Throwback Thursday – A Smooth Ride Down
To celebrate the launch of our new News page we are going back in time to the article written by Cranes Today featuring our own Darren Appleyard.
A new Terex CDK-100 Derrick with a hydraulic luffing jib was put to the test removing a CTL180 Comedil tower on Europe’s tallest skyscraper, the Shard.
The Shard tower is at 310 metres high with 72 habitable floors, and an open-air observation deck on the 72nd floor.
Darren Appleyard of High Sparks TCS Ltd, Select Plant Hires former senior operations manager and appointed person for erection, dismantles and climbing operations for this Shard site, was responsible for planning the lifts for all seven of the tower crane installations and removals for the project.
In addition, Appleyard managed the disassembly of the CTL180 tower using the Terex CDK-100 Derrick.
It has a maximum capacity of 16t, lifting 5.4t at the tip of the 21.5m jib used in this application
Appleyard said “The plan was always to use a Derrick to remove the final tower, but the initial plan was to use the old version of the Derrick. Select Plant contacted Comedil and gave them the requirements needed to remove the CTL180 and the new version of the Derrick was devised. It would also be made easier to dismantle than the older Derrick.”
The Derrick was used to remove the tower crane before being used to remove the grillage that the tower crane had been attached to.
“It was on a cantilever grillage system from level 56 from the tower crane and tied to the structure at level 65” says Appleyard. “The Derrick itself was erected by the CTL180 on another cantilever grillage system on level 72. Obviously when the Derrick was erected it was commissioned tested and then left out of service while we then climbed the tower down to the level which the Derrick could dismantle it. We climbed out 7- 6m sections of the tower crane from the 84 metres of mast to the 42 metres of mast” says Appleyard. “There was an Anemometer on the Derrick as well so we could keep a check on the wind. It was cloudy but the wind was okay. “The Derrick removed the counterweights first as the laydown area of the jib was small, the main jib of the tower crane had to be removed in 2 sections “We took the 15m of Jib down first then the inside 20 m of jib. “Because of the length of the jibs that the Derrick crane had to lower, there was only one position from which we could lower them to the ground.”
As the building jetted out at the bottom the Derrick had a 5m to window to drop the tower jib through and get it down to the street.
“It was the site itself and the building shape that presented most of the problems because it tapered. “The base of the building was wider than where the tower crane was situated, so that itself created the problem. You needed the crane to pass the parts down the side without causing damage to the building” says Appleyard. Because of this removing the 2 tower jibs were not easy.
“The jibs would have been the tricky part, you’re working over 200m in the air and you have a tagline. “Holding it straight is important. It was attached to each part of the Crane sections being removed. “If the Derrick was to slew it would come into the building, with a 2.5 metre gap on either side, so we had to drop it straight down essentially. We couldn’t do anything else apart from drop each component virtually straight down. Consideration was taken to make sure the capacities would equal the safe working loads, even at full radius and with the added weights of the rigging and hoist rope” Appleyard explains. “If we had put more jib on the Derrick to give us extra reach it wouldn’t have had the capacity to lift the items we had. “When the hook block is at ground level you’ve got that much hoist rope coming off the Derrick, increasing the load on the Derrick, this needs to be taken into account for the safe working load for the crane. You’re losing 650KG of safe working load capacity over that height.”
The 100t Demag mobile crane, over 20 metres away in the haul road nearby, was used to reach down into the drop off area on the street and bring the jib back to where the transport could be reached.
Terex’s CDK-100 Derrick, which is still in its post-prototype phase, features a small footprint of 3.8x 3.8 metres and uses a hydraulic arm instead of a hoist for luffing which Terex says adds smoothness and precision control of movement.
Darren has commented on the usability of the new CDK-100. “It’s a good bit of kit! I’ve worked with the old Derrick and put it in some tricky places, especially during Canary Wharf works. “With the new one you have more control is not as sharp and it’s got such a small footprint for what it can lift.”
He says that being able to use the Derrick’s luffing hydraulic jib to carry out the disassembly of the jib itself was one of the highlights of the lift this. “This was where the hydraulics come into its own. We turned the jib of the Derrick towards the building and with the help of additional equipment called a Tirak winch, that was bolted to the floor at level 81 along with a deflection sheet on the same floor and the rope passed up through another sheave attached to a Haki span beam on level 84 – we put the jib of the Derrick vertically and used slings to remove the jib sections in smaller sections . The Tirak winch removed the jib sections and lowered to level 72, were they were removed using the external hoist. Attached to the same grillage as the Derrick was a Palfinger arm which was then used to remove the remaining parts of the Derrick, which all went down using the external hoist,” Appleyard concludes. This article was extracted from the June 2012 Cranes Today edition