Jeep Hardtop Hoist Mount Location

[rockcrawler]

I mounted an electric hoist on a ceiling beam (M8 10#) in my shop to lift and store my 200 lb. Jeep hardtop. The hoist is mounted to steel square tubing and the tubing is mounted to the beam with beam clamps. I posted something about this in the past and I’m still pondering my decision. The hoist is mounted close to the center of the beam, which is about 20’ long. I spoke with a guy at the steel supply place near my house and he told me it should be fine. But, some members here voiced that they were concerned the beam may not support the top without additional support. I have not used this yet due to fear of causing damage to my roof structure. If I were able to mount the hoist at the peak, would this be a stronger point due to the “pull” essentially causing the beams push against each other at the peak? I hope I’m explaining my thoughts clearly. Maybe I’m overthinking this and I should just use the hoist where I have it. Anyone have thoughts on this? Any structural engineers out there have an opinion?

 

[Garcky]

Hmm...200 lb. is not a lot of weight. However, I'm not familiar with that type of construction. What are the dimensions of those steel rafters and the tubing your winch is mounted on? How is that crossmember attached to the long rafters. Clearly, the rafters are designed to carry the load of the roof materials and wind loads. I'd guess the 200 lb. Jeep hardtop wouldn't overstress that set-up, but I'm not an engineer.

You might ask the company that makes that building what they think. Send them the photos, and describe the situation. I'm sure they've answered questions like yours before.

 

[rlitman]

I'll leave the engineering up to the building manufacturer's opinion, but I will say that I like how you mounted it in the rafter close to the purlin. That eliminates the chance of an offset cable's pull starts to twist the rafter.

 

[Garcky]

I'll leave the engineering up to the building manufacturer's opinion, but I will say that I like how you mounted it in the rafter close to the purlin. That eliminates the chance of an offset cable's pull starts to twist the rafter.

That's what I was thinking, too. It looks as strong as it can be in that type of construction. I'd think it could handle a couple hundred pounds with zero deflection. But, I'm not an engineer, and I don't know the specs on any of the materials.

 

[rockcrawler]

Hmm...200 lb. is not a lot of weight. However, I'm not familiar with that type of construction. What are the dimensions of those steel rafters and the tubing your winch is mounted on? How is that crossmember attached to the long rafters. Clearly, the rafters are designed to carry the load of the roof materials and wind loads. I'd guess the 200 lb. Jeep hardtop wouldn't overstress that set-up, but I'm not an engineer.

You might ask the company that makes that building what they think. Send them the photos, and describe the situation. I'm sure they've answered questions like yours before.

W8x10 Beam
Lbs/ft. 10
Depth 7.89”
Flange 3.94”
Web 0.17”

The square tubing used to mount the hoist to the beam is 2” if I remember correctly and the tubing is mounted to the beam with Superstrut beam clamps. The building was not a kit. It was built from parts my builder bought from the local steel supplier. It is 35x45 weld up steel building built with I-beams and red iron purlins. The builder turned out to be a total flake, as many contractors in Texas are, so I no longer have communication with him. It seems to be built fairly well, but I’m not a builder. I consider myself lucky that he even finished it.

 

[dagoat_1]

I'd rock your setup all day long without a worry. But I'm only an Internet engineer

 

[dfiler2]

I'll bet a 200lb man standing in that spot on the roof would barely move it. That foam also adds a lot of strength.

 

[FredWanaker]

I had a CJ7 hardtop that I used to pull off sometimes and put the bikini top on, the issue won't be the hardtop. It will be when you are swinging it and accidentally bounce it a little taking it off or putting it on. Personally, I don't like the way it looks, the mount is in the center of the tube where the most deflection will be, and the lowest frequency harmonic when bouncing. I am more worried about the tubing than the roof, but the tubing holds the roof up. I might have added a 2 x 10 or another thickwall piece of tubing to the roof, and mounted to that, so that many ROOF beams support both 200+ lbs spread out instead of just the tube supporting the roof overall AND the jeep hardtop in just one place. I had to use a block and tackle pulley system to lift mine as inexpensive electric lifts were not available. They are heavy because of the side and rear glass. The other issue will come when someone eyes it to lift something heavier than the hardtop, one time. The end will come quickly if overstressed the way it is designed. There won't be a lot of warning before damage is done.

If you want a definitive answer, consult an engineer, OR do some deflection testing by hanging a string with a small weight, like a plumb bob and watching to see how much it deflects with 50 lbs, 100 lbs, 150 lbs etc.. Go up to 75% more than the hardtop. Engine hoists are made of tubular steel too. Ever see how little weight they will carry when they are fully extended?

 

[tncatadjuster]

Looks good to me, there is nothing that stands out as failure point. I would not exceed 200 pounds by much as it is a dynamic load. A leaking roof is no fun though, does it make a sound when you stand beneath it and lift yourself with your arms? I know the winch is so loud it will need to be turned off.

 

[rockcrawler]

I had a CJ7 hardtop that I used to pull off sometimes and put the bikini top on, the issue won't be the hardtop. It will be when you are swinging it and accidentally bounce it a little taking it off or putting it on. Personally, I don't like the way it looks, the mount is in the center of the tube where the most deflection will be, and the lowest frequency harmonic when bouncing. I am more worried about the tubing than the roof, but the tubing holds the roof up. I might have added a 2 x 10 or another thickwall piece of tubing to the roof, and mounted to that, so that many ROOF beams support both 200+ lbs spread out instead of just the tube supporting the roof overall AND the jeep hardtop in just one place. I had to use a block and tackle pulley system to lift mine as inexpensive electric lifts were not available. They are heavy because of the side and rear glass. The other issue will come when someone eyes it to lift something heavier than the hardtop, one time. The end will come quickly if overstressed the way it is designed. There won't be a lot of warning before damage is done.

If you want a definitive answer, consult an engineer, OR do some deflection testing by hanging a string with a small weight, like a plumb bob and watching to see how much it deflects with 50 lbs, 100 lbs, 150 lbs etc.. Go up to 75% more than the hardtop. Engine hoists are made of tubular steel too. Ever see how little weight they will carry when they are fully extended?

The hoist is mounted to a piece of 2x2 steel tube and the tube is mounted to the I-Beam. It’s an I-Beam, not square tubing.

 

[rockcrawler]

Looks good to me, there is nothing that stands out as failure point. I would not exceed 200 pounds by much as it is a dynamic load. A leaking roof is no fun though, does it make a sound when you stand beneath it and lift yourself with your arms? I know the winch is so loud it will need to be turned off.

The hoist will never be used for anything but the hardtop. I lowered the bracket that holds the top and used it to pull my body weight (220 lbs) up, like a couple of pull-ups and didn’t hear anything.

 

[rockcrawler]

Thanks for all the input. I’m feeling a bit more comfortable with the idea. I guess I’ll give it a shot. I’ll definitely check for any deflection when I lift the top the first time.

 

[FredWanaker]

I did not know it was an I-Beam. To me it looked like 4" tubing in the picture. If there is a question on it just dangle a line and small weight, then load it and see how much it deflects and how much.

 

[nitroracer20]

Wouldnt even think twice if it was mine.

 

[ybnormal]

as Garcky said, contact the company who supplied the design. what I don't like is that you essentially have all that weight concentrated at one point on that I-beam. I would have stretched that 2x2 across 2 or 3 beams