Idle hands.........

[wroughtn_harv]

For years now I've thought what would make a trick single axle dump trailer would be to use chains and reverse instead of hydraulics.

Think about this if you've considered having a small trailer that could dump on it's own with minimum fuss and without hydraulics.

To dump it you pull the keeper at the front. And then you let down two snow chains that are attached to the part of the bed that dumps at the rear of the trailer. You want the chains attached as far back away from the tires as possible. You just lay out the snow chains so that when you back up the trailer tires roll up on them.

Of course when you back up further the trailer tires will roll up on the chains pulling down the bed.

It's something on my list of things that would be fun to do. And to be honest what I like about the idea is it's simplicity. You figure everything in this world is about push or pull. But with this concept you get both. You push the trailer back and it's own weight pulls down the bed. /w3tcompact/icons/laugh.gif

And yes, idle hands are the debil's workshop. But the busy man gets the job done! And I do play both ends against the middle. But I never ever mess with a cliche.

 

[Soundguy]

Interesting idea. I think you will find this works best on paper, and in practice, will be limited to a small dumping trailer. As the trailer gets larger ( wider and longer ) its volume will increase dramatically.
To get maximum dump effect from this, the chains will need to be attached to the rear top of the dump bed. The hinge will be the fulcrom, and the length of the bed will be a big lever, and leverage against the pulling force. Considering a yard of material can weight up to a ton, if you have hundreds of pounds sitting out on the front end of that lever, it will multiply the force needed to lift it.

I would also install chain guards, as I predict you will have a chain flying out from under a tire at high speed with this design. I doubt the down force from the tire will stabilize the chain.. especially on a sopft ground. Not to 'rain on the parade', but I think this will only be feasable on a prohibitively small trailer. Perhaps, if you are trying to avoid hyd's.. a gear reduction sprocket and the chain? to a fixed point on the trailer... better have a good reinforced rear part of the bed to handle the force necescary to elevate the front of the bed though.

Other engineers comments? Preferably a mechanical engineer.

Soundguy

 

[JimC]

I get more good ideas from you, I don't do all of them, but it sure gets me thinking.

Would your idea work on a small tilt bed trailer that I carry my ridding lawn mower on?

I would back the mower up so that the rear tires are close to the back of the trailer, then put the chains down and back up.

I'll try it and let you know.

Next time I go up to the Lake Texoma area to see my old sailing buddy, I will have to see if we could get together, I usually go through Fort Worth on I35W, but Wylie isn't to far off my route

 

[Boone]

My thought was to box up a base on the tongue and a pin connection to the bed for a farm jack as the hoist for a small trailer. I haven't tried it yet but have a couple of dead riding lawn mowers waiting to donate some parts.

 

[RobS]

The analytical side of me is still playing with the free body diagrams and force vectors. Bringing back all sorts of memories from Engineering school. Nothing concluded yet, however...

The practical side of me says there is no reason this won't work. It's all about balancing the load relative to the bed pivot. You won't be able to have the be pivot at the rear like a dump truck, it'll be more towards the middle. Like one of those little garden tractor dump carts you see at Lowes. You could balance the load such that it won't take too much to get it to tip and once it starts unloading you're off to the races. Fully unloaded, it'll still come crashing back down as it'll be rebalanced to it's starting point again.

I'd say go ahead and make a working prototype /w3tcompact/icons/smile.gif

 

[Soundguy]

Speaking of 'practicle', If he has a dumping bed that is middle ballanced, the maximum length of the bed from the pivot point will be directly related to the height of the pivot atachment in reference to the ground. If the length of the bed from the pivot is greater than the pivot to ground distance, he will not be able to accomplish a full dump, and he will be stuck with a low dump angle when the bed hits the ground. A 20-25 degree down angle will not be sufficient for wet materials, nor will the entire contents unload without driving forward. Load ballancing will help.. but what about odd loads? Loads with different inertial properties, such as a high volume of sand, with a low volume but large dense rock at one end.

All in all, the ballanced load will be a much better premis to start on than the original rear pivot. Also, with the middle ballance, he could do away with the possible dangerous 'drive over the chains' idea, and use either a fixed jack idea like someone else suggested, or a gear reduction ratcheting crank like I suggested. Safer ideas imho.
I'm all for home inovations & inventions.. but this may need some more work on paper before he makes an engineering mock up.. unless he actually has the oxy/acet and metal to spare. I would think he would want a closer working model on paper, then do a mockup, and adjust it from there to make up for unknown variables, etc.

Just my opinions.... but then when we build roads and drainiage/water supply systems... we don't have the room to construct every idea at its first iteration...has to be more or less final stage and past theory before we break ground. I see that metal fab may be less cost prohibitive if non-operable designs are encountered.

Soundguy

<font color=red>PS.. mechanical eng right? Ever heard the " Civil eng's make targets, and mech. eng's make the things that shoot at the targets".. /w3tcompact/icons/smile.gif

<font color=blue>The practical side of me says there is no reason this won't work. It's all about balancing the load relative to the bed pivot. You won't be able to have the be pivot at the rear like a dump truck, it'll be more towards the middle. Like one of those little garden tractor dump carts you see at Lowes. You could balance the load such that it won't take too much to get it to tip and once it starts unloading you're off to the races. Fully unloaded, it'll still come crashing back down as it'll be rebalanced to it's starting point again.

 

[beenthere]

Clever idea. I am wondering if a chain sprocket (12" diam.) attached to each trailer wheel, with a roller chain on each side (similarly placed as your tire chains). When wanting to dump, place the roller chain around the sprockets on each side, and then back up. The friction between the tire and the ground would be the only limitation. The roller chains could be stored on the trailer when not in use.

Incidentally, I saw a trailer with a very clever design for sale at Sam's Club last week. It would tilt, the tongue would extend, the sides were removable, the front and rear 'gates' would fold down. Didn't get the price, but it was a good design for an all-around handy trailer (4 1/2 by 8') with 12" tires, steel and some treated wood in the floor.

 

[Anonymous Poster]

I've built enough dump trailers to know the idea of snow chains under the tires won't work cause the whole trailer will begin slipping before enough force can be developed. A tremendous amount of force is needed to dump a trailer, even when the wheels are the pivot. If the pics are still available on the original Yahoo site, a couple of mine are posted there.
It's very easy to build a dump setup with a boat winch though, cheap too. Just remember, most over the road dump trailers tipped with a winch till around 1960.

 

[bnixon]

beenthere may be on to something with the chain and sprocket idea!

What if you had a sprocket on the axle of the trailer that was attached to a sprocket at the front of the trailer that had a gear drive that could be engaged or disengaged that would turn some type of screw jack.

Then you could just engage it and pull forward to dump the load.

This is a very rough idea...there are a lot of detail that would have to be looked at like auto disengage when it reaches its full extension or compression and maybe a direction selection so you can dump either driving forwards or backwards....

Wow this sure got complicated quick!/w3tcompact/icons/smile.gif

 

[wroughtn_harv]

<font color=blue>Wow this sure got complicated quick!</font color=blue>

You ought to be in my shoes! I feel like the girl who kissed a guy on the cheek at the diner and by the time I get home dad's wanting to know if I used protection!

I came up with this idea when I was trying to come up with a simple method of building a dump trailer for the guy who hauls his trash to the dump and maybe picks up a yard of sand once a year etc. The guy who would love to have the four thousand dollar dump trailer that's totally kewl but can only afford something a fifth of that.

Having a dump trailer is one of those things doers dream of doing. Especially those days when unloading is only twice as hard as loading was.

Here's why and how I think the theory will work. And I'll be up front with what I consider the weakest point of the principles involved. The traction of the tow vehicle in reverse when initiating the dump cycle.

The pivot point should be about fifty five to sixty percent of the length of the bed from the front. That limits the box to being short. Heck Napolean was short I hear. Didn't stop him. It also means the box should be high, don't use a dropped axle etc. The chain attachment point should be at the end of the bed, leverage.

Loading the trailer properly should always be a consideration. Something probably learned rather quickly when having a dump trailer and having to hand unload half of it I'm sure.

But again, for the guy who needs, wants, or has a small trailer that would be umpteen times more handy if it would dump this is a viable option. For everyone else there's other options, right?