No reason why slightly modified or home built
versions of these can't operate as steam engines.
Cutaway drawings of piston and rotary vane types etc.:
"Power characteristics of air motors are similar to those of series-wound DC motors. With a constant inlet pressure, the brake horsepower of an air motor is zero at zero speed. Power increases with increasing speed until it peaks at around 50% of free speed (maximum speed under no-load conditions), Figure 4.
At the peak point, torque decrease balances speed increase. Power decreases to zero when torque is zero, because all the inlet air power is used to force the volume of air required to maintain this speed through the motor."
Frederick
