A railroad crane (US: crane car or wrecker; UK: breakdown crane) is a type of crane used on a railroad for one of three primary purposes: freight handling in goods yards, permanent way (PW) maintenance, and accident recovery work. Although the design differs according to the type of work, the basic configuration is similar in all cases: a rotating crane body is mounted on a sturdy chassis fitted with flanged wheels. The body supports the jib (UK; US: boom) and provides all the lifting and operating mechanisms; on larger cranes, an operator's cabin is usually provided. The chassis is fitted with buffing (UK) and/or coupling gear to allow the crane to be moved by a locomotive, although many are also self-propelled to allow limited movement about a work site.
For cranes with a jib that extends beyond the length of the chassis, an idler car (also known as a 'jib carrier' (UK) or 'boom car' (US)) is provided to protect the jib and to allow the crane to be coupled within a train. The idler car is usually a long, flat wagon (i.e. a flatcar) that provides a means of securing the jib for transportation; storage areas for special equipment or supplies are usually fitted too. It was[when?] not uncommon for the idler car to be built on a withdrawn revenue-earning wagon.
Railroad cranes are usually designed specifically for one of three purposes:
Goods yard cranes
Usually the smallest of the railroad cranes, goods yard cranes were used in the larger goods yards to provide lifting capability in areas away from the ground-mounted goods cranes normally provided in such yards.
They were often small enough to be operated by hand, and were not normally self-propelled, instead requiring the use of a shunting engine to move them into position. Once cheap road-going mobile cranes were available, these superseded the rail-mounted variety due to their greater flexibility and mobility.
The most varied forms of crane are used for maintenance work. General purpose cranes may be used for installing signalling equipment or pointwork, for example, while more specialised types are used for track laying.
The largest cranes are used for accident recovery work, usually forming part of a breakdown train that includes staff accommodation and recovery equipment. These are large enough to lift derailed rolling stock back onto the track, although two or more cranes may be required to safely recover a locomotive. In US terminology, a 'breakdown crane' is often referred to as a 'wrecker'.