Viewed another way, it is the fraction of total vehicle weight resting on a given axle. Because track and especially axle design calculations pdf rails are expensive, it is desirable to optimise the track for a given axle load. If the track is overloaded by trains that are too heavy, it can be destroyed in a short time.
However, it is also convenient for the steelworks that rails are made in a limited number of sizes, so that a perfect match of rail weight and axle load is rarely achieved. New rail is often reserved for heavy main line use, which releases good but lighter rail that can be cascaded for lighter duties on branch lines. The lightest rail cascaded from the lightest branch lines may have no railway use other that for structural items such as fenceposts, telegraph posts and for reinforcing concrete. Higher operating speeds can be achieved through reduced axle loads and increased density of sleepers. Higher axle loads are now permitted, e. So long as the width of the base of the rail, or timber sleepers are in use, lighter rail can be replaced with heavier rail.
The absolute maximum axle load for railways depends on the rail used, above the indicated load the rails will start to bend between sleepers and can cause de-railment. Additional calculations must be made for bridges since a span may have to carry several locomotives and wagons at once. Heavy braking also imposes limits on the strength of piers. In this case, the axle load remains the same, but the load borne by the individual wheels is reduced by having more wheels to distribute the load. NVF committee Vehicles and Transports. This page was last edited on 28 November 2017, at 10:28.
This article is semi-protected until March 25, 2018. This article is about devices designed to perform tasks. Modern machines are complex systems that consist of structural elements, mechanisms and control components and include interfaces for convenient use. However, the Ancient Greeks probably borrowed the word “mekhane” from the ancient Hebrews. The ancient Greeks were familiar with the Hebrew scriptures and language, and often borrowed words and terms. A wider meaning of “fabric, structure” is found in classical Latin, but not in Greek usage.