Geodetic surveying and levelling

Levelling of crane runway

  An overhead crane consists of a steel bridge with travelling wheels moving along the runways in the form of railroad or special rails. Load lifting and shifting along the bridge is performed by the load trolley. As a rule, movable fastening is used to fasten rails to crane beams allowing for easy and quick shifting of rails during installation and operational alignment. Normal overhead crane operation is mainly dependent on the following technical requirements of crane runway geometry. The main requirements are as follows. Each line shall be straight and horizontal. Both lines shall be parallel, in one horizontal plane, at such distance from each other that corresponds to overhead crane bay length.  

  The following main requirements to be followed during installation and operation of overhead crane railways:

•rail deviation from straight line shall not be higher than 15 mm when installation and 20 mm when operation;

•difference in elevations of rail heads of one cross-section shall not be higher than 15 mm when installation and 20 mm when operation;

•difference in elevations of rail heads of neighboring columns shall not be higher than 10 mm when installation and 15 mm when operation;

•deviation of distance between the rails shall not be higher than 10 mm when installation and 15 mm when operation.

   Geodetic surveying of overhead cranes is not limited only to activities related to erection of crane runways at construction stage. Crane operation requires systematic monitoring of crane runway position. It is to be done due to changes in crane runways geometry resulting from crane loads, foundation and supporting column settlement, crane beam deformation, wear of rails and fastening elements and others.