Fabricating Think Tank

[near horse]

Hey Old Kat –
Funny you should mention taking digital photos of dismantling equipment. A local mechanic of ours told me that’s what they need to do when dismantling the dash of most cars – like when replacing a heater core. He said it’s almost impossible to remember all the little steps, in reverse. Nice use of new technology for us Luddites!

[jac]

Found this site that might be usefull for anyone fabricating new machines or building new versions of old ones …http://www.freepatentsonline.com[/url%5D..
Found a harrow cart.. patent number 1604897 and a plastic film applicator for field work.. patent number US5226376
Good line drawings and lots of detailed writting..
John

[Andy Carson]

I have used this website for determining the size and shape of steel for different applications.
http://www.engineersedge.com/
The beam deflection calculators on this site are great and they have almost every different type of stress and strain imaginable. There are charts that tell you the moment of inertia for standard structural shapes (like I beams) or let you calculate the moment based on the dimensions and thickness (it will determine the moment of a 2×2 inch steel tube with 1/4 inch thick wall for example). They even have a trigonometry calculator for those of you that (like me) are not as confident of your trig as you once where… Optimising the size and shape of beams used for different projects makes the equipment lighter to handle and cheaper to make, without any loss of strength. For me, I have been suprised how far off my “gut reaction” was from the calculated optimal beam size. In most cases, I would have picked a much bigger peice of steel. Just a warning, these calculators do not have a safety factor built into them. I usually double the loads to engineer in a safety factor.

[Joshua Kingsley]

Good idea on doubbling the loads as younever know what could happen and you don’t want the newly fabricated proto type / implement to fold when the going gets tough.

Joshua

[jac]

Ok think tank… get the thinking caps on.. Im finishing off my slitter/seeder {fotos next week}. It has one small hydraulic ram 2″ with 12″ throw to lift approx 1/4ton and even some of that is on the hitch cart drawbar ..I dont have hydraulics on the hitch cart but thought this idea might work.. I have the hydraulic motor off an old fertilizer spreader, so if I put a small rubber tyre on the flange that the spinner came off of and mounted it on a sprung loaded bracket mounted on top of one of the hitch cart tyres, this would drive the motor and if I mounted a gravity oil tank above and fed the oil through the motor and on through a spool valve with a return to tank. would need to think ahead with this system:rolleyes: its easy to switch into auto pilot when the teams going nice… Anyway.. what do you think? would it have too much resistance or would the tyre slip?. any other home made devices for lifting without having to resort to engines…
John

[Joshua Kingsley]

John,
You may want to consider a spring system that lifts your seeder. With the springs having the right amount of tension the machine would “Float” and then you could use a lever back to the cart to gain your lift.

I am just thinking that the tractor drawn mowing machines can float an extream amount of weight on a couple of springs that makes the cutter head weight into a lifting weight of only a few pounds. This also allows the machine to glide over obsticals where as a heavy weight would make the machine dig in. Think of the difference of a light stick or a heavy log when it comes to gliding across the ground when being dragged.

In regards to the idea of running the hydrolics from a wheel you should be able to keep the hydrolics engaged all the time as the valve should allow the oil to pass through in the “off” position. Think of tractor pumps, the pump is running all the time weather the hydrolics are being used or not. The only thing to take into account is what is the proper rotation of the pump to gain the right amount of flow. To get the right flow you need to get the ratio correct for the pump rotation.

You may want to use both to get a rapid response from the hydrolics as the springs would allow the rapid lift at the end of a pass.

Joshua

[Andy Carson]

Hi John, this sounds like a fun problem to work on… OK, lets begin with a hitch cart with 30 inch (2.5 foot) diameter wheels traveling at 3 MPH. 3 miles = 15840 feet per 60 minutes or 264 feet per minute. A 2.5 foot diameter wheel has a radius of 7.9 feet. 264/7.9 = 33 rpm. Lets assume you use a 1 foot diameter drive wheel on top of the hitch cart tire, that would be a radius of 3.1. So, for every rotation of the big tire (7.9 foot radius), the small drive tire would rotate 2.5 times (7.9/3.1) asuming no slippage. That would be 83 rpm (or 1.4 rotations per second). Now the big unknown is how many cubic inches your hydraulic motor displaces per rotation. If it’s only .2 cubic inches per rotation the motor would yield .22 cubic inches per second. A 2 cubic inch per second pump would spit out 2.2 cubic inches per second. The surface area of a 2 inch cylinder is 3.14 square inches, so the small displacement pump would move at a rate of 0.07 inches per second and take over 3 minutes to travel 12 inches. The larger pump would travel 0.70 inches per second and move a foot in 17 seconds. Either way, this is a pretty slow way to lift something… As 550 pounds travelling 12 inches per second is 1 HP, you have plenty of power for either of these conditions. Enough traction, though, I’m not sure… The spring that presses the small wheel onto the large drive wheel could be made to apply as much downforce as you design, but the downforce between the cart wheel and the ground would be roughly half the total cart weight (I am assuming this is a two wheeled cart). Let’s assume your cart weighs 800 pounds with you on it, that would be 400 pounds of downpressure on one tire. I don’t know what kind of wheels/tires you have, but I’ll assume a friction coefficient of 0.5. That means the tires might slide if more than 200 pounds force is applied to them along the ground. I’ll calculate the mechanical advantage over one second by using force x distance = force x distance. 500 pounds (1/4 ton) x 3.5 inches (fast pump) = 18 pounds x 94 inches. So, you are no where need a point where your tire will slide. You might risk a slide if your pump is 20 cubic inches per rotation, but that’s a big pump! You might want to run through my math again to check for blunders. I would think about using a couple drive gears to speed up your pump and make the whole thing lift faster (depending on the size of your pump).

[jac]

Thanks guys. Two great answers that are adding to the info that is turning this thread into a great resource… Josh the spring idea would work but the lifting set up wouldnt suit that.. when you see the fotos all will become plain.
The formula countymouse wrote is a real bonus for us basic fabricators. Thank you.. I appear to have disobeyed my “how hard can this be rule”:D I mesured my hitch cart wheel. its only 27″ which makes it harder to gear the pump up to speed, however the pump appears to have a gear reduction set up which might work in my favour if it gets driven as opposed to being the driver !!! I thought of using a metal spar wheel of about 6″.. like the miniature version of the cage wheels you get for tractors.. instead of rubber. If the tyres pick up some mud the traction would be lost. I will do a trial set up and keep you all posted. I used to think that the engineers of the horse era were hampered purely by the technologies ot the time, but now I see that they were stuck with the same laws that we face now. Any amount of modern materials and practices cant overcome them… well without resorting to engines that is !!
John

[Andy Carson]

“I used to think that the engineers of the horse era were hampered purely by the technologies of the time, but now I see that they were stuck with the same laws that we face now. Any amount of modern materials and practices cant overcome them…”

I have designed much more equipment on paper than I have actually built precisly for that reason… I think it’s fun to design new ways of getting things done, but I have rarely made something better than traditional equipment. The process I usually go through is:

A. Research traditional equipment for performing a task
B. Think I know a better way to perform task
C. Do some math and realize that it won’t my “better” way
D. Try a different (but still improved) concept
E. Do more math and realize that won’t work either
F. Buy an old piece of equipment
G. Break the old piece of equipment
H. Repair
I. Break something that is irrepairable and irreplaceable (not hard)
J. Return to “A”

I am not saying it is not worth trying to make equipment better, but sometimes I feel like I have been reinventing the wheel. I do think the use of hydraulics is probably a modern invention that would lend itself to many horse powered applications. I have to say, though, the power required to lift 500 pounds at a slow rate is pretty small and well within human capability given mechanical advantage or the use of a spring. If you can use human power to do something, you can be much more flexible in how that power is delivered (levers, wheels, ropes, etc). We are agile and smart little monkeys, even though we are weak.

[Iron Rose]

I’m in the process of building a three wheel cart with a 3point hitch . For power I’m using a 12 volt pump set up off a power lift gate from a delivery truck ( found used one on craigslist for $35) . Lift is not real fast (approx 30 seconds for full stroke of 8 inches) but has enough pressure to do the job. There are other 12 volt pumps that deliver more flow if speed is needed. At this time I haven’t been able to field test the unit , but works in the shop.

Your idea of a wheel driven hyd pump is something that I have been thinking about for some time. Although I decided to go with the 12 volt system because I could lift the hitch with out moving. My figuring is not in vain though . I’m now designing a ground drive PTO. Present plans are to weld roller chain to the inside of the wheel and use a sprocket drive. Looks like it will work on paper, but I’ll see when I get started.

If anyone has done this or has any other ideas on ground drive PTO I would welcome any inputs.

Good Luck on your project

Dan Rasmussen
SE MN

[Marshall]

John, I can’t remember where I saw it but there was someone that made a hydraulic forecart with a piston pump. The wheel had a cam setup with three or four arms like the ones on a mccormick manure spreader to drive the apron chain. When each arm came around it stroked the pump causing the oil to build pressure in an accumulator. After the accumulator was full the oil would bypass until need again. With an accumulator full of oil all you had to do was move the lever and there was enough pressure to raise the load. This way as long as the accumulator was full you could raise a load at a stand still. Just and idea, hope it helps.

[jac]

Hey Marshall.. How does an accumulator work ?. Could one be made by a farm boy ? ..So many ideas my heads more confused now than ever.. Dan the chain link inside the wheel is a great plan too . .Be sure to keep us all up to speed on the pto hitch cart. Someday the perfect hitch cart with pto is going to be created and it would be nice if it came off these pages.. mine is a blatant copy of Lynn Millers by the way.. .I was out at the “project” tonight and think it might just be possible to use levers with spring assist..nod to Countymouse and Josh… However the hydraulic function needs explored to … You will probably laugh but I had even thought of hanging a light truck gearbox out the side of the hitch cart with a wheel on the propshaft end and the pump on the input end:D talk about the sledge hammer to crack the nut !!!…
John

[LostFarmer]

I have looked into several different methods of getting hydraulics to horse drawn stuff. One of the methods is an accumulator like was mentioned above. The concept is that you have a gas above a liquid in a reservoir. As the pump runs either by hand, cam, or other method the air in the top of the reservoir is compressed. The liquid or oil on the bottom is then under pressure. Open the valve and the liquid operates the ram. Nitrogen accumulators are sometimes used on heavy equipment to speed the ram. The pump runs constantly and then gives you a burst when the valve is opened. This concept would work well where there is time in between cycles.

It is not all that unlike a pressure tank on a water well. The air over the water allows the water to be under pressure and the pump not always on.

I have an older neighbor that is a fabricator of all things steel. He has worked horses and then builds equipment that works. He builds one of the finest steel bob sleds you will ever have the privilege of working. Light, tracks perfect, strong and plenty of flex for walking that frozen turd tundra that I spent too much time driving in. I get thinking I am a pretty smart feller until I talk to my neighbor and see what he builds and his ideas on things. I find out all I am is a fart smeller.
LF

[near horse]

Is there a way to utilize the hydrostatic drive off of an old swather in a system we’re talking about? I’m thinking in sort of using the ground drive (however you set it up) to run a hydrostatic pump (off a swather) which in turn could run the hydraulics or motors (off the swather wheels). I am probably missing something obvious as to why this can’t work – it just seems that some of these parts might fit the bill – and I’ve got this old swather staring at me each day …..

[Joshua Kingsley]

Geoff,
As far as I know alot of old swathers had at least one high volume hydrolic pump on them. The pump will allow for a higher pressure build up while utilizing a low ground speed. With the use of a pressure resivor you can have the power at your finger tips and the advantage of rapid recovery. So IF and that could be a big IF I am correct in my thinking you have the right parts to allow for some hydrolic use with minimal investment. You may have to do some digging in the “guts” of the machine to find all the parts that you are going to need in order to make the system work but if you already own it then you don’t have to buy it.
Joshua

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