Crane (rail)

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 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.

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It was not uncommon for the idler car to be built on a withdrawn revenue-earning wagon, such as on the Great Western Railway after the Grouping and in the 1930s (where they were referred to as 'match trucks').

General purpose cranes may be used for installing signalling equipment or pointwork, for example, while more specialised types are used for track laying.

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.

Sleepers (ties) are often carried on the idler car to put under the outriggers to spread the weight applied to the trackbed.

In the early days of the railways, locomotives and rolling stock were small enough to be re-railed manually using jacks and tackle, but as they became bigger and heavier this method became inadequate.

The use of caterpillar tractor mounted sidebooms (pipelayers) enabled the contractors to mobilize around a site without having the need for crane mats and multiple lifting locations.

While the conventional diesel hydraulic road cranes were adopted with some small trolleys to move on the rail track, the new generation had a professional high speed railway chassis for up to 120 kilometres per hour (75 mph).

Although not normally required for re-railing activities, they are exceptionally useful for track relaying and the restoration of locomotives and rolling stock, and help to avoid expenditure on outside contractors.