railroad spikes

engraving of a spikeThe spikes used to fasten T-shaped railroad track to wooden ties have an L-shaped head and a square shank. The tip is wedge-shaped, not pointed. The wedge is driven into the tie across the grain, that is, parallel to the track.  

Its square cross section gives a railroad spike much higher holding strength than a fastener having the same amount of metal but a circular cross section has; roughly speaking, about 50% more. A spike with the wedge driven across the grain will have about twice as much holding power as one driven with the grain.  Early experiments showed that pulling out a 9/16″ × 9/16″ spike driven 4¼ inches into dry cedar required on average a force of 857 pounds.  In seasoned oak, another experimenter needed 4281 pounds.

Current standards for track spikes define two grades: 1 (soft) and 2 (high carbon).  The stronger high carbon spikes must be marked "HC".

American, Early 20th Century
Length
under
head
(inches)
Width
of shank
side
(inches)
Number
in a
200-pound keg
9/16 360
5 9/16 405
9/16 460
5 ½ 505
½ 535
4 ½ 605
½ 670
7/16 690
4 7/16 780
7/16 890
3/8 780
4 3/8 1025
3/8 1250
3 3/8 1380
5/16 1650

ASTM A65-01. Standard Specification for Steel Track Spikes. For ASTM standards, access www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard's Document Summary page on the ASTM website.

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