Gantry Crane Travel Unit

A gantry crane travel unit is the assembly of wheels, gearbox, motor and frame that moves the crane on floor rails. On a gantry crane this group works under a different kind of stress than on an overhead crane.

What makes gantry different: the ground

On an overhead crane the rail sits on a runway carried by the building columns, and the geometry of the track is protected by the structure. On a gantry crane the rail is laid directly on the ground. Settlement, differences in fill and thermal expansion create deviation in the track over time.

The travel unit is designed to tolerate that deviation. Wheel flange clearances, flexing allowances and, where needed, horizontal guide rollers are specified for this purpose.

Wheel pressure and the ground

On a gantry crane the entire load goes into the ground. Pressure per wheel directly governs the fill and foundation beneath the rail. If pressure comes out high there are two routes: increase the number of wheels or increase wheel diameter. Both affect frame size and cost.

Drive and synchronism

Gantry cranes have a large span between the two legs; when drive synchronism is lost the crane skews and rapidly wears both rail and wheels. Drive groups on both legs are therefore calculated together, with acceleration and braking values matched.

Sizing

Wheel count and diameter, rail profile, wheel pressure, acceleration and braking values and duty class are assessed together. For a retrofit, rail profile and wheel track are measured to confirm compatibility.