Our Solar-Powered Tractor


A little over a year ago, my husband, Terry, started talking about building a solar tractor. Since we were planning a move to a thirty-acre farm in Arkansas, the tractor would have to actually be the workhorse we expected we would need rather than a conversation piece shown off in parades. The original tractor — and I use that expression loosely — was a Ford 1950 8n bound for the scrap metal pile. When Terry told me he paid $200 for the rusty tractor pieces he proudly showed me I admit I wondered about his sanity. The front tires were lying off to one side and there was no motor, seat or fenders. Despite my doubts, his enthusiasm never waned and he began building his solar tractor.

For those who are mechanically-minded and are thinking about building their own solar tractor I willSolar Powered Tractor attempt to relay the information given to me by Terry—also sometimes known as “MacGyver” due to his ability to fix anything and make something out of nothing! So, according to my mad scientist…

First, the crank shaft was removed and cut at the last rod bearing, leaving the rear main, flywheel attachment and collection pressure plate. Next the crank shaft was machined to accept the end cap of a universal joint after the drilling and tapping on the crank shaft was completed. The crank shaft was re-installed into the tractor, leaving the two rear main bearings. A grease fitting was installed into the block of the tractor. A rubber bladder was located—an automatic lubricator which keeps the rear main lubricated.

A trip to the welding shop for steel—including sixteen inches of a 16” pipe to cradle the 36-48 volt Hyster forklift motor purchased in Dallas at a rewinding shop for $600—came next. The pipe was cut in half, leaving two “cradles,” one of which was attached by welding a bracket to hold the pipe. The bracket was attached to the front frame of the tractor and a chain was welded over the top of the forklift motor once it was set inside its cradle. The chain basically works as a strap which holds the motor in place, preventing it from slipping backwards or forwards or rotating under torque. Next I searched (and searched and searched) on the Internet to find a spline to fit on the 21-tooth motor drive shaft. Eventually we ended up ordering a 21-spline clutch and taking it apart. (Price for steel and spline—approximately $250)

A bolt was run through a link of the chain with a nut threaded onto the bolt which pulls the chain down tight against the forklift motor, creating a tensioning chain bracket. A steel bracket was then fabricated and bolted to the original cast iron oil pan. Two block bearings with a drive shaft between them were installed, then a pulley was installed on the drive shaft and a universal attached to the end of the drive shaft to mate with the universal joint on the crank shaft. Terry next installed a double-belt pulley on the 21-tooth spline onto the motor drive shaft. After another Internet search we ordered an Alltrax Performance Controller ($700) to control the voltage which goes to the motor and to allow operation of the electronic foot pedal.

The electronic foot pedal was then attached to the original tractor throttle lever. The Alltrax Performance Controller is programmable; it works in a 300-650 amp range, 12-72 volts DC. Terry selected a 48-volt system so it would work with the 48-volt solar photovoltaic system installed at our home. In this way, when the batteries on the tractor are running low it can be plugged into the household battery bank.

6/19/2019 8:19:00 AM

And you work under a shade, ever in the blazing sun!

11/22/2013 11:36:49 AM

@Kathryn & Terry, and others needing good batteries, go to a truck salvage yard and buy used truck batteries, usually 800/1000 amps for $10 to $40. TIP: go on youtube and learn to check the batteries, typically truckers change all batteries when they have a problem but only one or two batteries will actually be bad out of four. Also on youtube you can learn how to chemically restore weak batteries. TIP: try to keep all your batteries the same amps or cold cranking amps (CCA). Great job on the tractor guys...

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