Eimco Power Horses: The Tractor That Drives Like A Horse

Let's Talk Rusty Iron: Harold Probasco shares part of his collection: two Eimco Power Horse tractors and the original prototype built by Bond and Bert Bonham in 1937.


| February 2001



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Detail from the original Bonham patent, filed June 26, 1937 and issued April 16, 1940.

The 'Let's Talk Rusty Iron' column in the June 1999 issue of Farm Collector was about tractors that could be driven with reins from a trailed implement. That brought a response from Harold Probasco of Huntsville, Utah, who not only owns two rare Eimco Power Horses, but has one of the very early models which is probably the prototype that the Bonham Brothers put together in 1937.

The story of the Eimco Power Horse has been told before, but briefly, here's how it began: Utah residents Bond and Bert Bonham invented a small, four-wheel drive tractor during the mid-19305. They applied for a patent in June 1937 and, though the patent wasn't granted until April 16, 1940, the Utah Construction Company of Ogden, Utah, began to build the machine in about 1937.

Mr. Probasco's early model has a Hercules IXB 3 1/2-inch bore by 4-inch stroke engine. It appears that the Hercules power plant was used for a year or two, until the Eimco Corporation of Salt Lake City, Utah, took over building the machine. After that, Allis-Chalmers model B engine skid units were used. This accounts for the definite resemblance of the Power Horse to an Allis-Chalmers model B, although the Eimco-built tractors were painted all copper (with the later version having a tan hood and wheels).

The Power Horse is lever-controlled and, with reins attached to the levers, can be driven from the seat of a trailed implement in much the same way as a team of horses is driven. The owner's manual for the Eimco Power Horse gives the following procedure for driving the machine: First, the engine is started and one of four transmission speeds is selected, using the master clutch lever to disengage the transmission. Then, after making sure the two control levers are locked in their center, or neutral position, the master clutch is engaged.

After mounting the seat of the implement, the driver gives the reins a slight tug, releasing the neutral lock. Both lines are then freed, so the control levers assume their spring-loaded forward (or run) position, at which time the Power Horse moves forward.

When one control lever is pulled to the rear and the other is left in its forward position, the Power Horse turns toward the side upon which the rein is pulled. The sharpness of the turn depends upon how far the levers are pulled back, or allowed to go forward, if in reverse. Steering is accomplished by the steering clutch disengaging power to both wheels on the turning side. If one lever is released, and the other is pulled all the way to the rear, the wheels on each side will turn in opposite directions, and the tractor will spin around in its own tracks.