Why small feet on lifts?

[1956chevy210]

Hi everyone,

So I'm looking at two post lifts, and I've noticed that the feet (baseplates, bottoms?) of the posts are not much bigger around then the post themselves. They are just big enough to allow a flange all around the edge to drive the anchors through. I haven't seen any lifts with large baseplates.

I haven't worked in shops in 15 years, but I'm sure I remember the baseplates of the posts were much bigger back in the day. The front of the post bottom extended out about 12" and about 24" on the back. At least from what I can remember.

Regardless of the trustworthiness of my memory, it seems like it would be much safer to have a larger baseplate to add stability. Sure, securing the post with multiple anchors to strong concrete obviously works, but extending the baseplates out would just make it that much more stable, especially front to rear.

What do you think?

56chevy

 

[ibedayank]

great way to void the warranty is to scew with them and change stuff

 

[Playwme]

Bigger plates would be a trip hazard, and they probably don't want people assuming they can skimp on the foundation and anchors because the base plates are bigger and more stable.
Anchor it right and the current size plate is more than adequate. Don't anchor it right and even a 4 foot wide baseplate won't do much to help.

 

[rburke65]

I wouldn't think you would have to reinvent the wheel here. I'm pretty sure the lift manufacturers have done their homework.

 

[finn]

Why not do a finite element / load analysis of the structure and joint to see if your hunch is correct??

I'm sure the engineers at the lift manufacturer have done one as part of the design process.

 

[sberry]

Mohawk has a bigger base. Depending on how its rigged and loaded will pick a car without any bolts in it.

 

[LAROKE]

I have an old Ben Pearson asymmetrical 9000 lb two-post lift that I don't have anchored yet. Both the posts and their base plates are much heavier than today's lifts. The base plates are 24" square and I'm happy that they are.

 

[srleen2]

In the failure videos I have seen - I haven't seen any that had failures at the base plate.

Here's one:

 

[papavolume]

I wouldn't think you would have to reinvent the wheel here. I'm pretty sure the lift manufacturers have done their homework.

This.

Thousands of people are under their lifts daily. If it wasn't safe there would be many injuries, deaths and lawsuits.

Just anchor it as they say to or better and your good.

 

[77Mini]

I have an older Ben Pearson that has a little larger pads.,. I think 18"x24".

 

[finn]

I would assert that many of the products manufactured and sold in the olden days, say before the early feedback 80s weren't really engineered in the modern sense.

They were "designed " by the seat of the pants by tinkerers and fabricators with little math and science background, and no modern design and modeling tools.

The advent of low cost computers and computer aided design software has put affordable tools in the hands of even small companies, like lift manufacturers, who have used these tools to drive waste and cost out of their designs and products.

Twenty years ago there was really a pretty small market for a hobbyist lift, as the available products were unaffordable to an no-professional user.

Design tools have brought "engineering ", and lower cost to these products, and tapped a new market.

 

[Ironcrow]

My lift has larger feet that are strengthen by a 6x6 angle iron running longitudinally to the rear of the column. You would think it would be a trip hazard, but I have found I don't walk there anyway as I would bonk my head on the rear lift arms. And when the arms are down they are folded to the back next to the angle iron, so not an issue.

 

[matt_i]

My guess is "value engineering" which either means make more profit for the OEM or else better able to compete with things manufactured with lower labor cost overseas.

 

[lakeroadster]

Hi everyone,

So I'm looking at two post lifts, and I've noticed that the feet (baseplates, bottoms?) of the posts are not much bigger around then the post themselves. They are just big enough to allow a flange all around the edge to drive the anchors through. I haven't seen any lifts with large baseplates.

I haven't worked in shops in 15 years, but I'm sure I remember the baseplates of the posts were much bigger back in the day. The front of the post bottom extended out about 12" and about 24" on the back. At least from what I can remember.

Regardless of the trustworthiness of my memory, it seems like it would be much safer to have a larger baseplate to add stability. Sure, securing the post with multiple anchors to strong concrete obviously works, but extending the baseplates out would just make it that much more stable, especially front to rear.

What do you think?

56chevy

Why are the base plates small? They aren't. They are engineered to meet the required loads and that is all that is needed.

When was the last time you saw a photo of a lift that failed due to a base plate issue?

It works, as is.

The loads on the lift, and the concrete, are not high, not in the least.

Folks really have to work at it, and do something horribly wrong, to experience a failure... IF they buy a quality ALI certified lift, installed per manufacturer specifications, on concrete that meets the manufacturer's specifications.

As for for/aft stability... place the vehicle correctly and it is not an issue. How do you know where to place the vehicle? The ALI has a quick reference guide... see below.

Check out these links:

• http://www.autolift.org/
  
• quick reference guide: http://www.autolift.org/ali-store/alilp-guide/

 

[Ironcrow]

...it seems like it would be much safer to have a larger baseplate to add stability. Sure, securing the post with multiple anchors to strong concrete obviously works, but extending the baseplates out would just make it that much more stable, especially front to rear...

Yes, for a cost adder of, like, 1% on the price of the lift you could double your floor anchor safety factor. Pull out failures are rare. If you do everything right the anchors will not pull out. The best argument I could think of would be if you didn't place the pad yourself how do you know it is the require 4 inches and 3000 psi or whatever? Could be 3 inches in one spot or have too much water in the mix and only be 2000 psi.

With safety factors, some people go with the idea that twice "sufficient" is still "sufficient".

Far and away the greatest number of lift failures are user error when the vehicle is loaded with the cg not centered and it falls off.

 

[lakeroadster]

The best argument I could think of would be if you didn't place the pad yourself how do you know it is the require 4 inches and 3000 psi or whatever? Could be 3 inches in one spot or have too much water in the mix and only be 2000 psi.

How do you know?

You have a core sample done and have it lab tested. That will tell you the strength of the concrete.

Then, when you drill for the anchors, drill the correct depth, as specified by the lift manufacturer. If the bit doesn't break through you'll know all the anchor points are correct.

For nearly every query there is a test that can be done to establish what you actually have.

 

[jb3]

You would need a hell of a huge baseplate before its physical size actually impacted the stability of a two post past the necessity of concrete anchors. Since it wouldnt matter, might as well make the flange small and save material and space.

The hard connection to the floor is what keeps the lift upright, the baseplate just needs to be big enough to make this hard connection

 

[75toolman]

My mohawks baseplate is 30 x 24.

 

[Aerogt01]

I think lifting structures for the commercial world are already designed to large safety factors.

If they are within thier capability and there are no gussets, the bolts closest to the post add the most rigidity.
Sure you could design structure that efficiently moves to load out from the post to increase the effective heel/toe moment arm, but at what cost? Is it worth it?

 

[robalmal]

Have you ever seem some of the massively high light poles along motor ways?
Even tall light towers? They all have narrow base plates too and they are designed to withstand cyclones.
As a long time mechanic,I used to think like you.My lift I have had in my home workshop for 9 years has the narrow base and is totally safe.

 

[ABADWILLYS]

Sorry, but older lifts were built much better, sure a newer lift may be engineered for the load capacity and operate as rated BUT.. speaking from real world experience, there is a difference. and its not just small base plates on the newer lifts,
i work on cars for a living and also as a hobby, so i use a lift pretty much 7 days a week, lifting hundreds of cars a month. For the last 8 years at my work, i have been using 25 year old Benwil Lifts, though made in Japan, they were 7000 pound rated, and built like a brick *********, probably way over engineered, even just looking at them, im surprised thats all the weight rating they had. Last Spring, where i worked, they decided to replace the lifts, and installed new Rotary SPOa-10's, a 10,000 pound rated lift, what a piece of ****! no disrespect to guys but own them, but compared to the 7000 pound Benwil, that was solid, the Rotary even with a passenger car on it, it wobbles around like a wet noodle!, the arms flex, the columns twist, wobble and shake, it has no problem lifting, and im getting use to the thing wobble around....but give me a older solid built lift over this newer **** anyday!!

 

[jb3]

Sorry, but older lifts were built much better, sure a newer lift may be engineered for the load capacity and operate as rated BUT.. speaking from real world experience, there is a difference. and its not just small base plates on the newer lifts,
i work on cars for a living and also as a hobby, so i use a lift pretty much 7 days a week, lifting hundreds of cars a month. For the last 8 years at my work, i have been using 25 year old Benwil Lifts, though made in Japan, they were 7000 pound rated, and built like a brick *********, probably way over engineered, even just looking at them, im surprised thats all the weight rating they had. Last Spring, where i worked, they decided to replace the lifts, and installed new Rotary SPOa-10's, a 10,000 pound rated lift, what a piece of ****! no disrespect to guys but own them, but compared to the 7000 pound Benwil, that was solid, the Rotary even with a passenger car on it, it wobbles around like a wet noodle!, the arms flex, the columns twist, wobble and shake, it has no problem lifting, and im getting use to the thing wobble around....but give me a older solid built lift over this newer **** anyday!!

Researching my own lift im betting that benwil lift was rated at 7k and in the process of being rated higher when it was bought. On the premise of build it HD and meet all the ratings at once

I have a early 90s forward 2 post, and it has a 7.5k rating, but is approximately built twice as heavy as other lifts ive seen with a 10k plus rating. When i called the lift company itself looking for specifications, turned out my lift with zero changes was later rated for 10k and 12k.

 

[gungatim]

my old wheeltronic lift has a huge baseplate and the "tower support angle" on each side...I think it's overkill, but it came out of a dealership and has decades of daily use so it obviously was built to last..you can see it in this pic.

 

[PoorOwner]

If it was 36" square it would probably wobble and be less stable And shim or fillers would be needed.
I know my garages elevation don't stay the same every couple of feet there is a bump or a dip.
Plus it would be like putting a longer prybar on the bolts, fulcrum, leverage etc.

Anyway should there be a sub forum for people wanting to weld bars, cables on lifts that are not necessary in the first place?

 

[Ironcrow]

... old Benwil Lifts, though made in Japan, they were 7000 pound rated, and built like a brick *********... Last Spring, where i worked, they decided to replace the lifts, and installed new Rotary SPOa-10's, a 10,000 pound rated lift, what a piece of ****! no disrespect to guys but own them, but compared to the 7000 pound Benwil, that was solid, the Rotary even with a passenger car on it, it wobbles around like a wet noodle!, the arms flex, the columns twist, wobble and shake, it has no problem lifting, and im getting use to the thing wobble around...

Why did they replace perfectly good Benwil's?!

 

[Ironcrow]

Anyway should there be a sub forum for people wanting to weld bars, cables on lifts that are not necessary in the first place?

I don't know what it is, but if a poster here buys 4 ton jackstands for a 2 ton car (!) and then welds a plate on the bottom to increase stability and prevent the jackstands from sinking into soft ground, nobody says a thing. Weld a brace on a lift and everybody goes insane...

 

[Ironcrow]

In the failure videos I have seen - I haven't seen any that had failures at the base plate.

Here's one:

What brand of lift is that?

 

[lakeroadster]

I don't know what it is, but if a poster here buys 4 ton jackstands for a 2 ton car (!) and then welds a plate on the bottom to increase stability and prevent the jackstands from sinking into soft ground, nobody says a thing. Weld a brace on a lift and everybody goes insane...

Please show us who went insane? Folks are simply answering the OP's question.

Honest, open discussion.... that's how we all learn.

Regardless of the trustworthiness of my memory, it seems like it would be much safer to have a larger baseplate to add stability. Sure, securing the post with multiple anchors to strong concrete obviously works, but extending the baseplates out would just make it that much more stable, especially front to rear.

What do you think?

56chevy

 

[Ironcrow]

Please tell us, Who is going insane? Sounds like folks are simply answering the OP's question.

Sorry, nobody is going insane. My mistake.

So I'm looking at two post lifts, and I've noticed that the feet (baseplates, bottoms?) of the posts are not much bigger around then the post themselves. They are just big enough to allow a flange all around the edge to drive the anchors through. I haven't seen any lifts with large baseplates....

.... it seems like it would be much safer to have a larger baseplate to add stability. Sure, securing the post with multiple anchors to strong concrete obviously works, but extending the baseplates out would just make it that much more stable, especially front to rear.

What do you think?

I should have done a better job of answering your question. I think you are entirely correct. I would not buy, own, install, or use most of the hobby lifts on the market today. I am not impressed with any two post lift that does not have a cross bar at the top preventing the columns from leaning together. Note the video of the test where the columns bent toward each other by several inches at the ALI certifying load. It also does not pull the anchors out, which is all good, but I'll not stand under a noodle. Additionally, as you point out, a longitudinally extended base plate greatly reduces fore/aft tipping strain at the anchors. I think 4 inch thick concrete pad is not something I want to load by bending it. Concrete testing is done by compression. I am perfectly happy to spend the time and money to have a lift that can solidly and easily lift and support 3 times the weight of the heaviest vehicle I typically work on.

 

[sberry]

This is a case of amateurs thinking the professionals are stupid. I for one am very careful about modifying engineered designs. One thing may effect another, well intentioned but not all is always obvious.
When I do this I do so at my own risk not the other way around. Look at all the idiot lights wanted on compressors after adding some more junk on it didn't come with, altering the wiring etc to do so. Even master sparkies who piss up a storm about the incoming power seem to often endorse some brain fart once it reaches the machine.
I learned some of this the hard way, when I was 20 or 25 I thought I knew and actually created a lot of dangers I didn't consider, still fixing some of them and today leave a lot more alone. Many times once something is worked on its never right again.

 

[dave*99]

This is a case of amateurs thinking the professionals are stupid. I for one am very careful about modifying engineered designs. One thing may effect another, well intentioned but not all is always obvious.
When I do this I do so at my own risk not the other way around. Look at all the idiot lights wanted on compressors after adding some more junk on it didn't come with, altering the wiring etc to do so. Even master sparkies who piss up a storm about the incoming power seem to often endorse some brain fart once it reaches the machine.
I learned some of this the hard way, when I was 20 or 25 I thought I knew and actually created a lot of dangers I didn't consider, still fixing some of them and today leave a lot more alone. Many times once something is worked on its never right again.

Yup. Been there done that.

 

[kaffine]

Most lifts are made for commercial shops. If you can make the lift smaller then you can get an extra bay in the same size building. And extra bay means more money for the shop.

 

[brownbagg]

think of how much money they save on weight and extra steel by not having big feet. the less it weight, the more that can be loaded on a truck, the less amount of steel used, its all about money.

 

[Ironcrow]

This is a case of amateurs thinking the professionals are stupid.

Not at all. I am seeking to understand the design constraints and engineering decisions made. What specifications and standards apply? How were these met? What limitations then apply?

A two post lift is definitely complicated enough to require engineering. But, it is not so complicated that sufficient understanding of its design is inaccessible to a knowledgable owner.

For the derision that has been heaped on my modified Benwil, let me give an example: I recently needed to compress the suspension on one front wheel to further some repair effort. While the car was on the lift. Due to some clearance issues, I could not get my spring compressor in the right spot. I quickly decided to apply the necessary force with a button jack on the ground and 4x4 post, pushing up with 500-750 lbs on one A-arm. I strapped the frame of the car to each lift pad, made sure the hydraulic jack was all square and straight, and did my work. Totally strange off-spec use? Yup. Get your picture on the Darwin Award plaque for next year? Maybe. With my lift this was totally rock solid, stable. My lift can lift the entire weight of my car on one rear arm. How do I know? I've done it.

 

[dave*99]

Most lifts are made for commercial shops. If you can make the lift smaller then you can get an extra bay in the same size building. And extra bay means more money for the shop.

This makes sense to me. The anchor bolts need to be typically 6 inches or more from the edge of the slab. Add another 12" to the base plate and I need to make my garage bigger.

 

[lakeroadster]

My lift can lift the entire weight of my car on one rear arm. How do I know? I've done it.

And that's a manuever.

Tell us more....

1. Was that car of yours in reality a "Hot Wheels", or maybe a "Big Wheel"?
   I'm hoping it was...
   But if by chance it was an actual real full size passenger car...
2. What would ever posses you to do that?
3. How did you get your car "balanced" on just one arm?
   Got any photo's 'cause that would just be awesome.
4. How did that off-center overload affect the rest of the lift?
   Did your actions overload the anchor bolts or damage anything else on the lift?
   How will you ever know... maybe when something breaks?

 

[Ironcrow]

1) I used the lift as a jib crane.
2) To unload a 2400 lb milling machine (which happens to be the same weight as the vehicle I most often work on).
3) It was not overloaded. The lift has a 9000 lb capacity frame so is rated for 2,250 lbs on each arm. Since it is ALI Certified it has been tested to 150% or 3,375 lbs. So, the arm/carriage was at about 70% maximum. The anchors were not stressed unusually as this column is attached solidly at the top (remember I "modified" this lift) as well as bolted to the floor. Without the top attachment, the tipping moment at the base would be around 10,000 ft-lb (4 foot arm x 2400 lb load). In my lift, this moment is also supported by the top mount to the wall. The tension in the top mount is about 800 lbs. This load is carried through two 3/4 inch bolts, being good for, whatever, 30,000 lbs so I didn't bother to calculate the safety factor there. Also, with a cross brace, this load is carried to the other column. Which is also bolted at the top.

 

[slowzuki]

I think if you looked into it the old big baseplates were more tolerant of poor quality floors. A lot of older shops had terrible floors. Bigger plate reduces anchor loads which reduces embedment and spacing requirements on the anchors.

 

[lakeroadster]

Now I understand Ironcrow why you are so animated about lift modifications.

Your advice on 2 post lifts needs a disclaimer.

"My 2 post lift was... but no longer is"

 

[ABADWILLYS]

Why did they replace perfectly good Benwil's?!

A lot of them were missing the lift arm locks, on some the arms were bent, i said they were 25 years old but after thinking about it they were 29 years old,
not that that makes much of a difference.
There are 14 lifts in our shop, they replaced them all with Rotaries.
they sold most of the old ones, there are 1 or 2 left, want one? LoL
heres my bays and the old Benwils