Re: lifts

[christian147@domain.elided]

I think I might know a bit about lifts seeing as how I have maid my
living with them for the last  20 years.  

Old style in ground lifts are now illegal to install in a commercial shop
due to the possibility of an oil leak. I am dreading the day EPA tells us
we have to remove the 20 we have replaced but are still in the floor.  
All 4 post lifts I have used were of the drive on ramp type and as such
must be considered special use tool.  Two post  above ground lifts are
now mostly of the asymmetrical type (front arms shorter then the rear ) 
which solves most door opening problems if you know the lift and the car.
 

My current favorite lift is of the 2 post in ground cassette electric
hydraulic type.  It solves most of my complaints about above ground
types,  lack of open space when lift is down, pump and lock mechanism is
in your face when you operate them and they exceed OSHA noise limits.  In
ground cassette's major draw back is cost.  They cost $6000 to $7000
installed where as above grounds are $3500 to $4000  installed.  

As for a floor all my lifts specify a minimum of 4 inches of concrete. 
Concrete is commercially sold by pressure rating, general use is 3500 psi
 a driveway should be 4000-4500 psi,  high strength mixes are available
up too at least 8000 psi but I know of no one who can think of a
reasonable justification for the cost of it.

Most information available is for commercial use and it is not likely you
can use a personal shop as hard as we professionals use our work spaces
(you should see what my tech's can do to something they don't own).  My
uncle, who is a commercial general contractor  insisted that I had to put
my Bridgeport mill on 6 inches of 4500 psi concrete with #5 rebar
reinforcement but it is doing just fine on 5inches of 4000 psi with 6
inch mesh.  The cost savings were well over $1000 in a small shop.

concrete is a very wide subject so talk to a qualified local concrete
contractor about what is right for your situation, but don't be afraid to
check on his suggestions we wouldn't want him blowing smoke up your
nether regions.

Chris Hall

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