Train wheel: Difference between revisions
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{{Short description|Wheel designed for railway tracks}} |
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{{Distinguish|Training wheels}} |
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{{no footnotes|date=September 2013}} |
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{{one source|date=September 2013}} |
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{{ref improve|date=September 2013}} |
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A '''train wheel''' or '''rail wheel''' is a type of [[wheel]] specially designed for use on [[Track (rail transport)|railway track]]s. The wheel acts as a rolling component, typically [[press fit]]ted onto an [[axle]] and mounted directly on a [[Railroad car|railway carriage]] or [[locomotive]], or indirectly on a [[bogie]] (in the UK), also called a ''truck'' (in North America). The powered wheels under the locomotive are called [[Driving wheel|driving wheels]]. Wheels are initially [[casting|cast]] or [[forging|forged]] and then heat-treated to have a specific hardness.<ref>{{Cite book|title=Wheel–Rail Interface Handbook |isbn=9781845694128 |url=https://www.sciencedirect.com/book/9781845694128/wheel-rail-interface-handbook|access-date=2020-10-29 |last1=Lewis |first1=R. |last2=Olofsson |first2=U. |date=25 September 2009 |publisher=Elsevier Science }}</ref> New wheels are machined using a [[lathe]] to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper [[wheel-rail interface|interaction between the wheel and the rail]]. Incorrectly profiled wheels and worn wheels can increase [[rolling resistance]], reduce [[energy efficiency in transport|energy efficiency]] and may even cause a [[derailment]].<ref>{{Cite book|url=https://www.worldcat.org/oclc/500906475|title=Wheel-rail interface handbook|date=2009|publisher=CRC Press|last1=Lewis |first1=Roger |last2=Olofsson |first2=Ulf|isbn=978-1-61583-153-1|location=Boca Raton, Florida|oclc=500906475}}</ref> The [[International Union of Railways]] has defined a standard wheel diameter of {{Convert|920|mm|in|abbr=on}}, although smaller sizes are used in some [[rapid transit]] railway systems and on [[Rolling highway|ro-ro carriages]].<ref>{{Cite book|last=Licitra|first=Gaetano|url=https://books.google.com/books?id=a9bKBQAAQBAJ&dq=train+wheels+rim+monoblock&pg=PA83|title=Noise Mapping in the EU: Models and Procedures|date=2012-09-06|publisher=CRC Press|isbn=978-0-203-84812-8|language=en}}</ref> |
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[[File:Flanged wheel.jpg|thumb|[[Flange]]d railway wheel]] |
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A '''train wheel''' or '''rail wheel''' is a type of [[wheel]] specially designed for use on [[Track (rail transport)|rail track]]s. A rolling component is typically pressed onto an [[axle]] and mounted directly on a [[Railroad car|rail car]] or [[locomotive]] or indirectly on a [[bogie]] (UK), also called a ''truck'' (North America). Wheels are [[casting|cast]] or [[forging|forged]] and are heat-treated to have a specific hardness. New wheels are trued, using a [[lathe]], to a specific profile before being pressed onto an axle. All wheel profiles need to be periodically monitored to ensure proper [[rail adhesion|wheel-rail interface]]. Improperly trued wheels increase [[rolling resistance]], reduce [[energy efficiency in transportation|energy efficiency]] and may create unsafe operation. A railroad wheel typically consists of two main parts: the wheel itself, and the [[tire]] (or ''tyre'') around the outside. A rail tire is usually made from [[steel]], and is typically heated and pressed onto the wheel, where it remains firmly as it shrinks and cools. Monobloc wheels do not have encircling tires, while ''resilient rail wheels'' have a resilient material, such as [[rubber]], between the wheel and tire. |
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==Wheel geometry and flange== |
==Wheel geometry and flange== |
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{{See also|Derailment|Adhesion railway|Hunting oscillation}} |
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[[File:TreinTramwielprofiel.svg|thumb|Railway wheel flange (left)<br>Tram wheel flange (right)]] |
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[[File:Drawing -- railway wheel and rail profiles.png|thumb|250px|{{ubl|A railway wheel's [[Wheelset (rail transport)#Conical wheel-tread|tread]] and [[Train wheel#Wheel geometry and flange|flange]] and its relationship to the load-bearing rail]] |
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The running surface of most train wheels is conical, which serves as the primary means of keeping the train aligned with the [[Track (rail transport)|track]] while in motion. The wheels are fixed on an axle, and when rounding a curve the mass of the train pushes the wheelset towards the outside of the track. The outside wheel rides up to contact the rail at a larger diameter, while the inside wheel drops down to contact its rail at a smaller diameter. The difference between the distances travelled by each wheel for each rotation of the axle causes the wheelset to follow the curve of the track. <ref name=":0">{{Cite web|title=Book : The Contact Patch|url=https://the-contact-patch.com/book/rail/r1610-the-wheelset|access-date=2020-10-29|website=the-contact-patch.com|language=en}}</ref> |
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Most train wheels have a conical geometry, which is the primary means of keeping the train's motion aligned with the track.<ref>{{cite news|last1=Liszewski|first1=Andrew|title=The Reason Trains Have Angled Wheels Is Incredibly Clever|url=https://gizmodo.com/the-reason-trains-have-angled-wheels-is-incredibly-clev-1793213013|accessdate=14 March 2017|work=[[Gizmodo]]|date=15 March 2017}}</ref> Train wheels have a flange on one side to keep the wheels, and hence the train, running on the [[Rail profile|rails]], when the limits of the geometry-based alignment are reached, e.g. due to some emergency or defect. See [[Hunting oscillation]]. Some wheels have a cylindrical geometry, where flanges are essential to keep the train on the [[Track (rail transport)|rail track]]. |
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Almost all train wheels have a projection, called a flange, on one side to keep the wheels, and hence the train, running on the [[Rail profile|rails]] when the limits or tests of alignment are reached: when a bend is taken at appropriate speed, when there are strong side-winds, and to withstand most common defects in trackbed, rail and mild debris. Some wheels do not have a conical profile and instead are cylindrical, such that the flanges are essential to keep the train on the track. |
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==Wheel arrangement== |
==Wheel arrangement== |
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{{Main|Wheel arrangement}}The number of wheels per locomotive or car varies in both size and number to accommodate the needs of the railcar or locomotive. Regardless of these factors, pairs of identically sized wheels are always affixed to a straight axle as a singular unit, called a [[Wheelset (rail transport)|wheelset]].<ref name=":0" /> |
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{{Main|Wheel arrangement}} |
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==Parts of a rail wheel== |
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'''Crank pin''': A pin protruding from a wheel into a main or coupling rod. |
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| ⚫ | Wheels used for [[road–rail vehicle]]s are normally smaller than those found on other types of [[rolling stock]], such as locomotives or carriages, because the wheel has to be stowed clear of the ground when the vehicle is in road-going mode. Such wheels can be as small as {{convert|245|mm|in|2|abbr=on}} in diameter. In Australia, wheels for [[road–rail vehicle]]s should comply with the requirements of AS7514.4, which is the Australian standard for infrastructure maintenance vehicle wheels. |
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{{clear}} |
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==Railway wheel and tire== |
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| ⚫ | Wheels used for [[ |
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==Tire== |
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{{main|Railway tire}} |
{{main|Railway tire}} |
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Modern railway wheels are usually machined from a single casting, also known as monoblock wheels.<ref name=":1">{{Cite book|last1=Milne|first1=Ian|url=https://books.google.com/books?id=hpc60yCsTPcC&dq=monoblock+train+wheels+advantage&pg=PA56|title=Comprehensive Structural Integrity|last2=Ritchie|first2=R. O.|last3=Karihaloo|first3=B. L.|date=2003-07-25|publisher=Elsevier|isbn=978-0-08-049073-1|language=en}}</ref> Some wheels, however, are made of two parts: the wheel core, and a [[tire]] ("tyre" in [[British English]], [[Australian English]] and other variants) around the perimeter. Separate tires are a component of some modern passenger rolling stock. The purpose of the separate tire is to provide a replaceable wearing element – an important factor for steam locomotives with their costly [[Spoke|spoked]] construction. In modern times the tire is invariably made from [[steel]], which is stronger than the [[cast iron]] of earlier eras. It is typically heated and pressed on to the wheel before it cools and shrinks. ''Resilient rail wheels'' have a resilient material, such as [[rubber]], between the wheel and tire. Failure of this type of wheel was one of the causes leading up to the [[Eschede train disaster#Wheel design|Eschede high-speed train crash]].<ref name=":1">{{Cite book|last1=Milne|first1=Ian|url=https://books.google.com/books?id=hpc60yCsTPcC&dq=monoblock+train+wheels+advantage&pg=PA56|title=Comprehensive Structural Integrity|last2=Ritchie|first2=R. O.|last3=Karihaloo|first3=B. L.|date=2003-07-25|publisher=Elsevier|isbn=978-0-08-049073-1|language=en}}</ref> |
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The wheels of many rail vehicles, especially steam locomotives and older types of rolling stock are fitted with steel [[tire]]s (or tyres in [[British English]], [[Australian English]] and others) to provide a replaceable wearing element on a costly wheel. |
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==Tire installation== |
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[[Image:Jack Delano - Retiring a locomotive driver wheel, Shopton, Iowa.jpg|thumb|250px|Steel tire on a [[steam locomotive]]'s driving wheel is heated with gas flames to expand and loosen it so it may be slipped over the wheel.]] |
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Replacing a whole wheel because of a worn contact surface is expensive, so older types of railway wheels were fitted with replaceable steel tires. The tire is a hoop of steel that is fitted around the steel wheel centre. The tire is machined with a shoulder on its outer face to locate it on the wheel centre, and a groove on the inside diameter of the flange face. |
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The inside diameter of the tire is machined to be slightly less than the diameter of the wheel centre on which it is mounted, to give an interference fit. |
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The tire is fitted by heating to a controlled temperature, avoiding overheating. This causes the tire to expand. The wheel centre, usually already mounted on the axle, is lowered into the tire which is flange side up. The tire cools, and the retaining ring (a shaped steel bar rolled into a hoop) is fitted into the groove. Hydraulically operated rolls [[swage]] the groove down on to the retaining ring. |
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The tire is primarily held in place by its [[interference fit]]. The shoulder on the outside and the retaining ring also keep the tire in place if the interference fit is lost. This is most often due to severe drag braking down a gradient, or due to an error in the machining. |
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Removal of a worn tire is by machining out the retaining ring and heating the tire to relax the interference fit. |
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Some steam locomotive wheels had tires bolted through the rim, or with a second smaller shoulder machined on the inside face of the tire. This shoulder was severely limited in size as it had to pass over the wheel centre for assembly. |
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Tires of different designs were fitted to wheels with wooden centers ([[Mansell wheel]]s in the UK) and to various other types. |
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The use of tires is becoming obsolete. The utilisation of traditional freight wagons was often so low that tires never needed renewal, so it was cheaper to fit a one-piece ("monoblock") wheel. Monoblock wheels are lighter and offer better integrity as there is no tire to come loose. Modern flow-line repair lines are disrupted by the inspection of the wheel centre once the tire is removed, possibly generating extra rectification work, and the need to make each tire fit its allocated wheel centre. Monoblock wheels are now more economical. |
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==Causes of damage== |
==Causes of damage== |
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The most common cause of wheel damage is severe braking. This activity includes sudden braking, braking on steep gradients and braking with high weight loads. The [[Railway brake|brake shoes]] (or blocks) are applied directly to the wheel surface which generates immense amounts of [[thermal energy]]. Under normal operation, a wheel may obtain a tread temperature of {{Convert|550|C|F|abbr=on}}.<ref>{{Cite journal|last1=Peters|first1=Carsten J.|last2=Eifler|first2=Dietmar|date=2009-11-01|title=Influence of Service Temperatures on the Fatigue Behaviour of Railway Wheel and Tyre Steels*|url=https://www.degruyter.com/document/doi/10.3139/120.110094/html|journal=Materials Testing|language=en|volume=51|issue=11–12|pages=748–754|doi=10.3139/120.110094|bibcode=2009MTest..51..748P |s2cid=135684020|issn=2195-8572}}</ref> Under severe braking conditions, the generated thermal energy can contribute to [[thermal shock]] or alteration of the wheel's mechanical properties. Ultimately, acute thermal loading leads to a phenomenon called [[spall]]ing. Alternatively, severe braking or [[Slippery rail|low adhesion]] may stop the rotation of the wheels while the vehicle is still moving, which may cause a [[flat spot]] on the [[Wheel–rail interface|wheel-rail interface]] and localized heat damage. |
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The most usual cause of damage is drag braking on severe gradients. Because the brake blocks apply directly on the tire, it is heated up, relaxing the interference fit. It is not feasible to fit the tire with such a heavy interference as to eliminate this risk entirely, and the retaining ring will ensure that the tire can only rotate on the wheel center, maintaining its alignment. In rare instances the rotation could be so severe as to wear the retaining ring down till it breaks, which could result in derailment. |
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Modern railway wheels are manufactured reasonably thick to provide an allowance of wear material. Worn wheels or wheels with a flat spot are machined on a wheel lathe if there is sufficient thickness of material remaining.<ref>{{Cite book|last=Nielsen|first=J.|title=8 - Out-of-round railway wheels|chapter=Out-of-round railway wheels |date=2009-01-01|chapter-url=http://www.sciencedirect.com/science/article/pii/B9781845694128500082|work=Wheel–Rail Interface Handbook|pages=245–279|editor-last=Lewis|editor-first=R.|publisher=Woodhead Publishing|language=en|doi=10.1533/9781845696788.1.245|isbn=978-1-84569-412-8|access-date=2020-10-29|editor2-last=Olofsson|editor2-first=U.}}</ref> |
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Severe braking or low adhesion may stop the rotation of the wheels while the vehicle is still moving can cause a [[flat spot]] on the tire and localized heat damage to the tire material. |
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== Guide wheel == |
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Tires are reasonably thick, about {{convert|3|in|mm}}, giving plenty of room for wear. Worn tires or tires with flats are re-profiled on a wheel lathe if there is sufficient thickness of material remaining. |
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[[Rubber-tyred metro]]s with a central [[Guide rail#Railway guide rail|guide rail]], such as the [[Busan Metro Line 4|Busan Metro]], [[Lille Metro]] and the [[Sapporo Municipal Subway]] as well as [[rubber-tyred tram]]s have '''guide wheels'''. |
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| align = center |
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| image1 = TranslohrGuideRail.svg |
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| width1 = 200 |
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| image2 = TVRGeleiding.svg |
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| footer = Left: diagram of the [[Translohr]] [[Guide rail#Railway guide rail|guide rail]] (green) and the tram's '''guide wheels''' (red). Right: cross section of the guide [[Rail profile|rail]] and '''guide wheel''' of the Bombardier's [[Bombardier Guided Light Transit|GLT]] |
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==See also== |
==See also== |
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* [[Adhesive weight]] |
* [[Adhesive weight]] |
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* [[Cycloid]] and [[trochoid]] |
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* [[Wheelset (rail transport)#Conical |
* [[Wheelset (rail transport)#Conical wheel-tread]] |
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==References== |
==References== |
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== External links == |
== External links == |
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* {{Cite web|title=APTA PR-CS-RP-003-98 Recommended Practice for Developing a Clearance Diagram for Passenger Equipment 5.3.2.1 Design tolerances|url=http://www.apta.com/resources/standards/Documents/APTA-PR-CS-RP-003-98.pdf|website=APTA.com|publisher=[[American Public Transportation Association]]|date=1998-03-26| |
* {{Cite web|title=APTA PR-CS-RP-003-98 Recommended Practice for Developing a Clearance Diagram for Passenger Equipment 5.3.2.1 Design tolerances|url=http://www.apta.com/resources/standards/Documents/APTA-PR-CS-RP-003-98.pdf|website=APTA.com|publisher=[[American Public Transportation Association]]|date=1998-03-26|access-date=2015-01-17}} |
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* [http://www.wheels-world.com/Wheels/?Show=Photos&AlbumID=6 Train wheels] |
* [http://www.wheels-world.com/Wheels/?Show=Photos&AlbumID=6 Train wheels] |
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{{Locomotive running gear}} |
{{Locomotive running gear}} |
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{{Authority control}} |
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[[Category:Train wheels| ]] |
[[Category:Train wheels| ]] |
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Latest revision as of 01:50, 31 October 2024
A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. The wheel acts as a rolling component, typically press fitted onto an axle and mounted directly on a railway carriage or locomotive, or indirectly on a bogie (in the UK), also called a truck (in North America). The powered wheels under the locomotive are called driving wheels. Wheels are initially cast or forged and then heat-treated to have a specific hardness.[1] New wheels are machined using a lathe to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly profiled wheels and worn wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment.[2] The International Union of Railways has defined a standard wheel diameter of 920 mm (36 in), although smaller sizes are used in some rapid transit railway systems and on ro-ro carriages.[3]
Wheel geometry and flange
[edit]
The running surface of most train wheels is conical, which serves as the primary means of keeping the train aligned with the track while in motion. The wheels are fixed on an axle, and when rounding a curve the mass of the train pushes the wheelset towards the outside of the track. The outside wheel rides up to contact the rail at a larger diameter, while the inside wheel drops down to contact its rail at a smaller diameter. The difference between the distances travelled by each wheel for each rotation of the axle causes the wheelset to follow the curve of the track. [4]
Almost all train wheels have a projection, called a flange, on one side to keep the wheels, and hence the train, running on the rails when the limits or tests of alignment are reached: when a bend is taken at appropriate speed, when there are strong side-winds, and to withstand most common defects in trackbed, rail and mild debris. Some wheels do not have a conical profile and instead are cylindrical, such that the flanges are essential to keep the train on the track.
Wheel arrangement
[edit]The number of wheels per locomotive or car varies in both size and number to accommodate the needs of the railcar or locomotive. Regardless of these factors, pairs of identically sized wheels are always affixed to a straight axle as a singular unit, called a wheelset.[4]
Wheels for road–rail vehicles
[edit]
Wheels used for road–rail vehicles are normally smaller than those found on other types of rolling stock, such as locomotives or carriages, because the wheel has to be stowed clear of the ground when the vehicle is in road-going mode. Such wheels can be as small as 245 mm (9.65 in) in diameter. In Australia, wheels for road–rail vehicles should comply with the requirements of AS7514.4, which is the Australian standard for infrastructure maintenance vehicle wheels.
Railway wheel and tire
[edit]Modern railway wheels are usually machined from a single casting, also known as monoblock wheels.[5] Some wheels, however, are made of two parts: the wheel core, and a tire ("tyre" in British English, Australian English and other variants) around the perimeter. Separate tires are a component of some modern passenger rolling stock. The purpose of the separate tire is to provide a replaceable wearing element – an important factor for steam locomotives with their costly spoked construction. In modern times the tire is invariably made from steel, which is stronger than the cast iron of earlier eras. It is typically heated and pressed on to the wheel before it cools and shrinks. Resilient rail wheels have a resilient material, such as rubber, between the wheel and tire. Failure of this type of wheel was one of the causes leading up to the Eschede high-speed train crash.[5]
Causes of damage
[edit]The most common cause of wheel damage is severe braking. This activity includes sudden braking, braking on steep gradients and braking with high weight loads. The brake shoes (or blocks) are applied directly to the wheel surface which generates immense amounts of thermal energy. Under normal operation, a wheel may obtain a tread temperature of 550 °C (1,022 °F).[6] Under severe braking conditions, the generated thermal energy can contribute to thermal shock or alteration of the wheel's mechanical properties. Ultimately, acute thermal loading leads to a phenomenon called spalling. Alternatively, severe braking or low adhesion may stop the rotation of the wheels while the vehicle is still moving, which may cause a flat spot on the wheel-rail interface and localized heat damage.
Modern railway wheels are manufactured reasonably thick to provide an allowance of wear material. Worn wheels or wheels with a flat spot are machined on a wheel lathe if there is sufficient thickness of material remaining.[7]
Guide wheel
[edit]Rubber-tyred metros with a central guide rail, such as the Busan Metro, Lille Metro and the Sapporo Municipal Subway as well as rubber-tyred trams have guide wheels.
See also
[edit]References
[edit]- ^ Lewis, R.; Olofsson, U. (25 September 2009). Wheel–Rail Interface Handbook. Elsevier Science. ISBN 9781845694128. Retrieved 2020-10-29.
- ^ Lewis, Roger; Olofsson, Ulf (2009). Wheel-rail interface handbook. Boca Raton, Florida: CRC Press. ISBN 978-1-61583-153-1. OCLC 500906475.
- ^ Licitra, Gaetano (2012-09-06). Noise Mapping in the EU: Models and Procedures. CRC Press. ISBN 978-0-203-84812-8.
- ^ a b "Book : The Contact Patch". the-contact-patch.com. Retrieved 2020-10-29.
- ^ a b Milne, Ian; Ritchie, R. O.; Karihaloo, B. L. (2003-07-25). Comprehensive Structural Integrity. Elsevier. ISBN 978-0-08-049073-1.
- ^ Peters, Carsten J.; Eifler, Dietmar (2009-11-01). "Influence of Service Temperatures on the Fatigue Behaviour of Railway Wheel and Tyre Steels*". Materials Testing. 51 (11–12): 748–754. Bibcode:2009MTest..51..748P. doi:10.3139/120.110094. ISSN 2195-8572. S2CID 135684020.
- ^ Nielsen, J. (2009-01-01). "Out-of-round railway wheels". In Lewis, R.; Olofsson, U. (eds.). 8 - Out-of-round railway wheels. Woodhead Publishing. pp. 245–279. doi:10.1533/9781845696788.1.245. ISBN 978-1-84569-412-8. Retrieved 2020-10-29.
{{cite book}}:|work=ignored (help)
ISO 1005 Parts 1-9 BS 5892 Parts 1-6 AS7414.4
External links
[edit]- "APTA PR-CS-RP-003-98 Recommended Practice for Developing a Clearance Diagram for Passenger Equipment 5.3.2.1 Design tolerances" (PDF). APTA.com. American Public Transportation Association. 1998-03-26. Retrieved 2015-01-17.
- Train wheels
