Twiflex to put the brakes on Chinese shiplift

Twiflex has been awarded a contract to supply a braking system for the Gaobazhou Hydroelectric Dam shiplift.

Twiflex has been awarded a contract to supply a braking system for the Gaobazhou Hydroelectric Dam shiplift.

This is the third major contract on the Qing Jiang River, Hubei Province and is the forth shiplift in China to be fitted with Twiflex safety brakes.

The contract, worth GBP 432,000, is to supply 24 VMS-2 safety brakes and four VCS mk-III working brakes along with a sophisticated hydraulic control system.

Also bidding for this prestigious contract were Sime-Stromag Brakes and Siegerland Bremsen (Sibre).

Ultimately, Twiflex won the bid owing to superior technology and its experience on similar installations elsewhere in the country.

Gaobazhou is located 12km from where the Qing Jiang river converges with the mighty Yangtze in Hubei province.

It is the lowest dam and also serves as a conditioning reservoir for the Geyehen power station.

The total capacity of the Gaobazhou power station is 252MW and the yearly output of electricity is 898GWh.

The dam is 435.9m wide by 83m tall.

The shiplift at Gabazhou is design to lift ships weighing up to 300t and will be the only means of navigating the power station dam.

Ships are to sail directly into a large water tank, water gates then seal the tank at each end and a 300kW hoist lifts the tank (with ship inside) 40.3m to the upper level.

The gates then open and the ship sails on up river.

The whole exercise will take less than 12 minutes, considerably faster than a conventional lock gate arrangement.

Four 75kW motors drive a total of eight hoists.

The total lift is 1560t but a counter balance of 1024t brings the out of balance load to just 536t.

A total brake torque of 1840kNm will be required to arrest the hoist under emergency conditions.

The braking system will have two modes of operation.

In normal operation the four VCS mk-III working brakes assist in stopping the hoist and then the 24 VMS-2 safety brakes come on at full torque in order to "park" the system.

In an accident situation the 24 VMS-2 spring applied, hydraulic released safety brakes come on in a "step by step" manner to arrest the hoist in a smooth and efficient manner.

The Twiflex VMS-2 safety brake was first designed in 1984 in response to a mine hoist requirement at the Falkonbridge mine, Sudbury Canada.

Since then over 200 systems have been sold around the world.

Perhaps one of the most famous applications is at the world's deepest, single run mine hoist, the 3.2km hoist at Moab Khotsong, Johannesburg South Africa.

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