Idler Car

An idler car is an empty car coupled into a train to serve as a spacer, most often used when a long or oversized load overhangs the end of the car carrying it. The idler car carries no lading itself; its job is to provide clearance so that an overhanging load does not strike or interfere with adjacent cars.

Why It Is Needed

Some shipments are longer than the car they ride on, so the load projects past one or both ends of that car - a dimensional load such as long pipe, steel, or other oversized material. Without protection, the overhanging end of the load could swing into or strike the car next to it, especially on curves where the cars angle relative to one another. An idler car placed at the overhanging end keeps the adjacent car far enough away that the load clears it.

How It Is Used

Idler cars are commonly used in pairs or singly depending on how far the load overhangs and on which ends. In some cases the load is allowed to extend over the idler car, with the idler simply providing length and clearance rather than support. Because the idler car is part of the special arrangement that makes an oversized shipment safe to move, its placement is specified as part of how the dimensional load is loaded and secured. The idler itself is ordinary equipment temporarily assigned to this protective role.