Originally Posted by Ironpony
I having worked as a heavy equipment mechanic for over 35 years I would like to add to this. 1st point is look at what almost every piece of AG. equipment and almost every piece of heavy equipment in the world uses for power. Diesel for lots of reasons. What moves a piece of equipment? Torque and a lot of it. Here is where a diesel shines. The ability to run for extended periods of time at not just full throttle but at full torque output as well. And yes some gasoline engines come close to what a diesel will do, And the operative word here is close. Most notably would be the gas engines used in heliocopters in there early years. The drawback to those are the really short TBO's (Time between overhauls) 2,500 hrs at the most. And very expensive to rebuild to boot. Whereas diesels in the Ag and construction industrys often see 10,000 hrs or more before overhaul. Add to that the one factor that keeps diesels firmly in the equipment of the world is they are very efficient for the torque produced and fuel burned they are hard to beat. One type of engine that does do that (Beat the diesel) Is a gas turbine. And they can come in small packages with high hp outputs. But they are hugely expensive to build and to maintain. If that wasn't the case then why aren't they used more. They too have short TBO's compared to diesels and are probably way to complex to put out in the field plowing. Not to mention the dust would kill them real fast. I do have quite a bit of experience with turbines as I used to work for GE in their marine propulsion division. The perfect environment for a turbine in there isn't much dust to deal with. But they are hardly used in marine propulsion. Why too expensive to operate.
Number 2 Are you going to drive this ag. tractor with hydraulics? Have you computed in the frictional losses from that many hydraulic pumps and motors? If you are going to have a drive motor in each wheel then the losses would be staggering. I think that you would need closer to 800 of a 1000 hp to function. One thought that comes to mind and would meet most of your requirements would be electrical drive. That way You could have several small generator sets that for cost reasons and the ability to sync together and to have variable speed would almost have to be DC generators. With dc drive motors in the wheels. The real problem with either electric or hydraulic drive is the cost. Hydraulic motors and pumps are very expensive to buy and the so are electric motors and generators. So that leaves mechanical drive. Lots of chains and sprockets or shafts and belt's to drive that many wheels, That to sounds pretty expensive too. And very labor intensive to keep running. Have You ever been around a baler of a combine. It takes a lot to keep them running. Lots of gears and pulleys and chains and belts. And costs with all of them. And ultimately cost is everything because you have to be able to sell your product, unless this is just for you. I am NOT saying this to discourage you far far from it. Almost every successful invention ever made has come from inside the industry that it was meant for. Racing is a good example for the forum we are on now. Racers gave us seat belts, rearview mirrors, high speed tires including radials, dry sump oiling systems and many more. So I am not discouraging you at all. I am just trying to give you some things to think about. And one of the things I see is that you will almost have to redesign this to use a larger engine and it will probably end up being a diesel. I do know what I'm talking about here as I have successfully prototyped many mechanical products over the years including some electrical products. I have also wrote a regular advice column on finding someone to prototype products and how to do prototyping yourself for the web site American Inventor Spot. And that was part of the TV show American Inventor. I don't want to see you fail, but also don't want to see you spend money you don't have to. I really hope this helps Bill
ya pretty much mirroring my own thoughts. sadly, i do not have the experience as you, so i have had to down play my own thoughts. and thanks for helping re-affirming them.
ya, i have kinda gotten away from turbine engines. i really had no choice but not look at them, due to small dimensions and HP they produced.
i am kinda hard pressed gas vs diesel at moment, i know i would prefer diesel. but i am so far out of my experience, and knowledge, of engines, that trying to understand, it is to point, i am making it up as i go. perhaps bad, perhaps good. no way for me to judge. without input. and i thank you for that.
i think i can still get my 20 inches width x 20 inches tall. for most part i been heading in direction of, trying to find a single large engine, to drive 60 foot width tractor. with say up to 16 plus wheels more likey 24 to 32 wheels possibly. but as i am finding out. that many HP of an engine just not gong to happen.
i still have an option. i already have 4 sections that make up 60 feet. i can place that say 600HP, up into 4 smaller engines. so now i am looking more at say 150HP engine to fit in a 20" inches wide x 20" inches tall. this is being more favorable for this SSTT and what engines are out there on the market already.
ya i would be duplicating everything 4 different times per each 60 foot errr for each 13 foot section. but that really is not all end. for smaller fields that can be a large plus. and for larger fields, being able to say hookup another 13 foot section, for say 73 feet. would not be that bad on additional cost vs having to buy a complete new set of tractors and implements. for just that little bit more. extra duplication also allows for "backup" if one engine goes down, maybe there is enough from other engines to keep on going.
while i was hoping to avoid above going with a single larger HP engine, *hey i had to see if it was possible, i did not know any better at the time*
ya i know about hydraulic issues, more so if all the wheels hub motors were hydraulic. the pure amount of GPM (gallons per minute) would quickly over whelm most things. and by the time i upped the inside diameter of pipe, and then upped the hydrualic pumps to produce a high enough pressure at the higher GPM. i would be getting into some major friction losses just trying to move that amount of fluid, let alone trying to place regulators on everything. to try and even out both pressure and GPM going to each wheel.
no way to use shafts, sprockets, chains, gears. would be a bloody nightmare on this tractor. and would cause to much slop at things furthest away from the engine. there would most likely be binding issues, twisting shaft issues, etc...
electrical wheel hub motors. give me a few more PRO's vs hydraulic. more so in finite control of RPM's and torque. i am hesitant of both A/C and D/C. and current doings out there. i have full control over the generator, and wheel hub motors. so i can run at any volts, any amount of phases, at any frequency i want. along with at any amps i want. and in all thought. i think i am going to use that to my benefit. of not needing to tie to a given standard of.... 110v, or 220v or 12,24,36,72 volts
the only exception is needing a standard 12V to deal with electronics, and road lights.
to above it will be a variable volts/amps/frequency at a certain amount of phases across the entire machine. with a 12v beside it.
if i do not approach things as dynamically changing volts/amps/frequency across entire machine. then i don't think i will have a chance of pulling things off. at least for the generator that would supply electricity to wheel hub motors.
there most likely will be inline filters (think regulators for hydraulics or fluid or gas), but to control amount of bad electricity (odd frequency, odd amps, odd volts)
to be honest i am not there yet, to actually figure electrical all out.
engines with generator/s and electrical wheel hub motors.
i am actually not worried about torque vs RPM's. torque x RPMs / 5210 = HP correct? i mean as long as i reach my HP requirement, and an engine that can withstand continuous heavy load placed on it. i really do not care what RPM's or torque it produces. like i said, i am not trying tie myself to a standard of 110v, 220v, 12,24, etc... volts. the only exception is the 12v that run along side. but i am looking for a dynamically changing variable volts/amps/frequency, at a given number of phases.
i am not really looking at regenerative braking, while that would be a plus. i am not counting on it to recharge batteries like a regular electrical car out there.
at this point in time, cost is last on list, it is just me at this point in time. and needing a team. but at this point it is concept, and trying to see what could work. and what would be needed to make it work. multi other things need to happen before cost of things will most likely get involved. to see were corners might be cut, or something else done. no real reason to have some bean counter saying OMG that is to expensive and creating an up war over things. when there no direct way to get a estimated cost atleast by myself. it is the other folks that are needed though in a team. that i am seriously lacking at moment.
ya electrical wheel hub motors are expensive, but so are physical transmissions, final drives. pick your poison. some areas are going to be more costly than current age tractors, while others it will be zero. and its not just tractor but also portions of implement costs, that might become null and void. with this SSTT and implements to go with it. that i am hoping will offset things enough to make it near current age tractors and the implements that go with them. there a lot of metal and weight that should be removed from the overall setup compared to current age tractors and implements.