22.09.2009

How tight can you get?

Scotland’s James Jack crane hire has completed a lift which required the crane to pass between two walls with just 20mm to spare.

Working with Ross-Shire based engineering experts Isleburn, the job involved lifting a 500Kg Head Stock, an essential part of the mechanism required to open the Loch gates, into position at Mullardoch Loch near Cannich..

A Kato CR-250 city crane was selected for the job and transported by low loader from Jack’s Aberdeen depot to Cannich, 130 miles away. The crane was then offloaded and completed the final nine miles of the journey to the Loch through the Mullardoch Estate, including wading the estate’s river due to a weight restriction on the bridge.
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The cranes eazes down the top of the dam

The skill and precision of James Jack’s crane operator, Walter Petrie, were then put to the test not only in the lift process itself which involved divers and instruction from below water by radio contact, but also in the positioning of the crane ahead of the lift.

The lift required the 2.39 metre wide crane to travel through the centre of the high sided concrete dam walls - a space measuring just 2.43 metres, allowing only 20 millimetres to spare on either side of the crane.
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With barely 20mm each side it was a tight squeeze

The crane then lowered the equipment 20 meters down the dam wall and a further 10 metres below the surface of the water, where divers instructed the operator via underwater radios to accurately position the headstock.

The result of the operation saw the Loch gates opened for the first time in the 50 years since the dam was built, diverting water into the river and allowing maintenance work to be carried out on the dam.
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Final load positioning was underwater