Travelling Full Circle with The Falkirk Wheel
The Falkirk Wheel remains one of the UK's most impressive feats of engineering. Opening in 2002, the Falkirk Wheel uniquely connected the Forth and Clyde Union Canals in Scotland.
It formed part of the British Waterways and other bodies plan to regenerate central Scotland's canals. This plan also sought to reconnect Glasgow and Edinburgh. Engineers involved wanted to craft an iconic 21st century landmark while fixing a logistical problem.
The Falkirk Wheel and Visitor Centre [Image Source: Pixabay]
The Forth and Clyde Union Canals were previously connected with 11 locks, with a 35 metres difference in height. Roughly 3,500 tonnes of water were needed per run taking most of a day to pass through the locks.
Falling into disuse in the 1930's the lock system was decommissioned and dismantled in 1933. The canals themselves also fell into disuse and closed in 1962 becoming impassable in the 1970's with two culverts and pipe runs from a nearby housing estate. On the same day, the British Waterways Board (BWB) was created strategize the future of all British Canals.
After meeting local councils in 1976, the BWB decided to keep all remaining canals navigable through bridge building and clearance raising for boats as well as maintain lock systems.
Re-inventing the wheel
In 1993 the Lotteries Act resulted in the formation of the Millennium Commission to use lottery ticket revenue for selected "good causes". According to writer Len Paterson, with sufficient funds accumulated by 1996 the commission sought applications to:
"do anything they thought desirable ... to support worthwhile causes which would mark the year 2000 and the start of the new millennium."
The conditions held that the Commission would fund no more than half of the project, with the remaining balance needing to covered by project backers. In 1994, BWB submitted its plan to the Millennium Commission to reopen the canal link. The plans called for the canals to be opened to their original operating dimensions, with 3 metres (9.8 ft) of headroom above the water. The whole project had a budget of £78 million.
The commission announced the proposal on Valentine's Day 1997. They accepted with £32 million of funding released, 42 percent of the project cost. The now iconic Falkirk Wheel and its associated basin were priced at £17 million, more than a fifth of the total budget. With the Lottery Commission funding, a further £46 million had to be raised in the next two years before construction could commence.
Wheel in Action: Source Scottish canals
In 1999, the original design was submitted by Morrison-Bachy Soletanche Joint Venture Team. This design resembled a Ferris Wheel with four gondolas. Despite its functionality, the commission didn't think it had enough to become iconic.
A 2o-strong team of architects and engineers under the leadership of Tony Kettle were assembled by British Waterways to produce a new design.This was an intense period of work with the final design concept completed in a three-week period during the summer of 1999. The final design was a cooperative effort between the British Waterways Board, engineering consultants Arup, Butterley Engineering and RMJM.
Diagrams of gear systems that had been proposed in the very first concepts were modelled by Kettle using his 8-year-old daughter's LEGO set. Drawings and artist impressions were shown to clients and funders and the visitor centre was designed by another RMJM architect, Paul Stallan.
Initial design concepts included a double-headed Celtic Axe, a ship propellor and whale's ribcage - all extremely interesting visual choices.
Kettle described the Wheel as "a beautiful, organic flowing thing, like the spine of a fish,"and the Royal Fine Art Commission for Scotland described it as "a form of contemporary sculpture."
In 2007, the Bank of Scotland featured the Falkirk Wheel on the reverse side of the new £50 notes.
[Image Source: Pixabay]
With an overall diameter of 35m the Falkirk Wheel consists of two opposing arms extending 15m beyond the central axle. The design is that of a Celtic double headed axe. Two sets of these axe-shaped arms are connected to a 3.8 m (12 ft) diameter central axle of length 28 m (92 ft). Two diametrically opposed water-filled caissons or gondolas, are fitted between the ends of the arms. These gondolas each have an impressive capacity of 250,000 litres.
The design takes advantage of the Archimedes principle to maintain water levels and thus balance the weight of the gondolas. It maintains the water levels on each side to within a difference of 37 mm (1.5 in) using a site-wide computer control system comprising water level sensors, automated sluices and pumps.
It takes 22.5 kilowatts (30.2 hp) to power ten hydraulic motors. This consumes 1.5 kilowatt-hours (5,100 BTU) per half-turn, roughly the same as boiling eight kettles of water.
Each of the two caissons is 6.5 metres (21 ft) wide and can hold up to four 20-metre-long (66 ft) canal boats.
The gondolas need to rotate with the axle in order to remain level. For the most part, the weight of them is sufficient to turn the gears. For precision, the gearing system is specially designed with two three identical large and two smaller gears to provide a smooth and controlled rotation.
Each end of each caisson is supported on small wheels, which run on rails on the inside face of the 8 m (26 ft) diameter holes at the ends of the arms.
View of the gondola gears [Image Source: Pixabay]
The rotation is controlled by a train of gears. It includes an alternating pattern of three 8 m (26 ft) diameter ring gears and two smaller idler gears, all with external teeth, as shown above. When the motors rotate the central axle, the arms swing and the small gears engage the central gear. The smaller gears then rotate at a higher speed than the wheel but in the same direction.
The smaller gears engage the large ring gears at the end of the caissons. This drives them at the same speed as the wheel but in the opposite direction. This cancels the rotation due to the arms and keeps the caissons stable and perfectly level.
The Falkirk Wheel represents a real life "rags to riches" engineering story. Seeing its history be transformed by a team of passionate engineers and architects continues to inspire. It remains a simple but very effective, and dare we say, beautiful design.
Source Scottish Canals
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