Attic hoist / elevator design

[gmgmgm]

It does look complex, and if/when it goes wrong, it's going to be bad. Over-sized mirror pulled through floor, damaging structural beams and sending glass/metal shards through to the valuable cars beneath...

If it was a DIY job then something like a simple hoist pulling up a cage (e.g. one of the smaller IBCs with a side cut out) would be simple and easy, but this might just be too much to go wrong.

Alternative thought - can you put a swing hoist on the /outside/ of the building (like on an old mill), near a window? Perhaps less to go wrong, no chance of damaging vehicles underneath.

 

[Spectric]

You need to take a look at forklift trucks, they come in various capacities and lift heights but are doing what you are looking at doing so use the basic concept and adapt to your needs.

Another option is to use a set of stairs / steps that can be lowered down and then you just walk up them, the angle and step height determines the effort needed.

Simplest option is a hoist and trap door as used in windmills for decades.

 

[MarkAW]

Could you base it on one of these?

https://liftingequipmentstore.com/c...weight-aluminium-hand-stacker-truck-wide-legs

An off the shelf solution. Would only need a basket and gate(s) to prevent falls. Also can be moved out of the way of cars

 

[BucksDad]

Simple approach - Perhaps you could offer to put all the boxes up there for them.. and remind them that it will be their children bringing them down when the time comes

 

[Fergie 307]

An off the shelf solution. Would only need a basket and gate(s) to prevent falls. Also can be moved out of the way of cars

Which takes me back to the car lift suggestion. Much more robust, and many use a screw to lift rather than cables so very little to go wrong. Safety measures already built in . Would be capable of lifting far more than the OP's future proof weight. Pic for illustration you could just use one leg. The arms fold away when not in use, or you could "store" it in the raised position. Obviously no one is likely to sell just one side, but you can pick these up complete second hand for about £500. Only problem might be that it will probably be 3ph, so you would need a vfd. This one is hydraulic, many just use a heavy motor driven screw to lift.
If you want an off the shelf solution you can also get scissor lifts than can be recessed into the floor so it is flush when not in use.
How high do you need it to lift?

 

[Fergie 307]

The difficulty you will have is that the upper rollers will be pulling into the front of the channel and the lower rollers pushing into the back of the channel.

Something like industrial sliding door channel might do, but 50% of the rollers (the lower ones) in your application will be exerting force on the channel in the opposite direction to its conventional use. Maybe you could supplement the lower ones with external wheels that press on the face of the U-channel so that the rollers that run inside the channel only act as guides.

Example product:

https://www.bullerltd.co.uk/sliding...gear-industrial-and-stainless-sliding-tracks/

Something like a round tube with a shaped roller on the back of it at the top and a shaped roller on the front of it at the bottom might work better. It does mean you have to fix the tube from the side so the rollers do not clash with the fixings. Look at how the mast of an Alimak hoist works - the hoist cage cantilevers from the mast in the same way as your design.

Apologies, when I suggested this with scaffold tubes I hadn't realised you had already suggested the same thing.

 

[Molynoox]

I deal with this sort of thing for a living have a look on Google for a geda wire rope hoist. The motor is mounted at the bottom and the wore runs up and over pulley at the top. The wheels of the trolley run inside of the squared C Chanel that make the uprights the uprights are in 2 meter sections. I know who I work for are sending a fair bit of kit to auction at the moment so might even be a set up for sale at one of them

I've looked on their website and I'm not sure i found anything suitable.
Did you have a particular one in mind? I might be just looking in the wrong place

 

[Molynoox]

Poo

Solid mounted with cupped wheels would not be a reliable way of holding the car on a roller coaster, they would also wear very much more quickly at the sort of speeds these things travel, hence the three flat wheels. And of course they have to deal with substantial lateral forces, not an issue for your lift. Cupped ones would be ideal for what you are doing, and I would guess probably the cheapest solution to the problem you have set yourself.

I've done some research on the cupped wheels. Very hard to find them to start with. But if you search for pulley guide wheels a load pop up. The issue I'm having is finding one that's compatible with scaffold tubes or any part of tube really.

The advantage of the U channel and trolley is it's sold as a matched pair. I also realized today that the moving metal frame will probably be quite happy simply sliding up against the face of the u channel, and I might not have to even think about if the trolley wheels will work up against the back inside face of u channel.

 

[Molynoox]

A really simple way would be just to have two cables and eye bolts attached to the platform with the cables running through them, just to keep it centred in the hole. For light loads this ought to be fine, and is probably the very simplest solution. Just depends how rigid you need it to be. If the objective is just to stop the load twisting about and banging into the sides of the hole then this would do it, and very cheap. You would probably want to use the type of eye bolts that have liners so there is no metal to metal contact with the cable. Or simple enough to make your own with something like acetal as a bush in a tube.

Not sure I follow completely but it sounds like it might be describing one of my other designs which I haven't modelled up yet but will be doing one evening this week.

 

[Molynoox]

Could you base it on one of these?

https://liftingequipmentstore.com/c...weight-aluminium-hand-stacker-truck-wide-legs

Weirdly I had that exact machine on site only a week ago. I wish I had taken a closer look at it now!

 

[Molynoox]

Which takes me back to the car lift suggestion. Much more robust, and many use a screw to lift rather than cables so very little to go wrong. Safety measures already built in . Would be capable of lifting far more than the OP's future proof weight. Pic for illustration you could just use one leg. The arms fold away when not in use, or you could "store" it in the raised position. Obviously no one is likely to sell just one side, but you can pick these up complete second hand for about £500. Only problem might be that it will probably be 3ph, so you would need a vfd. This one is hydraulic, many just use a heavy motor driven screw to lift.
If you want an off the shelf solution you can also get scissor lifts than can be recessed into the floor so it is flush when not in use.
How high do you need it to lift?

Looking like a decent option.
It will be about 2.5 metres. Maybe 2.7
I wonder if I could buy just one leg, sounds ridiculous but maybe it isn't.

 

[Molynoox]

Regarding the safety stuff that many have mentioned, I have given that some thought, and it is important. I don't think it kills the project.
I need to design in multiple safety features, and / or use off the shelf, tested designs where possible.
But I also need to have this conversation with the client... He is a smart guy, and if comfortable he could perhaps opt to accept responsibility for it, after I take him through the design in detail (including the specs and SWL of each component part). He could then own the design, after I give him it for free, and then commisson me to build it. At the end he could then also inspect it and approve it as complete and in line with his request and essentially take ownership.

I don't know, just thinking out loud.

 

[profchris]

But I also need to have this conversation with the client... He is a smart guy, and if comfortable he could perhaps opt to accept responsibility for it, after I take him through the design in detail (including the specs and SWL of each component part). He could then own the design, after I give him it for free, and then commisson me to build it. At the end he could then also inspect it and approve it as complete and in line with his request and essentially take ownership.

I don't know, just thinking out loud.

That's not how negligence liability works. If the client is in reality relying on your design then you have an obligation to take reasonable care and skill in both design and build. And signing an agreement won't help, you can't exclude liability for death or injury, full stop.

Check with your insurer if you're covered for this. If not, serious personal injury is a claim which can run into the millions in the worst case.

Plus, of course, potential criminal liability if it goes badly wrong.

I think you need to give this more thought, do you really have the necessary expertise? If so, at a minimum be properly insured.

 

[Dabop]

Back when I was still doing solar panel installs on a daily basis, we had a panel lift that was basically a pair of 'u channels' with an electric winch (it could go up to 6 stories high with ease in sections that joined together) and had a SWL of 250kg- it looked VERY similar to an aluminium ladder (almost identical in fact) and they use single pairs of wheels per side inside a u channel with no issues...

In fact this is it... this exact unit...

https://www.esw.net.au/our-products/geda-solarlift

Forklift masts also use wheels inside u channels so the concept is quite valid...

In fact old forklift masts are quite cheap secondhand at forklift wreckers- and the smaller ones are still rated at 1500kg... (probably still massively oversized for it though and a lift system would need to be put in place (mains hydraulic pumps are readily available though, thats what garage hoists use), but still a look at how the mast works on a forklift may give some ideas)

A mate bought a 2 stage mast (thats a three stage above) to put on the back of his tractor recently to use on his farm as a home made forklift, picked it up from a forklift wrecker for $150!!!

 

[Fergie 307]

Forklift is a good shout. For the height you want a car lift is unlikely to be high enough, they generally only go to about 7 feet.

 

[Fergie 307]

Weirdly I had that exact machine on site only a week ago. I wish I had taken a closer look at it now!
View attachment 186413
View attachment 186414

You can get hydraulic versions, which have the advantage of not having to have the winch etc at the rear, so might be ideal. And you can bolt the pillar to a suitable plate set into the floor.

Going back to your original winch idea, have you discussed it with whoever designed the roof? I am just wondering what their views would be of suspending 250kg from the structure at a single point.
I have an I beam as the central spine of my roof. When ordering the steel work I specified that I intended to use a chain hoist on runners on the beam, and that it needed to be able to hold up to 200kg, they designed it accordingly.
You need to be sure as it will dictate the design. If the roof can't safely support that weight as a point load, then you are going to have to go for some kind of self contained pillar lift, whether that be forklift legs or whatever.

All the advice about liability is good, however good friends people may be things can change very quickly if someone gets squashed by whatever you install !

 

[Molynoox]

Good call on the car jacks being too short.
I've looked at the hydraulic ones, here is one:
Lift

The hardest part is knowing what to type into Google to find what you are looking for
Any suggestions?

Regarding the roof, I planned to strengthen it in select places and distribute the load.

 

[Ozi]

In a previous job I used to be a lift inspector ( LOLER ), I saw many one off designs, some exceptionally well made and some true horrors. In almost all the good cases what they had achieved had no advantage over what could have been purchased off the shelf at lower cost.

My approach would be buy a proven lifting machine of what ever type best suites the job and add the quality in the installation. Top mounted will have the advantage of being out of the way when not in use but will need the load to be guided through the trap. Bottom mounted will need to be movable and then need to be stored, but you would be supplying a complete machine and if you can show it's adequate for the job you have met your liability. All lifting equipment needs regular inspection and maintenance which in a domestic situation is unlikely to happen so I would go as "bomb proof" as you can.

What budget are you working with, how much weight do they want to lift and to what height?

Always double what the client says they will lift ALWAYS!

 

[Molynoox]

In a previous job I used to be a lift inspector ( LOLER ), I saw many one off designs, some exceptionally well made and some true horrors. In almost all the good cases what they had achieved had no advantage over what could have been purchased off the shelf at lower cost.

My approach would be buy a proven lifting machine of what ever type best suites the job and add the quality in the installation. Top mounted will have the advantage of being out of the way when not in use but will need the load to be guided through the trap. Bottom mounted will need to be movable and then need to be stored, but you would be supplying a complete machine and if you can show it's adequate for the job you have met your liability. All lifting equipment needs regular inspection and maintenance which in a domestic situation is unlikely to happen so I would go as "bomb proof" as you can.

What budget are you working with, how much weight do they want to lift and to what height?

Always double what the client says they will lift ALWAYS!

Thanks that's great info!
I need it to lift 100kg and go up about 2.7 metres, let's call it 3m. Let's also at least double the weight based on your advice
In terms of budget we haven't discussed anything, I said I would just take a look at it for him and give him a number. It doesn't need to be super budget but at same time it's just for Xmas decorations and the like so we cant be looking at mega money.

Have you any ideas what's available off the shelf?

Top mounted would be great, but without the steering inputs needed ideally.

 

[Ozi]

Thanks that's great info!
I need it to lift 100kg and go up about 2.7 metres, let's call it 3m. Let's also at least double the weight based on your advice
In terms of budget we haven't discussed anything, I said I would just take a look at it for him and give him a number. It doesn't need to be super budget but at same time it's just for Xmas decorations and the like so we cant be looking at mega money.

Have you any ideas what's available off the shelf?

Top mounted would be great, but without the steering inputs needed ideally.

This is way over capacity and probably more than you want to spend

very good machine I have used a lot, quite easy to move on a good surface. The cost goes up significantly when you go over about 2.5 meters lift. If using something like this I would make a small docking point on the wall to receive the front wheels that lined up with the hatch and make a box permanently secured to the forks which pushed open a twin leaved hatch strong enough to walk on when closed.

Come down in capacity and lift height and you get

The attached box now needs to provide some extra height, if your original figure of 2.7m is enough that's only 200mm so no stability issues but the capacity is getting lower and you would have to be careful of any additional weight pushing open the hatch, might want to provide another way to open.

I have only made a brief search you will probably be able to find better with a bit more effort.


Top mounting is significantly cheaper but you need to be very sure of the loading capacity of the structure you are fixing to and personally I would do a load test and issue a certificate to show what you have done, very easy to do, never run a test you believe could fail, always test as if it's going to fail ie. the weight will drop about 20mm load to 200 kg certify for 100kg, photo of structure pre-test, under test and post test showing no permanent deformation, all the law requires is that a test be carried out by a competent person, not defined. Record everything (so any user modification will be obvious). When you make a certificate imagine standing in court presenting it to show any accident was not your fault, if it's not good enough for that don't build the machine.

Most common mistake I have seen with top mounting is a good machine bolted to a wall that will not support the turning moment, some very big companies who should know better have made this mistake and done a lot of damage in the process. Top mounting you usually need to open the hatch first with the obvious fall hazard, if you can avoid this by opening with the load (in a box or cage) I would but then you loose the advantage of everything being self storing as you have the box below to deal with unless it can stay in or be the ceiling when not in use, you still need to guide it on the way up, your rail design would do that well and with a top hoist not need to support significant loads. Lots of good hoists available, how you mount them and to what is the most critical consideration. Do the maths and keep a copy.

Hope my ramblings may be of use - good luck.