High level lifting revisited

[The Medway Handyman]

Done a lot more research into this. Previous post for info;

--------------------------------------------------------------- Starting to get more work installing patio awnings for a company.

The larger ones are heavy. Up to about 4 metres long is manageable by 2 people, above that, especially on the half cassette jobbies (the brackets need careful alignment) is a bit of a struggle.

Current method is me & Desmond & two step ladders.

Looking for a more controlled mechanical way of lifting to around 8' above ground.

No clearance behind awning to speak of, so it needs lifting from above or below.

I'm considering a ladder leaning against the wall, with a block & tackle to give a 3 fold advantage. Slightly worried that the base may slip away from the wall.

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Thanks for all the helpful suggestions & ideas - apart from the f****it Unbeliever obviously.

Sorted out the weights of the largest awnings - around 65kg max for the really big ones.

Sorted out the hoist, scaffold poles & clamps to build something like this;

someone pointed out they want silly money for it.

Only question - what are the maths behind the relationship between the two front legs & the long leg?

The top of the long leg is freestanding. Apart from trial & error, how would one calculate the point at which the front legs meet the long leg - so the whole thing doesn't tip forward - or the long leg doesn't slip backwards?

Still looking for rubber feet to protect surfaces, chains to prevent legs moving, lifting bar & straps etc, but this looks like a good DIY alternative to spending £2K.

[Roger Mills]

I don't think it will tip forwards, because the bottoms of the short legs are presumably against the wall, and the weight being lifted is

*behind* this point.

What *will* happen, however, if counter measures are not taken is that the base of the long leg will slide backwards, and the short legs will fold down. To avoid this, the base of the long leg either needs to be fixed to the ground, or it needs to be braced to the bottoms of the short legs with tension straps.

I'm not sure that the relative lengths of the legs is that critical, but

- assuming the one in the video actually works ok - you could estimate the proportions from that.

[george [dicegeorge]]

Inthe video almost all of the weight is on the front legs, which is why man 3 is nonchalantly leaning on the the back leg, in case it lifts up of slides back!

[g]

[fred]

In article , The Medway Handyman writes

Your life will be infinitely easier if you can rest the long leg against the wall (like a ladder) and remove the cantilever effect altogether, otherwise it is a variation on a see-saw and much more likely to end in tears. Note that theirs has bars at ground level linking the stays back to bottom of the cantilever to stop it moving back but there will be mucho bending stress in the cantilevered beam.

Have you had any installations yet where you couldn't have rested it against the wall?

[Dave Liquorice]

Only *just* behind that point, it might be a little "unpredictable" and if it did tip it would keep going, as it would become more and more unblanced as it tipped.

The bottoms of all three legs need to be connected together.

[Roger Mills]

As long as the long leg can't move backwards - i.e. it's tied to the other two legs at ground level, it couldn't tip forwards very far because the 'load' would come into contact with the wall.

Agreed.

[Takes me back a bit. When I did A-level Applied Maths, I used to analyse hundreds of similar structures - resolving all the forces and moments - but that was 50 years ago, and I'm a bit rusty!]

[Cicero]

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The main central member in the commercial version (your picture)looks to be quite a substantial cross section of tubing. Your proposed version (presumably using a single scaffold pole) might not be rigid enough to give a comparable safe lift. If it bent to one side (or the load was slightly off-centre) your whole structure could collapse sideways. I think you should try to get two supports (and lifts) - they need only be two or three feet apart.

Since you've decided on scaffold pole construction have another look at my original suggestion and consider putting an adjustable horizontal arm near the top of each to carry the gin wheels and to contact the wall for stability. Even if you find that a single lifting arm is strong enough you might consider adding the adjustable horizontal to get some space and to lean against the wall.

My original suggestion:

If you can transport some scaffold poles (and clips) then this will work.

Two 'A frames' made from scaffold poles thus:

|\ | \ | \ | \ | \ |-----\

Join the two A frames with further scaffold poles and attach one or two gin wheels to the topmost horizontal pole.

As far as rubber feet are concerned I don't think you need bother; suitable offcuts of wood can be used both for levelling and protecting paving etc. This is what I've always used for my scaffold towers and never caused any damage.

Cic.

[Dave Liquorice]

"unpredictable"

Or window... and keep going...

Ah the only bit of Pure Maths I could understand were those bits that I needed to do the Applied Maths...

[The Medway Handyman]

Thanks for all the comments & tips. I reckon that a) it needs to touch the wall at the apex and b) the legs need to be tied together.

I've found the winch

yesterday and I'm amazed at how well made it is for the price. Straight lift 50 kg, but comes with a block so you can rig a gun tackle to advantage & get a 100 kg lift to 4 metres.

Current thoughs are to use a double extension ladder resting against the wall as the main arm, then sort out a triangular base for extra stability.

[Dave Liquorice]

Twenty quid! Flippin heck, this does worry me though:

Q) Can it unwind freely under load? A) Yes the product does support that.

Has it got a brake or lock?

Ladder sabilisers?

=A395 + VAT.

[The Medway Handyman]

Just tried it with 2 x bags of post crete - they must be 20 kg + each? If you let go of the button it just stops where it is. Don't know what they are on about.

I'll check those out. Ladder seems to get more stable with the weight. Tried to move the bugger & couldn't. Might be different if the load sways - I'll have to play a bit more!

Looking good so far.

[Pete Verdon]

I've used one of these to lift a boat engine. (Winch was bought off eBay by a mate, but looks identical.) Worked very well.

I think the Maplin monkey has got his wires crossed - by "unwind freely" he means that if you press the down button the hook goes down. It doesn't unwind on its own.

Pete