The Surveyor and Municipal and County Engineer Volume 31

The Surveyor and Municipal and County Engineer Volume 31

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: only one limitation. The strains on a road surface produced by a horse-drawn vehicle are of two classes---the crushing strains which for equal weights and for equal tyre widths are the same as those for motor vehicles, and the other or traction strains produced by the angular impact of the iron-shod horses' feet which is a well-known cause contributing to the destruction of the surface, particularly when the road is soft after rain or after the breaking up of frosts. "When the vehicles are self-propelled and the tractive effort has to be transmitted through the wheels, it becomes important to know what will be the horizontal stress or tendency of the driving wheels to move the road metal backwards, also measured in pounds per inch of surface. Now this tractive effort varies greatly. It reaches its maximum when heavily loaded vehicles are climbing gradients. Experiments have shown that this horizontal or nearly horizontal strain transmitted to the road metal cannot much exceed one-third of the crushing strain, for the simple reason that the adhesion with smooth wheels is, under ordinary circumstances, limited to one-third of the insistmt weight. It is probably slightly increased on hard roads by the cross strips which are used on traction engines, and which are allowed in a modified form by the regulations of the Local Government Board, but I do not think that the increase of tractive effort, and hence horizontal strains on the road metal, are greatly increased by the cross strips when the road is dry and the co-efficient of adhesion is at its maximum. The cross strips are much more useful for soft ground or when the hard surface is covered with a thick greasy mud, as at such times they are the only portions of the more

Product details

  • Paperback | 972 pages
  • 189 x 246 x 49mm | 1,696g
  • United States
  • English
  • black & white illustrations
  • 1236880609
  • 9781236880604