded thepossibilities for the manufacture of larger and morecomplex bearing types. Increasing customer demandsfor ever tighter production and quality tolerances aresatisfied by the creation of climate-controlled productionzones for sensitive bearings and component parts.

The introduction of a pre-tool setting-machine hasfurther enhanced John Crane's product quality. Thisensures that all functional tool characteristics aremeasured, with this data then being fed directly into theproduction machine programs.

In batch production, and especially critical bearingparts, dedicated process control plans ensure 100%process integrity. The use of FMEA principles increasesprocess optimisation and also helps maintain highquality levels. John Crane's SAP order processingdepartment ensures that on-time delivery performanceis provided as standard.

John Crane Bearing Technology has been certified toDIN EN ISO 9001:2000 and DIN EN ISO 14001. It alsoboasts customer-specific certification which is regularlyupdated. In 2003 the company also became able tocomply with the EU ATEX Directive.

John Crane also applies a 100% traceability principle to itsmaterial procurement processes, and to both individualproduction steps and overall production mechanisms.

Acknowledging the increasing complexity and criticalnature of customer requirements, John Crane has investedheavily in additional control techniques and measurementtechnology, and each bearing or component undergoesnon-destructive testing procedures to ensure that it is ofthe highest possible quality.

Working principle

Customer reference list:

SteamturbinesMAN Turbo AG, OberhausenMAN Turbo AG, HamburgSiemens AG PG, Mlheim

GasturbinesSiemens Industrial Turbomachinery Ltd., Lincoln

TurbogearsVoith Turbo BHS Getriebe GmbH, SonthofenRenk AG, Augsburg and RheineFlender-Graffenstaden S.A.S., IllkirchMAAG-Gear AG, Winterthur

TurbocompressorsMAN Turbo AG, ZrichMAN Turbo AG, OberhausenMAN Turbo AG, BerlinSiemens AG PGI, Duisburg

TurbochargersMAN Diesel SE, AugsburgSiemens Industrial Turbomachinery Ltd., Lincoln

TurbopumpsSulzer Pumpen GmbH, BruchsalSulzer Pumps Ltd., LeedsTermomeccanica Pompe S.p.A., La Spezia

RefrigerationturbinesMAN Turbo AG, RavensburgFriotherm AG, Winterthur

ExpansionturbinesAtlas Copco Energas GmbH, KlnCryostar France S.A., Hesingue

If the products featured will be used in a potentially dangerous and/or hazardous process, your John Crane representative should be consulted prior totheir selection and use. In the interest of continuous development, John Crane Companies reserve the right to alter designs and specifications withoutprior notice. ISO 9001, ISO 14001 Certified. Details available on request.

2008 John Crane Print 05/08 www.johncrane.com B-Bearings/Eng

For your nearest John Crane facility, please contact one of the locations below.

EuropeSlough, UK

Tel: +44-1753-224000Fax: +44-1753-224224

John Crane Bearing TechnologyGttingen, Germany

Tel: +49 551 308 0Fax: +49 551 308 3489

North AmericaMorton Grove

Tel: +1-847-967-2400Fax: +1-847-967-3915

Latin AmericaSo Paulo, Brazil

Tel: +55-11-3371-2500Fax: +55-11-3371-2599

Middle East & AfricaDubai, United Arab Emirates

Tel: +971-488-39510Fax: +971-488-37766

Asia PacificSingapore

Tel: +65-6512-5200Fax: +65-6512-5233