Extended 4 post lift

[Belgique Basterd]

Accidentally posted this in the general tools forum by accident, sorry for the double thread.

I'm in need of a 4 post lift that can lift about 120 inches, I know they can be bought commercially but they are very expensive. Good quality 4 post lift can be bought second hand at a very reasonable price where I live.

Been playing around with the idea of buying a regular 4 post lift and extending it myself. Extending the legs and the safety latch locking bars is not a problem, that is just a matter of copying the design, having is bent up and welding it onto the posts. The lifting system is offcourse a different matter.

The type I would buy is the cable lifting type, I've been searching around the web looking at installation manuals/drawings and have noticed that the diference in the cable lifting system is that with the regular 80" 4 post lifts the cable to the ram is single shear and with the higher 120" 4 post lifts the cable to the ram is double shear, that way they get more lifting heigth out of the same length of hydraulic ram.

Drawing of an 80" lift, as you can see the cable is single shear attached to the ram:

Drawing of an 120" lift, as you can see the cable is double shear attached tot the ram:

Offcourse new properly sized/rated cables and pulleys would need to be bought, but in the end it would still be a lot cheaper than buying a new extended lift.

My question now is, what am I missing, is there anything I am overlooking that could cause trouble or disaster?

Thank you for your input.

 

[DodgeMech]

i'm sure it's an ******* question, but, why do you need a lift that can go up 10 feet? parking a fullsize truck under another fullsize truck on the lift? i'm guessing your shop has at least 20 feet ceilings?

again, if these are ******* questions, disregard, but i am curious

 

[Belgique Basterd]

Cellar workshop under my house, would like to use this lift both for transport of cars/trailers to the cellar and to work on my truck. Access to the lift would be from inside the normal garage in the house, the lift would have a 'roof', that way when the lift is in the low/down position, the roof of the lift would close the hole in the garage, that way I can use the garage also

Picture says a thousand words, instead of scissor lift I would use regular 4 post lift.

Cellar/house is currently being built, can't use a sloped ramp access due to building regulations:

 

[turbodave]

Wouldn't the hydraulics need to be changed as well? if changing the cables so you get double the height per movement of the hydraulics, that sounds like 1/2 the lifting ability in my mind. Plus add the weight of the structure you want to attach to it, you might end up with a basement full of cars you can't lift out...

 

[Belgique Basterd]

I'll make sure that the lift is rated for the weigth of my truck + the extra platform.

Hydraulics should be ok, double shear needs more cable, so you can lift the platform higher.

 

[CombatNinja]

Okay, so that is about the coolest possible answer to the "why do you need a 10' lift?" question. I am so in for seeing this.

 

[DodgeMech]

so yeah, cool answer haha...fwiw, i've seen videos on youtube, and i think even here where someone makes exactly what you're wanting...they show it lifting small super cars though

 

[DodgeMech]

here's your 4 post haha

 

[Belgique Basterd]

here's your 4 post haha

Just a touch over my budget

 

[DodgeMech]

haha, yeah a bit over mine too...well anyway, i'll shut up so maybe some folks who can help will comment...i'll be watching the thread though

 

[LXCam]

The only down side I foresee is the amount of time it takes raise and lower all things being equal since this rigging will take twice as long as normal. As it is I have a 12klb four poster, extra long and extra wide and it can really take a while lowering when empty. Other then that, I can't wait to see what you do. Good luck!

 

[KDXSR5]

Is there any way to build a raised platform out of steel or concrete in the basement that would allow you to use a "normal" rise 4 post vs the higher rise? What about the lifts with two giant vertical cylinders? I have never looked into them, but I used one back in high school that seemed to work well and raised higher than the other lifts in the shop. No idea on what they cost though.

 

[Belgique Basterd]

The only down side I foresee is the amount of time it takes raise and lower all things being equal since this rigging will take twice as long as normal. As it is I have a 12klb four poster, extra long and extra wide and it can really take a while lowering when empty. Other then that, I can't wait to see what you do. Good luck!

I would think it's the other way around, the stroke of the piston would stay the same, but because the cable is double shear, twice the amount of cable would be pulled/extended for the same stroke distance, therefore it would lift/lower faster I think. Or am I missing something here, anyways, if it does go slower, I can live with that, this is purely for a hobby so time isn't an issue.

 

[Belgique Basterd]

Is there any way to build a raised platform out of steel or concrete in the basement that would allow you to use a "normal" rise 4 post vs the higher rise? What about the lifts with two giant vertical cylinders? I have never looked into them, but I used one back in high school that seemed to work well and raised higher than the other lifts in the shop. No idea on what they cost though.

The plan is also that I can drive off the lift when it's in the lower position to store my truck in the basement when I'm away from home for a longer time. I also have a car trailer which I would like to store in the basement, my original plan was to do as you suggest to raise the 4 post lift, but then I'd have to use really long ramps to get anything off the lift and into the basement and it would not be very practical.

4 post lifts are the cheapest solution, all the other options I found are a lot more expensive.

 

[sublimate]

I'll make sure that the lift is rated for the weigth of my truck + the extra platform.

Hydraulics should be ok, double shear needs more cable, so you can lift the platform higher.

Double shear also needs a hydraulic cylinder that exerts twice (2x) the force as a single shear. The pulleys which double the lift also double the force.

Four new custom made columns, new cylinder, new custom made cables, new pulleys... only reusing the motor/pump (cheap) and the ramps (which probably aren't ideal for your setup)... might as well just scratch build the whole thing.

Also, a 4 post doesn't seem great for this as the posts stick up above the ramps at their highest point, so you'll always have these 4 posts sticking up through the floor on the level above.

 

[Belgique Basterd]

Double shear also needs a hydraulic cylinder that exerts twice (2x) the force as a single shear. The pulleys which double the lift also double the force.

Four new custom made columns, new cylinder, new custom made cables, new pulleys... only reusing the motor/pump (cheap) and the ramps (which probably aren't ideal for your setup)... might as well just scratch build the whole thing.

Also, a 4 post doesn't seem great for this as the posts stick up above the ramps at their highest point, so you'll always have these 4 posts sticking up through the floor on the level above.

Again in my opinion (which is probably wrong lol), the hydraulic cylinder would only need half the force since the cable is double shear. Explaining my train of thought , if i pull something up by hand on a straight rope I exert a lot more force than if I pull something up by hand on a rope through a pulley? Or am I completely missing something here?

I would extend the existing columns, use the same cylinders only add new cables and extra pulleys.

The posts will indeed stick up above the ramps, but will probably box them in on the top level (still accessible) so they aren't in the way.

 

[sublimate]

Again in my opinion (which is probably wrong lol), the hydraulic cylinder would only need half the force since the cable is double shear. Explaining my train of thought , if i pull something up by hand on a straight rope I exert a lot more force than if I pull something up by hand on a rope through a pulley? Or am I completely missing something here?

Yes, in this case you're essentially using the mechanical advantage of the pulley backwards.
Using the example you gave where you're lifting a box with a pulley - in this case you're replacing the box with the cylinder and you are being replaced with weight of the car. So now the car can exert a lot more force (twice as much) on the cylinder as before.

 

[Belgique Basterd]

Yes, in this case you're essentially using the mechanical advantage of the pulley backwards.
Using the example you gave where you're lifting a box with a pulley - in this case you're replacing the box with the cylinder and you are being replaced with weight of the car. So now the car can exert a lot more force (twice as much) on the cylinder as before.

Hmmm, I'm all confused now , anybody else got any input on this?

Thanks!

 

[Belgique Basterd]

Found this, it seems to me if the car is the weight and the pull on the hook (in the picture) comes from the hydraulic cylinder, double shear would need less force than single shear?

 

[sublimate]

But that's backwards.
Look at your drawing of the double shear in your first post - the cylinder is not pulling directly on a cable (as it would if it was pulling on the hook above). Instead the cylinder is pulling on the pulley (like the weight in the drawing above).

Case #2 is the double shear:
The cylinder is replacing the weight and the car is hanging from the hook. So if the car is 50N then your cylinder has to pull 100N.

Case #1 is the single shear:
If the car is 50N then the cylinder only has to pull 50N.

 

[LXCam]

BB, look up block and tackle rigging. You have one example there, but you'll find all your answers.

 

[Belgique Basterd]

Finally got it, thanks for your patience guys. Back to the drawing board and off to find prices on a stronger hydraulic ram and pulleys !!

 

[wssix99]

My question now is, what am I missing, is there anything I am overlooking that could cause trouble or disaster?

The lift you are looking at is not designed for the dynamic loads experienced with driving a car off of it when extended at height. (Making it taller, would compound any related issues.) The higher lift will also put greater forces on the slab it's mounted to and the bolts connecting it to the floor. (So, the manufacturer installation specs would not be applicable to your situation.) The base plates for the lift legs could also be undersized for what you are looking to do.

You can get around some of this by making the lift integral to the structure of the building, but that will impart additional loads on to the building, which can cause problems there.

You can probably pull this off, but to do it safely, you should hire a structural and a mechanical engineer to design the details and confirm the integration with the structure. ... At that point, you may be better off by purchasing a proper elevator/lift designed for the height and application.

 

[Belgique Basterd]

The lift you are looking at is not designed for the dynamic loads experienced with driving a car off of it when extended at height. (Making it taller, would compound any related issues.) The higher lift will also put greater forces on the slab it's mounted to and the bolts connecting it to the floor. (So, the manufacturer installation specs would not be applicable to your situation.) The base plates for the lift legs could also be undersized for what you are looking to do.

You can get around some of this by making the lift integral to the structure of the building, but that will impart additional loads on to the building, which can cause problems there.

You can probably pull this off, but to do it safely, you should hire a structural and a mechanical engineer to design the details and confirm the integration with the structure. ... At that point, you may be better off by purchasing a proper elevator/lift designed for the height and application.

Should've mentioned this before but it is indeed my intention of attaching the top of the 4 lift posts to the cellar/building itself. I plan on using 4 M16 bolts per post to attach is to the floor (50cm of reinforced concrete) and another 4 M 16 bolts to attach the top of the posts to the reinforced concrete ceiling of the cellar. I have no worries whatsoever that this will be strong enough.

 

[sublimate]

Check these out:

http://tinyurl.com/oykm7aa
http://tinyurl.com/ohf7h77

 

[wssix99]

Should've mentioned this before but it is indeed my intention of attaching the top of the 4 lift posts to the cellar/building itself. I plan on using 4 M16 bolts per post to attach is to the floor (50cm of reinforced concrete) and another 4 M 16 bolts to attach the top of the posts to the reinforced concrete ceiling of the cellar. I have no worries whatsoever that this will be strong enough.

If the tops are attached to the structure, that should take care of any additional moments around the bases. Have you confirmed that the structure can take the lateral loads that will arise from the attached lift?

I see that you have columns in the pictures. Will you have beams spanning the cellar, or will you be doing a reinforced concrete floor?

 

[Belgique Basterd]

If the tops are attached to the structure, that should take care of any additional moments around the bases. Have you confirmed that the structure can take the lateral loads that will arise from the attached lift?

I see that you have columns in the pictures. Will you have beams spanning the cellar, or will you be doing a reinforced concrete floor?

In my opinion the load will be minimum, everything is already designed with a large safety factor, the very minor weigth (compared to a house) that loading a truck on the lift will add will not be a problem.

The ground water level is very high here, as a result of the groundwater 'hydrostatic' forces on the cellar the concrete and the rebar in the concrete is a lot thicker than it should be for the weigth of the house, therefore I have no worries about the structure being strong enough for the lift.

Steel I beams are going to be placed on top of the columns around the hole for the lift, the cellar will be covered with pretensioned concrete beams and on top of that there will be a 15cm reinforced slab of concrete.

Rebar in the floor, due to the high hydrostatic forces nearly double the amount of rebar than usual:

 

[Belgique Basterd]

Check these out:

http://tinyurl.com/oykm7aa
http://tinyurl.com/ohf7h77

Not really what I'm looking for, lift not only has to transport my cars to the cellar but also double as a lift when I need to work on my car.

 

[Badhabit]

The pump may not be up to the task as it will have to put out double the pressure to lift the same load. Either that or a new cyl should have double the surface area for the oil to push on. The load will not only lift twice as far but twice as fast.

H

 

[motofool33]

have you asked bendpak to make one for your needs?

they made a custom double wide lift for my neighbors garage condo.

 

[Belgique Basterd]

have you asked bendpak to make one for your needs?

they made a custom double wide lift for my neighbors garage condo.

Bendpak has one that suits my needs, as do many other manufacturers, just can't afford them .

 

[Belgique Basterd]

The pump may not be up to the task as it will have to put out double the pressure to lift the same load. Either that or a new cyl should have double the surface area for the oil to push on. The load will not only lift twice as far but twice as fast.

H

If I'm not mistaken, pressure stays the same (200 bar/2900psi), only the volume of oil needed would change.

I'll probably have to change out the stock cylinder to a higher rated one for this to work.

 

[youwish2bme]

I know Utah on the Corvette Forum did this and I think he is a member here too...


Hitch

 

[Belgique Basterd]

I know Utah on the Corvette Forum did this and I think he is a member here too...


Hitch

Found an awesome thread about the most epic garage/man cave ever but nothing on an extended car lift, you happen to have a link to the 'Utah' you mean??

One I found:

 

[wssix99]

Not really what I'm looking for, lift not only has to transport my cars to the cellar but also double as a lift when I need to work on my car.

I'm curious. With the cellar completely inclosed, what did you select for venting the heavier-than-air flammable gasses up and out of the building? (This is a common topic of conversation with folks looking to put in garage pits and I don't think I've seen a simple residential solution, yet.)

 

[Belgique Basterd]

There are ventilation holes placed strategically to have some natural movement of air, I also plan to have mechanical ventilation which i'll turn on whenever doing woodworking, welding, etc...

 

[sublimate]

Suggest something like this:
http://www.homedepot.com/p/First-Al...e-Alarm-with-Digital-Display-GCO1CN/202433880

It's cheap insurance.

 

[Belgique Basterd]

Suggest something like this:
http://www.homedepot.com/p/First-Al...e-Alarm-with-Digital-Display-GCO1CN/202433880

It's cheap insurance.

, that is a good tip, will see what similar things we got available over here.

 

[Belgique Basterd]

What are you guys thoughts on using an electrical/hydraulic winch instead of a hydraulic ram? I could divide the spool into 4 section so that each individual cable has it's own space on the drum and they all spool the same?

Edit: what about attaching the 4 cables to a steel plate and then from that plate 1 single properly rated cable goes to the winch, that way no more worries about the multiple cables on the drum and synchronizing?

Example of plate, offcourse instead of a 2 into 1, it would be a 4 into 1.

 

[lynnbilodeau]

Bendpak has one that suits my needs, as do many other manufacturers, just can't afford them .

I fully understand you wanting to DIY this. I am a firm believer in DIY.

I am pretty brave and have taken on a few projects that made other people question my sanity. However, I think this is one of those instances where I would bite the bullet, sell off something, borrow, or figure out how to generate some cash (i.e. beg borrow steal... not literally mind you) and just get the right tool for the job. Safety features will already be built in.

Looks like you are building this place right, and NOT cutting corners. I don't think this lift is the place to start.

Not trying to be a wet blanket, but there are reasons what you need is expensive. It takes a lot of engineering and materials to do it right.

Take all that energy you would spend (invest or waste depending on how it turns out) on this project and use it to generate some extra cash. Buy the right tool.