I'm installing an Atlas 9KBP in my garage right now. The ceiling is 10', so a bottom plate 2 post lift made the most sense. I've already stood up / positioned the posts and everything looks great. I'm wondering if I can add a steel plate (1/2" x 20" x 135", or 2 narrower plates for $$$ savings) across the top of the posts. There isn't anything wrong or suspect with the concrete/foundation. I'm simply asking if anyone has done this before or if anyone knows a reason why this might be a bad idea. The goal would just be adding some strength to the posts. It won't really get in the way of lifting a vehicle since I'd only be losing a few inches between the garage ceiling and this top plate. Thanks in advance for any thoughts/feedback!
Adding a Top Plate to a Bottom Plate 2 Post Lift
- Thread starter Relic50
- Start date
I can't really see why it would be an issue. But I also don't see the need for it.
Having said that, if you do I think you would be better off with a beam or a boxed cross brace instead of just a chunk of plate. 1/2" plate spanning 11-12 ft. is sure to sag in the middle....not to mention be expensive.
Having said that, if you do I think you would be better off with a beam or a boxed cross brace instead of just a chunk of plate. 1/2" plate spanning 11-12 ft. is sure to sag in the middle....not to mention be expensive.
kbuhagiar
Well-known member
Is the lift brand new? If so, be aware that any modification such as this would almost surely void any warranty from the manufacturer.
Also, is there any chance that a modification such as this could possibly affect the operation of the lift, or it load rating?
Just thinking out loud here, you never know.
It is brand new. I'm not so much concerned about the warranty, I guess. I would assume if there was an issue and Atlas wanted out of the warranty they could find some kind of reason?
To your second point though, I did read in another thread that adding a brace like that might negatively impact desired bending/flexing of the posts. I know it wasn't specifically designed for a top bar, but I'm pretty sure that is because it is designed to lift a vehicle higher than what an added top bar would restrict the lift height to. I'm just already restricted to the height of the ceiling which is only inches away from the top of the posts anyway.
That is a good point. I didn't consider the sagging issue.
Homewrecker
Well-known member
I've got a Peak Lift BP10000X Baseplate lift. I was originally thinking the same thing as you but determined that the cross-beam would limit how high I could lift vehicles. My Ceiling is about a foot short (~11 feet) to fit a clear floor unit so that's why I went with a baseplate Model. I did add base extensions to each post. My floor is 6" thick but wanted the added stability.
Atlas also appear to sell this for their lifts --> https://www.atlasautoequipment.com/...ories/extension-kits/base-plate-extension-kit
You might want to consider those instead.
Atlas also appear to sell this for their lifts --> https://www.atlasautoequipment.com/...ories/extension-kits/base-plate-extension-kit
You might want to consider those instead.
wssix99
Well-known member
If you went with a bottom plate lift because you couldn't have the top plate, I'm confused why you are considering putting in a top plate now...
It may seem intuitive that putting in a top plate will make it 'stronger' but the posts are going to bend no matter what you do. A top plate is pointless. (Even the columns on a top plate lift bend inward.) If you strengthen the top plate one way, it will just bow laterally so the columns will do what they want to do.
In order to box out a structure that would really stiffen the columns, you'd end up with a ridiculous structure at the top of your lift, which would rob you of precious headroom.
You can trust the design, engineering and experience of your manufacturer. They have thousands of these lifts installed in commercial settings without issues. There is nothing in your one-off non-commercial setting that is special or problematic as long as you follow the instructions.
It may seem intuitive that putting in a top plate will make it 'stronger' but the posts are going to bend no matter what you do. A top plate is pointless. (Even the columns on a top plate lift bend inward.) If you strengthen the top plate one way, it will just bow laterally so the columns will do what they want to do.
In order to box out a structure that would really stiffen the columns, you'd end up with a ridiculous structure at the top of your lift, which would rob you of precious headroom.
You can trust the design, engineering and experience of your manufacturer. They have thousands of these lifts installed in commercial settings without issues. There is nothing in your one-off non-commercial setting that is special or problematic as long as you follow the instructions.
whateg01
Well-known member
I'm not sure what desired bending would be. Accounted for? Maybe. But lifting a lawn tractor isn't going to cause as much movement as a vehicle at the lift's capacity. In general, I would expect the mfr to design out any flexing. To that end, I would expect a cross brace at the top to help out.
That is a great suggestion! I might do that instead.I've got a Peak Lift BP10000X Baseplate lift. I was originally thinking the same thing as you but determined that the cross-beam would limit how high I could lift vehicles. My Ceiling is about a foot short (~11 feet) to fit a clear floor unit so that's why I went with a baseplate Model. I did add base extensions to each post. My floor is 6" thick but wanted the added stability.
Atlas also appear to sell this for their lifts --> https://www.atlasautoequipment.com/...ories/extension-kits/base-plate-extension-kit
You might want to consider those instead.
The overall height of bottom plate lifts are typically two feet shorter than top plate lifts. I don’t have the extra clearance for a true top plate lift in this spot of my garage, even if I removed the drywall ceiling and had it go up into the attic area.
wssix99
Well-known member
Structures are never designed to be fully constrained at two ends. This causes extra forces to build up in the structure and the results are explosive.
You can see examples of this the next time you drive under a bridge. One end will be physically pinned (can't move in space - like the base of a 2 post lift) and the other end will be free to move on a rolling or moving bearing: (like the top of a 2 post lift)
^ Movable bearing.
IF the OP were to create what is being discussed here and constrain both the bottom and top of the post in space so the column doesn't bend, then stresses would build up in the middle of the column and it would 'try' to bend there. The lift isn't designed for the bending to be gradual and spread across the entire length of the post. If it were to all be concentrated in the center, the post would fail.
^ This all being said, I don't think it is realistic to create such a structure and would be a total waste of time. But any measure of success in this quest would cause unanticipated stresses to be concentrated in the middle of the posts (Not what the manufacturer designed for.) and would erode the unit's safety.
For reference: the top plate on 2 post lifts designed with them is not structural and it bends like a wet noodle. (by design)
Thanks!Structures are never designed to be fully constrained at two ends. This causes extra forces to build up in the structure and the results are explosive.
You can see examples of this the next time you drive under a bridge. One end will be physically pinned (can't move in space - like the base of a 2 post lift) and the other end will be free to move on a rolling or moving bearing: (like the top of a 2 post lift)
^ Movable bearing.
IF the OP were to create what is being discussed here and constrain both the bottom and top of the post in space so the column doesn't bend, then stresses would build up in the middle of the column and it would 'try' to bend there. The lift isn't designed for the bending to be gradual and spread across the entire length of the post. If it were to all be concentrated in the center, the post would fail.
^ This all being said, I don't think it is realistic to create such a structure and would be a total waste of time. But any measure of success in this quest would cause unanticipated stresses to be concentrated in the middle of the posts (Not what the manufacturer designed for.) and would erode the unit's safety.
For reference: the top plate on 2 post lifts designed with them is not structural and it bends like a wet noodle. (by design)
CraigStu
Well-known member
I have had the same thought as you, if I want to help keep the lift posts from leaning toward each other a top plate is obviously the way to do it. But I have also looked at a few top plate lifts. What surprised me was that the top plate, to my eyes anyway, was strong enough to contain the crossover cables but that was about it. It was just heavy sheet metal.
Was there any real engineering done on adding that rectangular tubing? I only ask because I question how much extra support that tubing supplies. If the anchor bolts failed I imagine the rectangular tubing will bend like a piece of licorice.I've got a Peak Lift BP10000X Baseplate lift. I was originally thinking the same thing as you but determined that the cross-beam would limit how high I could lift vehicles. My Ceiling is about a foot short (~11 feet) to fit a clear floor unit so that's why I went with a baseplate Model. I did add base extensions to each post. My floor is 6" thick but wanted the added stability.
Atlas also appear to sell this for their lifts --> https://www.atlasautoequipment.com/...ories/extension-kits/base-plate-extension-kit
You might want to consider those instead.
He is using a manufacturer's product - https://www.atlasautoequipment.com/...on-kits/base-plate-extension-kit-for-bp10000x.
I unfortunately can't add on such an extension kit. Atlas only makes it for their 8000 and 10000 series base plate lifts, not the 9KBP model which has a different bolt pattern.
I'm not going down the road of adding something like this because the concrete is cracked / inadequate. I just figured if I was going to install this lift in my garage I'd look into any additional options to make it a little stronger than how it comes out of the box.
The compressive force in the top strut is not all that high. But designing the lift with the top strut produces a bending moment envelope in the posts that is equal to or less than the cantilever post lift design at all points. The base moment will reverse in direction as you raise the car. So the bolt pattern at the base plate might not work if you add the top strut. I am talking about moments in the plane of the post/strut.
Say for 10000lb truck, moment is 10000lb/ 2 * (3' post to lift pads) = 15000 #'. The top strap force is about 15000#'*1.5/(10' lift height) = 2300# compression. So an engineer needs to design the top strap for that force plus dead load, eccentric effects, etc. The 1/2x20 plate is no where close to working.
wssix99
Well-known member
And check the design of the posts to make sure they won't buckle.
Homewrecker
Well-known member
You think I made this? I wish I had the equipment for that lol. Like Relic50 said, I purchased it from the lift manufacturer whom I'm sure would have put some engineering time into it.
Interesting! I still question the added strength. It seems like it would add very little to the integrity of the lift. Seems like a "feel good" addition to me.
Homewrecker
Well-known member
They're extremely heavy and well built. I'm not concerned. My floor is plenty thick but nothing wrong with some added reinforcement. Not gonna lose any sleep over it. A few lift companies have these for their products.
i always wanted to do this with like a 4x4 foot plate about 3/4 thick, Im more afraid of the bolt pulling out than the lift failI've got a Peak Lift BP10000X Baseplate lift. I was originally thinking the same thing as you but determined that the cross-beam would limit how high I could lift vehicles. My Ceiling is about a foot short (~11 feet) to fit a clear floor unit so that's why I went with a baseplate Model. I did add base extensions to each post. My floor is 6" thick but wanted the added stability.
Atlas also appear to sell this for their lifts --> https://www.atlasautoequipment.com/...ories/extension-kits/base-plate-extension-kit
You might want to consider those instead.
WNYflyer
Well-known member
Structures are never designed to be fully constrained at two ends. This causes extra forces to build up in the structure and the results are explosive.
You can see examples of this the next time you drive under a bridge. One end will be physically pinned (can't move in space - like the base of a 2 post lift) and the other end will be free to move on a rolling or moving bearing: (like the top of a 2 post lift)
^ Movable bearing.
IF the OP were to create what is being discussed here and constrain both the bottom and top of the post in space so the column doesn't bend, then stresses would build up in the middle of the column and it would 'try' to bend there. The lift isn't designed for the bending to be gradual and spread across the entire length of the post. If it were to all be concentrated in the center, the post would fail.
^ This all being said, I don't think it is realistic to create such a structure and would be a total waste of time. But any measure of success in this quest would cause unanticipated stresses to be concentrated in the middle of the posts (Not what the manufacturer designed for.) and would erode the unit's safety.
For reference: the top plate on 2 post lifts designed with them is not structural and it bends like a wet noodle. (by design)
Not necessarily true, BendPak has sample calculations indicating that for some of their lift models the top member is structural and acts as a compression strut under normal loading conditions.
https://www.bendpak.com/a-study-in-lift-design/engineering-report/
Last two diagrams indicate shear and moment diagrams with top member acting as a structural member.
^^^^ This is correct.
zkdiesel
Well-known member
Top bar doesn’t add strength. It’s for the cables……
No top bar on this unit. Hasn’t fallen down yet
No top bar on this unit. Hasn’t fallen down yet
Homewrecker
Well-known member
Mohawk lifts are on another level. They're built like battleships lol. I got tired of jumping through hoops sourcing one up here though and finally gave up.Top bar doesn’t add strength. It’s for the cables……
No top bar on this unit. Hasn’t fallen down yet
zkdiesel
Well-known member
This one could possibly lift a battleship. Had a 33k rear heavy truck on it and it handled it amazingly
wyb2
Well-known member
Bridges are built that way for CTE (thermal expansion) reasons. Not really a concern for a 2 post lift.Structures are never designed to be fully constrained at two ends. This causes extra forces to build up in the structure and the results are explosive.
You can see examples of this the next time you drive under a bridge. One end will be physically pinned (can't move in space - like the base of a 2 post lift) and the other end will be free to move on a rolling or moving bearing: (like the top of a 2 post lift)
^ Movable bearing.
IF the OP were to create what is being discussed here and constrain both the bottom and top of the post in space so the column doesn't bend, then stresses would build up in the middle of the column and it would 'try' to bend there. The lift isn't designed for the bending to be gradual and spread across the entire length of the post. If it were to all be concentrated in the center, the post would fail.
^ This all being said, I don't think it is realistic to create such a structure and would be a total waste of time. But any measure of success in this quest would cause unanticipated stresses to be concentrated in the middle of the posts (Not what the manufacturer designed for.) and would erode the unit's safety.
For reference: the top plate on 2 post lifts designed with them is not structural and it bends like a wet noodle. (by design)
Adding support at the end of a cantilever beam (top of a lift column) can only make it stronger. There could be other concerns, like over constraining for CTE or changing the natural frequency, but I can’t think of any that would matter for the case of a lift.
But 10 ft of 1/2” plate you could probably wobble by hand (if you could lift it). It will be useless in compression and add negligible strength.
3rdgendslmech
Well-known member
So, I like you ended up with a 10K base plate lift and I thought about adding an I beam across the top. I've got 10' ceilings though. It was going to serve 2 purposes, extra strength, and I was going to add a trolly and hoist for picking motors and other heavy jobs. Fast forward a few years.....I've got 2 kids, one is five and a 10 month old, I've yet to pull a motor out of anything.....and some stuff I can use the lift arms for. I picked up a friend's crew cab long bed cummins with some tools for concrete work in the back ( 2 plate tamps, and a couple short forms) and it picked it up no problem and being how that was the heaviest truck that I'd put on it, I put a level on the posts before I lifted, and after I lifted, and while the truck was in the air, the posts were maybe 1/8 pulled in, and straightened back up once back on the ground.
With 6" of concrete and a 9K lift, you'll probably be fine.
With 6" of concrete and a 9K lift, you'll probably be fine.