Engineering toleranceEngineering tolerance is the permissible limit or limits of variation in: a physical dimension; a measured value or physical property of a material, manufactured object, system, or service; other measured values (such as temperature, humidity, etc.); in engineering and safety, a physical distance or space (tolerance), as in a truck (lorry), train or boat under a bridge as well as a train in a tunnel (see structure gauge and loading gauge); in mechanical engineering, the space between a bolt and a nut or a hole, etc.
AutorackAn autorack, also known as an auto carrier (also car transporter outside the US), is a specialized piece of railroad rolling stock used to transport automobiles and light trucks. Autoracks are used to transport new vehicles from factories to automotive distributors, and to transport passengers' vehicles in car shuttles and motorail services, such as Amtrak's Auto Train route. In the early 20th century, when automobiles were still new technology, their production levels were low enough that they could be shipped in sufficient quantities in boxcars.
Loading gaugeA loading gauge is a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. Their purpose is to ensure that rail vehicles can pass safely through tunnels and under bridges, and keep clear of platforms, trackside buildings and structures. Classification systems vary between different countries, and gauges may vary across a network, even if the track gauge is uniform.
Overhead lineAn overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, trolleybuses or trams. The generic term used by the International Union of Railways for the technology is overhead line. It is known variously as overhead catenary, overhead contact line (OCL), overhead contact system (OCS), overhead equipment (OHE), overhead line equipment (OLE or OHLE), overhead lines (OHL), overhead wiring (OHW), traction wire, and trolley wire.
