THE PROPORTIONING OF BRAKE BLOCKS

Excerpts are presented from an article dealing with the temperature effects produced between two sliding bodies. The investigation had two main aspects: first, the development of a satisfactory method of measuring the surface temperatures and, second, the application of this method to actual railway brake blocks in a full-scale series of tests. In applying the apparatus to the measurement of surface temperatures of a railway tyre, the aim of the experiment was to correlate the results obtained with three variables: speed, block pressure, and contact area. It was found that in all the tests contact area was very small and moved along longitudinal strips parallel to the width of the block. Working on the assumption that contact area should be a function of block material and block pressure, and should thus vary with the ratio of block length to block width, the authors began the most striking part of their research. A block was progressively shortened to give three-quarters, one-half, and one-quarter the original area. Blocks of type 1 and type 2 were used, as well as cast iron, at initial speeds of 60 and 30 m.p.h. and a brake block pressure of 1,240 lb. The result was an astonishing decrease of temperature maxima for both the non-metallic blocks, although there was no such decrease in the cast-iron blocks. Contact areas in the nonmetallic blocks now covered the full tyre width, instead of being confined to narrow longitudinal strips. Measurements of wear show that the normal and half-blocks wear at exactly the same rate. Since cracking of the tyre is known to arise from the true heat spots, it can be taken that by reducing brake block areas from the present standard size, in the case on non-metallic materials, the liability to the formation of cracks is minimized and the life of tyres can thus be greatly increased.

• Corporate Authors:

  Temple Press Limited

  161-166 Fleet Street
  Longon EC4,   England 
• Authors:
  • Parker, R C
  • Marshall, P R
• Publication Date: 1947-11-14

Media Info

• Pagination: p. 546-547
• Serial:
  • RAILWAY GAZETTE
  • Volume: 87

Subject/Index Terms

• TRT Terms: Brake shoes; Braking; Cracking; Defects; Friction; Technology; Temperature; Thermal degradation; Velocity; Wheels
• Geographic Terms: United Kingdom
• Old TRIS Terms: Thermal cracks; Thermal cracks (Wheels); Wheel defects
• Subject Areas: Railroads; Vehicles and Equipment;

Filing Info

• Accession Number: 00037922
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 4 1994 12:00AM