If I were to install a lift I would insist on some overkill for sure. More inches of concrete floor thickness as well as oversized high quality bolts.
I wasn't too concerned about the compressive "load bearing" capability of the concrete slab in my garage, but more concerned with the thickness for the anchors to be effective/safe. I also did not like the idea of bolting/unbolting from an anchor with this being a portable lift. Mind you, in the end, my columns are staying in place. Its just nice to know you can easily move a column if I want to. And owners have been doing so without reports of issues.
Some have had issues with the anchors not grabbing; they probably had the drill wobble while drilling and the hole got a tad bigger. Someone I know had that happen so he opted for special anchors set with epoxy.
The "worst case - lift arms fully extended" tensile load is 3238 pounds per bolt on the MaxJax. The supplied bolts are 5/8 - 11 which would have a rating ~10 X if they are a grade 8. I used M16 x 2 12.9 grade socket head cap screws which are rated even higher. Overkill! Edited to add: the anchors themselves are rated for 16500 pounds each, so roughly 5X (16500/3238)
MaxJax Specifications and Load Analysis:
http://www.maxjaxusa.com/specifications.htmlThis isn't going anywhere...
![](http://edelweiss.smugmug.com/Category/Max-Jax-2-Post-Lift/i-NfJrMjP/0/L/IMG_3344-L.jpg)
As far as the lift structure is concerned, when a 1/4" aircraft cable can hold up a car and almost the heaviest truck, I'm not too worried about some 12 inches of weld (the section under tension) not being 100%.