Derailer
Derailer may refer to: * A railroad derail, also called a ''derailer'', used to prevent fouling of a railroad track * Derailleur gears Shimano 600 front derailleur (1980) A derailleur is a variable-ratio bicycle gearing system consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another. Modern front and rear ..., a variable-ratio transmission system commonly used on bicycles {{Disambig ...
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Derail
A derail or derailer is a device used to prevent fouling (blocking or compromising) of a rail track (or collision with anything present on the track, such as a person, or a train) by unauthorized movements of trains or unattended rolling stock. The device works by derailing the equipment as it rolls over or through it. Although accidental derailment is damaging to equipment and track, and requires considerable time and expense to remedy, derails are used in situations where there is a risk of greater damage to equipment, injury or death if equipment is allowed to proceed past the derail point. Applications Derails may be applied: *where sidings meet main lines or other through tracks *at junctions or other crossings to protect the interlocking against unauthorized movement *temporarily at an area where crews are working on a rail line *approaching a drawbridge, dead end, or similar hazard. Design There are four basic forms of derail. Wedge The most common form is a wedg ...
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