Engineering/Technical Assistance Needed

[alirawk]

Hello all. I'm hoping to find somebody to help me rig up a pulley system to easily take my alu-cab RTT on and off my rig.

My vision is to drive under a gantry crane I bought specifically for this and use an electric winch to pull RTT off. Leave suspended on crane and then lower when I need it. Although there a giant wood beams in my workshop -- I don't want to connect hoist/pulley system to them as I want to be able to take the system to whatever space I might have in the future. I've looked at various garage systems, i.e. Racor, but I don't think they'll work given the ceiling height of my workshop.

So I need help figuring out the center of gravity on the winch system, a method of balancing the RTT and means of connecting it to hoist, a second or maybe even a third pair of hands to make this happen.

Open to suggestions for engineering this or references to people who do this kind of work -- but really want somebody local, with a free day to come to my workshop in Inglewood and help me with this. Happy to compensate you for your time with booze, food, and cash.

My shop is directly across the street from where the new stadium is going up.

 

[Captain Planet]

It's going to heavily depend on the load and the structure of the building.

Those rafters or beams are typically in tension between the walls, and not typically laterally loaded.

You may need some sort or reinforcement, like sistering, kneewall, collar-ties, etc.

The Racor style distributes the load over a larger area than say just mounting a winch and few pulleys.

You would need to hire a PE for this or at least someone who can do load calcs.

That's assuming you're going to get a permit of some sort.

 

[Transient]

Everything posted above is solid advice.

Pics of the space would also be very helpful.

 

[alirawk]

It's going to heavily depend on the load and the structure of the building.

Those rafters or beams are typically in tension between the walls, and not typically laterally loaded.

You may need some sort or reinforcement, like sistering, kneewall, collar-ties, etc.

The Racor style distributes the load over a larger area than say just mounting a winch and few pulleys.

You would need to hire a PE for this or at least someone who can do load calcs.

That's assuming you're going to get a permit of some sort.

Not connecting to building. Bought a 1000lbs rated gantry crane solely/specifically for this.

 

[El Dusty]

Not connecting to building. Bought a 1000lbs rated gantry crane solely/specifically for this.

Pics would help. Just my thoughts below.

How much clearance is there between the gantry connection point(s) and your rtt? A simple 5 to 1 rope pulley would reduce the load enough that you shouldn't need a winch. Going to need to an anchor the rope properly.

I could see 4 eye bolts installed to the rtt to keep it from rolling over. Rope from each eye bolt to the base of the pulley. A tag line to keep the load from rotating would probably be needed. Also is the gantry mobile or fixed to your floor? GLHF

 

[alirawk]

Pics would help. Just my thoughts below.

How much clearance is there between the gantry connection point(s) and your rtt? A simple 5 to 1 rope pulley would reduce the load enough that you shouldn't need a winch. Going to need to an anchor the rope properly.

I could see 4 eye bolts installed to the rtt to keep it from rolling over. Rope from each eye bolt to the base of the pulley. A tag line to keep the load from rotating would probably be needed. Also is the gantry mobile or fixed to your floor? GLHF

I will try to take pics soon -- I actually took the gantry crane apart and have to reassemble soon to actually do this. Again, part of the reason I posted here was in hopes of finding somebody local to hire to help pull this off.

I'm not too keen on drilling holes in the RTT. I'm thinking of perhaps stringing some webbing or webbing wrapped around cable under it, to then connect to the hoist. When I put the system together in the first place, I bought extra cross bars for the roof rack specifically to permanently afix to the RTT, so I could simply take of those bolts, lift the RTT up and then lower back when I wanted to use.

I suppose, I mostly need an extra hand with a little bit of patience and engineer insight who wants to make a little cash for a few hours of help.

 

[El Dusty]

I suppose, I mostly need an extra hand with a little bit of patience and engineer insight who wants to make a little cash for a few hours of help.

Here's a product that you could try as well. You could mount this to your gantry but may need longer straps?

Amazon.com : VIVOHOME Heavy Duty Ceiling Mount Bicycle Kayak Canoe Garage Storage Lift Hoists Pulley System 125lbs Capacity Pack of 2 : Sports & Outdoors

 

[Transient]

Weight of the RTT?

 

[DBR4runner]

I'm a licensed professional engineer (mechanical). I would build a gantry on casters from wood. Should be easy to assemble/disassemble and cheap to build. I would use multiple manual pulleys. Simple and effective

 

[Narat_524]

Kiss

I like this guy's approach for $40. Kayak hoist.

A Simple $40 RTT Storage Hoist!

 

[alirawk]

Weight of the RTT?

RTT plus the awning which attaches to the RTT comes close to 200 lbs. As such the kayak hoist won't work.

Now thinking I'll forget the whole gantry crane thing and connect directly to the rafters. I believe they are 4 by 12. With some support they should be fine. Thoughts?

 

[alirawk]

Finally did it!!!

Literally years after I bought a gantry crane for this, which I never used. A winch that I never unboxed. And so many nights of tired to figure out the easiest way of getting it done. I realized I was way over thinking it and I got tired of looking at the rafters and the winch every day -- so I just pulled the trigger and rigged up this thing. Works really well.

Basically I wrapped a couple of ratchet straps around the RTT. Then brought them together with a 3rd strap that connected to winch. And just like that, it came straight off the rig. (Note: when I first set up the RTT, I bought extra cross bars for the RTT that I planned to permanently fixed to the RTT, so I could just unscrew those 12 bolts and take the RTT, still attached to crossbars off and back on. This was my plan all along. I've had this RTT for at least 3 years -- so yeah, I've really been procrastinating on completing this ultimately very simple operation.)

The winch is bolted to length of steel square tubing which is bolted directly up to the rafter. A couple of strong ties are added on each end of the square tubing to reinforce.

Added a couple of fat eye bolts to the rafter and after the RTT was hoisted up, used webbing and some locking carabiners to equalize weight.

I'll still need to finagle it a bit more -- but I'm stoked to be able to take it off and put back on my rig by myself with a little bit of effort. With a second hand it's super easy.

Ironically, I did all of this and took off the RTT just before climbing season. So I'll probably be putting it right back on my rig pretty soon. :doh:

Thanks for all the help. It's great to have the RTT off the ride for a while. It's to be expected, but nevertheless shocking, to experience the drastic change it makes to the handling and ride of the rig.