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In order to deal with the different tasks, the machine was designed for three different modes of operation for which essentially the same components can be used. In all modes, a main shaft is mounted in two support bearings. Test bearings, in various configurations, are carried on the front end of the shaft, which is directly driven by a hydraulic motor mounted on tire other end. Loads are produced by five hydraulic cylinders with a closed loop electronic system.
Test rig for high speed train bearings Axle bearings in high speed trains encounter more critical problems than those in conventional trains, particularly regarding running temperature and shock loading. The running temperature of an axle bearing is proportional to the speed of the train and the friction torque of the bearing. This can be shown more precisely with the simple formulae: P=M.~ AT=k.P
which give A T = M . co.k
where p=
dissipated energy in the bearing M = the bearing friction torque CO= the angular velocity AT= difference between bearing temperature and ambient temperature k = a constant depending on the axlebox geometry In high speed trains the angular velocity of the axle bearings is high and it is difficult to vary k as it is determined by the application. Therefore the friction torque is the main factor determining the heat generation and thus influencing bearing performance at high speeds. Furthermore, at high speeds the bearings are subjected to more severe accelerations and higher peak loads, which particularly influence the loads on the cage and the grease behaviour.
The mechanical equipment is mounted on a frame, with heavy cast iron base plates. The frame is placed on resilient feet in order to isolate the electronic equipment and the building from vibrations.
ment and design of axle bearings for high speed trains. There are a variety of bearings for which claims of optimum high speed capabilities are made. Consequently a first step in the project is to compare the performance of these bearings. To do this the most critical operating parameters must be measured. This means that friction torque of the bearings must be investigated under a variety of operating conditions, the temperature distribution determined, and the heat sources in the bearing located. Furthermore the bearing performance must be investigated under dynamic loading conditions.
Mode I
In Mode I the support bearing housings are rigidly mounted to the machine base. The outer ring of the test bearing is housed in the inner ring of a stationary hydrostatic bearing. Loads are transmitted to the test bearing via this hydrostatic bearing. All parasitic friction in the loading device is thus eliminated enabling friction torque to be measured (Fig 1).
Bearing life is not a specific problem at high speeds and can be calculated with satisfactory accuracy.
1 Measure friction torque of axle bearings under different combined load conditions;
The operating parameters which can be simulated at the same time are: the vertical force (weight of the vehicle) Fx , the lateral force (hunting and curve driving) Fz, the longitudinal force (braking) Fv, a moment in the vertical or horizontal plane My, and the speed of rotation w.
2 Monitor bearings subjected to dynamic loading conditions and accelerations
By choosing fixed values for four of the independent parameters and varying the fifth from zero to a chosen
Since a suitable test rig did not exist, SKF decided to build a device which could:
Hy~lraulic Motor
H/yd__rostatic
Bearing
Test Bearing
p_p ~ g s
Ydraulic tuators Hydraulic Act u a t o r , ~
The SKF-project
Considering this situation SKF has initiated a project to provide a comprehensive experimental and theoretical background to support the develop-
222
Fig 1
TRIBOLOGY intemational October 1975
~
SKF test rig for high speed railway bearings set up to operate in Mode 1.
maximum, a characteristic friction torque is obtained. The rig can be programmed to produce 25 such curves as a function of the 5 independent parameters. The evaluation and plotting is executed on-line by the central computer at SKFs European Research Centre, Jutphaas, in the Netherlands, where the rig is situated.
Vat iz]ble Speed "X
JSuspef SlOn
A£ tLl~ttO~
Lold C~'lJ
\\
....~
....
"
=Support A .....
Mode II
Heat distribution in the test bearing will be measured under both static and dynamic loading conditions. With the aid of a computerized heat flow calculation, the location of heat sources and the heat flow pattern of the bearing will be determined.
~ Actuator
In Mode lI the arrangement is basically the same, but the test bearing is mounted in its normal axlebox instead of in the hydrostatic bearing. Loads are transmitted to the axlebox through a load frame. Airflow is directed onto the axlebox to approach real cooling conditions.
In Mode lIl the housings of the support bearings are connected to the frame by hinged level arms which enable the shaft to move vertically and longitudinally. In this case the axial load Fz, is transmitted to the shaft via the rear support bearing, and the radial load Fx, via the front support bearing which represents the wheel (Fig 2). The axlebox is supported by a spring system having a similar dynamic response in the frequency region of interest to an actual train suspension. In this mode the advantages of the hydraulic drive become apparent, since it would be impossible for other systems to follow the shaft movements.
~
II
Jl
"Y"""'--
Load Cell
Ja_lze LRecorder
Control Console
Fig 2
The rest rig set up to operate in Mode IlL
Freq. range: 0 - 1 0 0 Hz for both channels
Mode 1II particular attention will be paid to the investigation of stresses in the cage and lubricant behaviour.
Max. torque: 80 nM
The use of this testing facility will enable the design of high speed train axle bearings to be optimized.
Max. power: 30 kW
Mode III
/
Weight of rig: 20 000 kg
SKF European Research Centre, Postbus 50, Nieuwegein/Jutphaas, Netherlands
Test programme The SKF test rig is, at present, being used to determine the friction torque characteristics of various bearing designs under different load conditions. Heat distribution in selected designs will be investigated in Mode II. In
Flame sprayed coatings Sprayed metal coatings are used to add a good quality surface to an inexpensive or easily obtainable base material. They are also used to re-build a worn surface.
This mode enables the simulation of acceleration in axial and radial directions. Tape recorded load spectra data, obtained from actual trains, will be used as input to the loading system. Technical data Max. radial load: 160 kN dynamic
200 kN static
Max. axial load: 25 kN dynamic
80 kN static
Max. braking force:
50 kN static
Max. speed: 400 rad sec-1 continuously variable and bi-directional
Application of plasma flame sprayed coating of wear-resistant materials to improve wear performance and abrasion resistance.
TRIBOLOGY international October 1975
223
Developments which widen the range of applications are two coating materials now available~from Metco Ltd; one is a copper-aluminium powder to produce an aluminium-bronze type of coating for bearing applications, the other, a nickel-aluminium-molyb denum for hard, high-strength, wear-resistant coatings. The powders are named METCO 445 and METCO 447. Both materials are composite powders which are injected into the flame of a 'ThermoSpray'gun or plasma spray gun where the coating material is melted and projected on to a prepared surface to build up into a coating. There is no limitation to coating thickness. Very little heat is generated in the base material. Internal diameters can be sprayed using an extension nozzle on the spray gun. Typical applications for the aluminiumbronze type of coating are wear-rings, piston guides, slippers or for coating required areas of a steel stamping as an alternative to making a complete component in bronze. It can also be used to restore an undersize surface. Similarly the nickel-aluminium-molybdenum can be used to apply a wearresistant coating on to a light weight or inexpensive base or to re-build a worn part. These materials have several features which make them easy to deposit. As composite materials they react exothermically when sprayed. The sprayed particle temperature is increased by this reaction, both in flight and for micro-seconds after deposition. This gives a consistent, high-strength bond to the base material and good interparticle bonding producing tough, dense, sprayed coatings.
METCO Ltd, Chobham, Woking, Surrey. GU24 8RD
Lubrication systems for small and medium sized machines A single line automatic lubrication system for use on small and medium sized machines is now available from Interlube Systems Ltd, a member of the Tecalemit Group. Known as the SL system it offers both versatility and accuracy, covering a wider range of applications than has previously been possible. The SL system features three new cyclic lubricator units, each designed for sump or reservoir mounting and having outputs of 1,3 and 5 cc per cycle respectively. Each lubricator can be fitted with any one of 7 different and easily interchangeable electric motors, giving the system wide operating flexibility within a discharge range of 0.2 to 40 cc/h and nominal discharge cycles from 3 rain up to 6 h. The system also includes an expanded and redesigned range of flow units which can satisfy bearing and lubrication requirements, differing by as much as 500 to 1. The design of the system is such that each bearing receives its planned quantity of lubricant regardless of changes in temperature, viscosity, fit of bearing surfaces, level of bearing or its distance
The 'one-step' coating system eliminates the need for an initial bonding coat: the area to be sprayed is cleaned and the required coating applied in one operation. Coatings can be applied with a minimum dependence on technique or need for temperature control. A heavy build-up can be deposited without interruption. Thin coatings can also be applied and finish machined to a feather-edge if required. Coatings of METCO 445 are easily machined by turning while METCO 447 takes a good finish by grinding. The spraying operation is relatively quiet. No acoustic protection is required for an' operator or those working in the vicinity.
224
from the oil source. Economy and accuracy are achieved through a rationalised range of standard components which together make up the whole system. Three versions of lubricator
At the heart of the SL system is the lubricator unit which incorporates a spring-operated accumulator for storing oil prior to discharge. Design of the lubricator is such that successive shots of lubricants are stored in the'accumulator until tile discharge valve is opened at the set pressure. It will not then reclose until the pressure drops below 1 bar (15 lbf/in 2) at which point the cycle begins again. However, with a suitable system design, including the right motor, the pressure can be set up to hold the discharge valve open, with the oil requirements being met entirely by the output of the piston pump. In this way continuous lubrication is provided. A safeguard is provided by the fact that the piston output cannot be reduced below 1/3 of its maximum. Thus the lubricant supply can never be accidentally cut off. Continuous gear pump lubricators are included in the SL systems, also hand operated units. Interlube Systems Ltd, Estover Road, Plymouth, Devon, PL6 8LA
C
llI~
Section view o f the Interlube proportioning flow units. The unit on the left is used in cyclic systems and the one on the right in continuous system.
TRIBOLOGY international October 1975
ton, Delaware, to Du Pont de Nemours (Belgium), a wholly-owned subsidiary with head office in Brussels. Manufacturing is carried out under contract to Du Pont (Belgium) by S. A. Floridienne NV, at a plant at Ath, south-west of Brussels. Floridienne also provides marketing services for the product.
% Applicator for feeding lubricant to wire during the wire drawing process
Lubricant applicator Several important improvements in design, along with a substantial reduction in price, are claimed to have been built into the Wilco LA-CW lubricant applicator for wire drawing applications, marketed in the US and Canada by the R. H. Miller Division of the Pennwalt Corporation. The LA-CW improves lubrication by providing positive pick-up of powdered lubricanf, resulting in increased amounts of residual film on the drawn wire. Consequently, this lube applicator minimizes scratching, and increases die life. In general, it is effective in any wiredrawing operation where dry powdered lubricants are being used. The LA-CW overcomes the problem of roller 'jam-up' through the use of 'pivot' bearing concept in place of the traditional ball bearing design. The 'V' groove design of the rollers makes them effective on a wider range of wire diameters. A viariable springpressure feature permits the operator to adjust roller pressure on rod or wire. No threading is necessary either during installation or removal, it sits freely inside the die box with no anchoring required. Price is $132.50 plus shipping. R. H. Miller Division, Pennwalt Corporation, Steelskin Square, Homer, New York 13077, USA.
Tribaloy made in Europe Licences to produce and market 'Tribaloy' in Europe were granted by E. I. Du Pont de Nemours & Co, of Wilming-
The material's combination of properties - resistance to galling and wear, low friction, high resistance to corrosion and good high temperature properties - make it ideal for bearings and surfaces exposed to wear, especially when used in air or with low-lubricity fluids such as petrol, water and refrigerants. 'Tribaloy' intermetallic materials can be based on either cobalt or nickel. Their structure consists of a hard Laves intermetallic phase dispersed in a softer matrix. The Laves phase has a Vickers hardness of about 1100, is congruent and thus stable up to its melting point, which is about 1595°C. These materials, either alone or in blends with other powders, such as nickel or 'Monel', can be fabricated by plasma-arc spraying or powder metallurgy. Casting and hard-facing are also possible. Successful plasma spraying applications to date include coatings for magnetic tape heads in peripheral computer equipment (replacing chrome plating), and coatings for air-pressure regulators in the nozzle actuation system of jet engines (replacing carbon graphite). Steel ball-bearings and sleeves hardfaced with 'Tribaloy' lasted 1½ years when used for submerged toe bearings in blenders for standardising dyes and pigments. Previously used conventionally cobalt-based overlays and sealed bearings used to last three weeks. In powder metallurgy applications, the addition of small proportions of the Du Pont intermetallic materials to the base metal greatly increases wear resistance and anti-galling properties. In the emission systems of 1975 cars one US automobile manufacturer is using an 80/20 composition of stainless steel and 'Tribaloy' for diverter bushings which have to operate smoothly for 80 000 km at temperatures between 650°C and 1050°C. In another powder metallurgy application, bronze bushings with 15% 'Tribaloy' show a fourfold increase in wear life over the previously used all-bronze bushings, which are for a shaft rotating at
7000 rpm in the large torque converter of a snowmobile. Valve seat inserts of the material, fabricated by casting, are used as critical components of the valve train in lorry and other heavy duty engines. Other applications for which it may be expected to offer superior performance include thrust washers, cams, brakes, seals, pistons and piston rings, tappet inserts and vanes, and numerous other devices where sliding or rolling contacts are involved and boundary lubrication conditions exist. Du Pont de Nemours International SA, PO Box, CH-1211 Geneva24
Gold Medal Award The 1975 Tribology Gold Medal has been awarded to Professor Igor Kragel'skii in recognition of his outstanding contribution to the science and technology of friction and wear. Professor Kragel'skii, one of the world's leading authorities in friction and wear research and its application to practical problems, has been an avid explorer in the field of tribology. In devoting the whole of his immensely successful scientific career to the development of tribology and to its introduction into mechanical engineering, he has been a superb guide and mentor to many young scientists and engineers. He is head of the Friction and Wear Laboratory of the Institute of Mechanical Engineering of the Academy of Sciences of the USSR. After graduating he worked for a period as a design engineer. He joined the Institute of
The 1975 Tribology Gold Medal has been awarded to Professor Igor Kragel'skii in recognition o f his outstanding contribution to the science and technology of friction and wear
TRIBOLOGY international October 1975
225
Mechanical Engineering in Moscow in 1939. Since then his name has become inseparable from the sphere of dry friction and wear of a vast variety of solid materials. Professor Kragel'skii was the first scientist in the USSR to carry out fundamental theoretical and experimental investigations in this area, in which he is the author of six fundamental books and several hundreds of scientific papers and articles.
Fluorocarbon coatings The availability of XYLAN-I700 Series fluorocarbon coatings, with water substituted for solvent as the carrier, has been announced by Whitford Corporation. The coatings make available to industry a tough, durable, self-renewing, corrosion- and wearresistant surface without the problems normally associated with solvents. Having a coefficient of friction between 0.02 and 0.04, the coatings combine non-stick abrasion resistance and selfrenewing lubrication with excellent substrate adhesion to all metals and most plastics. Extensive surface preparation is not necessary. The coatings have an operating temperature capability in the - 4 2 2 ° F to 500°F range and curing schedules are flexible enough to match the requirements of any substrate or operating condition. They meet all current and anticipated OSHA and environmental regulations and embody the same properties as the XYLAN-1000 Series which have been in use since 1969. Whitford Corporation, West Chester, Pa. 19380, USA.
Plastic air bearings The National Centre of Tribology has licensed Fulmer Components Ltd, of Berwick Avenue, Slough, to manufacture plastic air bearings, developed by the Centre, for industrial applications. The particular advantages of air lubricated bearings are their low friction (and hence low power consumption), their adaptability to high speed and high temperature applications, their relative silence in operation and the lack of maintenance they require. Their use yields obvious benefits in many applications in which conventional lubrication leads to contamination and sealing problems.
226
Air lubricated bearings have hitherto been relatively expensive but NCT has developed plastic air bearings which are significantly cheaper to manufacture, making their use by industry more attractive. Fulmer Research Institute Ltd, Hollybill, Stoke Poges, Bucks, UK.
power spray precisely where it is needed and to ensure proper lubrication without waste or mess. The manufacturers recommend regular light applications - preferably once a week but at least once every 500 miles, whichever is the sooner.
Scanning electron microscopes Motorcycle chain lubricant The prospect of substantially extending motorcycle chain life is offered by a new chain lubricant jointly developed by Duckhams Oils and Renold Chains. Chain wear starts from tile inside and cannot be prevented by external lubrication. Use of inappropriate lubricants - eg, surplus engine oil - is ineffective since the bulk is thrown off by centrifugal force when the chain is running at speed.
International Scientific Instruments Incorporated have announced two new versions of its table-top-scanningelectron-microscope. Called Super M1NI-SEM 1 and Super M1NI-SEM I1, these two instruments have the following specifications:
Super MINI-SEM II Resolution - 70 A guaranteed Magnification - 30 to 160 000 times Variable high voltage - 2 to 25 kV Dynamic focussing Waveform monitor Two oscilloscopes Built in TV scanning - 4 other scanning speeds Automatic vacuum pumping Universal sample stage: For samples up to 3 in, Tilt - 1 0 ° to +70 °, Rotation 0 - 3 6 0 °, X-Y movements (-+20 ram) Z movement (8 to 38 ram) Automatic magnification correction for variable working distance camera system Super MINI-SEM I
Simple but effective application of Duchams motorcycle chain lubricant. The extension tube ensures that the full power of the propellant carries the lubricant into the inner chain surfaces where wear is concentrated
In contrast, Renold Duckhams Chain Lubricant has been specially formulated to be drip-free when stationary and to cling to the chain at speed. The extreme pressure grease is also water repellant and contains a volatile penetrant which takes it right into the narrow clearances between each bearingpin, bush and roller and between the side-plates, and then evaporates to leave a tenacious fihn of protective lubricant. To further ensure full penetration to tile critical inner surfaces of the chain, it is packed in a very highpressure aerosol, to which a flexible extension tube is fitted to direct the
TRIBOLOGY international October 1975
As Super M1NI-SEM !i except: Resolution - 100 a guaranteed One oscilloscope (second available as option) Manual vacuum system TV monitor available as option Universal sample stage available as option International Scientific Instruments, Inc. GmbH, 8 Mtinchen 90, Rotbuchenstrasse 1, West Germany. or
Polaron Equipment Ltd, 60/62 Greenhill Crescent, Holywell Industrial Estate, Watford/Herts, UK.
Deep drawing lubricant A deep drawing and pressing lubricant has been introduced by BurmahCastrol Industrial Limited. Known as lloj"orm PN 230 it leaves a thin film which adheres well without dripping and is easily removed after the operation where necessary.
The damper uses a magnetic piston assembly and ferromagnetic damping fluids that are permanently contained around the piston where the damping occurs. This design eliminates the large volume of fluid traditionally used in open dashpot dampers. By holding the ferrofluid in place magnetically, the system obviates the need to seal the damper prior to shipment, and the need to unseal it for installation. Further, it eliminates the special precautions required to guard against accidental loss of damping fluid after installation due to customer mishandling.
The lubricant was developed principally for use in automotive press-shops, where production can be restricted by the time and labour involved in cleaning drawn or pressed components. It is a soft brown opaque pourable material without the unpleasant fatty odour often associated with this type of lubricant. Despite the fact that it does not contain any of the conventional E.P. additives, such as chlorine, sulphur or phosphorus compounds, it is capable of producing difficult components. It is easily applied by brush or roller. Successful applications of lloform PN230 have included the deep drawing and production of petrol tank pressings, and the pressing of vehicle rear wings and petrol filler pipe shrouds.
Ferrofluidics Corporation, 144 Middlesex Turnpike, Burlington, Massachusetts, 01803, USA,
Although testing has been confined to the automotive industry, Iloform PN230 would be equally suitable for severe drawings and presswork operations in other industries.
Forklift chain lubricant A lubricant has been specifically developed for the lifting chains on fork trucks. An important requirement of forklift truck maintenance, is to protect the lifting chains from wear, because only a small amount of wear is acceptable before chains have to be replaced.
Burmah-Castrol Industrial Ltd, Burmah House, Pipers Way, Swindon SN3 1RE, UK.
Ferrofluidic Damper
Lifting chains carry loads of up to 10 t/sq in of bearing surface and previously any lubricant capable of protecting against wear has been too thick to penetrate into chains to the points at which wear occurs. Lubricants thin
A zero leakage, Ferrofluidic open dashpot damper that offers trouble-free shipment, installation, and use is available from Ferrofluidics Corporation, Burlington, Massachusetts.
f NON-MAGNET,C
(
.oo
MAGNETIC PI
GNETIC FLUID
Zero leakage, open dashpot damper from Ferrofluidics that offers troublefree shipment, installation and use
enough to penetrate have not been capable of supporting the bearing loads. Acheson Colloids claim to have solved the problem with HI LOAD Forklift Chain Lubricant. This is a light aerosol spray which rapidly penetrates into the chain, coats working surfaces completely, and then increases in viscosity forty times to form a heavy duty lubricant able to carry the heaviest working loads. It does not drain out of the chain and so gives long-lasting protection against high loads and wear. The narrow concentrated spray is easy to apply and a typical chain can' be coated in one minute. One 450gin can is sufficient for five applications. Nationally distributed by A. E. Edmunds Walker Ltd., and engineers' merchants, Acheson HI LOAD Forklift Chain Lubricant is available, packed in cartons of 12, at 95p per can, plus V.A.T. in the UK. Acheson Colloids Company, Prince Rock, Plymouth, PL40SP, UK.
Lubrication from the mains? The factory of the future may incorporate a 'mains' pressurised lubrication line each piece of equipment needing lubrication being connected into the line and lubricated automatically. That is the implication of a novel Bielomatik group-lubrication system recently installed at a Newcastle factory. This development in lubrication technology is essentially a logical extension of the existing IVO single line one-shot lubrication systems. Each machine needing lubrication is fitted with individual main pressure line, distributor blocks and metering valves plus feed lines, but, instead of being fitted with individual hand-operated pumps, each machine, or section of the machine is connected to the main supply line via a quick connective coupling. The group system main itself can theoretically support any number of machines. At various locations in the main supply circuit pressure stations are installed which maintain pressure in the system even though oil or grease is being taken out of the main at several points. Each will supply up to 4500 lube points and one or more of these units can be supplied depending on the total number of points to be served.
TRIBOLOGY international October 1975
227
~
Pres Pressure
Statij~~istributio on
nLine
ation
Group lubrication system from Beilomatic London Ltd which allows the I VO "one-shot" system to be extended to cover eidTer large scale production lines or complete groups o f machines while main taining the advantages o f a cen tralised system
When an individual machine is lubricated the lubeshot is delivered under pressure from a pressure station. These stations are regularly topped up from the pumping station which delivers pressurised lubricant into the system at predetermined intervals. Bielomatik London Ltd., 15 Cotswold Street, London, S.E.27.
Specialised oils in wire drawing In Spring 1974, Fredrick Smith & Co (Wire Manufacturers) Ltd of Halifax, commenced tests on the specialised range of Lubrication products manufactured by Lubrication Engineers Inc of Fort Worth, Texas. According to Mr G Earnshaw, Research Manager at Fredrick Smiths and Mr D T Jenkins, who has an overall interest in all aspects
of Tribology, the products have resulted in substantial savings in down-time a~d maintenance in a variety of production processes. One of the more dramatic demonstrations of the efficiency of the lubricants has been in the use of LE 1275 waterproof grease in tiny high speed ball races on wire straightening units for fine wire drawing machines. Before using the LE product, bearings had frequently collapsed completely in less than a week of running at 23 000 revs/ rain. In the trials the bearings ran for three weeks on one application of grease and without any indication of damage. LE 1275 is now the standard grease gun lubricant throughout the plant and it has been possible to extend the intervals between applications knowing that the product stays on the job, even at temperatures of up to 400°F, where normal greases would soften. LE 185 Open Gear Lubricant is another product which, after intial trials, is now used in a variety of applications. One chain drive in a corrosive environment was formerly lubricated at intervals of a week. The trial application of LE 185 was inspected at intervals during an initial run of six weeks and gave a convincing demonstration of its ability to retain complete coverage of mating surfaces over an extended period. It is also used on crane ropes where its ability to stop acid fume penetration and prevent metal to metal chafing of rope and pulleys is a great help. The largest single application of LE products, as far as volume is concerned, is of LE 607 Enclosed Gear Oil in the Company's fine wet wire drawing machines. These machines operate at extremely high speeds and lubrication failure leading to mechanical breakdown can cause serious losses to wire production. LE 607 has been under extended trial on one Farmer Norton machine where its non-foaming, waterproof and 'clinging' properties have been amply demonstrated. This lubricant is now adopted as standard for the whole class of machines whenever they fall due for a gear oil change. Future oil changes will be at far longer intervals.
Wire straightening unit or "casting set" which uses nine ball races to produce a consistently straight wire. Theseraces operate at high speed and LE 1275 waterproof grease has been found to be most effective
228
TRIBOLOGY international October 1975
Lubrication Engineers (UK) Ltd., Forward House, Birmingham Airport, Birmingham, UK.
Test rig for high speed train bearings Axle bearings in high speed trains encounter more critical problems than those in conventional trains, particularly regarding running temperature and shock loading. The running temperature of an axle bearing is proportional to the speed of the train and the friction torque of the bearing. This can be shown more precisely with the simple formulae: P=M.~ AT=k.P
which give A T = M . co.k
where p=
dissipated energy in the bearing M = the bearing friction torque CO= the angular velocity AT= difference between bearing temperature and ambient temperature k = a constant depending on the axlebox geometry In high speed trains the angular velocity of the axle bearings is high and it is difficult to vary k as it is determined by the application. Therefore the friction torque is the main factor determining the heat generation and thus influencing bearing performance at high speeds. Furthermore, at high speeds the bearings are subjected to more severe accelerations and higher peak loads, which particularly influence the loads on the cage and the grease behaviour.
The mechanical equipment is mounted on a frame, with heavy cast iron base plates. The frame is placed on resilient feet in order to isolate the electronic equipment and the building from vibrations.
ment and design of axle bearings for high speed trains. There are a variety of bearings for which claims of optimum high speed capabilities are made. Consequently a first step in the project is to compare the performance of these bearings. To do this the most critical operating parameters must be measured. This means that friction torque of the bearings must be investigated under a variety of operating conditions, the temperature distribution determined, and the heat sources in the bearing located. Furthermore the bearing performance must be investigated under dynamic loading conditions.
Mode I
In Mode I the support bearing housings are rigidly mounted to the machine base. The outer ring of the test bearing is housed in the inner ring of a stationary hydrostatic bearing. Loads are transmitted to the test bearing via this hydrostatic bearing. All parasitic friction in the loading device is thus eliminated enabling friction torque to be measured (Fig 1).
Bearing life is not a specific problem at high speeds and can be calculated with satisfactory accuracy.
1 Measure friction torque of axle bearings under different combined load conditions;
The operating parameters which can be simulated at the same time are: the vertical force (weight of the vehicle) Fx , the lateral force (hunting and curve driving) Fz, the longitudinal force (braking) Fv, a moment in the vertical or horizontal plane My, and the speed of rotation w.
2 Monitor bearings subjected to dynamic loading conditions and accelerations
By choosing fixed values for four of the independent parameters and varying the fifth from zero to a chosen
Since a suitable test rig did not exist, SKF decided to build a device which could:
Hy~lraulic Motor
H/yd__rostatic
Bearing
Test Bearing
p_p ~ g s
Ydraulic tuators Hydraulic Act u a t o r , ~
The SKF-project
Considering this situation SKF has initiated a project to provide a comprehensive experimental and theoretical background to support the develop-
222
Fig 1
TRIBOLOGY intemational October 1975
~
SKF test rig for high speed railway bearings set up to operate in Mode 1.
maximum, a characteristic friction torque is obtained. The rig can be programmed to produce 25 such curves as a function of the 5 independent parameters. The evaluation and plotting is executed on-line by the central computer at SKFs European Research Centre, Jutphaas, in the Netherlands, where the rig is situated.
Vat iz]ble Speed "X
JSuspef SlOn
A£ tLl~ttO~
Lold C~'lJ
\\
....~
....
"
=Support A .....
Mode II
Heat distribution in the test bearing will be measured under both static and dynamic loading conditions. With the aid of a computerized heat flow calculation, the location of heat sources and the heat flow pattern of the bearing will be determined.
~ Actuator
In Mode lI the arrangement is basically the same, but the test bearing is mounted in its normal axlebox instead of in the hydrostatic bearing. Loads are transmitted to the axlebox through a load frame. Airflow is directed onto the axlebox to approach real cooling conditions.
In Mode lIl the housings of the support bearings are connected to the frame by hinged level arms which enable the shaft to move vertically and longitudinally. In this case the axial load Fz, is transmitted to the shaft via the rear support bearing, and the radial load Fx, via the front support bearing which represents the wheel (Fig 2). The axlebox is supported by a spring system having a similar dynamic response in the frequency region of interest to an actual train suspension. In this mode the advantages of the hydraulic drive become apparent, since it would be impossible for other systems to follow the shaft movements.
~
II
Jl
"Y"""'--
Load Cell
Ja_lze LRecorder
Control Console
Fig 2
The rest rig set up to operate in Mode IlL
Freq. range: 0 - 1 0 0 Hz for both channels
Mode 1II particular attention will be paid to the investigation of stresses in the cage and lubricant behaviour.
Max. torque: 80 nM
The use of this testing facility will enable the design of high speed train axle bearings to be optimized.
Max. power: 30 kW
Mode III
/
Weight of rig: 20 000 kg
SKF European Research Centre, Postbus 50, Nieuwegein/Jutphaas, Netherlands
Test programme The SKF test rig is, at present, being used to determine the friction torque characteristics of various bearing designs under different load conditions. Heat distribution in selected designs will be investigated in Mode II. In
Flame sprayed coatings Sprayed metal coatings are used to add a good quality surface to an inexpensive or easily obtainable base material. They are also used to re-build a worn surface.
This mode enables the simulation of acceleration in axial and radial directions. Tape recorded load spectra data, obtained from actual trains, will be used as input to the loading system. Technical data Max. radial load: 160 kN dynamic
200 kN static
Max. axial load: 25 kN dynamic
80 kN static
Max. braking force:
50 kN static
Max. speed: 400 rad sec-1 continuously variable and bi-directional
Application of plasma flame sprayed coating of wear-resistant materials to improve wear performance and abrasion resistance.
TRIBOLOGY international October 1975
223
Developments which widen the range of applications are two coating materials now available~from Metco Ltd; one is a copper-aluminium powder to produce an aluminium-bronze type of coating for bearing applications, the other, a nickel-aluminium-molyb denum for hard, high-strength, wear-resistant coatings. The powders are named METCO 445 and METCO 447. Both materials are composite powders which are injected into the flame of a 'ThermoSpray'gun or plasma spray gun where the coating material is melted and projected on to a prepared surface to build up into a coating. There is no limitation to coating thickness. Very little heat is generated in the base material. Internal diameters can be sprayed using an extension nozzle on the spray gun. Typical applications for the aluminiumbronze type of coating are wear-rings, piston guides, slippers or for coating required areas of a steel stamping as an alternative to making a complete component in bronze. It can also be used to restore an undersize surface. Similarly the nickel-aluminium-molybdenum can be used to apply a wearresistant coating on to a light weight or inexpensive base or to re-build a worn part. These materials have several features which make them easy to deposit. As composite materials they react exothermically when sprayed. The sprayed particle temperature is increased by this reaction, both in flight and for micro-seconds after deposition. This gives a consistent, high-strength bond to the base material and good interparticle bonding producing tough, dense, sprayed coatings.
METCO Ltd, Chobham, Woking, Surrey. GU24 8RD
Lubrication systems for small and medium sized machines A single line automatic lubrication system for use on small and medium sized machines is now available from Interlube Systems Ltd, a member of the Tecalemit Group. Known as the SL system it offers both versatility and accuracy, covering a wider range of applications than has previously been possible. The SL system features three new cyclic lubricator units, each designed for sump or reservoir mounting and having outputs of 1,3 and 5 cc per cycle respectively. Each lubricator can be fitted with any one of 7 different and easily interchangeable electric motors, giving the system wide operating flexibility within a discharge range of 0.2 to 40 cc/h and nominal discharge cycles from 3 rain up to 6 h. The system also includes an expanded and redesigned range of flow units which can satisfy bearing and lubrication requirements, differing by as much as 500 to 1. The design of the system is such that each bearing receives its planned quantity of lubricant regardless of changes in temperature, viscosity, fit of bearing surfaces, level of bearing or its distance
The 'one-step' coating system eliminates the need for an initial bonding coat: the area to be sprayed is cleaned and the required coating applied in one operation. Coatings can be applied with a minimum dependence on technique or need for temperature control. A heavy build-up can be deposited without interruption. Thin coatings can also be applied and finish machined to a feather-edge if required. Coatings of METCO 445 are easily machined by turning while METCO 447 takes a good finish by grinding. The spraying operation is relatively quiet. No acoustic protection is required for an' operator or those working in the vicinity.
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from the oil source. Economy and accuracy are achieved through a rationalised range of standard components which together make up the whole system. Three versions of lubricator
At the heart of the SL system is the lubricator unit which incorporates a spring-operated accumulator for storing oil prior to discharge. Design of the lubricator is such that successive shots of lubricants are stored in the'accumulator until tile discharge valve is opened at the set pressure. It will not then reclose until the pressure drops below 1 bar (15 lbf/in 2) at which point the cycle begins again. However, with a suitable system design, including the right motor, the pressure can be set up to hold the discharge valve open, with the oil requirements being met entirely by the output of the piston pump. In this way continuous lubrication is provided. A safeguard is provided by the fact that the piston output cannot be reduced below 1/3 of its maximum. Thus the lubricant supply can never be accidentally cut off. Continuous gear pump lubricators are included in the SL systems, also hand operated units. Interlube Systems Ltd, Estover Road, Plymouth, Devon, PL6 8LA
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Section view o f the Interlube proportioning flow units. The unit on the left is used in cyclic systems and the one on the right in continuous system.
TRIBOLOGY international October 1975
ton, Delaware, to Du Pont de Nemours (Belgium), a wholly-owned subsidiary with head office in Brussels. Manufacturing is carried out under contract to Du Pont (Belgium) by S. A. Floridienne NV, at a plant at Ath, south-west of Brussels. Floridienne also provides marketing services for the product.
% Applicator for feeding lubricant to wire during the wire drawing process
Lubricant applicator Several important improvements in design, along with a substantial reduction in price, are claimed to have been built into the Wilco LA-CW lubricant applicator for wire drawing applications, marketed in the US and Canada by the R. H. Miller Division of the Pennwalt Corporation. The LA-CW improves lubrication by providing positive pick-up of powdered lubricanf, resulting in increased amounts of residual film on the drawn wire. Consequently, this lube applicator minimizes scratching, and increases die life. In general, it is effective in any wiredrawing operation where dry powdered lubricants are being used. The LA-CW overcomes the problem of roller 'jam-up' through the use of 'pivot' bearing concept in place of the traditional ball bearing design. The 'V' groove design of the rollers makes them effective on a wider range of wire diameters. A viariable springpressure feature permits the operator to adjust roller pressure on rod or wire. No threading is necessary either during installation or removal, it sits freely inside the die box with no anchoring required. Price is $132.50 plus shipping. R. H. Miller Division, Pennwalt Corporation, Steelskin Square, Homer, New York 13077, USA.
Tribaloy made in Europe Licences to produce and market 'Tribaloy' in Europe were granted by E. I. Du Pont de Nemours & Co, of Wilming-
The material's combination of properties - resistance to galling and wear, low friction, high resistance to corrosion and good high temperature properties - make it ideal for bearings and surfaces exposed to wear, especially when used in air or with low-lubricity fluids such as petrol, water and refrigerants. 'Tribaloy' intermetallic materials can be based on either cobalt or nickel. Their structure consists of a hard Laves intermetallic phase dispersed in a softer matrix. The Laves phase has a Vickers hardness of about 1100, is congruent and thus stable up to its melting point, which is about 1595°C. These materials, either alone or in blends with other powders, such as nickel or 'Monel', can be fabricated by plasma-arc spraying or powder metallurgy. Casting and hard-facing are also possible. Successful plasma spraying applications to date include coatings for magnetic tape heads in peripheral computer equipment (replacing chrome plating), and coatings for air-pressure regulators in the nozzle actuation system of jet engines (replacing carbon graphite). Steel ball-bearings and sleeves hardfaced with 'Tribaloy' lasted 1½ years when used for submerged toe bearings in blenders for standardising dyes and pigments. Previously used conventionally cobalt-based overlays and sealed bearings used to last three weeks. In powder metallurgy applications, the addition of small proportions of the Du Pont intermetallic materials to the base metal greatly increases wear resistance and anti-galling properties. In the emission systems of 1975 cars one US automobile manufacturer is using an 80/20 composition of stainless steel and 'Tribaloy' for diverter bushings which have to operate smoothly for 80 000 km at temperatures between 650°C and 1050°C. In another powder metallurgy application, bronze bushings with 15% 'Tribaloy' show a fourfold increase in wear life over the previously used all-bronze bushings, which are for a shaft rotating at
7000 rpm in the large torque converter of a snowmobile. Valve seat inserts of the material, fabricated by casting, are used as critical components of the valve train in lorry and other heavy duty engines. Other applications for which it may be expected to offer superior performance include thrust washers, cams, brakes, seals, pistons and piston rings, tappet inserts and vanes, and numerous other devices where sliding or rolling contacts are involved and boundary lubrication conditions exist. Du Pont de Nemours International SA, PO Box, CH-1211 Geneva24
Gold Medal Award The 1975 Tribology Gold Medal has been awarded to Professor Igor Kragel'skii in recognition of his outstanding contribution to the science and technology of friction and wear. Professor Kragel'skii, one of the world's leading authorities in friction and wear research and its application to practical problems, has been an avid explorer in the field of tribology. In devoting the whole of his immensely successful scientific career to the development of tribology and to its introduction into mechanical engineering, he has been a superb guide and mentor to many young scientists and engineers. He is head of the Friction and Wear Laboratory of the Institute of Mechanical Engineering of the Academy of Sciences of the USSR. After graduating he worked for a period as a design engineer. He joined the Institute of
The 1975 Tribology Gold Medal has been awarded to Professor Igor Kragel'skii in recognition o f his outstanding contribution to the science and technology of friction and wear
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Mechanical Engineering in Moscow in 1939. Since then his name has become inseparable from the sphere of dry friction and wear of a vast variety of solid materials. Professor Kragel'skii was the first scientist in the USSR to carry out fundamental theoretical and experimental investigations in this area, in which he is the author of six fundamental books and several hundreds of scientific papers and articles.
Fluorocarbon coatings The availability of XYLAN-I700 Series fluorocarbon coatings, with water substituted for solvent as the carrier, has been announced by Whitford Corporation. The coatings make available to industry a tough, durable, self-renewing, corrosion- and wearresistant surface without the problems normally associated with solvents. Having a coefficient of friction between 0.02 and 0.04, the coatings combine non-stick abrasion resistance and selfrenewing lubrication with excellent substrate adhesion to all metals and most plastics. Extensive surface preparation is not necessary. The coatings have an operating temperature capability in the - 4 2 2 ° F to 500°F range and curing schedules are flexible enough to match the requirements of any substrate or operating condition. They meet all current and anticipated OSHA and environmental regulations and embody the same properties as the XYLAN-1000 Series which have been in use since 1969. Whitford Corporation, West Chester, Pa. 19380, USA.
Plastic air bearings The National Centre of Tribology has licensed Fulmer Components Ltd, of Berwick Avenue, Slough, to manufacture plastic air bearings, developed by the Centre, for industrial applications. The particular advantages of air lubricated bearings are their low friction (and hence low power consumption), their adaptability to high speed and high temperature applications, their relative silence in operation and the lack of maintenance they require. Their use yields obvious benefits in many applications in which conventional lubrication leads to contamination and sealing problems.
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Air lubricated bearings have hitherto been relatively expensive but NCT has developed plastic air bearings which are significantly cheaper to manufacture, making their use by industry more attractive. Fulmer Research Institute Ltd, Hollybill, Stoke Poges, Bucks, UK.
power spray precisely where it is needed and to ensure proper lubrication without waste or mess. The manufacturers recommend regular light applications - preferably once a week but at least once every 500 miles, whichever is the sooner.
Scanning electron microscopes Motorcycle chain lubricant The prospect of substantially extending motorcycle chain life is offered by a new chain lubricant jointly developed by Duckhams Oils and Renold Chains. Chain wear starts from tile inside and cannot be prevented by external lubrication. Use of inappropriate lubricants - eg, surplus engine oil - is ineffective since the bulk is thrown off by centrifugal force when the chain is running at speed.
International Scientific Instruments Incorporated have announced two new versions of its table-top-scanningelectron-microscope. Called Super M1NI-SEM 1 and Super M1NI-SEM I1, these two instruments have the following specifications:
Super MINI-SEM II Resolution - 70 A guaranteed Magnification - 30 to 160 000 times Variable high voltage - 2 to 25 kV Dynamic focussing Waveform monitor Two oscilloscopes Built in TV scanning - 4 other scanning speeds Automatic vacuum pumping Universal sample stage: For samples up to 3 in, Tilt - 1 0 ° to +70 °, Rotation 0 - 3 6 0 °, X-Y movements (-+20 ram) Z movement (8 to 38 ram) Automatic magnification correction for variable working distance camera system Super MINI-SEM I
Simple but effective application of Duchams motorcycle chain lubricant. The extension tube ensures that the full power of the propellant carries the lubricant into the inner chain surfaces where wear is concentrated
In contrast, Renold Duckhams Chain Lubricant has been specially formulated to be drip-free when stationary and to cling to the chain at speed. The extreme pressure grease is also water repellant and contains a volatile penetrant which takes it right into the narrow clearances between each bearingpin, bush and roller and between the side-plates, and then evaporates to leave a tenacious fihn of protective lubricant. To further ensure full penetration to tile critical inner surfaces of the chain, it is packed in a very highpressure aerosol, to which a flexible extension tube is fitted to direct the
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As Super M1NI-SEM !i except: Resolution - 100 a guaranteed One oscilloscope (second available as option) Manual vacuum system TV monitor available as option Universal sample stage available as option International Scientific Instruments, Inc. GmbH, 8 Mtinchen 90, Rotbuchenstrasse 1, West Germany. or
Polaron Equipment Ltd, 60/62 Greenhill Crescent, Holywell Industrial Estate, Watford/Herts, UK.
Deep drawing lubricant A deep drawing and pressing lubricant has been introduced by BurmahCastrol Industrial Limited. Known as lloj"orm PN 230 it leaves a thin film which adheres well without dripping and is easily removed after the operation where necessary.
The damper uses a magnetic piston assembly and ferromagnetic damping fluids that are permanently contained around the piston where the damping occurs. This design eliminates the large volume of fluid traditionally used in open dashpot dampers. By holding the ferrofluid in place magnetically, the system obviates the need to seal the damper prior to shipment, and the need to unseal it for installation. Further, it eliminates the special precautions required to guard against accidental loss of damping fluid after installation due to customer mishandling.
The lubricant was developed principally for use in automotive press-shops, where production can be restricted by the time and labour involved in cleaning drawn or pressed components. It is a soft brown opaque pourable material without the unpleasant fatty odour often associated with this type of lubricant. Despite the fact that it does not contain any of the conventional E.P. additives, such as chlorine, sulphur or phosphorus compounds, it is capable of producing difficult components. It is easily applied by brush or roller. Successful applications of lloform PN230 have included the deep drawing and production of petrol tank pressings, and the pressing of vehicle rear wings and petrol filler pipe shrouds.
Ferrofluidics Corporation, 144 Middlesex Turnpike, Burlington, Massachusetts, 01803, USA,
Although testing has been confined to the automotive industry, Iloform PN230 would be equally suitable for severe drawings and presswork operations in other industries.
Forklift chain lubricant A lubricant has been specifically developed for the lifting chains on fork trucks. An important requirement of forklift truck maintenance, is to protect the lifting chains from wear, because only a small amount of wear is acceptable before chains have to be replaced.
Burmah-Castrol Industrial Ltd, Burmah House, Pipers Way, Swindon SN3 1RE, UK.
Ferrofluidic Damper
Lifting chains carry loads of up to 10 t/sq in of bearing surface and previously any lubricant capable of protecting against wear has been too thick to penetrate into chains to the points at which wear occurs. Lubricants thin
A zero leakage, Ferrofluidic open dashpot damper that offers trouble-free shipment, installation, and use is available from Ferrofluidics Corporation, Burlington, Massachusetts.
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Zero leakage, open dashpot damper from Ferrofluidics that offers troublefree shipment, installation and use
enough to penetrate have not been capable of supporting the bearing loads. Acheson Colloids claim to have solved the problem with HI LOAD Forklift Chain Lubricant. This is a light aerosol spray which rapidly penetrates into the chain, coats working surfaces completely, and then increases in viscosity forty times to form a heavy duty lubricant able to carry the heaviest working loads. It does not drain out of the chain and so gives long-lasting protection against high loads and wear. The narrow concentrated spray is easy to apply and a typical chain can' be coated in one minute. One 450gin can is sufficient for five applications. Nationally distributed by A. E. Edmunds Walker Ltd., and engineers' merchants, Acheson HI LOAD Forklift Chain Lubricant is available, packed in cartons of 12, at 95p per can, plus V.A.T. in the UK. Acheson Colloids Company, Prince Rock, Plymouth, PL40SP, UK.
Lubrication from the mains? The factory of the future may incorporate a 'mains' pressurised lubrication line each piece of equipment needing lubrication being connected into the line and lubricated automatically. That is the implication of a novel Bielomatik group-lubrication system recently installed at a Newcastle factory. This development in lubrication technology is essentially a logical extension of the existing IVO single line one-shot lubrication systems. Each machine needing lubrication is fitted with individual main pressure line, distributor blocks and metering valves plus feed lines, but, instead of being fitted with individual hand-operated pumps, each machine, or section of the machine is connected to the main supply line via a quick connective coupling. The group system main itself can theoretically support any number of machines. At various locations in the main supply circuit pressure stations are installed which maintain pressure in the system even though oil or grease is being taken out of the main at several points. Each will supply up to 4500 lube points and one or more of these units can be supplied depending on the total number of points to be served.
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Group lubrication system from Beilomatic London Ltd which allows the I VO "one-shot" system to be extended to cover eidTer large scale production lines or complete groups o f machines while main taining the advantages o f a cen tralised system
When an individual machine is lubricated the lubeshot is delivered under pressure from a pressure station. These stations are regularly topped up from the pumping station which delivers pressurised lubricant into the system at predetermined intervals. Bielomatik London Ltd., 15 Cotswold Street, London, S.E.27.
Specialised oils in wire drawing In Spring 1974, Fredrick Smith & Co (Wire Manufacturers) Ltd of Halifax, commenced tests on the specialised range of Lubrication products manufactured by Lubrication Engineers Inc of Fort Worth, Texas. According to Mr G Earnshaw, Research Manager at Fredrick Smiths and Mr D T Jenkins, who has an overall interest in all aspects
of Tribology, the products have resulted in substantial savings in down-time a~d maintenance in a variety of production processes. One of the more dramatic demonstrations of the efficiency of the lubricants has been in the use of LE 1275 waterproof grease in tiny high speed ball races on wire straightening units for fine wire drawing machines. Before using the LE product, bearings had frequently collapsed completely in less than a week of running at 23 000 revs/ rain. In the trials the bearings ran for three weeks on one application of grease and without any indication of damage. LE 1275 is now the standard grease gun lubricant throughout the plant and it has been possible to extend the intervals between applications knowing that the product stays on the job, even at temperatures of up to 400°F, where normal greases would soften. LE 185 Open Gear Lubricant is another product which, after intial trials, is now used in a variety of applications. One chain drive in a corrosive environment was formerly lubricated at intervals of a week. The trial application of LE 185 was inspected at intervals during an initial run of six weeks and gave a convincing demonstration of its ability to retain complete coverage of mating surfaces over an extended period. It is also used on crane ropes where its ability to stop acid fume penetration and prevent metal to metal chafing of rope and pulleys is a great help. The largest single application of LE products, as far as volume is concerned, is of LE 607 Enclosed Gear Oil in the Company's fine wet wire drawing machines. These machines operate at extremely high speeds and lubrication failure leading to mechanical breakdown can cause serious losses to wire production. LE 607 has been under extended trial on one Farmer Norton machine where its non-foaming, waterproof and 'clinging' properties have been amply demonstrated. This lubricant is now adopted as standard for the whole class of machines whenever they fall due for a gear oil change. Future oil changes will be at far longer intervals.
Wire straightening unit or "casting set" which uses nine ball races to produce a consistently straight wire. Theseraces operate at high speed and LE 1275 waterproof grease has been found to be most effective
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Lubrication Engineers (UK) Ltd., Forward House, Birmingham Airport, Birmingham, UK.