1921 American La France Type 75 Triple.  Edgarton, Wisconsin bought this pumper in 1921.  A few years later they removed its chemical tank and added a booster tank.  This is simply a water tank connected to 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.  Many engines also featured hard rubber tires.  Pneumatic tires were common on automobiles and light trucks by 1910, but were not reliable on heavy trucks.  Fire engine makers conservatively stuck with hard rubber tires until the mid twenties, although reliable heavy truck pneumatic tires were available in 1920.  By 1930 most departments had replaced their rigs'  hard rubber tires with pneumatics that increased the truck's speed and greatly improved traction on wet or snowy streets.  For some reason Edgerton chose to stick with the hard rubber tires.

On display at the Hall of Flames Fire Museum.