TRACTOR DESIGN

TRACTOR DESIGN


| April/May 1990



Tie road ahead of axle

461 Algonquin Place, Webster Groves, Missouri 63119

Everyone likes to see the small tractors running around the grounds at thresher reunions. Whether you have a reproduction of an Oil Pull or Mogul, or just parts you put together from the scrap pile, you have a popular display. Kids want a ride and the older folks want to see how it works,

It doesn't matter whether you have a fancy machine shop or just use stove bolts and a 5-pound hammer, some simple rules must be followed in steering and chassis layout. You don't repeal laws of chassis design by ignoring them. If you use these rules, your tractor will be easy to steer, will drive a straight line over rough ground and will not scrub the wheels in a turn.

These geometric rules apply to any vehicle controlled by steering arms and kingpins. Center-pivot tractors like row-crops and most steam tractors do not have the opportunities for steering sophistication (or errors) that steering-arm geometry affords. I have simplified things from what you would need on a 150 miles per hour race car but everything will work fine at 5 mph. These steps are easy. Just lay everything out on the floor before you start to weld.

ACKERMANN STEERING

FIGURE 1: ACKERMANN STEERING