Remember the 50 cubic meter concrete pad that was installed on the construction site?
Well now it is ready for its job as a tower crane base. A 6t Liebherr 100 LC tower crane will be installed.
A team of riggers from Morrow have the task of putting up the crane. Using a 100t Liebherr mobile crane and 20 tonne Terex franna crane from Gillespies Cranes.
It was an early start for the team, trucks with tower sections and the mobile crane were there when I arrived at 630am. The tower crane sections kept arriving all day. The 100t mobile crane has the task of building the crane whilst the franna crane does some lifting off the truck and helps with dual lifts to re position tower sections and counterweights.
At the start of the day the mobile crane sets up, the bigger the mobile the longer the set up, this one took about 40 minutes to set up. The mobile crane operator has a major role, as every piece of the tower crane has to be installed with this mobile.
The base tower section is being lifted off the truck, the bolts in the concrete pad will attach to the bottom of this tower section, securing it to the ground
The rigger bolts the tower section to the pad. The nuts on the bolts must be tightened with a hydraulic torque wrench to get them to the required torque.
The riggers set up a frame to work from whilst they are bolting the tower sections together. Although they are not always used, they make it easier and safer when connecting and bolting the tower sections together.
Tower sections keep being installed, the tower sections connect together and all up will reach 50 meters on this crane.
Now that the towers have all been installed its onto the next step, the A frame. On a flat top tower crane there is no A frame to install, making for quicker installation
Up goes the crane cabin, it will attach to the slewing assembly. As the crane is operated the cabin rotates with the cranes jib.
The counter jib is installed. This will hold the counterweights that balance the cranes jib and loads it lifts as well as house the electrical power board for the crane and computer for remote control operation.
Before the jib is installed, some counterweights are installed. Its very important to put the exact amount of counterweight in before putting on the jib. Too much can tip the crane in the counterjib direction. To little can tip the crane in the jib direction. Remember the purpose of the counterweights is not just to balance the loads the crane lifts but also the weight of the actual crane.
The jib is transported in pieces as its too big to travel as a single piece. When it arrives it is assembled on the ground before it is raised an in this case assembled to the crane in two pieces
first piece of the Jib is installed then the pendant that attaches to the A frame is installed
Trolley being connected to the tower crane jib, this moves up and down the jib and along with the slew and hoist control the movement of the hook block and the loads hooked up to the block.
The second part of the jib is installed
Now the counterweights go in. They simply drop into the counter jib, a steel pin running through the counterweight keeps them from dropping to the ground.
That's the fun stuff over. The rest of the install is quite slow. Now the hoist and trolley cables have to be run out as well as electrical cable that will run up to the power board on the counter jib. A specialised electrician will wire it up, the electricians used usually only do tower cranes and often have a background in plant and machinery if they didn't first start on tower cranes.
The crane is installed, before the builder can use the crane the crane must be calibrated. Limits are set on the crane to ensure that it wont lift in excess of its capacity and damage or tip the crane. The crane operator is inducted by someone from the rental company on the operation and basic maintenance of the crane.
After reading this article you may want to have a look at the tower crane anatomy for a better understanding of the parts that make up the tower crane and what they do.
Column Climbers are an attachment you strap to your boots to allow you to climb steel I beams. I have never seen them in use in Australia as of yet, but they look pretty neat. Not as useful as a scissor lift but much cheaper and a better option than a ladder in my opinion.
They cannot be used on the round hollow section columns or square hollow sections as they need to hook into the flange of the I beam.
Anyone with any experience with the product happy to hear what you think of them.
Today we review the Cattano CM371 4 tonne self erecting tower crane. This is an Italian made crane with a 37 meter jib.
There were a few issues that may prejudice my review. The crane was poorly maintained by the crane hire company. When it was erected the hoist rope was completely grease free and they didn't even bother earthing the crane, they didn't bother calibrating the crane for weights, radius, hook height, deflection etc. so the screen on the remote was completely useless.
The crane was too small for the site, it only reached half the site. The site manager quit half way through this job, and the last thing he said to me was 'when I saw the crane they got for this site I should not have joined the company' haha!
It really was the wrong crane for this job, every trade would ask... 'why did they get such a small crane' my reply was always different... 'because it was on special' 'it was the only crane they could get' and other stupid replies
The crane can lift 4 tonne in 4 part and drops to 1 tonne at 37 meter max radius though the 1 tonne was more like 800kg and had to be lifted in 1st gear. If the load was too heavy the hoist up and trolley out were disabled, like most other cranes.
Changing from 2 to 4 part and back was by taking weight off the big block and droping the small block and pinning together or unpinning (although after a while the small block wouldn't drop, causing the hoist rope to spool everywhere, it was a mission getting it back on)
These small cranes are quite reactive and easy to operate but there was a problem with the slew brake, it was always on, the second you stop slewing it would stop you and make the crane a bit jerky. The free slew was different to every other crane, it has an in service / out of service lever on the base of the crane... it did nothing though, every night I would park the crane in the same spot and no matter how windy it would always be in the same spot every morning. The hoist was painfully slow, even for a self erecting tower crane. The Potain HD40 is faster in 4 part setup than this crane is in 2 part.
The jib must of been slightly bent because at about 30 meters radius it made a horrible sound when trolleying... every single time!
The weird thing was that with all its faults the crane never actually broke down to where we had to stop working, we actually kept working when other cranes stopped because this crane goes really well in the wind which usually isn't the case for self erectors.
Maybe its impossible to give this crane a completely honest review as my experience was so badly tainted. At the end of this job I told my employer I could no longer work operating self erecting tower cranes.
It was a terrible choice of crane for the job
The builder didn't know the go
The crane hire company just didn't care
I'm giving this crane 2 stars out of 5
Previously we looked at static tower crane bases, however the most common tower crane base is a concrete pad with anchor bolts cast into the pad.
The process for making this crane base starts with the engineer. The engineer specifies the size of concrete pad and dimensions required, steel reinforcing and concrete strength. This varies depending on soil type (clay requires a bigger pad, sandstone and rock much smaller) free standing or ties in (free standing requires a bigger pad) the use of rock anchors (anchors can reduce the pad size required) and if the pad is in ground or only partially in ground or above ground (in ground is best)
This concrete pad was constructed for a 6 tonne Liebherr tower crane with a 50 meter jib.
Although the crane is fairly small, and the pad is on sandstone it required a huge pad.
A total of 50 cubic meters of 65 MPa concrete was used to make this pad.
The reason for the large pad was that it is not in ground but above ground and only supported by two sides. A much larger and more expensive option than a pad in ground, if pad in ground were used it would also of eliminated the need for using form work.
Knowlegable readers are probally wondering why 65 MPa concrete was used. The reason being the builder postponed building the pad untill a week before the crane was due to be erected. The engineer specified the concrete must be minimum 38 MPa. Concrete takes 28 days generally to reach its specified MPa. By using 65 MPa concrete it could reach 38 MPa (which it did) in one week not one month as would of been the case with 38 MPa.
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