For most fire departments the graceful old steam fire engines, the tall water towers and aerial ladders represented a sizeable investment.  Most communities could not afford to expend large sums of cash for new motorized equipment, especially when existing equipment was still meeting the needs of the community.

However several companies began manufacturing tractors to easily convert earlier horse drawn equipment. J.W. Christe produced the first of more than 700 two wheel transverse-engine tractors in 1912, becoming one of the more successful tractor producers.  Seagrave, American LaFrance as well as Boyd, Garford and Robinson produced tractors to convert older horse-drawn equipment, or as motive power for new equipment.

Knox-Martin, located in Springfield, Massachusetts produced a unique tractor for fire apparatus beginning in 1909.  The Knox-Martin was a three-wheeled unit with a long steering column extending over the hood to a single from wheel.  With this design, the tractor had the advantage of being able to turn nearly 90 degrees, allowing a high degree of maneuverability for larger apparatus such as long aerial ladders.  These units were powered by 40 horsepower, 4 cylinder engines could achieve 30 mile per hour.  They achieved a degree of popularity being employed in Philadelphia, San Jose and Springfield and many other cities.

There are only two known Knox-Martin tractors in the world, and the San Jose Fire Museum has the only known Knox-Martin fire engine combination.  The other Knox-Martin tractor, a logging truck combination is on display at the Smithsonian Institution.