Falkirk Wheel, Central Scotland (video 8:02) – A real time view of the Falkirk Wheel turning 180 degrees. The wheel joins two canals and gives access to Glasgow and Edinburgh.
The Falkirk Wheel has an overall diameter of 35 metres. It consists of two opposing arms which extend 15 metres beyond the central axle, and which take the shape of a Celtic-inspired, double-headed axe. Two sets of these axe-shaped arms are attached about 25 metres apart to a 3.5 metre diameter axle. Two diametrically opposed water-filled caissons, each with a capacity of 80,000 gallons (302 tons), are fitted between the ends of the arms.
These caissons always weigh the same whether or not they are carrying their combined capacity of 600 tonnes of floating canal barges as, according to Archimedes’ principle, floating objects displace their own weight in water, so when the boat enters, the amount of water leaving the caisson has exactly the same as the boat. This keeps the wheel balanced and so, despite its enormous mass, it rotates through 180° in less than four minutes while using very little power. It takes just 22.5 kilowatts (kW) to power the electric motors, which consume just 1.5 kilowatt-hours (kWh) of energy in four minutes, roughly the same as boiling eight kettles of water.
That’s engineering
- Archimedes’ principle
Engineering ideas
- balance, kilowatts (kW), diametrically opposed, axle
Learn more…
- Archimedes’ principle – history
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