One of the advanced and precise heavy lifting systems was employed in Australia recently to help strengthen a heritage-listed bridge that was beginning to sag in the middle after generations of service.
Coates introduced the Enerpac PLC controlled synchronous lifting system to exactly position a 54-ton concrete and steel strengthening arch under the graceful old bluestone bridge on the Gheringhap to Warrenheip railway line in Victoria.
The removable arch was specified by infrastructure owner Pacific National so it would provide great safety and prevent further cracking while the line is in service, but can be removed to restore the bridge to its original vintage shape when the line is no longer needed.
The strengthening arch had to be precisely positioned within tolerances of less than 1mm so that the bond between the arch and the bridge offered the maximum amount of strength while reducing the amount of concrete required in the pour to mould them to each other.
The Enerpac Synchlift system which can simultaneously govern multiple cylinders with pinpoint precision was required to lift the arch by just 50 mm after it was positioned by a 30 ton excavator for the fine setup work to begin.
The Synchlift system enables one man in a remote position to simply and safely control massive lifts of thousands of tons and scores of cylinders if required. In this instance, only 10 RSC302 Enerpac cylinders were required, with 62mm strokes and combined capacity of 300 tons to deliver the high safety margins required by Coates Hire for Pacific National.
“Coates employs a wide range of Enerpac lifting, professional bolting and precision hydraulics technology across a variety of civil, mechanical, industrial, infrastructure and maintenance engineering tasks. This partnership and ongoing product familiarity and expertise simplified the task of setup and safety checks,” said Enerpac Technical Support Engineer Ray Paasila.
Using a touch screen linked to all 10 sensor-equipped cylinders, Paasila and Coates were able to dispense with conventional heavy lifts involving a team of engineers setting up individual cylinders and moving around checking to ensure they are all lifting at the same rate (to avoid imbalance and stresses in the load).
“The maximum deviation of any cylinder from the average position during the lift was 0.8mm; the average deviation was 0.4mm. The PLC had been set to give an alarm at 1mm deviation,” said Paasila.
Functions of the Synch Lift employed on the bridge lift included:
- Data logging
- Tilt function
- Centre of gravity display
- Displays of absolute position, relative position and deviation
- Load per lift point, and total load
- Pressure display for each lift point
- Ability to toggle lift points on or off at will
- Valves that lock cylinders in position (do not allow return flow until manually opened)
- Valves to control flow: this enables the operator to achieve greater lift accuracy
- The synch lift can synchronise stroke position or load; it is normal to synchronise for stroke
“We have achieved an accuracy of 0.2mm during testing with 30-ton cylinders and I would expect to be able to achieve even better with larger cylinders than we did on this bridge lift. The latest Synch Lift Technology gives accuracies down to .1mm,” said Ray Paasila.
The Synchronous Lifting system detailed in Enerpac’s new E325A catalogue is available in configurations from 4-64 lifting points. They system electronically controls and monitor movement during the hydraulic raising, lowering, positioning or testing of really heavy objects such as manufacturing machinery, motors, manufactured structures, buildings, bridges, oil platforms, ships, turbines, generators, mills, mining equipment and heavy but delicate computerised/electrical equipment.
“With manual control, differences arising between the lifting points are unavoidable, because measurement of the movement and control of the lifting points are never optimal. Internal stresses resulting can ultimately cause hidden damage compromising serviceability and safety,” says Paasila.
Synchronous lifting offers users significant advantages over manual control, including safety, considerable time savings and virtually no internal stress in the object, helping to obviate potential problems arising later.
Enerpac’s Synchronous Lifting systems have already demonstrated their prodigious lifting ability on tasks where safety and precision were at a premium, including splitting of a 3,500-tonne dragline at Curragh in Queensland for maintenance and lifting of bridges for repair.
The Lifting Systems have also been used in the construction of the world’s highest bridge, the 343 metre high Millau Viaduct in France (which is twice as high as the Sydney Harbour Bridge), and the construction of North Sea oil rigs.
Other innovative technology employed by Coates on the Australian bridge lift included an ingeniously robust and versatile propping structure used to support the bridge for three months until the permanent solution could be completed.
The propping solution employed Coates’ new system of propping componentry, which features 30 integrated components offering meccano-like connectability.
This flexible system means that portal frame structures that were previously unachievable are now possible.
Benefits include ease of assembly and reduced labour costs because of the simple and effective nature of the system.
Pacific National’s ruggedly reinforced bridge is now back in service without major infrastructure downtime and with the job achieved with much greater safety and precision than conventional lifting.