MOTHER'S MINI-TRACTOR (PART I)

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Because the Volkswagen transmission is geared for travel at highway speeds, rather than for agricultural purposes, we had to step down the ratio in the drive between the engine and the transaxle assembly to 8.85:1. To accomplish this, we used a series of toothed-belt pulleys connected to 1 " jackshafts riding in supported bearings. The final drive is a chainand-sprocket arrangement, and fastens to the clutch input shaft.

(Note: The toothed-belt Gilmer drives that we used are reliable—but expensive—components. It's possible to substitute conventional sprockets and chains for those parts, but be aware that the engine crankshaft may spin at an RPM rate greater than that recommended for some chains.)

Since the "crank" was originally mated with the clutch (and, of course, we did not use the VW powerplant), we had to have a machinist make an adapter coupling and thread it with a 28mm, 1.5-pitch tap. We also had him cut keyways into the power shafts to accept the pulleys and sprockets.

Then, to support the shaft and its bearing, we cut and drilled a 1/2" plate—using the VW bellhousing as a template—before welding a 5"diameter, 1-1/2"-long section of Schedule 40 pipe to its center. A 3/8" X 5-1/2" circular flat plate, welded to the end of this pipe, served as a bearing mount . . . and the whole assembly was shimmed out to the proper distance from the bellhousing with a 1/8" flat metal spacer, template-cut and - bored to match the main plate.

THERE'S MORE TO FOLLOW

REAR AND SUPPORT BEAM
click here to enlarge

Thus far, we've described the bare-bones tractor and running gear. In our next issue, we'll detail the fabrication of the fuel tank and the sheet-metal parts (and show you a design for a manual bending brake that costs far less than a commercial model) . . . finish up the braking and electrical systems . . . and tell you how we built our threepoint hitch and hydraulic lift, as well as the optional power take-off arrangement for use with specialized implements.

So take a good look at the photos and illustrations accompanying this article, and keep an eye open for bargain buys on small engines and Volkswagen components . . . with some luck you may be able to catch up with us before the next issue reaches your home!

EDITOR'S NOTE: Since space limita tions prevent a detailed description of every phase of this project's construction, MOTHER's research staffers are in the process of putting together—for those of you who might want more details than the essentials that appear in the magazine—step-by-step, illustrated plans for our tractor. The on-sale date of these construction prints will be announced in next issue's article, after final testing of the tractor and its implements has been completed.

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