The PALFINGER turntable bearing permits an unrestricted radius of action. The crane is rotated or 'slewed' using a gear box and hydraulic motor rather than a rack and pinion system. All slewing mechanisms come as standard with a high quality roller ball bearing.
How It Works
A hydraulic motor drives a pinion which meshes with a basemounted high quality roller ball bearing, rotating the crane. The gears are precision machined to minimize back lash between the gears. The roller ball bearing is made with very tight tolerances for width, flatness, and perpendicularity. The matching surfaces on the base and the column are machined in a single clamping for the highest possible accuracy. On larger cranes two identically sized slewing motors are set across from each other on the column. One motor is hydraulically preloaded against the other, which eliminates all backlashes in the rotation system.