How to design and build a belt driven generator for a small tractor? Answered
The storm that swept through Ohio last Friday (seems like an eternity ago) took out our power. It may not be restored until sometime next week (ah, life in the country). We are used to this sort of thing in the winter and are prepared for it. However, we are not prepared to deal with it when it is this hot. I have a small generator that can run a fan and a few lights and am prepared to sacrifice the contents of the fridge. My generator doesn't put out enough power to run a window AC unit much less our central AC unit. My neighbor has a gas powered generator that is big enough to do the trick but he is pouring so much money into the tank that he might as well stay at a hotel.
So anyhow I looked into getting a PTO driven generator to run off my Kubota BX1500 (think diesel engined, 4wd lawn mower on steroids rather than tractor-it's a tiny little thing). It really doesn't burn all that much fuel and it offers the option of using home brewed biodiesel (damn the Tax Man-full speed ahead!). Here's the rub though: you need about 2 hp/kw to run a generator off the PTO. My Kubota has about 12.5 hp. The smallest PTO driven generator I can find (Norther Tool) is a 10 KW unit. That won't work out very well. However, they also have a 2900 watt belt driven generator head that would be large enough to do the job.
I suppose I could mig together an angle iron frame that will hook to the three point hitch and mount the generator head and the driven jack shaft but I don't have any experience in building belt drive units. Soooo, anybody out there have any experience in cobbling together belt drive units from scratch? The tractor's PTO shaft turns at 540 rpm but the generator really won't work right unless it turns at least 3600 rpm (interestingly the ratio works out to be 6.66 to 1, possibly not a good omen). Grainger has a large (if over priced) selection of pulleys that will get me in the ballpark. This still leaves a lot of questions though, probably more that I can think of since I have no experience in belt drive systems. I am specifically worried about how to set up the necessary bearings to support the jack shaft that connects the PTO shaft to the drive pulley. For that matter I don't know where to get a shaft that has PTO splines on one end and a keyway on the other.
In any case, one of you guys have probably already done this or something pretty close to it. So how about letting the rest of us in on all the necessary tricks?