Hypothetical Question

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I think you would have to fill the exact same amount of air in each one, at exactly the same time for it to work.

But those bags you link to look like rubbish. That's just my opinion mind, for what it's worth.

They are however a very useful tool for breaking into cars with.

Don't ask me how I know this.
 
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Theoretically, yes but that would take no account of margin of error in production or safety. Probably better to get 500 or 750kg tested bags to give a safety margin that is acceptable
 
My thoughts were the maximum weight would be 255kg or whatever the limit per leveller was. So if I had 4 that could lift 500kg each then the heaviest cube/object that could be lifted would be 500kg and not 4 x 500kg (2000kg)
 
Not sure if it's relevant or helpful (like most of my answers) but a 2 tonne trailer on 4 tyres rated at 700 kg each works so I think you'd need a bit of leeway if you want to lift it.
 
If you had 4 air levelling bags that can each hold upto 255kg and you had a cube weighing 1000kg, Could you put one bag at each of the bottom corners or would they burst?

I am talking about this sort of thing (Not this one though) https://www.amazon.co.uk/eSynic-Ali...t=&hvlocphy=9046370&hvtargid=pla-830063512465
Should be fine as long as the weight is balanced equally, straight lift up or down, no tilting. Pumped up together or one by one just a little at a time
 
It would almost certainly work because at no point would a single bag be carrying the full weight. However, I would want to build in a level of ‘safety’ by having more leeway on the bags capacity.

Of course there are other factors like load balance etc and what you’re going to do with it once lifted.
 
If you were calculating the lifting capacity of 4 chains for instance you only take into account 3 of the chains for the calculation meaning 75% of the total. I would suggest this to be the same for airbags. This however is for calculating lifting capacity.

I would assume in reality they would lift the 1000kg if you loaded them equally but with a reduced safety margin.
 
May I ask what you are trying to lift, how high, and why? You don't have to answer.

I'm not actually looking to lift anything. A friend of mine showed me 4 of the first ones I linked to that he has purchased. He has an American style Fridge freezer that is a big lump of a thing and when he put it in his kitchen he did not level it up properly. What I think he is planning to do is to put one of the bags under each foot and level it up that way. I am not sure if he is planning to leave the bags underneath it but with him getting 4 of them it does look that way. Anyway that got me wondering if 4 x 250kg could support 1000kg or if they could jointly only support 250kg. (I know ........... but in my defence it has been a slow day) 😜
 
Not sure if it's relevant or helpful (like most of my answers) but a 2 tonne trailer on 4 tyres rated at 700 kg each works so I think you'd need a bit of leeway if you want to lift it.

I never thought of it like that but you are right :)
 
Consider a four-legged chair stood on an uneven floor. The chair rocks a bit. At mid-rock, there is a point at which all the weight is on two diagonally opposite corners, with the legs on the other diagonal clear of the floor.

Many moons ago, an incident occurred at work. A large tank full of cooling coils and other gubbins was being constructed, and for reasons we need not discuss this was happening away from the tank's final resting place, thus necessitating the finished fabrication being moved. To place it on skates, it had to be lifted - 40 tons of it. Some bright spark decided that this would be done by 4 10-ton chain blocks equally spaced round it. The riggers, when they saw the job, were not happy, reportedly; but were told to get on with it. This they did, and despite their best efforts, one chain went a bit slack. This effectively threw 40 tons on to two 10 ton blocks, with the inevitable brown-trouser inducing result - fortunately, without any injuries. After much faffing, it was found that damage was not severe, but - erm - lessons were learned. (NB - happened before my time, so not guilty - but it obviously became a much-related incident.)

Rule is, if you're lifting something at four points, rate each of the four items of lifting equipment at half the item's weight. Thus, for a 1000kg fridge, four bags at 500kg per bag would be wise. Four off at 250kg risks all 1000kg resting on two bags at opposite corners, and the other two doing nothing much. There may be an exception if the 1000kg is flexible enough to evenly distribute it's own weight, but in the case of a fridge, I suspect that's not the case.

Four bags rated to 500kg each, or stay well away.
 
Consider a four-legged chair stood on an uneven floor. The chair rocks a bit. At mid-rock, there is a point at which all the weight is on two diagonally opposite corners, with the legs on the other diagonal clear of the floor.

Many moons ago, an incident occurred at work. A large tank full of cooling coils and other gubbins was being constructed, and for reasons we need not discuss this was happening away from the tank's final resting place, thus necessitating the finished fabrication being moved. To place it on skates, it had to be lifted - 40 tons of it. Some bright spark decided that this would be done by 4 10-ton chain blocks equally spaced round it. The riggers, when they saw the job, were not happy, reportedly; but were told to get on with it. This they did, and despite their best efforts, one chain went a bit slack. This effectively threw 40 tons on to two 10 ton blocks, with the inevitable brown-trouser inducing result - fortunately, without any injuries. After much faffing, it was found that damage was not severe, but - erm - lessons were learned. (NB - happened before my time, so not guilty - but it obviously became a much-related incident.)

Rule is, if you're lifting something at four points, rate each of the four items of lifting equipment at half the item's weight. Thus, for a 1000kg fridge, four bags at 500kg per bag would be wise. Four off at 250kg risks all 1000kg resting on two bags at opposite corners, and the other two doing nothing much. There may be an exception if the 1000kg is flexible enough to evenly distribute it's own weight, but in the case of a fridge, I suspect that's not the case.

Four bags rated to 500kg each, or stay well away.


I've just phoned my mate up and explained the 50% rule to him and we both agree it does make sense, we can't believe we hadn't thought of it ourselves. Thank you for the explanation.
 
If the bags were interconnected the pressure in each would be identical - failure in a bag would ultimately be related to pressure not weight. A small safety margin "may" be OK.

However one could conceive a situation where two corners were carrying (say) 800kg, and the other two 200kg. Inflating interconnected bags would cause what ever is being lifted to tip and possibly topple!

Pumping up the bags individually to raise the items evenly with uneven weight distribution would likely fail as one or more bags would be overloaded unless there were a significant safety margin.
 
The prudent answer is “possibly not”. In theory the stated capacity is there (a quarter of the load is distributed to each bag) but that only holds true for a uniformly distributed load so if there is an imbalance, you might overload a single bag.

With the above being said... the actual answer is “probably fine”. The stated capacity of the bag will likely have a margin of safety applied to it which will be more than capable of tolerating any typical imbalance.
 
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