The trolleys of small- and medium-duty cranes adopt P series steel train rails and the trolley or crane running mechanisms of heavy-duty cranes adopt QU series special steel rails or square rails for cranes.

Check the steel rails, bolts, clamps and other parts before installation. Promptly replace cracked, corroded or nonconforming ones. For steel rails allowing the repair of rail surfaces and sides and wear defects no greater than 3 mm, do not use them unless repair is done.

The shim plates should be in close contact with the rails and crane girder. Each group should have no more than 20 shim plates with a length more than 100 mm and a width 10 to 20 mm wider than the rail bottom. The gap between two groups of shim plates should not exceed 200 mm. The shim plates should be securely welded on the steel crane girder, with the contact area of the shim plate with rail section no less than 60% and the local gap no greater than 1 mm.

Steel rail joints may be straight or 45° inclined. Inclined joints facilitate smooth transition of wheels at the joint. The joint gap is generally 1 to 2 mm. For construction in winter in cold areas, or if the ambient temperature during installation is more than 20 ℃ lower than the working temperature throughout the year, compensation for temperature should be considered and it is generally 4 to 6 mm. The terminals of two steel rails at the joint should be more than 500 mm apart.

Baffles should be installed at both ends of a rail to prevent derailment of the crane at rail ends.

The actual center line of the rail should not deviate from its geometric center line for more than 3 mm. The track center of bridge cranes allows a deviation of ±5 mm; longitudinal inclination of the rail is 1/1500; the allowable deviation of the relative elevation of two rails is 10 mm.