Some people talk about a 100 ton crane, some people say 300 txm. Who is right?
Both; but who tells us what the crane can really do? Only the specific load chart for every crane model.
It will tell you at what distance from the centre you can lift what load. These values are calculated according to standards (defining for example how often one is supposed to lift something without breaking the crane under extra stress, like wind, fast movements, etc.) and depend on the materials used in construction of the crane (steels) and on the kind of control (hydraulically and/or electronically) used to steer the crane and limit excessive movements of the load.
Here the engineering skills start: Do you regularly want to lift heavy loads close to the centre or do you want to lift lighter loads at a long distance? Do you need a certain capacity at a certain distance? The boom construction will have to change accordingly and the load chart will tell you whether the crane is the right one for your job.
More about the very different concepts (a more theoretical one, like 100 ton or a more practical one, like 300 txm):
100 ton means, that theoretically the crane could lift one metre from the center of the column 100 ton. This is only theoretically possible, because
a) the crane comes with a long boom, hook, etc. All this weight would have to be deducted or cut off. The crane would not be a crane anymore.
b) The crane is usually mounted on a truck – you cannot lift anything one metre away from the centre of the column, because the truck is in the way.
This value gives you an idea about the strength of the lifting cylinder(s) between the column and the first boom. It can be completely theoretical or practically tested. As a rule of thumb it is multiplied by three to give you the txm (100 t x 3 = 300 txm).
The txm gives you a better indication about what the crane can do in real life:
100 t at 3 metre
50 t at 6 metre
10 t at 30 metre
(Please bear in mind that these values are completely theoretical values, because you need to lift the boom construction as well – therefore you will never be able to lift 10 t at 30 metre).
Moment is the combination of a weight, distance and speed. When you lift or lower a weight with the crane boom or the winch, or if you move the boom in another direction you will always have a moment on the load and moving parts of the crane.
Too much moment will either break the lifting gear or crane and/or topple the crane over.
With the help of sensors and electronics these forces are controlled by slowing down or even stopping the movement of the various crane parts before serious damage is done to man or machine.
Values shown on load charts are always based on the assumption that all stabilisers of the crane are fully extended. Unfortunately, real life does not always give you that opportunity. You can rely on the common sense and experience of the crane operator (too many accidents have shown that this is not a good option) or leave this job to electronics and sensors.
How valuable is a life lost under a crane fallen over due to wrong positioning and lifting?
With the right stability control you can even increase the lifting values of your crane, because the security factors calculated for a certain degree of misuse can be reduced. The investment pays basically for itself, because you can do bigger jobs with a smaller crane in more confined spaces and even in areas not possible before (eg. in front of the cab).
You have already a crane with load moment and area control to lift things. Can you also use it to lift people in a specially designed basket?
Legally, in most countries you must not. You will need to use a specially designed aerial work platform or elevator for this.
What is so special about the platform? The construction, sensors and the electronics. The construction has higher safety factors, more sensors (some double) and different load moment and stability control parameters.
Only if your crane has the necessary lifting capacity and is equipped with the right sensors and electronics it may be used legally for person lifting. In some countries specific additional equipment is called for and needs to be installed as well.
Standards are set to make life easier - our brochures will tell you to what standard the crane has been designed and manufactured.
When you look at a load chart, you need to refer to the applied standards, too.
According to the standards applied, the manufacturer or the person who makes the product available guarantees the safety of the product. The visible sign for this promise is the CE-logo, applied on the product.
Standards evolve and are set higher in some countries than in others. You may even find that within the EU the same standard is applied slightly different in the many different countries that make up the EU.
When a crane is sold with CE-Certification, it is either sold as
a) incompleted machinery (means that the crane is a machine, but needs to be mounted (ie completed) on something (eg. a truck) to function safe and properly, as intended. The installer is responsible for the full certification of the installed crane and must receive from the manufacturer the technical information needed for the proper installation and documentation thereof.
b) it is sold as completed machinery (ie. mounted on a truck). Again, the installer is responsible for the full certification and documentation thereof.
As said before, standards are set to make life easier. But what does this combination of letters and figures mean?
UNI: Ente Nazionale Italiano di Unificazione (Italian National Standards Institute).
EN 12999: A standard for (loader) cranes, approved as as European Norm.
HC1: The crane is regarded as a loader crane (mounted on a vehicle or on a fixed plinth). This has an effect on safety factor calculations for various forces on the crane's parts.
S1: This is an indicator for the kind of usage (eg. hook, grapple or bucket) and the intensity of use of these various attachments; all these factors go into the safety factor calculations for various forces on the crane's parts.
Eg. S1 for a hook means moderate use; S1 for a bucket means very light use.
A standard loader crane is not designed to work regularly as a timber or scrap crane.
HD4: means that the crane picks up the load with increasing speed (which needs a higher safety factor for the calculations). If you would have a special control limiting these forces (ie. lifting the load gently), the same construction could be classified HD5 and you would be able to lift higher loads.
Some world-wide known brands seem to have different points of view compared to the rest of us.
We at EFFER are proud of our engineering and show the information every crane driver needs in a clear way.
A static load chart show values where the crane just holds the load – it cannot move that load up or down…
Some companies use static and dynamic load charts – make sure to get the right one.
Effer load charts are always dynamic.
Some manufacturers start counting from -2; ie the height of the truck chassis counts as zero –
adding 2 metres height that you will never achieve in real life…
Effer starts counting from the ground up, ie zero.
Some manufacturers show manual extension like hydraulic extensions –
in real life you have to buy, carry and fit those extensions to reach the distance shown.
Effer gives separate, clear information about hydraulic and manual reach.
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