Concrete slabs and 2 post hoist

Zedn · #1 (**permalink**) 03-25-2016, 02:06 AM

You can test concrete compressive strength with a Schmidt hammer fro a crude reading. Otherwise coring out samples is required.

I just looked at the manual and it only needs 100mm thick 20mPa. Your slab wouldn't be less than 20mPa. I'm surprised that's all it requires with a few anchor bolts drilled in.

boxhead · #2 (**permalink**) 03-25-2016, 02:41 AM

Pretty sure hoists require 175mm from memory. I think they require 100mm dynabolts to secure.

Zedn · #3 (**permalink**) 03-25-2016, 02:48 AM

not this one. 4 inch minimum 6inch preferred according to the manual.
http://www.tufflift.com.au/wp-conten...PDI-Manual.pdf

Bernica · #4 (**permalink**) 03-25-2016, 11:32 AM

Personally, and for my own piece of mind, I would be cutting a roughly 30"x30" section of the slab on each side and digging a hole for a footing. put a rebar cage in the hole and drill into the edges of the existing slab and using some epoxy grout, install some rebar dowels that protrude into the opening about 6" all around. Then purchase some high-strength anchor bolts and insert them in the hole tie-wired to the rebar cage. Make a template out of plywood for the bolt layout to hold them in proper position. Fill the holes and finish with some good high-strength concrete (5,000 psi). Remove the template and finish around the anchor bolts.

Sounds like overkill, I know. But am not so fond of the idea of a two-post lift rolling over!

My 2c

Zedn · #5 (**permalink**) 03-25-2016, 12:18 PM

I agree with you Bernica. I would have thought they would have a cast in anchor plate with studs on it that ties into the steel like they do with a crane base. I wouldn't be trusting it to Dyna bolts.

Bernica · #6 (**permalink**) 03-25-2016, 01:16 PM

Quote:

Originally Posted by Zedn

I agree with you Bernica. I would have thought they would have a cast in anchor plate with studs on it that ties into the steel like they do with a crane base. I wouldn't be trusting it to Dyna bolts.

Nope, wouldn't trust a Dynabolt through a 4-6" slab. To add to my worries of doing something like that, I live in earthquake country.

But regardless, I would do it the way I described no matter where I lived.
Some engineers here might be able to explain a "hinge point" or "overturn" better than I could, but I'm sure you get the idea.

Zedn · #7 (**permalink**) 03-25-2016, 02:35 PM

I have one of those engineering degrees so yes I understand

Bernica · #8 (**permalink**) 03-25-2016, 02:44 PM

Quote:

Originally Posted by Zedn

I would have thought they would have a cast in anchor plate with studs on it that ties into the steel like they do with a crane base.

Yup, same concept. I have set lots of crane bases over the years.

Tonus72 · #9 (**permalink**) 03-25-2016, 03:32 PM

Hi.

I am looking at the same thing.

When I did the shed slab a few years ago I put in a trench footing across the spot where I 'thought' I wanted the lift.

Now I think it would be better about 1 metre closer to the roller door. Doh...

There is a trench footer the whole way around the perimeter of the slab and the slab is min 100mm thick.

Bearing in mind it still complies, and the trench footing is nearby, I am hoping it will be ok to move it to suit my layout...

I got a price a few years ago for a Tech Lift 6253 delivered to Tassie - I just need to get an updated price.

Cheers

Tony

Quote:

Originally Posted by iseovodoia

Hey Fella's

I am planning on installing a Tuff Lift 2 post hoist in my shed. My slab is about 8 years old and 100mm concrete with steel reinforcement. Do you think this slab is up to handling a hoist? How do I test to see the compression strenght?

Bernica · #10 (**permalink**) 03-25-2016, 03:41 PM

Quote:

Originally Posted by Tonus72

Hi.

I am looking at the same thing.

When I did the shed slab a few years ago I put in a trench footing across the spot where I 'thought' I wanted the lift.

Now I think it would be better about 1 metre closer to the roller door. Doh...

There is a trench footer the whole way around the perimeter of the slab and the slab is min 100mm thick.

Bearing in mind it still complies, and the trench footing is nearby, I am hoping it will be ok to move it to suit my layout...

I got a price a few years ago for a Tech Lift 6253 delivered to Tassie - I just need to get an updated price.

Cheers

Tony

I am thinking that if your current trench footing for this lift is 1 metre away, then you do the same thing I recommended BUT, since it's down there and you will be digging anyways, tie into it with some rebar dowels epoxied into the trench footing if you can. If you can't, just forget the old footing and do new one(s).
Again, my 2c

Zedn · #11 (**permalink**) 03-25-2016, 04:49 PM

The manual referenced above includes the pad footing instructions also for weaker slabs

byroncobra · #12 (**permalink**) 03-25-2016, 05:18 PM

Well, mine is bolted as per instructions with 100mm dynabolts to the concrete floor.
It hasn't fallen over yet.

RockBit · #13 (**permalink**) 03-25-2016, 06:42 PM

I'm all for safety, but a 2 post lift is a lot different from a jib crane. The 2 post is lifting near the center of the car and near the center of gravity off the car. There isn't much force trying to tip it over, the force is mostly straight Down. A jib crane is lifting a heavy load off to one side of the base, so the forces on the floor are much higher. Just saying.

Bernica · #14 (**permalink**) 03-25-2016, 06:54 PM

Very good points. The load is technically centered over the posts and transfers down to the base, which in theory would take the direct load. But still have to question lateral or transverse loads and strength to accommodate the lateral loads.

Gav · #15 (**permalink**) 03-25-2016, 08:02 PM

Buy a four post hoist.

Zedn · #16 (**permalink**) 03-26-2016, 12:27 AM

Quote:

Originally Posted by RockBit

I'm all for safety, but a 2 post lift is a lot different from a jib crane. The 2 post is lifting near the center of the car and near the center of gravity off the car. There isn't much force trying to tip it over, the force is mostly straight Down. A jib crane is lifting a heavy load off to one side of the base, so the forces on the floor are much higher. Just saying.

For a cobra maybe, but not a normal car with motor in the front.

Jaydee · #17 (**permalink**) 03-26-2016, 04:21 AM

I have a molnar 2 post and the base legs are 1 metre forward and back of the main column. The arms that hold up the vehicle doesn't extend much further then that. If you have a vehicle that far forward to be a problem, it would then tip of the hoist. I have on some vehicles on the hoist being able to lift the rear of the car up by hand. Scary stuff. I don't like the hoists that have a tiny base. I would be welding up arms along the floor or make up a triangulation type setup?
JD

Bernica · #18 (**permalink**) 03-26-2016, 11:35 AM

Quote:

Originally Posted by Jaydee

Scary stuff. I don't like the hoists that have a tiny base. I would be welding up arms along the floor or make up a triangulation type setup?
JD

Yes, but then you've got a bunch of stuff to trip over on the floor!
To me, nothing beats a good quality 4-post like a BendPak or similar.
That's the direction I will be going when I build the new garage.

JohnnyRay · #19 (**permalink**) 03-26-2016, 03:28 PM

Quote:

Originally Posted by Jaydee

I have a molnar 2 post and the base legs are 1 metre forward and back of the main column. The arms that hold up the vehicle doesn't extend much further then that. If you have a vehicle that far forward to be a problem, it would then tip of the hoist. I have on some vehicles on the hoist being able to lift the rear of the car up by hand. Scary stuff. I don't like the hoists that have a tiny base. I would be welding up arms along the floor or make up a triangulation type setup?
JD

I would like to find something like this available in the US...

Jaydee · #20 (**permalink**) 03-26-2016, 09:57 PM

I must admit that I would like a 2 poster with the cross bar up high, so you have a smooth floor. It can be annoying when removing a gearbox on a trolley. A 4 poster is good for lifting a car quickly for trans jobs, storing cars, large 4 wheel drives etc. It gives you a nice platform when working on brakes etc. But it can also get in the way. The ones I really hate are the old fashion single huge pole that comes out of the ground with the huge pad. Totally useless trying to get a trans or exhaust out of a car. A 4 poster with the 2 i beams that lock at certain positions that allow the wheels to be free would be a great way to go.
JD