Standing clam-shell mousetrip sleeper

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Re: Standing clam-shell mousetrip sleeper

Postby OP827 » Tue Jan 15, 2019 4:18 pm

Bluebunny wrote:
OP827 wrote: I have sketched it here in case you are not familiar with that mechanism.

Thanks for the thinks everyone! Other than the weight of the lifting aid, I'm getting confidence that the system will work OK (and yes, the beauty of it is that it assists EVENLY at each rear corner. I'll think about the straps, I worry a little about them walking on the pulleys.
And OP; awesome sketch; thanks for your thoughtful effort! I like the contrast between our sketching abilities :bowdown:


Yes, I would want to have such even lift with this two points design to avoid jamming. Now, I did not do webbing lift myself (steel cables only), but it should work. I personally don't like torsion spring idea as I see it as something that complicates things and make it more dangerous due to stored energy. With your light roof it would be an overkill. Garage doors are much heavier than your roof. You can also install a long shaft made from electric conduit for example, along the back with two points in each corner and have no issue with either ark or diameter increase (twice as less), let me know if you want another option sketch. the crank will then be located on the side. And you need a thin webbing as the load as small, it is not a car seat belts size(6000lbs load rating), something much narrower, smaller and thinner than that. Look at the load rating. I like nylon belts idea as they would be mush less noise comparing to cable and steel pulleys. Once stretched they should work evenly. You could also use Dyneema which is comparable to steel cable for elasticity and strength, but plastic flexible rope or webbing, but that is expensive and not really needed for this application. Also you can make pulleys with positive side flanges to ensure the webbing belt stays on the pulley. What is needed is a stopper that will lock the shaft at any given moment to prevent unwinding, similar to what is done on manual utility winch. I feel that the force to rotate the handle will be small and most likely does not need any power, torsion, or gas strut assist. This is based on my experience with my build. Let me know what you think. You right, you can incorporate the lifting system later, just keep in mind where you potentially route it so you can later drill slots and put a cover etc.. Sorry for the long post, but I thought it was useful to discuss the options.
My foldable foam trailer build: http://www.tnttt.com/viewtopic.php?f=50&t=61344
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Re: Standing clam-shell mousetrip sleeper

Postby Pmullen503 » Tue Jan 15, 2019 5:01 pm

If you are willing to use a crank, a small boat winch might work. They have a ratchet mechanism to hold tension while you crank (and hold the top up.) I would use polypropylene web rather than nylon for outdoor applications. 3/4" wide would have plenty of tensile strength in this application.

I had a winch on a pop up I once had with the handle held on with a hitch pin so it was removable. Easy way to lock the top down: just remove the handle!
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Re: Standing clam-shell mousetrip sleeper

Postby Bluebunny » Tue Jan 15, 2019 8:50 pm

I love the idea of attaching a rod, pulleys and cables or strap to a manual winch. Lifting winches are very difficult to find, and I have been taught and believe "never use a pulling winch (like a boat winch) to lift!" But I'd rather crank a crank than lift and pull with a spring assist. I'll so some more research. Thanks guys.
off topic Stitch-and-Glue ply kayak build... https://www.facebook.com/media/set/?set ... 254&type=3
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Re: Standing clam-shell mousetrip sleeper

Postby Pmullen503 » Tue Jan 15, 2019 9:59 pm

With a normal boat winch, If you let go of the winch handle it will spin so you have to act as the brake when lowering. Depending on the weight lifted and the ratio of the winch, that could be easy or not.

A brake winch (think boat lifts) brakes in both directions unless you turn the handle.
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