for the bob the builder... concrete pouring question

[dutch]

a friend asked me to help him installing a car lift in his shop.  There is a 4-5" concrete floor inside and he wants the lift to sit flush with the top of the floor, for better clearance for really low cars. This means a hole has to be cut and concrete has to be poured.  How should I work?  pour the floor first, with reinforcement sticking out where the "walls" go?  These walls will only be about 8"high.  I guess there is no way to pour floor and walls in one piece, is there?
Would it be a wise thing to drill a bunch of bars into the cutting edge of the existing floor to achor the walls of the box/pit?
thanks

['Cuda Hunter]

I would use L bolts through the existing floor into the soon to be approximate 8" wall.
Pour the bottom first.
Use bolts sticking up into the soon to be 8" wall.
After the floor pour is complete then put up wall forms with holes on the ends.
You can get a slurry mix that can be pumped in at high speeds that will fill the cavity.
The hard part is getting enough crete in the holes on the ends when you seal them up.
Once sealed you would want to push the L bolts down into the mud.  Already installed before the form of course. Did that make sense?
You can still get high psi slurry.
Well, I can over here.  Not sure if you have that but I would expect that someone close would have the slurry mix.
You might have to put holes on both ends of the long runs.
Do the long runs, then do the short runs after the long runs have dried.

[ourname]

Would it not be easier to set the hoist and build up the floor around it with the Garage tiles you can get. I have seen them that are 1-1.5" thick.
It would look really nice as well.

Problem with cutting into the floor, is you are going to lose the strength of the slab. If you cut holes into it you will need to dig down deeper than the slab 16-24" belling it out as you go down. You will have to have this poured with concrete and tied into the slab with Rebar. All your weight is transfered to this "Bell Pile"
Even doing this I would not recommend it. Your hoist is going to be totally dependant on the Piles you build to support whatever weight your hoist is going to lift.

I put 2" x 10" board beside my hoist to raise the lower cars up.

Just My $0.02 

['Cuda Hunter]

I can agree with the bell piles.