Laying down the rails pdf

Rail from 1896 showing manufacturer’s name and specification formed onto the web of rail laying down the rails pdf rolling. Early rails were made of wood, cast iron or wrought iron.

The head is profiled to resist wear and to give a good ride, and the foot profiled to suit the fixing system. It took many decades to improve the quality of the materials, including the change from iron to steel. Rails represent a substantial fraction of the cost of a railway line. Only a small number of rail sizes are made by steelworks at one time, so a railway must choose the nearest suitable size. Rails are made in a large number of different sizes. Disadvantages of the narrower foot were overcome through use of tie-plates. Attention was also focused on improved fillet radii to reduce stress concentration at the web junction with the head.

Old ASCE rails of lighter weight remained in use, and satisfied the limited demand for light rail for a few decades. 50 kg and 60 kg are the current standard, although some other sizes are still manufactured. These rails were too fragile to carry heavy loads, but because the initial construction cost was less, this method was sometimes used to quickly build an inexpensive rail line. Strap rails sometimes separated from the wooden base and speared into the floor of the carriages above, creating what was referred to as a “snake head”. However, the long-term expense involved in frequent maintenance outweighed any savings. 1789 where the wheels were flanged and, over time, it was realised that this combination worked better.

They could only be made in short lengths which would soon become uneven. The cross-section varied widely from one line to another, but were of three basic types as shown in the diagram. Steel is a much stronger material, which steadily replaced iron for use on railway rail and allowed much longer lengths of rails to be rolled. Tensile strength increases with carbon content, while ductility decreases.

AREA and ASTM specified 0. 82 percent for heavier rails. Manganese increases strength and resistance to abrasion. 9 percent manganese in 70 to 90 pound rail and 0. 7 to 1 percent in heavier rails.