28.11.2003

Brevini takes the strain

Brevini UK has supplied the hoisting power for a special application crane, designed to maintain HV power lines in Argentina. The crane, designed and built by Rob Sonnex and based on a tracked Athey logging trailer, will be used to restore power after outages in bad weather to power lines that run for over 1,000 miles across arduous terrain in the country.

The design specification requires the crane to lift 500kV electricity towers, each weighing over 8 tonnes, while standing in up to 2 metres of flooded pampas ground and often in high winds. Brevini supplied two of its TNE Model winches, one to lift the crane’s boom and a second to act as a hoist winch.

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The design specification requires the crane to lift 500kV electricity towers, each weighing over 8 tonnes, while standing in up to 2 metres of flooded pampas ground.

The latter mentioned winch is a TNE 6000 unit that incorporates the drum drive and brake, mounted onto an A-frame, which itself is bolted on to the crane’s structure. The winch design combines small hydraulic or electric motors with planetary gear stages to increase torque and reduce weight. The drive arrangement also minimises the torque stress within the system by using smaller, faster drive elements and distributing any point pressure across many planet gears.

“Line speed was important here as the time taken to hoist these pylons is just 30 minutes, compared to a full day that it takes to erect European-style four-leg pylons,” said Jon Snaith at Brevini UK. “We achieved a 39 metre per minute line speed with a continuous 5 tonne load using a three-stage planetary reduction, an adapter plate and a hydraulic piston motor of just 90 cubic centimetres. We were also able to incorporate an fail to safe multi disk brake at the input shaft.

“The winch brakes are specified with a 10 tonne capacity to compensate for wind loading, as the crane is used to restore power lines and pylons that have been blown down in storms and conditions can still be fairly inhospitable when they are being erected. A two-part hoist is used to lift an SWL of 10 tonnes.”