Railway Rolling Stock

Railway Rolling Stock

It is always useful at the outset of consideration of a subject to pause for a moment and to ponder the definitions, attributes range and scope of the matter. Rolling stock used on railways in the earliest days evolved from carriages and wagons which ran on highways to carry both people and bulk materials.

As early as the sixteenth century wooden wheeled carts were used in mines and quarries running on longitudinal timber rails. With the progressive evolution of the skills and crafts of the wheelwright, metalworker and the ironmaker, wheels improved through various phases from simple rough turned wooden spools through spoked and rimmed construction to fully cast and turned metal wheels.

Similarly, body construction and springing, particularly for passenger carrying vehicles, relied very heavily on the experience gained in the construction of stagecoaches in the seventeenth and eighteenth centuries. At the end of the eighteenth century, horse drawn trams running on metal rails began to appear in a number of European cities. These horse drawn tramways were literally to pave the way for development of railways when steam power began to be developed early in the 1800s. One has only to look at illustrations of early passenger coaches to see how closely they resemble the road vehicles of the previous century.

As railway experience was gained, the design of rolling stock also evolved. Springing, body structure, wheels and axles all are subject to varying loads and stresses, when comparing slower speeds on rough roads to much faster speeds on railways, with a comparatively smoother ride.

Railway rolling stock generally runs on hard wheels on hard rails. The wheels are not only supported by the rails but are guided by them. The only exception to this is for a small number of metros where rubber tyres have been introduced. In this case the supporting function of the rail may be separated from the guiding function.

In all cases railway rolling stock will transmit vertical, horizontal and longitudinal forces to the track and its supports. Most railways have adopted twin rails and flanged wheels. Forces are transmitted to the rail

structure either by direct bearing on the rail top from the wheel tyre, or by bearing laterally through the flange, or by longitudinal friction. Potential ?overturning' force centrifugal force on curves, coupled with wind forces on exposed locations are resisted by vertical dead weight and super-elevation   or   ?cant'   on   curves.

The Range of Railway Rolling Stock

Today there is a very wide range of rolling stock used throughout the world on different railways. This range includes the following basic types:

•Locomotives

•Freight wagons

•Passenger coaches

•Multiple units (with motive power in-built)

•Metro cars (usually multiple units)

•Light rail/Trams (usually articulated units)

•Rail mounted machines (cranes, tampers etc.)

•Inspection and maintenance trolleys