We need a crane thread ....... so here it is

V8Druid

V8Druid

do it as well as you can,but learn to do it better
I’m in the French Alps on holiday and there are quite a few of these around on new-build sites. I had a close(ish) look at one today and can only deduce that it is held up by magic alone, as the footprint is tiny (12 feet square) and cribbage looks like zero shits are given. I paced the outreach at over 30m(!) - it’s ridiculous!
Haven’t seen one working so not sure what sort of weight they hang off them but the fact it doesn’t just tip over anyway is very impressive - it has around 16 tonnes of concrete counterweight but the minuscule footprint makes no sense at all when viewed ‘in the flesh’.View attachment 55643View attachment 55642View attachment 55622View attachment 55621View attachment 55620View attachment 55619
that's a LOT of ballast Dan :giggle:;)
 
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Rob65

Well-known member
I’m in the French Alps on holiday and there are quite a few of these around on new-build sites. I had a close(ish) look at one today and can only deduce that it is held up by magic alone, as the footprint is tiny (12 feet square) and cribbage looks like zero shits are given. I paced the outreach at over 30m(!) - it’s ridiculous!
Haven’t seen one working so not sure what sort of weight they hang off them but the fact it doesn’t just tip over anyway is very impressive - it has around 16 tonnes of concrete counterweight but the minuscule footprint makes no sense at all when viewed ‘in the flesh’.
If the base is 12 ft that’s about 4m. The mast is in the centre so call that 2m x 16tonnes is 32te.m resisting over turning (this called the restoring moment) if it’s got 30m of reach divide 30m in to 32te.m and you get about 1tonne capacity at full reach.

That does not make any allowance for a safety factor though. I’m sure Druid will put me right on this but I think it’s 75% on tipping capacity so that give a safe working load of about 750kg so I would think that’s workable on a residential build.
 
V8Druid

V8Druid

do it as well as you can,but learn to do it better
If the base is 12 ft that’s about 4m. The mast is in the centre so call that 2m x 16tonnes is 32te.m resisting over turning (this called the restoring moment) if it’s got 30m of reach divide 30m in to 32te.m and you get about 1tonne capacity at full reach.

That does not make any allowance for a safety factor though. I’m sure Druid will put me right on this but I think it’s 75% on tipping capacity so that give a safe working load of about 750kg so I would think that’s workable on a residential build.
(y)(y)
 
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Monkeybusiness

Well-known member
Had another shufty at it on the way past to the lifts today - I reckon the counterweight is only centred approx 1m from the centre of the slewring (it’s well within the outriggers) so I guess @rob65’s calcs need halving (and the weight/radius of the boom and lifting equipment needs to be taken into account also).
Still looks wrong in every single way, without lifting anything!
IMG_8765.jpeg
 
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Monkeybusiness

Well-known member
Doesn’t look a very busy site , so I’d say everything is broken down into very lightweight lifts..
They’ve done bugger all this week since I’ve been here the lazy bastardos! You’d think it was the holidays or something?!
 
TiltyShaun

TiltyShaun

Well-known member
I looked into those cranes quite heavily in 2007 and was almost tempted to buy one. From memory the capacity was around 1ton at full reach as said by others. Got a client site coming up which would be ideal for one but it still would take a leap of faith to invest.
 
V8Druid

V8Druid

do it as well as you can,but learn to do it better
I looked into those cranes quite heavily in 2007 and was almost tempted to buy one. From memory the capacity was around 1ton at full reach as said by others. Got a client site coming up which would be ideal for one but it still would take a leap of faith to invest.
don't think they're MASSIVE cost to rent in on contract Shaun :unsure:
 
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Rob65

Well-known member
Had another shufty at it on the way past to the lifts today - I reckon the counterweight is only centred approx 1m from the centre of the slewring (it’s well within the outriggers) so I guess @rob65’s calcs need halving (and the weight/radius of the boom and lifting equipment needs to be taken into account also).
Still looks wrong in every single way, without lifting anything!
It’s about where the centre of mass of the ballast weight is, so if it’s all in the. centre that’s fine.

I didn’t make any allowance for wind load or the self weight of the crane though so the actual capacity will be a bit lower than I said but the basis of my ‘back of envelope calc’ won’t be far out. 😀😀😀
 
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