I am shopping for a piece of land now - about 10 acres - with the intention of planting about 3 acres of it for field crops and growing veggies and fruits in a large green house. I am kicking around an idea that I would like input on. I have attached a photo to this post - I would like to make a multipurpose "tractor" that looks like this that will:
- be able to plow, disc and till the 3 acres.
- have a robotic arm/crane on it that will enable it to lift heavy objects on and off of the platform
- will be used often as an intelligent wheelbarrow, an "i-barrow" (sorry Mr. Jobs)
- can be used as a mobile power source to operate other electric appliances for a short time when necessary, i.e. water pumps
- can be used indoors (hence the desirableness of electricity)
This tractor will not be working with virgin land. All of the land will already have been plowed, moved, contoured by heavier equipment. The land is likely to be in Arizona or very southern New Mexico, so will have a higher sand content than usual. I might even ditch the use of the tracks to save a few hundred $.
I would like to use 4 or 6 geared hub motors to power this, making it all wheel drive. I think I have found a source for 1 and 2kw geared motors with peak performance reached at 350 rpm. I like the idea of hub motors because there is no need for transmissions or drive trains. Hub motors may not be quite as durable as other kinds but I am hoping that this factor may be overcome with duplicity. Top speed of 8-10 mph is ok.
How much torque do I need from these motors to make my little droid do it's job? There will be a pto on it, operated by a separate motor or even a hydraulic pump operated by an electric motor, depending on the accessories that I can find. So I need one set of specs to have the droid pull and carry and one to have it power the accessories. Ideal maximum width is 36", so that it will fit through the greenhouse door. There are a variety of accessories from garden tractors and walk behinds that look like they could be used with this width. Assuming it is 3' by 4', (with batteries) the weight would be about 500 pounds, depending on the type of the battery and desired run time.