Rail fastening system

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Elements of a baseplate based rail fastening system
1. Screw for fixing plate to sleeper
2. Elastomeric pad supporting rail
3. Tension washer
4. Rail clamp
5. Tensioning bolt (nut not shown)
6. Baseplate
assembled example
This article is about devices used to fasten rail to railroad ties (sleepers), for devices used to join lengths of rail see Fishplate
"Rail spike" redirects here. For the Transformer, see Railspike.

A rail fastening system is a means of fixing rails to railroad ties (United States) or sleepers (international). The terms rail anchors, tie plates, chairs and track fasteners are used to refer to parts or all of a rail fastening system. Various types of fastening have been used over the years.

History and overview[edit]

The earliest wooden rails were fixed to wooden sleepers by pegs through holes in the rail, or by nails. By the 18th century cast iron rails had come into use, and also had holes in the rail itself to allow them to be fixed to a support.[1] 18th century developments such as the flanged rail and fish bellied rail also had holes in the rail itself; when stone block sleepers were used the nails were driven into a wooden block which had been inserted into a recess in the block. The first chair for a rail is thought to have been introduced in 1797 which attached to the rail on the vertical web via bolts.[2]

By the 1820s the first shaped rolled rails had begun to be produced initially of a T shape which required a chair to hold them; the rails were held in position by iron wedges (which sometimes caused the rail to break when forced in) and later by wooden wedges, which became the standard.[3] In the 1830s Robert L. Stevens invented the flanged 'tee' rail (actually a distorted I beam), which had a flat bottom and required no chair, a similar design was the contemporary bridge rail (an inverted 'U' shaped with bottom flange and used on longitudinal sleepers); these rails were initially nailed directly to the sleeper.[4]

In North American practice the flanged T rail became the standard, later being used with tie-plates. Elsewhere T rails were replaced by bull head rails of a rounded 'I' or 'figure-8' appearance which still required a supporting chair. Eventually the flanged T rail became commonplace on all the worlds railways, though differences in the fixing system still exist.

Spikes and screws[edit]

Rail spikes[edit]

Rusted cut spikes (scale in inches)
Dog spike

A rail spike (also known as a cut spike or crampon) is a large nail with an offset head that is used to secure rails and base plates to railroad ties in the track. Robert Livingston Stevens is credited with the invention of the railroad spike,[5] being first used in at least 1832.[6] The railroad spike was an invention which resulted from the state of industrialisation in the United States in the early 19th century: English mainline railways of that period used heavy and expensive cast iron chairs to secure T shaped rails; instead, Stevens added a supporting base to the T rail which could be fixed with a simple spike.[7][8] As of 1982, the spike was still the most common rail fastening in North America. Common sizes are from 9 to 10/16 inch square and ~5.5 to 6 inch long.[9]

A rail spike is roughly chisel shaped and with a flat edged point; the spike is driven with the edge perpendicular to the grain, which gives greater resistance to loosening.[10] The main function is to keep the rail in gauge. When attaching tie plates the attachment is made as strong as possible, whereas when attaching a rail to tie or tie plate the spike is not normally required to provide a strong vertical force, allowing the rail some freedom of movement.[9]

Originally spikes were driven into wooden sleepers by hammering them with a heavy hammer by hand. This manual work has been replaced by machines, commonly called "spike drivers" (A machine that removes spikes is called a "spike puller").[11] Splitting of the wood can be limited by pre-boring spike holes or adding steel bands around the wood.[12]

For use in the United States three basic standards are described in the ASTM A65 standard, for different carbon steel contents.[13]

The rail spike has entered American popular consciousness; the driving of the "Golden Spike" was a key point in North American development of the western seaboard. Also characters such John Henry (folklore) have been celebrated in song and verse, as have railroad workers in general.[14]

A dog spike is functionally equivalent to a cut spike and is also square in horizontal section and of similar dimensions but has a pointed penetrating head, and the rail (or "plate holding") head has two lugs on either side (which aid spike removal) giving the impression of a dog's head.[15]

Screw spikes[edit]

Rusted screw spike
Railway Tire-fonds

A screw spike, rail screw (or lag bolt) is a large (~6" length, slightly under 1" diameter) metal screw used to fix a tie plate or fasten rail. Screw spikes are fixed into a hole bored in the sleeper.[16] The screw spike has a higher cost to manufacture than the rail spike but has the advantage of greater fixing power; approximately twice that of a rail spike,[17] and can be used in combination with spring washers.[16]

The screw spike was first introduced in 1860 in France (French tire-fond), and became common in continental Europe.[18]

Dog screw[edit]

A dog screw is somewhat similar to a screw spike, except that the screw thread doesn't spiral. The dogscrew is hammered in, and grips the timber better than a dogspike which is smooth. At the same time, the dogscrew is cold-forged, which reduces cost.

Fang bolts[edit]

Fang bolts have also been used for fixing rails or chairs to sleepers; the fang bolt is a bolt inserted through a hole in the sleeper with a fanged nut that bites into the lower surface of the sleeper. For fastening flat-bottomed rails an upper-lipped washer can be used to grip the edge of the rail. They are more resistant to loosening by vibrations and movement of the rail.[19] They are thought more effective than spikes and screws and so are used in positions such as switch (point) tieplates,[20] and on sharp curves.[21]

Spring spikes[edit]

Spring spike fastener (German Oberbau Hf[22])

Spring spikes, (or elastic rail spikes[23]) are used with flat-bottomed rail, baseplates and wooden sleepers; the spring spike holds the rail down and prevents tipping, and also secures the baseplate to the sleeper.[24] The Macbeth spike (trade name) is a two-pronged U-shaped staple-like spike bent so that it appears M-shaped when viewed from the side.[25][26] Inverted J-shaped single pointed spikes have also been used.[27]

Fixing equipment[edit]

The spike maul, also known as a spiking hammer, is a type of sledgehammer with a long thin head which was originally used to drive spikes.[28][29]

Manual hole drilling and spike or screw insertion and removal have been replaced by semi-automated or automated machines, both pneumatic and hydraulic. Machines that remove spikes are called spike pullers.[30][31][32]

Rail supports[edit]

Chairs[edit]

Cross section of early T rail, chair and key

The earliest railway chairs, made of cast iron, were introduced around 1800 used to fix and support cast-iron rails at the ends;[2] they were also used to join the adjacent rails.[33]

In the 1830s T-shaped (or single-flanged T parallel rail) and I-shaped rails (double-flanged T parallel or bullhead rail) rolled rails were introduced; both required cast-iron chairs to support them.[34] Originally, iron keys were used to wedge the rail into the vertical parallel jaws of the chair; these were superseded by entirely wooden keys.[34] The wooden keys were formed from oak, steam softened and then compressed with hydraulic presses and stored in a drying house; when inserted into the chair, exposure to the wet atmosphere would cause the key to expand, firmly holding the rail.[35] The wedge may be on the inside or outside of the rail (usually the outside).[36]

Chairs have been fixed to the sleeper using wooden spikes (trenails), screws, fang-bolts or spikes.[37]

In most of the world, flat-bottomed rail and baseplates became the standard, however in Britain, bullhead rail-and-chairs remained in use until the middle of the twentieth century.[24] They are now largely obsolete but can still be found on London Underground and sidings.[where?][when?][citation needed]

Tie plates[edit]

A tie plate, baseplate or sole plate is a steel plate used on rail tracks between flanged T rail and the crossties. The tie plate increases bearing area and holds the rail to correct gauge. They are fastened to wooden ties by means of spikes or bolts through holes in the plate.

The part of the plate under the rail base is tapered, setting the cant of the rail, an inward rotation from the vertical. The usual slope is one in forty ( 1.4 degrees ). The top surface of the plate has one or two shoulders that fit against the edges of the base of the rail. The double-shoulder type is currently used. Older single-shoulder types were adaptable for various rail widths, with the single shoulder positioned on the outside (field side) of the rails. Most plates are slightly wider on the field side, without which the plates tend to cut more into the outsides of the tie, reducing cant angle.

Many railways use large wood screws, also called lag screws, to fasten the tie plates (or baseplates) to the railroad ties.

Tie plates came into use around the year 1900, before which time flanged T rail was spiked directly to the ties.

Clips[edit]

A variety of different types of heavy-duty clips are used to fasten the rails to the underlying baseplate, one common one being the Pandrol fastener (Pandrol clip), named after its maker, which is shaped like a stubby paperclip.[38] Another one is the Vossloh Tension Clamp.[39]

The newer Pandrol fastclip is applied at right angles to the rail. Because the clip is captive, it has to be installed at the time of manufacture of the concrete sleeper.

Rail fastening types
Rail spike with baseplate above the tie 
Track joint and chairs 
Pandrol 'e-Clip' fastening 
Pandrol 'fastclip' fastening 
Tension clamp fastening 
Bolt clamped fastening 
Steel spring keyed rail in chair 

See also[edit]

References[edit]

  1. ^ Origin and Development of the Railway Rail, G. P. Raidabaugh, pp.5-7
  2. ^ a b Origin and Development of the Railway Rail, G. P. Raidabaugh, pp.8-9
  3. ^ Origin and Development of the Railway Rail, G. P. Raidabaugh, pp.14-19
  4. ^ Origin and Development of the Railway Rail, G. P. Raidabaugh, pp.19-24
  5. ^ "October 18 - Today in Science History". www.todayinsci.com. Robert Livingston Stevens. 
  6. ^ George Iles (1912). Leading American inventors. H. Holt and company, New York. p. 23. 
  7. ^ Origin and Development of the Railway Rail, G. P. Raidabaugh, p.20
  8. ^ "The Rail Spike and The Locomotive". chestofbooks.com. Scientific American. 
  9. ^ a b Railroad engineering, Volume 1, William Walter Hay, pp.582-3
  10. ^ "railroad spikes". www.sizes.com. 
  11. ^ Brian Solomon (2001). Railway maintenance: the men and machines that keep the railroads running. MBI Publishing Company. pp. 61, 64. 
  12. ^ Railroad engineering, Volume 1, William Walter Hay, p.455
  13. ^ "ASTM A65 - 07". www.astm.org. ASTM International (American Society for Testing and Materials). 
  14. ^ Norm Cohen; David Cohen (2000). Long steel rail: the railroad in American folksong. University of Illinois Press. 
  15. ^ Mundrey (2000). Railway Track Engineering. Tata McGraw-Hill. pp. 130–131. 
  16. ^ a b Railroad engineering, Volume 1, William Walter Hay, pp.585
  17. ^ Orrock John Wilson (1918). "Railroad Structure and Estimates". J. Wiley & Sons, New York. pp. 198–204. 
  18. ^ Railway Maintenance Engineering, William Sellew, pp.161-3
  19. ^ Railway Appliances, John Wolfe Barry, pp.53-54,73
  20. ^ Mundrey (2000). Railway Track Engineering. Tata McGraw-Hill. pp. 156–7. 
  21. ^ William Hemingway Mills (1898). Railway Construction. Longmans, Green, and Co. pp. 224, also fig.331–334 (p.221). 
  22. ^ Wolfgang Schiemann (2002). Schienenverkehrstechnik: Grundlagen der Gleistrassierung. Teubner B.G. p. 283. ISBN 3519003635. 
  23. ^ Clifford F. Bonnett (2005). Practical railway engineering. Imperial College Press. 5.10 Rail fastenings, Baseplates and Pads, p.65. 
  24. ^ a b Colin Craig. "THE MODERN PERMANENT WAY (Part 1)". THE MANCHESTER MODEL RAILWAY SOCIETY. 
  25. ^ National Research Council (U.S.). Railroad Research Information Service; United States. Federal Railroad Administration (1973). Special bibliography: safety-related technology. National Academies. 032978 Spring Steel Rail Spikes (from Railway Gazette, Feb. 1948, Vol.88, pp.191-2). 
  26. ^ Iain Ellis (2006). Ellis' British Railway Engineering Encyclopaedia. Lulu.com. Macbeth spike, p.211. 
  27. ^ Iain Ellis (2006). Ellis' British Railway Engineering Encyclopaedia. Lulu.com. Elastic Spike, p.114. 
  28. ^ Railway Maintenance Engineering, William Sellew, p.215-6
  29. ^ Ron Fitch (2006). Australian Railwayman: From Cadet Engineer to Railways Commissioner. Rosenberg Publishing. p. 220. 
  30. ^ Brian Solomon (2001). Railway maintenance: the men and machines that keep the railroads running. MBI Publishing Company. pp. 59–62. 
  31. ^ "Workin' on the Railroad". Popular Mechanics (Hearst Magazines) 84 (4): 20–27. October 1945. ISSN 0032-4558. 
  32. ^ "Mechanised section gang now lays railroad ties". Popular Science (Bonnier Corporation) 168 (2): 168–9. February 1956. ISSN 0161-7370. 
  33. ^ Origin and Development of the Railway Rail, G. P. Raidabaugh, pp.11-12
  34. ^ a b Daniel Kinnear Clark (1855). Railway machinery: a treatise on the mechanical engineering of railways: embracing the principles and construction of rolling and fixed plant; illustrated by a series of plates on a large scale, and by numerous engravings on wood, Volume 2. Blackie and Son. p. 280. 
  35. ^ Frederick Smeaton Williams (1852). Our Iron Roads: their history, construction and influences: With numerous illustrations. Ingram. pp. 199–200. 
  36. ^ Railway Appliances, John Wolfe Barry, pp.43-51
  37. ^ Railway Appliances, John Wolfe Barry, pp.71
  38. ^ "Pandrol - Pandrol - The future of rail fastenings". www.pandrol.com. 
  39. ^ "vossloh-fastening-systems.com - Home". www.vosslo-fastening-systems.de. 

Sources[edit]

Further reading[edit]

  • Railway locomotives and cars, Volume 6. Simmons-Boardman Pub. Corp. 1838. From the American Journal of Science and Arts "Experiments on the adhesion of iron spikes of various forms, when driven into different specimins of timber"; by Walter B. Johnson, Professor of mechanics and natural philosophy in the Franklin Institute, Philadelphia , pp.357-360. 

External links[edit]