Just curious here; From the "advice" thread: Under what kind of circumstances would a crane be de-rated to a lower rating, with the possibility to be re-rated to the original, higher rating ?
To get around certain laws. In California there were certain laws that only applied to 15 ton or bigger cranes. So people would have the manufacturer derate the crane. In Chicago there were certain cranes derated to 20ton and New York has cranes that were derated to 35 ton. I always heard that it was due to Union law on what size crane required an oiler. But I don't know for sure. I do know you can get some bargains on a crane that has been derated if the seller isn't aware of the actual model or tonnage. It's really not practical to have one re-rated tho.
So, on a de-rated crane, would the mfr. then publish a separate lift chart for that particular unit ? I had initially thought of the de-rating as something the Certifying Engineer would do in response to wear or some kind of damage, or the way that unit may have been equipped / rigged.
Yes they just slap a different load chart on it and record it as that tonnage. Most cranes are rated at a ten ft radius. Our tms200a just has three sheaves on the boom for a max six part line where a tms250 has four sheaves so you can have an eight part line. From 15ft on the load charts are identical. From a certain radius on a derated crane will have an identical load chart to the original load chart. They did it so that crane companies didn't have to send an oiler along. Since you can never really lift the max rated load because it's never really practical most of the time the load chart within 20ft is pretty much unused you can call it whatever you want to. I'm guessing those loop holes have been closed by now.
I just came across this Link-Belt HTC 14 . It was just as Knepptune described in post# 2 . http://www.machinerytrader.com/listingsdetail/detail.aspx?OHID=11115035 Seems like a lot of military cranes were de rated as well .
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I don't know what the cutoff is but I find it a little humorous that the manufacturers got involved in getting around Union laws. I think the requirements for an oiler are now based upon number of axles or crane gvwr. Don't hold me to it tho. I think some jurisdictions now require different licenses for 15t and bigger cranes. May be interesting to show up to one of those places in that tms145 and explain to them that it's only a 14.5 ton crane. Bet you'd get some interesting reactions.
I've bought a couple of de-rated cranes from the military in the 25-35 ton range. TMS250's and TMS300's, but I have no clue why the military would care to de-rate a crane, being that they pretty much make their own rules and most are used on a base. My guess as to why you would want to re-rate a de-rated crane would be for resale value most likely.
I work crane rental in Northern CA. Whenever counterweight has to be brought to the crane an oiler is required. We have an 80 ton link belt that when the cheek weights are needed, so is an oiler. on the flip side, we also have a 90 ton Link Belt RT that doesn't need an oiler.
Most likely to absolve the government of responsibility should something break and someone injured or killed. Rick
My thinking on the military de rating a crane is to make the load chart more realistic in adverse conditions . Kind of how they rated the military trucks . 2-1/2 , 5 , & 10 ton rated for those loads under poor road ( or no road ) conditions .
Our local requires an oiler an any lattice rig or any hydraulic over 60 ton..( 61 and up)
That would make sense but every de-rated crane I've ever seen had a normal load chart from 15 ft on. if it's derated for ground conditions it needs to be derated throughout the whole chart.
Funny you mention New York. Check this crane out. https://old.cranenetwork.com/detail...iling=2535.00&suggested_search=true&id=182316