An electric slewing motor/generator produces electrical power (as a generator) when braking the upper structure, and stores the current in the ultracapacitor bank.
Slewing bearings are often made with gear teeth integral with the inner or outer race, used to drive the platform relative to the base.
The slewing ends are also wound on to another half-barrel.
Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340.
However, there is a damping moment (proportional to roll "rate") created by the slewing-about of long wings.
Slewing bearings often use two rows of rolling elements.
Slewing bearings resemble oversize aircraft control surface bearings.
The main difference between a swing yarder and a tower yarder is that the upperworks is mounted on a large slewing bearing.