Edgerton, Wisconsin bought this engine in 1921. Pumping capacity is 750 gallons per minute at 120 pounds per square inch of pressure at the pump. A few years later the EFD removed its chemical tank and added a “booster” tank. This is simply a water tank connected by a hose to the engine’s pump. Water from the tank flows by gravity into the pump, which can discharge it onto the fire through a small diameter rubber hose stored on a reel near the tank.
Water can be applied at once and in a small enough quantity to minimize water damage. The tank can be refilled from the pump once it starts drawing water from a hydrant. It made no sense to equip pumpers with chemical tanks instead of water tanks, but a few chiefs insisted on their purchase until as late as 1935. Many engines, like this one, were retrofitted with the more capable booster tanks. The engine also features hard rubber tires. Pneumatic tires were common on automobiles and light trucks by 1910, but were not reliable on heavy trucks.
Fire engines makers conservatively stuck with hard rubber tires until the mid twenties, although reliable heavy truck pneumatic tires were available by 1920. By 1930 most departments had replaced their rigs’ hard rubber tires with pneumatics that increased the trucks’ speed and greatly improved traction on wet or snowy streets. For some reason Edgerton chose to stick with the hard rubber tires.