Hoist & Winch Ltd. recently supplied a special tandem-lifting hoist system as part of improvements to Environment Agency flood defence assets at Taplow Weir on the Jubilee Relief Channel, a 7 mi (11.6 km) asset that reduces flood risk to 3,200 properties by diverting water from the River Thames when flows are high.
The tandem hoist lifts 23-ft (7-m) long galvanized steel stop logs, weighing 2,000 kg each. These stop logs provide a temporary barrier to the channel so that workers can perform maintenance on the hydraulically controlled sluice gates.
Working for a large water industry engineering contractor, Hoist & Winch designed the remote-controlled tandem-lifting system to the agency's requirements. In terms of operating, the tandem hoist raises and lowers the stop logs in a level position so they align correctly in the guide rails without any misalignment. At the heart of the system is a pair of Yale CPV 5,500 lb. (2,500 kg) safe working load, single-fall, electric-powered chain hoists mounted in motor trolleys to provide fast and slow speed operation.
A Danfoss/Ikusi wireless remote control handset offers individual control of either hoist raise/lower motion for initial leveling of the load hooks before lifting operations. The wireless remote also provides dual tandem hoist control for the accurate level positioning of the stop-log load during lifting and lowering.
In the event of power loss or activation of a raise/lower limit switch, special software ensures that the system fails safely and the load does not lift unevenly. As a point of note, the mechanical linking of the hoist units ensures correct load-hook separation at all times, while both hoist units also feature audible and visual operating alarms.
From an electrical perspective, Hoist & Winch provided heavy-duty plug and socket connectors for ease of maintenance and installation. In addition, the company used a fully enclosed (outdoor specification) power-feed system to provide safe maximum hoist-hook coverage across the entire gantry. PVC covers provide added protection for the IP55 hoist enclosure and electrical control panels from weather conditions.
Installation took place over five days and involved a barge-mounted hydraulic crane. Testing of the complete system took place using a dynamic test load of 2.5t + 2.5t + 125% proof load. Additional repeated function tests involved the dynamic test load and actual stop-log load to prove system functionality and satisfy Environment Agency requirements. On completion, Hoist & Winch Ltd issued a LOLER Thorough Examination report and provided operator training for site personnel.
“The project to install the special tandem-lifting hoist system supports the Environment Agency’s annual maintenance program, which is essential to ensure its flood defence assets remain in good working order,” says Andy Allen, Director of Hoist & Winch Ltd.
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