Zoomlion Crane Slewing Bearing and Slew Reducer

Slewing bearing, slew reducer and slew motor sourcing for Zoomlion truck cranes. The bearing is sized to load moment, not to the tonnage badge: the ZTC250V carries 960 kN.m on the base boom while the ZTC550V carries 2,033 kN.m, so raceway diameter, ball size and bolt count are a full size class apart, and the older QY25V is a different bearing again from the ZTC250V it was replaced by. Zoomlion also builds a heavier 25 t platform, the ZTC251 series, on a different chassis with a different bearing, which is why we ask for the full model code on the nameplate rather than the tonnage. A slewing bearing is a structural safety part and is quoted only against the superstructure serial number. Before ordering one for a crane that slews roughly or with play, measure the tilt clearance with the boom loaded and unloaded and compare it with the wear limit in the manual; a bearing that is still inside the limit usually has a reducer or pinion problem instead, and those are far cheaper to fix.