Tandem Operating Double-Wide 4-Post Lift

JSK · May 14, 2014

Thought I'd share.

Brand new. One-off. Special-made for a customer in so-Cal.

He was first planning on two four posts installed side-by-side but didn’t like the idea of columns smack-dab in the middle of his garage to ultimately crash in to. He liked the idea of a double-wide four post lift but didn’t like the idea of having to move both cars on the bottom every time.

It started out as a drawing on a cement bag six months ago.

Tada!

A couple of install pix then first use.

readhead · May 14, 2014

Very cool. I guess with that many Bentleys the owner could afford the custom work. Is there going to be drip pans?

wise · May 14, 2014

Beauty!

Automobilist · May 14, 2014

Very nice execution, even though there is only one Bentley...

That would work well in my new garage. Plan on doing more units? Cost uninstalled?

JSK · May 14, 2014

readhead said:
Very cool. I guess with that many Bentleys the owner could afford the custom work. Is there going to be drip pans?

Hard to tell, but full-length diamond-plate aluminum decks are installed.

JSK · May 14, 2014

Automobilist said:
Very nice execution, even though there is only one Bentley...

That would work well in my new garage. Plan on doing more units? Cost uninstalled?

Yes, this model will go in full production but a complete re-design/makeover is planned. Hopefully will have something to offer by year end. Shooting for $8,000 - $10,000.00'ish range.......

JK

Automobilist · May 14, 2014

Keep it relatively reasonable and you'll sell a bunch I predict.

bobbitwoshoes · May 14, 2014

Wow, there is no redundant safety mechanism on the inboard cables. A single point failure anywhere in those cable/connections will result in, well, it won't be pretty especially if someone is under the lift.............

JSK · May 14, 2014

bobbitwoshoes said:
Wow, there is no redundant safety mechanism on the inboard cables. A single point failure anywhere in those cable/connections will result in, well, it won't be pretty especially if someone is under the lift.............

Yea, that's why we used the same cable that is used on our 27,000-lb four post lifts. Those 16 mm. cables have been tested at over 37,000-pounds each. Plus the sheaves are the size of pizzas so there will be little if any cable fatigue.

Each platform is rated at 7,000 pounds, so even at full capacity, each cable will be supporting no more than 1750-pounds,

rburke65 · May 14, 2014

That should probably be 17,500#......

JSK · May 14, 2014

rburke65 said:
That should probably be 17,500#......

Actually much higher.

stonesfan68 · May 14, 2014

That looks really cool; however, even with the design, testing and certificates I don't think that I'd want to be near it during an earthquake!

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metaleltr · May 15, 2014

i would like to see a brace from the platform and the side posts that rides on rollers to keep the load from swaying

JSK · May 15, 2014

metaleltr said:
i would like to see a brace from the platform and the side posts that rides on rollers to keep the load from swaying

Hard to believe, but you can push as hard as you want to on the suspended side, (either the runways, cables or cross tubes) and the platforms do not sway at all. The outside platforms are tied to the columns via UHMW slide block retainers so I think that’s what keeps everything rigid. I was surprised when I first tried it because I too thought you could get it swinging but it’s solid.

I'm heading back to the property tomorrow and will take a video as someone tries to push hard on the platforms.

metaleltr · May 15, 2014

JSK said:
Hard to believe, but you can push as hard as you want to on the suspended side, (either the runways, cables or cross tubes) and the platforms do not sway at all. The outside platforms are tied to the columns via UHMW slide block retainers so I think that’s what keeps everything rigid. I was surprised when I first tried it because I too thought you could get it swinging but it’s solid.

I'm heading back to the property tomorrow and will take a video as someone tries to push hard on the platforms.

Ok looking now that is exactly what i was thinking of, it was just hard to see in the photo, it appeared that the platforms were only connected to the cables

bobbitwoshoes · May 16, 2014

JSK said:
Yea, that's why we used the same cable that is used on our 27,000-lb four post lifts. Those 16 mm. cables have been tested at over 37,000-pounds each. Plus the sheaves are the size of pizzas so there will be little if any cable fatigue.

Each platform is rated at 7,000 pounds, so even at full capacity, each cable will be supporting no more than 1750-pounds,

Designs are often good, but the manufacturing process can really screw things up. It only takes one person to make an incorrect decision during manufacturing, when nobody is watching, that can have disastrous effects months or years later. Myself, I'll stick with redundancy over a larger factor of safety any day of the week.

You can see what happened with a single point system at Ringling with a factor of safety of 6.7.

(CNN) -- The weekend accident that injured nine members of a circus troupe...., was caused by a 5-inch D-ring that snapped, the lead investigator for the city's fire department said Monday.

"It was a single piece of equipment that failed," fire investigator Paul Doughty told reporters.

The steel caribiner was part of a rig designed to hoist performers by their hair into the air above the audience, where they would perform acrobatics. When it snapped, the rig fell to the ground to the confusion and horror of the audience.

The caribiner was rated for about 10,000 pounds, and the weight of the performers and the rig that fell was about 1,500 pounds, he said.

sublimate · May 16, 2014

bobbitwoshoes said:
Myself, I'll stick with redundancy over a larger factor of safety any day of the week.

Well, technically cable offers redundancy as it's made up of multiple strands and any one strand (or in this case like 80% of the strands) could fail and it would still hold. Yeah, the anchor endpoints could fail, but even on your lift with multiple-lock "redundancy" there's still single-point failure paths - if your runway, crossbar or column fails your lift is still coming down no matter how many safety locks you have.

alberto · May 16, 2014

I love that design. I'm in SoCal also and have interest, but need to wrap my head around what happens during an earthquake. Have you guys done any modeling to figure out what the results are?

JSK · May 27, 2014

alberto said:
I love that design. I'm in SoCal also and have interest, but need to wrap my head around what happens during an earthquake. Have you guys done any modeling to figure out what the results are?

Would easily pass any CA seismic reqs. Yes, we would be able to supply calcs and modeling.

JSK · May 27, 2014

Finally got the video done.

https://www.youtube.com/watch?v=8vHdGshWSE0&feature=youtu.be

ibedayank · May 27, 2014

wonder how well this lift will work when pulling a transmission and transfer case out of a 1ton truck.... sway to the left..... sway to the right..... sway everywhere

smithred67 · May 28, 2014

Very Cool!!

rsanter · May 28, 2014

I like it....
I can't afford it....

Bob

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