Hello to everyone, this is my first time posting here. I've joined after searching the web for ideas and inspiration for my project, and found all of that right here!

I have a need for a sprayer in the banana fields I'm growing here in the Philippines, and being constrained by budget and availability of materials around here, I want to build up a tractor that will also run a spray pump, incorporate the chemical solution tank and have the necessary boom. For the sake of simplicity and limitation of my own skills, I am looking at a 3 wheeled tractor set-up based on plans for just such a unit I found online called the “Farmette.” The plans I am roughly following are available for free download Farmette here. The plans have a 7 HP engine, 4 speed truck trans and cut-down differential. I’ve found the differential, transmission, and some wheels at a salvage yard for about $160. The engine I’m still looking for and will try for a used diesel unit, since it is the cheaper fuel here, but with more HP than 7 (they must have had bigger horses back in the 1940’s?). The plans show a clutch set-up with a flat belt from engine to the trans, the 19th century technology which, surprising to me, is still alive and well in this part of the world. Oh, and the tractor’s frame rails are wooden, but I’m going to use steel here. There is also a VEE belt-driven PTO off of one side, which I will use for running the small piston pump everyone here calls a “power sprayer” but might be more well known to many of you as a pressure washer. I’ve built a few complicated projects in the past, such as a small CNC, a thickness sander for woodworking as well as a trailer for my Honda Goldwing. So, I might qualify as a machine builder of sorts, but I find I usually work best from plans rather than being able to dream up what seem to me to be complicated assemblies, like a drive train with a PTO for instance. But looking at these plans for the Farmette, I right away knew I could handle this, and certainly against all of the protestations of my wonderful filipina wife, who cannot possibly imagine building something like this from scratch here at our farm. My biggest hurdle right now is the 24 ft. high boom. I can see how to weld up this thing and get it to spray, but sure hope it won’t be tippy, and what if I want to clean out a spray nozzle? Any ideas on how I can make it easily retract, or fold back down? I know some complicated scissors arrangement with hydraulics would be cool, but I think it’s outside of my budget and expertise, plus I don't have good sources around here.

Here's a photo of what I'm using to spray with now:

The tractor needs to drive down these rows and turn. The plants are spaced 2 by 2.5 meters:

Here's a model of the Farmette with 24 ft. spray boom:

As the boom only needs to support your sprayer, I'd keep it as light as possible. Maybe using say 1.5-2" pvc pipe pieces connected in a triangular radio tower type design, with three legs interconnected at regular intervals. This will give the structure regidity while still keeping the weight down.
Best of luck to you.
Doc

Thanks Doc. I'll probably try your suggestion, hadn't thought of using quite such light materials, as I was thinking more of EMT. One of the advantages of the sloping front upright is that it can act sort of like a "cow-catcher," pushing leaves aside as the boom moves through the lane. I like your pvc pipe idea though, since it might even be a little gentler on them and even more slippery. I am planning on building a hand-pulled model with bicycle wheels and a barrel (as in my previous photo) for experimentation of the boom moving through the leaves; looks like this: http://i156.photobucket.com/albums/t12/chasbear/Tractor%20Project/HandRolledSprayr.jpg

Lots of questions here.
How tall do you need to go? Based on the picture, I am guessing about 15 feet or so.
Does the spray need to be directed down into the top of the plant or would a vertical boom with horizontal jets work?
or even nozzles pointed upwards.

I think a wide front end would be more stable and is my personal preference.

John: If you notice next to the boom pic, he's going 24', which is why I suggested the larger sized PVC. But I agree that a front end spaced as wide as the rear would definately make a more stable base.
Doc

Hi John, thanks for the questions... they help me think! Doc is right, currently I spray with a hose strapped to a bamboo pole, nozzle at the end that points roughly 45 degrees. I'm doing this trying to spray the youngest center leaves, and by holding the pole as high as I can with arms stretched up I'm reaching 24 feet, which is certainly not as high as many of the leaves are, but the spray reaches up the distance needed.

I know I'm probably being lazy by choosing to have only one steer wheel, as I'm trying to avoid the complications of fabricating the articulation for that axle plus also avoiding the needed linkage. I guess I like the KISS method?

Chasbear: Two wheel steering is realy not much more complicated than single wheeled steering, and in some cases may even be simpler (as in center driven rack). Each side has a pivot point, they are tied side to side with a "Tie Rod". You somehow point one wheel in the direction you want it to go and the other has no choice but to tag along and do the same. If you get ANY mud at all where you'll be running this, I'd go with two wheel steering, just for the extra surface area and weight distribution on the steering tires. Just my $0.02 worth.
Doc

I musta got confused with the metric conversions in my head (coff coff BS coff coff)maybe next time I will read all of the post thoroughly...

That is a long way up, lightweight up top is a must.

now for something totally different, there used to be some early farm sprayers, cant remember the make right now, that were a tricycle type with a single large drive wheel up front. The reason I mention it is because the tank was mounted low in the center for better stability and even then they offered outriggers.

this leads me to my next thought, make the tractor as drawn and build a pull type sprayer, it could be a 4 wheel wagon with water in the tires for better stability, just pull a pin and away you go with the tractor to do something else.

As a horrid thought, I might also query if there are ANY POWER LINES about?

I think the trailer idea has merit. Could then maybe put a pivot at the base and lay it down Gib pole style as they are doing with windmill masts nowadays.

As an afterthought on the pvc, for stuctural uses it can be made more stable by shooting it full of ureathane foam. Otherwise it has a tendency to very slowly bend when under tension and especially when warm.
Doc

Doc, no power lines for a few kilometers, but always a good thing to keep in mind, thanks.

My field isn't set up for turning about. I've followed the layout of others here, who spray by hand and plant out to the furthest edge for maximum yield. So its a real challenge to turn within the layout of the plants. Also, I'll have to watch the boom closely that it clears the fruit bunches overhead while spraying and my neck doesn't pivot as well as it used to. I've though about a trailer already and rather like the idea of a small single purpose sprayer. The boxy design of the lower portion will be built strong enough to work as roll over protection, and the upper boom will be removable (I'm still working in SketchyPhysics on a way for it to fold down on top of the ROP.) I really doubt I'd be able to get my hands on ureathane foam to fill pvc pipes around here. So, I'm back to thinking of using EMT.
Charles

Chasbear: Didn't mean to turn you off to PVC for structural members. The ureathane foam isn't mandatory, just one way to deal with long spans. A triangle design actually nullifys all but outward bow, which itself can easily be countered by gluing smaller sized leg to leg connects between the leg sections. One very nice thing about PVC is that it will stick to itself with the same solvent cement used on the joints. So you can just sand or rasp curved connection points on the ends of regular smaller pvc pipe and then glue them between the legs. As a design concept, I'd think about using decreasing sized triangular sections that would fit inside each other allowing for a telescoping tower that could be easily extended or retracted using nylon rope or small cable off a winch system.
Best of luck on your project.
Doc

Wow, Doc, great ideas on the PVC. I've been theoretically welding up a tower of EMT with several hinges to allow it to fold down upon the ROP roof, but I like this idea of the PVC sections "nesting" within themselves. So then how about once they're extended by the cable or rope, how would they then attach to each other and become a unit?

You'll love this... or not...
Okay, to keep from binding / pushing all the way out and falling over, you maintain an overlap and max lift limit point which is where you mount your top lift pullies, either inside or to the side of your uprights. Put a pully on ALL three. All three lift ropes/cables get pulled together. As base of inner section reaches pullies, can go no further up, BUT equal lateral tension on all three points LOCKS base of inner section to legs of outer section. Simplicity, no? Also, only need one lift wench. Anchor lift ropes for next section inside to base of lifting section, and as second section rises, it concurrently pulls on ropes to raise third. All reach max rigid lock point at same time.
At least that's how it works inside my muddled brain.
Doc

Yeah Doc!
I'm sure I'm looking at the same muddled picture as you and its great! So, to unlock and lower the unit, just start releasing the winch, eh?

Yeper! (Uh, yes.) You lose some height from each section due to the mandatory overlap, but the inner structures can be made of smaller pipe, so get cheaper to add one extra if needed.

Using ten foot plus fittings per section, I'd set overlap at at least 2.5 foot and 3 foot would be even better.

But even at three foot that still gives you 21 foot of stable three leg structure, and presumably the base will add some height, so a short (~2 foot) center mast piece nets you your 24 foot fully extended but under 15 or so retracted. Trickiest part is getting relative sections just right sized for a resultant tight fit for stability but loose enough to slide easily. Since all lift ropes run to same winch, easy to make it all automatic electric up/down by setting limit switches. But winch could be anything from boat loader crank style to small ATV electric. Could even be home made from multiple electric scooter chains and sprockets and a jack shaft or two.
Original concept of nested tower sections isn't mine, but borrowed from ham radio world, but as far as I know the described lift system is mine alone. Been toying with it as a possible system for a windmill tower for my property in southern Utah.
Doc

P.S. Chasbear.. if you want to explore muddle territory, some of the things that occurred to me while thinking about this was a sprayer pressure driven ram lift that automatically lifted the tower when the sprayer got up steam. Then a TV antenna rotor to direct spray and a small CCD camera on sprayer arm that showed you right where it was spraying from the sprayer's perspective... muddled enough?
Doc

Nope, not muddled at all, Doc. In fact, I've now got your way of thinking crystal clear. Well, maybe a little muddled with the pressure driven ram lift, so let's start there? It's reminding me of a simple water well pumping system I saw that's intended for developing nations like the one I'm in now, using white (PVC) pipe with hand made rubber washers. I like this idea, if it doesn't leak my spray solution all over of course.

Yeah, properly sealing the ram was what stoppe'd that particular thought tangent rather abruptly. Especially against a high pressure pump. But such a ram isn't necessary to the rest of the design. Some sort of winch system will work just fine... and in fact add more stability to the structure by locking the sections in place at full extension as previously mentioned.

Problem area I still see is constructing the odd degree coupler pieces for connecting the tower legs in a triangular shape at top and bottom points. No way to connect them all at same height using off the shelf parts. But accomplishable using T's at staggered heights. Just have to be very careful getting them pointed exactly the right direction when you glue them.
Once again best of luck on the project... and please keep us informed as to progress on it.
Doc

Hey guys, see if you can get some MEK solvent. You can fit everything up to where it moves nice, then put a dab of it on the joint. It will run around the joint, wick down into it and weld it together in a flash. I'd let it sit for a day or so before I used it though.

Thanks for the tip Terry, but I'm not so sure about the availability of MEK on Mindanao in the Phillipines.
Doc