A recent load sent to a gold mine in the Pilbara region of Western Australia provided a challenge that was a little out of the norm. A stockpile reclaimer 5.3 metres wide, 5 metres high, 13 metres long and weighing approximately 42 tonnes is the largest item designed and built to date by MCS, and was an over-dimensional load requiring transport on a platform trailer with dolly, and a police escort.
Economies of a larger crane
Because of the size of the reclaimer, CabCranes elected to perform a dual crane lift, using its 130 tonne Demag AC130-5 and 70 tonne Tadano ATF70G-4, each with minimum counterweight, with the lift study showing that this configuration would comfortably handle the lift.
CabCranes MD Dave Hamill said: “In situations like this lift for MCS, we used bigger than needed cranes as it made the lift progress much more quickly and with a much greater safety margin.
“The extra cost of the bigger cranes is sometimes more than compensated for in shorter job times. Customers like Graeme (Cooney, MD of MCS and a former crane operator) are a pleasure to work with as MCS prioritises safety and efficiency as highly as we do.”
The Demag and Tadano are the largest two slewing cranes in a fleet that also includes Frannas and smaller slewing cranes starting with a 12-tonne City Crane. A single support semi-trailer was required for the lift, and this was designed by CabCranes and fitted out to its specifications, with the main aim being ensure safety for the crew when climbing up and operating on the trailer (it is fitted with a ladder and rails, has mounting points for counterweight and outrigger pads to ensure that the load doesn’t move; and has self-contained lighting for night work).
The reclaimer was fabricated with eight lifting lugs at the top, simplifying rigging. Four chains were used to connect the Demag to the load, and two soft slings were used with the Tadano. The load was raised above the deck height of the trailer and rotated approximately 90 degrees, with the cranes slewing in opposite directions to achieve this.
Positioning for transport
The trailer (with dolly removed) was then backed under the load. The real skill was required in positioning the load on the trailer. Hamill explained: “Centring the over-dimensional load does require a high level of skill with the crane operators but particularly with the riggers as sometimes the load will tend to shift as the weight comes off the crane. I count myself fortunate that I have a great crew with plenty of years’ of experience to call on.”
A further issue was ensuring that the trailer ramps, when folded, did not impact on the protruding conveyor discharge section during transit, and some experiment with trailer extension was involved.