Fabricating Think Tank

[jac]

Geoff… I dont know the lay out of swathers but am I right in thinking the wheels are driven by hydraulics ?? If thats thats the case, then would it work if the wheel became the driver in a land drive system. That would turn the motor into the pump and speed the system up.. I think ????…. LF.. would an old gas bottle turned upside down with the oil being pumped in from the bottom work ??
John

[LostFarmer]

I would think that an old gas bottle would work as the pressure vessle. You need enough oil to cycle any ram in your system plus a little and enough space above to compress the air. The more air space the more cycles the system will have in it. LF

[Marshall]

John, I am not exactly sure how the accummulator works. I think that is a part that was purchased. I have not done much research on anything hydraulic. I am trying to keep all my machinery like me, simple.

[jac]

Ok guys we’re getting close to a ground drive hydraulic system.. Im going with the piston pump pressurising an accumulator.. I thot of using a 2 gallon fire extinguisher. they are tested to 25bar and work at 9bar,even taking it to 10bar thats just over 112psi.. Is that enuf to lift a 1/4 ton 12″ ?? I plan on using one way valves and a dump valve that kicks in a bit before wheel slip. Big question is … how much psi could you hope to build up with land drive ??? I know you can buy the components from White Horse but if a system can be made using stuff you may have around the yard then all the better.If the figures add up and it works we have a page where people can come to without having to search..
John

[Marshall]

John, It seems to me you might need a little more pressure than that. The old farmall belly pumps ran around 800 psi. I know you won’t be lifting anything super heavy, but a little much pressure is better than not enough. Also you piston diameter on the cylinder is going to come into play. The larger the diameter the more grunt you get, but you will lose in speed.

[jac]

Hi Marshall.. You beat me too it on the figures.I foned a friend who’s a hydraulic fitter.. Back to the drawing board again:rolleyes:
John

[Andy Carson]

I like this hydraulic accumulator idea alot. Another type of hydraulic accumulator stores energy by using a hydraulic cylinder to compress a large spring. That might give you more options to play with. Possibly a very stiff recycled coil spring from a junk yard (maybe with a spring constant of 400 pounds per inch)? I would be careful about how you put this together (if you try it) as a breakage on the housing of a compressed coil spring could be very dangerous. Maybe I’ll play with the math and see if this might work… If you have 500 pounds to lift with a 12 inch stroke a 2 inch bore (surface area = 3.14), that is about 38 cubic inches of fluid (3.14×12) at a minimum of 159 psi (500/3.14). If you put a 4 inch bore cylinder (area = 12.6) on the spring, it will generate 159 psi at a compression of 5.0 inches (400 x inches compressed / 12.6 = 159 psi). To produce 38 cubic inches more fluid, the spring will need to be compressed another 3.0 inches (38/12.6) and the fluid would be at 255 psi (400×8/12.6). i think this has potential, but you will have to be careful with the spring stiffness and cylinder size. The potential of this system to store energy and oil volume gets exponentially better as you increase cylinder bore and spring stiffness and mathematically seems kinda marginal for this application. Finding and buying a big cylinder and really stiff spring might be just as hard as finding an air type accumulator designed for this work. If you have access to salvage from heavy equipment, though, that might change things… Be careful with your spring housing if you try this!!!

[Marshall]

Hey John, lets complicate this a little more. You could always use a trip rope setup off from an old plow. No hydraulics, but it would also have to be moving to raise. Just a thought.

[Simple Living]

Am I thinking too simple? Why couldn’t you use a truck rear end as your forecart axle and link the “driveshaft” end to a hydraulic pump with an accumulator tank for back up? Some of the ground drive ones I have seen use just 4-6″ square steel tube standing 4′ tall on the cart with ends welded into it for the accumulator tank. I know that I am not the one to do that type of welding, but I am sure there are others out there who can.

Gordon

[jac]

Countymouse your math skills are invaluable here. The accumulator does seem like its a great asset for the horsesdrawn machine but my fitter friend says the air accumlators are really expensive. Now I know we have to try and make horse drawn machinary seem up to date and modern but try as I might , I cant get the sums to add up, which is why Im so keen to develope machines that the average fabricating farmer can make and take to the fields without being branded as someone stuck in the 19th century.. and I know that certain machines are beyond compare and hard to improve on, like the mower, but modern machines can bring animal traction to the attention of a larger audience. Enterprises like vegetable production is one area that springs to mind.. Marshalls plastic film applicator is one machine I am keen to see.. BTW an accumulator might be a way of driving the fan on your machine Marshall ….I wonder if an oxygen cylinder would have the psi rating high enuf so we can put together a home made job without running the risk of taking the shed roof off or worse… Is there a formula to work out how much psi of oil/air pressure that could be pumped up with an 800lb hitch cart ??. Gordon when I build another cart it will have a set up like that. I thot of an old Jaguar car axle and that way a portal axle could be built to help with passing over fluffed up hay for example… Marshall that is another option, again, if I was starting fresh it could be built in.. but I fell for the old “how hard can this be”……
John

[LostFarmer]

Without question an oxygen bottle would have the needed pressure rating to do what you want as an accumulator. I have thought about this a bunch. Thinking of a way to get live hydraulics to a round bale mover. The more I think about it the more I am inclined to look at a salvaged pump from a gleaner combine of a C to G model. They had a reserior, pump, and valves all on one bank. That with a little Honda motor would be a great power source. Taking that a step further would be to use the pump and an accumulator to make it happen. I am still putzing with this but some day when I have time and money this will be a reality.

LF

[Andy Carson]

The most important equation I know for pressure and gases is pressure x volume = pressure x volume. From what I remember, this equation is pretty accurate in normal situations and becomes inaccurate if gases are compressed or decompressed very quickly or to very high pressures and heat is generated or lost from the system. So lets say you were using a 1 cubic foot oxygen tank (that’s a pretty big tank), that’s 1728 cubic inches (12x12x12=1728). Let’s say we start the tank out at 1 atmosphere pressure (or 15 psi). If 864 (1728/2) cubic inches of fluid is pumped into the tank, the pressure would double to 30 psi, still not enough to lift your 2 inch cylinder (500 pounds/3.14= 159 pounds). If we add another 432 cubic inches (864/2) of fluid, the pressure would double again to 60 psi, still not enough… To reach 159 psi, you would need to add 1565 cubic inches of fluid (15×1728=159 x volume of air, volume of fluid = 1728 – volume of air). If we pick a maximum pressure of 800 psi, this will be reached after adding 1696 cubic inches of fluid (15×1728=800 x (1728-volume of fluid)). As these tanks are sometimes filled to 3000 psi, 800 psi is definitely safe. Unfortunately, you only have 131 cubic inches (1696-1565) to work for you. That’s enough to lift Johns cylinder about 3 times (131/(3.14×12)), but if you are doing jobs requiring larger volumes of fluid, it might be better to have the tank under some pressure before any fluid is pumped into the system. If this same tank had 100 psi air in it before any fluid was added (like from a home air compressor) it would reach 159 psi when only 641 cubic inches of fluid are added and would not exceed 800 psi until 1512 cubic inches of fluid are added. That is 871 cubic inches of fluid capable of delivering more than 159 psi, so you could lift John’s cylinder about 23 times! Much better to start with a prepressurized vessel!

[Barw]

I think White Horse Equipment has a hydraulic forecart-wheel driven.

[Author]

Posts