Falkirk Wheel, a perfect balance between weight and movement: how this feat of engineering works

The Falkirk Wheel is the only one rotating lift for boats and is able to overcome a difference in altitude of 24 metersequal to 8 floors of a building, in less than 10 minutes. This careful engineering work connects two channels, the Forth and Clyde Canal and the Union Canalwhich are found in Scotlandnear the city of Falkirkfrom which the wheel takes its name. What makes this wheel so special?

Farkirk’s Wheel. Credit: Lowattboy at English Wikipedia, Public domain, via Wikimedia Commons

What is the Falkirk Wheel and how was it designed?

From the beginning the project proved to be very creative: the first original version in 1999 was inspired by a Ferris wheel. But then he was the architect Tony Kettle to design the definitive version inaugurated in 2002. Small curiosity: to illustrate how it works he created a model of the wheel with the Lego of his 8 year old daughter. The Falkirk Wheel is not the world’s first boat lift, but unlike the others this is truly a brilliant model for several reasons. First of all because it is capable of moving boats up to 400 tons with the energy used to power 8 water boilers. But how does he do it?

How does the Falkirk Wheel work?

The entire system was designed with the aim of reducing consumption to a minimum, from the construction material to the innovative design. Let’s start from the materials and elements that compose it. The wheel is composed entirely of steelto ensure long-term resistance.

There are 3 pieces that make up the wheel: the two tubs or “gondolas” where boats enter; the two arms which support the tanks; the central axis which acts as the pivot of the rotation.

The operation of the Falkirk wheel is based on the Archimedes’ principle. In very simple words: when a boat enters the tank, thanks to precision sensors, a quantity of water necessary to balance the weight of the boat and its load is released. In this way the overall weight is always the same and the tub remains in balance, does not overturn and acts as a counterweight by exploiting the force of gravity.

This is why the energy used is minimal, precisely just 1.5 kWh to do half a turn. Because all you need is a little push to activate the rotation and to brake. The movement of the wheel is driven by 10 powerful synchronized hydraulic motorswhich make it rotate 180 degrees, allowing the tanks to reverse their position: once the exchange has taken place, the gondola doors open and the boats can continue their journey.

The gear system of the wheel

But this is only what happens outside, because the beating heart of this system is inside. This is a gear composed of helical wheelsthe cogwheels that are also inside watches and which are designed to fit together perfectly. This system takes advantage of the principle of motion propagation. Think of the bicycle chain: pedaling activates the chain that turns the wheel.

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This is also how the gears of the Falkirk wheel work: when the motors we were talking about before come into operation, a wheel is activated toothed belt placed on the central axiswhich in turn, when moving, activates the toothed wheels that rotate the structure.

If on the one hand this very high precision system greatly reduces the friction between the mechanical components, further limiting energy expenditure, on the other it is essential to make a continuous maintenance lubricating the gears and making sure the sprockets do not wear out. With correct management of the plant, according to the engineers who designed it, the Falkirk wheel could last up to 120 years.

Before the Falkirk Wheel

Just think that before this wheel the two channels remained disconnected for about 70 years. The old system 11 closed it was decommissioned in 1933 and it took a whole day to do what the Falkirk Wheel does in 10 minutes. Another curious aspect: have you noticed this elongated pointed shape? It almost looks like a sharp tooth. It seems that Kettle drew inspiration for the design from rather bizarre elements: a ship’s propeller, a whale’s thorax, a bearded axe, and described his Wheel as “a fluid, organic and beautiful thing, like the spine of a fish”.