Dump wagon build

[CDN Farm Boy]

You quite welcome.


Umm ... you need to be thinking about mechanical advantage ...

Check out the three different types/classes of levers:

Lever ...

The type you are using is a Class III ... which always has a mechanical advantage of less than 1 (which means mechanical disadvantage)

This can be overcome by shear force ... assuming you have it ... and the equipment will take it.

I'm suggesting a setup with a Class II lever ... which always has a mechanical advantage greater than 1 ...

Right, hadn't been considering the mechanical (dis)advantage of the lever of the bed, just the angle of the cyl vs the angle of the bed. I know my cyl angle isn't much and right now it's way to frickin cold to go lie on my back in the snow to measure so I'm just guessing here to help me understand. If the angle is say 10 deg, from the calculator I have 4812 lbs of lift. With that force being applied roughly in the middle of the bed, maximum lift will be less than that due to (particularly) the lever of the weight in the front half of the bed. With the same 10 deg cyl angle but the ends reversed as you suggest, the same 4812 lbs will lift more regardless of the fact that the direction of travel of the cyl is opposite that of the bed. Did I get that right?

I believe in the end you will have to go to a scissor hoist design. Amazing what they will lift. Your design expends more energy pushing rearward than it does pushing upward. I ran into a similar problem when building my Grapple. At full open my claws have minimal strength until they start closing and the triangle opens, then they develop tremendous strength. In you design the triangle is very thin in the beginning, unlike the scissor design.

Awesome looking wagon though. You'll get a lot of use out of it once you fine tune the hoist!!!

I always thought the point of the scissor lift was just to be able to use a shorter cyl to accomplish the lift. I've never looked carefully at the resting angles but going to have to now. Would the any potential gains from the improved angle not be lost on the negative mechanical advantage that is also present within the scissor itself? The pic posted by Barry has the scissor mounted at the front of the bed. Every dump trailer I've seen with a scissor lift has it mounted in the middle which would have the same issue that rswyan is mentioning.

Before re-designing or rebuilding any mounts I've got to get it anchored better since right now the cyl is the only thing tying the 2 halves together (well, and gravity but that doesn't help when trying to dump a load of logs). Raising the whole thing another 4" is easy to do while re-anchoring it....if it will be enough. I'll do the math on the angles with the above calculator first to see if it's worth it. While I may not have enough lift force, that is to be determined. I know for sure the anchoring was the weak point. Once I've got that beefed up (Help!!!) I can then see if it either works or the geometry of my design is the weak point. There's obviously plenty of strength in the 4" cyl with 27,700 lbs of push if it's properly used. If I'm generous on the amount of wood I had in the bed when it failed, I had at best 4000 lbs, 2500-3000 is more likely and as there's no way I had a full bush cord in it.

 

[Leejohn]

I use something like these for my rear hinge with a 3/4" top link pins.

I have found setting the cyl. at 15 degs seems to give good power for start of dump. I would go along with what someone else said and that was to raise the bed.

 

[CDN Farm Boy]

I use something like these for my rear hinge with a 3/4" top link pins.

I have found setting the cyl. at 15 degs seems to give good power for start of dump. I would go along with what someone else said and that was to raise the bed.

I made my own greaseable hinges for this project but those would be just the ticket for another project in the cue. Where do those come from

 

[rswyan]

Right, hadn't been considering the mechanical (dis)advantage of the lever of the bed, just the angle of the cyl vs the angle of the bed. I know my cyl angle isn't much and right now it's way to frickin cold to go lie on my back in the snow to measure so I'm just guessing here to help me understand.

Ok.

If the angle is say 10 deg, from the calculator I have 4812 lbs of lift. With that force being applied roughly in the middle of the bed, maximum lift will be less than that due to (particularly) the lever of the weight in the front half of the bed.

Correct.

With the same 10 deg cyl angle but the ends reversed as you suggest, the same 4812 lbs will lift more regardless of the fact that the direction of travel of the cyl is opposite that of the bed. Did I get that right?

Assuming all else (starting angle, etc.) being equal, yes.

Another way to work the mechanical advantage is to extend the bed rearward past the hinge (overhang) - when this area is loaded it supplies force in the direction you want to go when dumping.

You have to watch using this method though, because you don't want the end of the bed hanging up on the ground.

Also be aware that the front of the wagon (tires, frame) will want to rise as the load is emptied.

... Before re-designing or rebuilding any mounts I've got to get it anchored better since right now the cyl is the only thing tying the 2 halves together (well, and gravity but that doesn't help when trying to dump a load of logs). Raising the whole thing another 4" is easy to do while re-anchoring it....if it will be enough. I'll do the math on the angles with the above calculator first to see if it's worth it. While I may not have enough lift force, that is to be determined. I know for sure the anchoring was the weak point.


Once I've got that beefed up (Help!!!) I can then see if it either works or the geometry of my design is the weak point. There's obviously plenty of strength in the 4" cyl with 27,700 lbs of push if it's properly used. If I'm generous on the amount of wood I had in the bed when it failed, I had at best 4000 lbs, 2500-3000 is more likely and as there's no way I had a full bush cord in it.

Well, lemme relate to you my experiences on that end:

I have a 4 x 24 cylinder on my Country Mfg. dump cart and it has been running @ 1900 psi.

When I have it really loaded up (4K to 5K pounds of wet sheep chit) it will barely move (raise) initially and it gains speed as it raises.

It also puts incredible stress on the frame, bed, and hinge. You can see (and hear) the bed flex, bend, and creak. The hinge has broken once while trying to raise it when I had it loaned to someone else.

The frame/bed/hinge is really under built ... it's made of C channel and angle ... should have all been square or rectangular tube.

I think you'll be ok with what you used - just be very cognizant of how much you have on it - and what it's doing - when you try and raise the bed.

Also, just like a FEL, make sure the wagon is level (side to side) before you attempt to raise it ... otherwise very bad things will happen.

 

[Leejohn]

They are for boat docks. Just make sure you get the ones that are made with 1/2" steel with the mounting plate around 3/8".

 

[Steve_Miller]

So a slight (cough, ya slight...sure) problem developed. Got back to the yard with the first load, tried to dump it and no dice. Too much rear-ward force from the cyl and not enough up for the weight that was on it to dump. Ended up breaking off the stop blocks that were trying to keep it from sliding off the back of the wagon frame. Now I need to re-engineer how it is anchored to the wagon, since the base of the cyl is mounted on it to keep it as low as I could.


I see 3 options to fix this:

a) Weld it solid both front and back. That would certainly be the most solid but I'm used to wagons having a bit of flex to the frame to help keep the tires on the ground, but does that really matter?

b) Weld the rear solid and all the forces are then transferred thru the reach. Need new grade 8 bolts on the reach if I do this but the bolts that are there really should be replaced anyway.

c) Beefier stop blocks on the front which would have the forces transferred thru my lower side rails. These would have to be floating blocks welded only to my new frame as when dumped the decks will sit firmly on the rear portion of the frame. This is by far the most difficult of the 3 options.

Thoughts?

Been there and done that, I think everything you mentioned I had happen. First dump broke rear pivot pin off on one side, second attempt bent the front piston block off, third time had everything reinforced and it worked fine ever since. I pushed the other way with my cylinder and you need the mount low so as to overcome the initial lifting force to get started. I've had two metric ton or more on this and it dumps with ease (which is more than it should have of coarse).

Steve

 

[FarmWrench]

Because you have a double acting cylinder, you have power down and can utilize that by compressing springs.

I've fixed a weak dump wagon with a spring right in the front pushing straight up. It only gave 4 inches of "help" but that was enough. After the fact I realized that if I had it closer to the back it would have been more helpful.

 

[rswyan]

Because you have a double acting cylinder, you have power down and can utilize that by compressing springs.

I've fixed a weak dump wagon with a spring right in the front pushing straight up. It only gave 4 inches of "help" but that was enough.

Great tip/trick ... :thumbsup:

 

[CDN Farm Boy]

The cold finally let up a bit and made it up to -8 today so I took the time to get some measurements and plug them into CAD to get the cyl angle. My 10 deg guess was pretty frickin close. Cad says 10.38 deg at rest. So using the link from Surplus Center forces go something like this:

Current:
10.38 deg = 4981 lbs of lift 4' from the box pivot
Lift whole thing 4": 13.39 deg = 6398 lbs of lift
Lift whole thing 6": 19.44 deg = 9201 lbs of lift - really don't want to raise it this much

If I were to reverse the mounts as rswyan suggests:
At existing height: 5.74 deg = 2765 lbs of lift 8' from the box pivot
Lift whole thing 4": 11.5 deg = 5512 lbs of lift

With factoring in the mechanical advantage of the lever of the box (if I"m calculating right), the second way would give me an extra 549 lbs of lift BUT also an extra 2216 lbs of horizontal push now trying to push the box off the front of the frame rather than the back. I'm not sure this is an improvement. Now if I were to reverse the cyl AND lift everything 4" I could gain 4626 lbs of effective lift for a total of 11024 lbs by comparison. This is obviously a big improvement but has the challenge of the cyl base mount being in the middle of the reach which is it's weakest point rather than now with it on the front frame. Anyone know how much force is required to bend a 3" pipe pushing in the middle of a 8' lenght?

If I got this right, I'm either going to weld it solid to the wagon frame at it's current height or raise it 4" and weld it solid. If that doesn't work, I'll incorporate a scissor lift once I look at the geometry a bit more.

 

[thirdroc17]

Correct me if I'm wrong, but location matters. The closer the cylinder attaches to the front of the box, the better. Lifting at the front edge of the box would need a lot less lift than lifting from the middle. Turning the cylinder and pushing from the back should or at least could, make for a more forward lift point on the box. A good thing. Course, this would also mean longer cylinder travel to achieve the same angle of dump. Seems like a longer cylinder would be easier and cheaper than building for less travel but higher total forces.
Or not.