1924 Doble E, Steam Powered car

Abner Doble was convinced steam power was perfect for cars. By 1922, the model E had been developed; this could be said to be the “classic“ Doble, of which the most examples have survived. The initial monotube boiler design was perfected into the “American“ type. This produced steam at a pressure of 750 psi (52 bar) and a temperature of 750 °F (400 °C). The tubing was formed from seamless cold drawn steel 575 ft 9 in (175 m) in total length, measuring 22 inches (560 mm) in diameter by 33 inches (840 mm) in height when coiled and assembled. The boiler was cold water tested to a pressure of 7,000 psi (480 bar).[9] Two 2-cylinder compound cylinder blocks were in effect placed back-to-back as the basis for a 4-cylinder Woolf compound unit with high pressure cylinders placed on the outside. A piston valve incorporating transfer ports was fitted between each high-pressure and low-pressure cylinder in an arrangement similar to Vauclain’s balanced compound system used on a number of railway locomotives around 1900.