"With the price of grain the way it is, the average farmer can't justify spending the money on a 300-hp tractor. We built our own for much less and it works just as well as anything out of a factory," says Glen Oetken who helped his father, Gerald Oetken of Larned, Kan., convert a semi truck into a powerful farm tractor.
The completed rig weighs in at about 22,000 lbs., which Gerald figures is about right since he rates it at about 234 drawbar hp (325 flywheel hp). He regularly pulls a 32-ft. double-offset disk or a 38-ft. fallow plow with the tractor and it handles the big equipment with no problem.
The men started with a 1978 International 4300 which originally had a twin-screw rear end with a 325 hp 855 Cummins engine and 10-speed Fuller transmission. They cut the frame off behind the cab and spliced in a shorter home-built frame made from 12-in. channel iron. It's fitted with a rear-end from a 1950's Euclid earth scraper. Glen says the 100-ton rear end's 13:1 gear ratio matched up perfectly with the semi's 10-speed transmission. The only thing they had to do to match them up was to make a new driveshaft.
The semi tractor is fitted with single flotation tires up front -- "I think the mag wheels are a nice touch," says Glen -- and dual 20.8 by R42 tires on back. Making the duals was one of the most difficult parts of the whole project. They made wheel spacers out of 30-in. dia. natural gas pipe.
They fitted the tractor with the 4-spool hydraulic system off a 4-WD Versatile tractor. The semi did not originally have power steering so the hydraulics provide that also.
The Cummins engine was completely rebuilt and the Oetkens installed a dual governor to maintain steady rpm's in the field. Glen says the governor is the same unit found on any farm tractor with a Cummins engine but notes that it's an expensive component to buy new. "You can save a lot of money if you can find a used one. The governor holds the tractor at about 1,800 rpm's in the field," he says.
The tractor has forward speeds ranging from 1.5 mph in 1st gear to over 40 mph in 10th.
One of the most essential features of the truck-tractor is the air brake system. "We rigged up individual air brakes using the truck's original air system," notes Glen. "We can brake either side of the tractor individually or brake all four wheels at once. You have to be able to brake either side to make turns on headlands."
The completed tractor has a much shorter wheelbase than the original twin screw semi. It's about as long as a standard 2-WD tractor, which Glen and Gerald say makes it very maneuverable in the field.
One of the best things about the truck is the comfortable ride. Glen says no tractor can match the home-built tractor's air ride suspension and great view.
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