Vehicle Lifts: 2-post, 4-post, etc (1 Viewer)

[ikarus]

It depends on what the compressive strength of your concrete is; there's no way to tell for sure, without coring a part of it and sending it to a testing lab. I'd personally doubt it was better than 2500 pound concrete, though. And probably less than 4 inches on average, at that. Worse, the base probably wasn't compacted, prior to placing the concrete.

All that means that you really need to do some preparation before you install the lift. If it was me, I'd cut a 12x12-inch square out of the floor, everywhere I was going to set the foot of the lift, oriented with the corners pointed in the direction of the entry/exit to the lift. Then, I'd excavate 12 inches down, place 6 inches of well compacted #72 aggregate, in at least two lifts, and then place minimum 4000 pound concrete in the hole, after I lined the sides with expansion material to isolate the pier. If you asked a structural engineer the question, that's the answer you'd get.

Having said that, I'm willing to bet you could find an unlimited number of people who haven't done any of that, and who'll swear there's nothing wrong with their floors or their lifts.

My personal preference would not be a post lift, although I know that's the current fashion. I favor the scissor type lifts, with the sliding scissor trays. You can drive on, without fiddling with arms, you have a place for tools and parts while you're working, and you can get the wheels off the ramps with the sliding trays. All this and the load is spread out over a larger area, so concrete strength cannot be a problem. Plus, if you prepared ahead of time, you can sink it into the floor, making it essentially flat all over the floor area (OK, the middle area is still non-skateboardable, but you can't have everything). If anyone has one for sale, I'm in the market

Lift manufacturers all have very clear published concrete and anchoring specs.

If your concrete does not meet spec they also have very clearly laid out remedies so you can still install one.

To test, you drill a hole through. You can tell exactly where you break through a slab with a hammer drill. A long 3/8 bit is a good size to test.

2500 psi concrete is not used in flatwork. You cannot finish concrete without atleast enough cement to make it 3500 psi. Most every slab is poured from 5k mix.

If your slab is too thin for a 2 post the remedy Rotary promotes is to cut about 3' x 4' under each post. Dig down a foot. Dig under the slab a few inches each side. Drill into sides of old slab. Epoxy in rebar. Tie your rebar grid to that. Pour new 12" thick slab and vibe well to ensure mud flows under old slab.

Not a big deal.

Thanks guys, I appreciate the insight! Part of my problem is not knowing what I don't know - but this gives me a good direction to start researching. I want to do it right and I don't trust the home builders.

 

[Malleus]

Thanks guys, I appreciate the insight! Part of my problem is not knowing what I don't know - but this gives me a good direction to start researching. I want to do it right and I don't trust the home builders.

FWIW, I was in the service bay of the Lexus dealership last month. They must have 40 post lifts. None are bolted onto piers; they're all bolted onto the slab with Hilti anchors. I doubt they paid for a foot thick slab.

 

[WarDamnEagle]

FWIW, I was in the service bay of the Lexus dealership last month. They must have 40 post lifts. None are bolted onto piers; they're all bolted onto the slab with Hilti anchors. I doubt they paid for a foot thick slab.

Rotary only requires 4.5" to anchor their 10k lifts. Not sure about their larger capacity lifts. They only specify 12" thick if the slab doesn't meet their minimum requirements and thus they are assuming no support from the existing slab. My shop has 6"+ so I was good to go thankfully.

Edit: Just double checked their installation manual. They specify 4 1/4" of 3000 psi concrete minimum for installation. They further specify 4' x 4' x 6" pads be installed if the existing concrete doesn't meet spec. These specs are specific to their non "shockwave" 7k and 10k lift units.

FWIW the shipping weight on the SPOA10 is 1750 lbs. I knew it was seriously heavy but didn't know the exact figure.

 

[Unimogguy]

You guys might want to check out this website: www.govdeals.com


They surplus local/state government equipment. They usually have 2 post, 4 post and column lifts.

Want to be able to use your lift inside or out(?):

https://www.govdeals.com/asset/2/25302

 

[ccasteel]

You bring up a good point and I think you touch on what his problem is- His lift has a single acting hydraulic cylinder. The hose that's blowing off is a vent line, not a return. The reason it's blowing off could be the piston seal is leaking, overpressurizing the vent tubing.

That was my first thought too but BendPak calls it a "return line" in their instructions so I went addle brain for a minute. Seals need to be replaced.

Installing the Return Line
The Return Line takes excess Hydraulic Fluid coming out of the Hydraulic Cylinder and sends it back
into the Fluid Reservoir on the Power Unit.
The Return Line is a single piece of ¼ inch, black, polyethylene Tubing with Elbow Compression
Fittings on each end. You need to cut off a piece of the supplied Tubing of the right length to create
the Return Line.
Important: The Return Line uses the same ¼ inch, black, polyethylene Tubing as the Air Lines. Be
sure not to confuse the two; the Return Line and the Air Lines do completely different
things and
must be kept separate from each other

Thank you both so much that is what I was missing. It makes sense now that the seals are leaking and causing the pressure to build popping off the vent line. Now to find some place to replace the seals.

 

[Waorani]

I recently had seals done in two small forklift cylinders (side-shift/tilt) - $400+! After that I did a Kubota lift cylinder myself. Kubota is proud of their parts but it wasn't hard to do. I'd bet the seals in your 4-post cylinder are simple and could be sourced from McMaster Carr/similar.

 

[Waorani]

Some two-post lift eye candy!

 

[WarDamnEagle]

Some two-post lift eye candy!

View attachment 3459484
View attachment 3459485

Nice Vette. My grandparents had that same glider at their house along with two matching rocking chairs. My mother inherited the house but a few years ago the glider and chairs disappeared. Pretty sure they got discarded during a sibling's periodic decluttering exercise. Would love to have them today.

 

[Waorani]

Nice Vette. My grandparents had that same glider at their house along with two matching rocking chairs. My mother inherited the house but a few years ago the glider and chairs disappeared. Pretty sure they got discarded during a sibling's periodic decluttering exercise. Would love to have them today.

That might be it!

 

[PAToyota]

There's another thing to consider: commercial and industrial construction bonds and licensed engineering specifications often require construction material testing. If the mix doesn't meet the specs, the plant pays for it. Around here, residential mixes are never tested, regardless of the mix strength.

Chances are that the mix exceeds specs for that reason. A number of recent seminars I've been in have talked about them raising the design strengths of CMU precisely because what you were getting exceeded the minimum values enough that you should be benefiting by taking advantage of it.

However, depending on how old the existing slab is and what the yahoos with a pickup truck and hammer that call themselves a "residential builder" actually did, I'd want some verification of what an existing slab actually is made of. The stuff I see in the residential world can be pretty crazy.

 

[shtbrwn86]

I'm pretty much a novice in all this stuff but I do enjoy working on my cars with the exception of crawling around underneath them. Jobs could be done in a fraction of the time with a lift but it seems like you can't have it all. For example, doing brake work, axles etc. a two post with arms would be the best option. But you can't do suspension work on those because the car has to be "at rest" when you tighten bushings, etc.

I guess the 2-post would be the best for MOST jobs, but just thinking out loud here. You would need two lifts to do EVERYTHING right? When I did my control arms on the 100-series I couldn't get a big enough torque wrench under there to tighten to 170lbf so I got it to like 120 or so and then had the alignment shop do the rest on their drive-on lift.

 

[Malleus]

The drive on scissor lifts are the all purpose lifts. The good ones have a pair of sliding trays fitted between the ramps that have scissor lifts on them at 90° to the ramps. This allows you to drive on them, support the frame and remove the wheels. It also allows you to support differential carriers, transmission and transfer cases.

The downside is the even if you sink them into the floor, you still don't have a flat floor between the ramps. Not a deal breaker for me, but it would be for some, and it does make cleaning under the lift more of a chore.

The reason you don't see them is 1) the aren't electric, they're electro-hydraulic and 2) they have lots of pieces, which equals most cost to produce. Both of these criteria make them more expensive to build and therefore there's less profit in them for the manufacturers. These things come and go in cycles. Forty years ago, there were hardly any post lifts, except in cheap garages. Now you can't find scissor lifts in the US except in alignment shops.

 

[WarDamnEagle]

But you can't do suspension work on those because the car has to be "at rest" when you tighten bushings, etc.

So I've replaced most suspension components with a two post (e.g. shocks, springs, tie-rods, etc.) without any issue. For springs you need a pogo stick or other way to hold the axle but otherwise I haven't had any issues.

The reason you don't see them is 1) the aren't electric, they're electro-hydraulic and...

Not exactly sure what you mean. My 2 post and all the two posts I've looked at for that matter are hydraulic (as in electric motor driven hydraulic pump). So is that different from electro-hydraulic? Just curious.

 

[Malleus]

I didn't mean to say the two posts won't work; I'm sure with a little creative thinking you can do anything you want with one.

The ramp scissor lifts have a hydraulic power unit which supplies fluid power to the cylinders. A small one to be sure, but an HPU just the same. The two post lifts I've seen, which are not everything on the market, are run by either linear actuators (all electric) or self contained cylinders with small bolt-on pumps (electro-hydraulic).

It's just a matter of technology really; that kind of power in that small package size wasn't available 50 or so years ago when the scissors lifts were being developed. There would be no reason not to use that technology on them today, for light trucks, and I don't know that they're not constructed that way. I haven't looked at the new offerings, because my garage can't justify $35,000 for a lift.

Kind of bums me out; they're available in all kinds of sizes in England (along with Tom Senior milling machines). Of course, they don't have decent food or beer, so there's that. I guess you can't have everything.

 

[WarDamnEagle]

I didn't mean to say the two posts won't work; I'm sure with a little creative thinking you can do anything you want with one.

The ramp scissor lifts have a hydraulic power unit which supplies fluid power to the cylinders. A small one to be sure, but an HPU just the same. The two post lifts I've seen, which are not everything on the market, are run by either linear actuators (all electric) or self contained cylinders with small bolt-on pumps (electro-hydraulic).

It's just a matter of technology really; that kind of power in that small package size wasn't available 50 or so years ago when the scissors lifts were being developed. There would be no reason not to use that technology on them today, for light trucks, and I don't know that they're not constructed that way. I haven't looked at the new offerings, because my garage can't justify $35,000 for a lift.

Kind of bums me out; they're available in all kinds of sizes in England (along with Tom Senior milling machines). Of course, they don't have decent food or beer, so there's that. I guess you can't have everything.

Interesting. Still not sure I understand the difference though. My Rotary unit, at least according to the replacement parts label, is powered by a hydraulic Power Unit (2 HP, 4 gal capacity, etc.). It's basically just a hydraulic pump operated by an electric motor with an attached reservoir. The cylinders are operated off of that and the fluid supply and return is via hydraulic hoses. All the 2 posts lifts I have looked at seem to be operated on that same concept but I only looked at a few of the top-end brands.

I lived 7 years in the UK, FWIW. You can get good food and beer.....just not British food or beer.

 

[Waorani]

I'm missing something here too. Every 2/4 post lift I've ever seen was hydraulic with an electric motor pump/reservoir mounted on one of the posts. And scissor lifts seem to be readily available from various mfgs. Scissor Lifts Archives - https://rotarylift.com/category/scissor-lifts/

A friend has a large BendPak 2-post with plates he made for each arm to hold a wheel securely. Never asked how he gets a vehicle on them. Guess he uses a floor jack and swings arms/plates under each wheel.

 

[Unimogguy]

I didn't mean to say the two posts won't work; I'm sure with a little creative thinking you can do anything you want with one.

The ramp scissor lifts have a hydraulic power unit which supplies fluid power to the cylinders. A small one to be sure, but an HPU just the same. The two post lifts I've seen, which are not everything on the market, are run by either linear actuators (all electric) or self contained cylinders with small bolt-on pumps (electro-hydraulic).

It's just a matter of technology really; that kind of power in that small package size wasn't available 50 or so years ago when the scissors lifts were being developed. There would be no reason not to use that technology on them today, for light trucks, and I don't know that they're not constructed that way. I haven't looked at the new offerings, because my garage can't justify $35,000 for a lift.

Kind of bums me out; they're available in all kinds of sizes in England (along with Tom Senior milling machines). Of course, they don't have decent food or beer, so there's that. I guess you can't have everything.

Are you opposed to buying a used lift? 2 post lifts can be purchased for less than $1,500. Many municipalities/state/government agencies have to sell them once their “useable life” is up or they have to exhaust theIr budget or lose it.

 

[Malleus]

Not at all. I don't have the headroom for a post lift.

 

[Unimogguy]

Not at all. I don't have the headroom for a post lift.

I would encourage you to still look at lifts for sale on the surplus sites as I have seen 4 post, individual wheel lifts (4) and scissor lifts for sale there.

Here’s a couple to check out:

www.govdeals.com

Government auctions of seized and surplus property | USAGov

Learn about the types of government auctions and the excess and seized property they sell, including computers, artwork, mobile homes, and more.

www.usa.gov

Public Surplus: Home

m.publicsurplus.com

www.govplanet.com

 

[Malleus]

I haven't looked at govdeals in a while; thanks for reminding me!