Anchoring a 4 post lift

[Bad Habit]

A friend of ours maybe getting an Atlas 408-SL 4 post lift (her company is buying it for her as a gift for a lot of hard extra work). Looks like I'm getting drafted into helping assemble.

Instructions say it doesn't have to be anchored, but if it is, they recommend that it's on a 6" slab with a 4' apron around the columns. Seems to be quite a variation between you don't have to anchor it all to you need 4' around each column of 6" slab. Digging around here on GJ, I see many don't anchor their 4 posts. I've seen one thread where it shifted but the consensus was it more because the shims slipped.

If it doesn't need to be anchored, it tells me it's just free standing and any anchoring is just to hold it in place from getting bumped, not structural like a 2 post. So why 4' around the columns?

 

[stingry]

So why 4' around the columns?

Not a clue why this is required but I have had two four post lifts in the last 25 years and never anchored either one. No problems whatsoever.

 

[king nero]

if not anchored, it is basically (even less than) a pinned connection.
This means that the colums can move freely (within limits of course). They will sway a bit when driving onto the lift for example.
By anchoring the columns, you make it a moment connection. This means that the connection should be able to react any forces or moments that occur. If you're bolting it to a 2" slab, you're likely to break the slab because it will be moving along with the posts.
Hence you need a decent slab and a decent bolted connection in order to make it work.

 

[glentre]

I have two four post lifts installed three years ago with neither one anchored. No problem although they do move a little. I've noticed some scratch marks on the floor about a half inch or so around the bottom plates proving they do move. I feel you also need to be careful about doing any yanking or abrupt pushing or pulling on the underside of a car because the lifts do sway a little also. A friend with a four post resolved this potential danger by using steel at the top of the posts to anchor the lift to a wall.

Whether you anchor or not depends on what kind of work you expect to do and how close to the lift's maximum weight rating your vehicles will be.

Glen

 

[Bad Habit]

Thank you for the responses, makes total sense now when they are anchored, Had never thought about a 4 post being able to be somewhat "mobile", always assumed they would be anchored like a 2 post. Assuming all things being equal, the recommended anchoring requirements are as much about preventing damage to the slab as it is about lift stability. Similar to seismic restraints, you're not going to stop all movement, you just want to constrain it to acceptable amounts. Once you anchor it, you transfer all that movement into the slab (loading, unloading, etc). Movement that wouldn't be present with a 2 post lift.

 

[boatshoes]

My Dannmar 4 post is anchored. I used it for a bit unanchored and didn't really enjoy the swaying. Anchored it and now it's solid as a rock. The manual for mine said to be 6" from a slab edge or seam.
If I were you I'd give Greg Smith a call for clarification to see if it is a typo. These manuals (mine included) often include typos.

 

[R. Deschain]

I live in a seismic zone and anchoring a 4 post is not recommended. My 2-post is sitting on a 36X36X18" rebar cage reinforced footing though...

 

[HotrodHR]

I have an Atlas 4 post... not anchored. Use the castors to move it around. BTW, I assembled my lift by myself... it's definitely a two, better yet, three man job! I used my engine hoist to lift and heavy duty dollies to move the pieces in place.

 

[glentre]

I have an Atlas 4 post... not anchored. Use the castors to move it around. BTW, I assembled my lift by myself... it's definitely a two, better yet, three man job! I used my engine hoist to lift and heavy duty dollies to move the pieces in place.

Agree that a man can install a four post lift alone so long as he uses his brain instead of his brawn. I installed my two lifts by myself when I was 78 yrs old and have not bolted them down as I moved them several times with the detachable wheels when painting the floor.

Glen

 

[santagary]

What does Jay Leno do??? He has lots of Bendpaks!

 

[MAYOR28]

I anchored my BendPak HD-9XW, but did not originally intend to. I found the columns too 'sloppy' without the anchors. I had a couple threads on the issues. But I am using the lift for maintenance, not just storage.

 

[IMXCITD]

Have never anchored my 4 post and it's been fine. Can move when I want and it's very stable otherwise.