Hello there, I'm pretty new to the field of cranes. I am a field engineer and have been dealing with cranes only for a month now. I was referring to a load chart and I have a doubt. I don't know what does the bold line indicate in a load chart indicate ? How is the telematic system in Liebherr Cranes different to that of the telescopic booms in Grove Cranes? Why is boom in liebherr referred to as Telematic? Regards..
https://www.youtube.com/watch?v=ur8nulpGweI The bold line denotes the tipping point between stability and structural strength being the limiting factor.
Structural strength ( below the bold line ) part of the chart means that a part will fail ( Boom collapse ) instead of the machine falling over or getting light
http://www.yourepeat.com/watch/?v=ur8nulpGweI
Haha we posted the same video, Tiny.
Great Minds .... and Us
Above the bold line is structural. Below is stability. Most close radius lifts are in the structural part. Most long radius picks fall in the stability part. Most newer AT cranes have pin and latch booms. They all call them something different but the basic principle is the same. Terex as far as I know uses one telescope cylinder for the 2nd section and chains and pulleys for the 3rd and 4th section. Grove and link belt enjoy making complicated four cylinders in one to run their booms out. A lot of boom trucks have one tell cylinder with cables and pulleys. Same setup as terex except terex uses chains.
It's a bit like defining the difference between understeer and oversteer when driving a car that goes off the road. For the uninitiated understeer is when you go through the hedge forwards, oversteer is you go through the hedge backwards ......... In the case of a crane exceeding the SWL above the black line you feel the crane going over through the seat of your pants, below the line you don't. However the result in both cases is the same in that the load ends up on the ground before you really wanted it, and most likely not in the place you really wanted to put it either...........
Are you saying one would probaly be dropping two loads? Neither where one would like them!
Gents , It's misinformation at the very least and for that I do apologize . There is a huge difference in the two . I have asked for this incorrect statement to be removed . Again I popped off an answer where I shouldn't have and my above statement should be completely ignored . I hate that I can't remember stuff like when I was working . My greatest fear is someone would get in trouble thru something I put up . Thank You Knepptune for putting up the correction .
Ah it happens. The biggest difference is what happens after an overload. If you believe a crane has been overloaded in structural part of the chart you need to stop work and do a full inspection before the crane is put back in service. Bent booms are easy to see, a cracked frame and/or stretched swing bearing bolts will usually hold long to hurt someone a year or two down the road. Overload it in the stability part of the chart and if you don't go over it generally won't damage the crane.
I don't think there's anything to worry about here Tiny, like Knepptune said, we all make mistakes, and the correction(s) are well written here in the thread, so it would be kinda messy to remove part of the thread just to leave other parts related to that post, context would be lost, the way it all worked out makes it far better to allow the posts and corrections stand.
One would probably be in the operator's seat.
The big difference is in tipping someone besides the operator can see if it's out of the chart by the machine wiggle or or a corner getting light . still have a chance to sing out and get things stopped . In structural you won't know until the BIG bang
And that typically happens faster than you can sneeze.
Just for my own little search I found an old P&H 8115 truck crane chart with 2 bold lines.
This has been informative so far. How is a actual load different from rated load?
As far as I'm concerned Rated load is what the lifting appliance is capable of lifting in any given configuration at any given radius - actual load is the load it's actually lifting at the time, which may be a lot less than rated load.
Yes , Rated load / capacity is what the machine is good for on the chart . Actual load is what's really hanging on the boom . On my chart I have to reduce overall rated capacity when using accessories like block , jib , rigging , and spreader bar. The weight of each accessory gets added to the weight of the load to be lifted . The final tally needs to be less than the rated load on the chart . Also other factors like wind, rain & snow add to the mix . Impact summed it up good in this post HeavyEquipmentForums 39,000 was the actual load and 42,000 was the rated load .
Well said. Also not to be forgotten is the weight of the line that is hanging from the tip. It can be quite substantial with a longer boom and multi-part line.
That's another good point old-iron-habit . It all adds up .
Aren't load charts fun? On Grove's load chart they don't have you include then weight of the cable UNLESS you are using more parts of line then you need. For example if you have 9k single line pull and you are lifting 10k with a two part line you don't include the weight of the cable. If you are lifting 8k with a 2 part line you include the weight of that extra cable wrap. I swear I wonder who comes up with this stuff sometimes.
You can explain it in one word - liability. All manufacturers make the best crane in the world (according to them) but when everything goes pear-shaped they hide behind the small print.
And when you get into tower cranes read the operators manual carefully on load charts. They normally figure things differently. Many times the load block and cable if figures in to the charts based on tower height and boom length but I am unsure if thats always the case.