The engine used was the German Fafnir, but converted to be water-cooled.
This design did not acquit itself well; as early as 1902 the dolly axle was removed and the engine converted into a normal 2'B1' locomotive.
Even an ideal, frictionless engine can't convert anywhere near 100% of its input heat into work.
But diesel engines converted to burn methanol could meet the standards, the experts say.
The pre-1928 engines not converted received the roller bearing levers in 1940, and no further conversions were made.
Converted to a dual sail/steam ship in 1858, engine removed and converted to transport in 1870.
Hydraulic (liquid) and pneumatic (gas) engines convert fluid pressure into other desirable mechanical or electrical work.
In general an engine converts energy to mechanical work.
Slowly the petroleum-burning engines were converting to methane or synfuels.
As an example, automotive engines convert chemical energy (enthalpy) from the fuel into heat, and then into mechanical work that eventually turns the wheels.