Why do San Francisco Fire Engines and Trucks still have bells? While it is tradition, a way of alerting horses and carriages before sirens were invented, the bells are a safer way to get the attention of pedestrians without using the loud air horn. You’ll often hear the bell as the units pull out of the firehouse, making sure folks walking nearby know to watch out! #yoursffd #sanfrancisco #firefighter #fireengine #tradition | San Francisco Fire Department