The only description I can find of the fire engine is when the alarm sounds and the firemen head to the house of the woman who burns herself with her books. As they leave the firehouse, the engine is described: "Below, the orange dragon coughed into life." The engine is also described as a dragon during the scene where Montag burns his own house. This fits Bradbury's imagery motifs, as everything associated with fire and the firemen has a sinister quality. Calling the engine a "dragon" implies a hidden danger. It also connects it to the Mechanical Hound, who will prove dangerous to Montag later in the story.