Although manufactured by David Bradley, the Tri-Trac concept was really the creation of Sears and Roebuck. In the ‘50s, Sears had it's own corporate Engineering Department. One of it's goals was to bring to market a new, low cost, riding tractor. The difficulty with riding tractors, in the view of the Sears engineers, was the complexity of the differential. If a tractor could be developed that did not require a differential, then costs could be reduced substantially. Thus was born the three wheel tractor concept.

At David Bradley, which had it's own Engineering Department, the Tri-Trac was a ‘high profile’ project driven directly by Sears. Perhaps because Sears engineers had their own personal prestige on the line, the Tri-Trac was extensively tested at Bradley. Unfortunately, as testing progressed, the Sears engineers solved minor short comings by ‘brute force’ methods, adding substantially to the cost of the tractor. As one story goes, the Tri-Trac was being driven around the Bradley test grounds one day when the driver accidentally drove it into a tree. This bent the front steering linkage to the point where the tractor could not be driven. The result was a directive from Sears that hence forth, all of the front end components would now be heat treated. Apparently, there were many similar stories, and the cost of the Tri-Trac went up with each.

While Sears drove the development of the tractor, Bradley engineers worked to design a new line of attachments. The nature of the tractor made the design of some of these attachments a challenge. Unfortunately, the high visibility of the Tri-Trac program caused other projects at Bradley to take a back seat. This fact, coupled with the direction from Sears, caused the Bradley engineering group to develop a bad feeling about the Tri-Trac. But, despite a lack of enthusiasm, the Tri-Trac was announced in 1953. Sears apparently spared no expense, and the Tri-Trac was featured in many news, agricultural, and engineering publications. In addition to advertising, Sears further promoted the Tri-Trac by offering to bring one directly to your farm or garden and demonstrate it for you on the spot.

In 1954, the first year of significant manufacture, the Tri-Trac was listed for $598.00 in the Sears catalog. This price was for the tractor only, and did not include any attachments. The lowest priced attachment, the spring tooth harrow, sold for an additional $30 making the cost of a usable Tri-Trac well over $600. In addition to cost, the Tri-Trac looked ‘unusual’. The back end of the machine resembled a motor cycle with sheet metal skirting. Even the seat looked like motor cycle seats of the day. The front of the tractor was, by comparison, conventional enough, but the presence of a hand crank that could be used to offset the front end by bending the tractor in the middle was certainly different. Finally, for a tractor with a big look (at 102 inches long the Tri-Trac was significantly larger then todays garden tractors), the Tri-Trac offered only 6 HP. This was not plenty of power to move a 894 pound tractor with a 200 pound rider, and still mow a 58 inch swath with the rotary mower!

With all of these problems, the Tri-Trac had one additional flaw, tipping. Even with the front end offset for operation on hills, the Tri-Trac was prone to tip over. This was especially true with the sickle bar mower attachment. At a recent show in Bradley IL. A former Bradley engineer was reluctant to have his picture taken on a stationary Tri-Trac resting on level ground with the mower attachment on it. He was afraid it ‘might tip over’. To counter this tendency, front wheel weights were made standard equipment by 1957. While this helped, Tri-Trac operators would always need to exercise caution on hills. A Tri-Trac owner once remarked that it gives no indication of tipping until it's too late.