A very tricky operation

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The crane jib at full stretch

If getting a 60 tonne capacity mobile crane through the Landgate and up to the Citadel of Rye had its challenges last Tuesday, May 5, the replacement of a three tonne transformer swinging over the historic rooftops was scarcely child’s play either.

The object of the exercise was to upgrade the power supply from the electricity substation, hidden behind the Kino cinema, and then to renew the underground cabling that serviced the nearby George Hotel and the preparatory work had been well planned and executed with prior route and site surveys identifying the likely problems.

And the main players subcontracted to UK Power Networks all knew what was required – Southern Cranes and Access, the crane operators from Horsham, West Sussex, Riglift the specialist machinery lifting contractor from Erith, Kent, and ALS the electricity cabling team from Ramsgate, Kent.

Outreach critical with lift

Waiting for action to commence, I chatted to Tony Simonsen, the crane driver. He had been driving cranes for the last seven years. This one was modern and capable of lifting 60 tonnes with its jib extended to 20 metres, but if extended to maximum outreach of 35 metres, the weight-lifting capacity is substantially reduced.

This became a critical factor later in the morning and inside the cab is an impressive array of controls, with computerised monitoring equipment.

George Sulman was the lift supervisor for Riglift. His team’s job was to place the key elements for lift-off and manoeuvre the new transformer into its final position. The tarmac area outside the St Mary’s Centre was covered in protective metal trackway and baulks of timber to spread the weight of the crane and avoid damaging the surface.

The old transformer had already been disconnected and was awaiting removal. The jib rose into the air with its four securing chains dangling high across the rooftops. Slowly lowered, they were attached for uplift, but then a snag was encountered. At some 26 metres extended, the distance/weight ratio was too great according to the computerised on-board monitor.

Chains tipped the balance

The weight of the chains (at two and a half cwt.) just tipped the balance into the danger zone. The chains were unhooked and replaced with heavy duty polyester slings, which looked too delicate to do the job, but were of course totally adequate. The load was safely hoisted and set down and the replacement transformer then installed.

Watching all this from the top of St Mary’s church tower was our cameraman who kindly volunteered to film the action, but neither of us reckoned that it would take the whole morning. As he remarked afterwards: “It’s rather like going fishing – there’s a lot of waiting before you catch the moment.”

At least he had the company of the project manager from UK Power Networks, who was keeping a weather eye on the whole affair and he was able to report mission successfully accomplished.

Three days later, the cabling team were still hard at work and Lion Street remained for the time being closed to traffic, with two-way working in East Street and Market Street.

Image Credits: Andy Stuart .

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