Falkirk Wheel, Scotland, United Kingdom

The wheel rotates together with the axle, which is supported by four-metre-diameter slewing bearings that are fitted to the ends of the axle and have their outer rings mounted on the plinths, which in turn are constructed on top of piled foundations.
The slewing bearing at the machine-room end of the axle has an inner ring gear which is configured to act as a rotating annulus. The rotating annulus is driven by ten hydraulic motors which are assembled on a stationary bearing and motor assembly known as the planet carrier which in turn is also mounted onto a plinth similar to the one at the other end of the axle. The drive-shafts of the motors have pinion gears which act as stationary planetary gears in this train of gears and engage the rotating annulus ring gear. An electric motor drives a hydraulic pump which is connected to the hydraulic motors by means of hoses and drive the wheel at 1/8 revolution per minute.
• How the caissons are kept level
The caissons need to rotate at the same speed as the wheel but in the opposite direction to keep them level and to ensure that the load of boats and water does not tip out when the wheel turns.