Dorrin K Mace, Horologost

Dorrin K Mace, Horologost
The Clock Man in a pensive moment

Wednesday, September 21, 2011

World's Largest Clock

I am often asked what the largest clock is that I have worked on.  I have worked on several tower and street clocks, but none comes close to the largest mechanical clock recently completed in China.  Below is an article from The Guardian in Great Britain.

It combines 150 years of expertise with cutting-edge racing car technology and makes Big Ben's clock look diminutive.Workers are this week beginning to install the world's largest mechanical clock in the unlikely surroundings of Ganzhou, a city in southeast China.
The faces are 13 metres in diameter – almost twice the size of those on the Houses of Parliament tower – while the minute hand is 7.8 metres long.
It may be a classic example of China's ambition, but the clock was made in England by the family firm Smith of Derby. Founded in 1846, the company also has timepieces in St Pancras station and St Paul's Cathedral.
The firm said the last time it built a large mechanical clock from scratch was in the 1950s, although it has continued to refurbish and repair them. In recent years most people have opted for cheaper, lighter electric versions.
The £1m project has required new technology as well as historical expertise. "When you get beyond a certain scale, the complexity and difficulty becomes magnified beyond the degree to which [a clock] is larger," said Jonathan Betts, senior specialist in horology at the National Maritime Museum in London. "It becomes much heavier than the size would suggest, because there is so much more mass to it."
Traditional steel hands would have weighed around 2 tonnes each. Instead, Smith turned to EPM Technology, a Derby firm that creates carbon fibre panels for F1 cars. It used its expertise to make hands weighing a mere 65 to 70kg (about 150lb). The four giant clock faces were produced by Yantai, a 95-year-old Chinese firm.
"The greatest challenge was to make it safe [given its size]," said Bob Betts, managing director of Smith of Derby. He pointed to the 1976 incident in which Big Ben's clock mechanism exploded.
"The [other] unusual thing is that it's exquisite – it has to look lovely because it's on public display."
The tower includes a viewing gallery so visitors can inspect the movement, which is made from hardened steel with bronze finishing and brass and gold-plated components. The clock is the largest of its kind in the world when measured by size of dial and hands and has taken a year to design and build.
Despite weighing 10 tonnes it was flown to China to meet the customer's deadline. Staff from Smith have travelled to Ganzhou to install it in the 113 metre high Harmony tower, at the heart of a new development described as part business, part residential and part horologically themed park.
The clock will be unveiled at the end of the month and the tower opened to the public next year. The timepiece is accurate to within 30 seconds a month and uses GPS technology to correct itself. It comes with a 100-year guarantee, though the company says it should last much longer.
"We were doing pieces in China 100 years ago," said Betts. "It's a delightful position to be working with them 100 years later and still looking after all these pieces." The clock on the customs house on Shanghai's Bund was made by JB Joyce and Co, now part of the group. Other timepieces were destroyed in the turmoil of the last century, but Betts said several cities were interested in reinstalling them.
"Low technology is not always bad, especially if you want it to last for a very long time," said Jonathan Betts, who is not related to the Smith of Derby boss. "As long as you don't want something that gives you the time to within 1/1,000th of a second, mechanical clocks are a very good option. They have centuries of working life in them."
He added that people also found the artistry behind them compelling. "Even on the most basic level they capture people's interest: to see these entirely man-made objects with lives of their own," he said.
A spokesman for the Ganzhou Expressway Company, which is developing Harmony park, said it chose a mechanical clock because it wanted a historical feel and turned to the UK on the advice of experts. The firm hopes the tower will be morally improving as well as useful.
"Not only will it record the time, but it will also remind people not to waste time," said the spokesman.

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