Lifting Capacity - Offset Loads

[Mark1982]

I'm trying to spec up an excavator but not sure how to calculate the capacity when centre of gravity of load is offset.

We are connecting a lifting attachment to the quick hitch for concrete pipes up to DN2400.

The combined weight of the hitch/lifter and pipe is 14.5t and the centre of gravity of the whole assembly is 1.4m in front of the quick hitch.

Can anyone suggest a way of getting the right sized machine?

[v8druid]

yer's gonna wanna big bar steward for sure ....... 14.5t ...... and at what sort of radius / reach

As for the CoG being off set on the att. .... the load remains at the lift point on the m/c ..... that is the point of downward force exerted on it ...... if it's suspended / free hanging, like a pipe hook. ..... if its a fixed att., like a set of forks, f'rinstance, then yes the additional distance to the CoG must be added to the equation

Good luck with finding anyone who'll give you a categorical yes on that one


Oh and welcome BTW

[Mark1982]

Thanks v8druid,

It is a pipe lifting device which acts like forks.

You are right, from the dozen phonecalls made I'm definitely not going to get a yes!

The advice I was given is to take the reach to the very tip of the load - not the centre of gravity which should account for the offset.

If I pick up as close to the tracks as possible - reach would be 6.0m.

To give some breathing space, I'm taking reach as 7.5m which is suggesting a CAT 349 FL is up to the job.

I'm tempted to hire a 52t just to take the pressure off.

What do you think?

[v8druid]

Thanks v8druid,

It is a pipe lifting device which acts like forks.

You are right, from the dozen phonecalls made I'm definitely not going to get a yes!

The advice I was given is to take the reach to the very tip of the load - not the centre of gravity which should account for the offset.

If I pick up as close to the tracks as possible - reach would be 6.0m.

To give some breathing space, I'm taking reach as 7.5m which is suggesting a CAT 349 FL is up to the job.

I'm tempted to hire a 52t just to take the pressure off.

What do you think?

I can understand taking the load to the extremity of it, as although you have a CoG for the load .... if it were suspended ...fixed like on a fork it is still exerting force from its extremity back wards, so I'd concur with that school of thought.

As for size ...... you can't beat a bit of overkill for a comfortable seat ....... having had the pleasure of handling loads at the limits (and a little beyond at times) with all sorts of lifting gear, especially cranes ... a margin (as large as possible) is always nice to have.

If your arse is in the sling .... go for gold

It's why you see inordinately large cranes turn up for what look like paltry lifts, these days ..... contract lifting and appointed persons have seen to that .... it's their arses that're gonna get the kicking, if anything goes south, so they just add huge margins .... and charge the customer for it, justifying it with a .. "well that's what size we need" when in actuality, a much smaller unit'd be perfectly adequate

If you ain't paying for it and/or would like a sweat free day, opt for the biggest margin ........ better that than causing damage .... or worse still death or injuries ....... always bear in mind the ultimate sanction .... corporate manslaughter