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latest design were effective drilling to moderate depths and, if
compounded; two pumps in series were suitable for relatively
deep drilling. The simplicity of this piece of equipment was one of
its most valuable features. Pistons in the steam cylinders are directly
connected by rods to pistons in the mud end of the pump.
The action is simple linear motion with one side starting its
movement just as the other side is completing its movement thus
producing a steady flow with little or no variation in rate of
discharge. The thermal efficiency of these pumps is poor since the
steam cylinder operates on a positive displacement cycle and thus
fails to realize any benefits of steam expansion.

Internal Combustion Gas Engines

While steam is still the yardstick of all power, advent of
torque converters brought the internal combustion engine to a par
with steam if not better. With the torque converter, the driller
feels less bounce when operating the throttle than with steam.
Also when feeling out the load, a cracked throttle on a
torque converter-equipped combustion engine will produce a
steady pull. The same cracked throttle on a steam engine may
allow a pressure buildup in the engine cylinders, causing a
constantly increasing pull on the load. Under certain conditions,
this might be important on the negative side.
More new changes in the concept of engine design have
appeared in the recent past than any time in history. These
advances are true of all types of engines, the Otto or 4-cycle, the
2-cycle and the diesel cycle. Probably the first noticeable change
was in cylinder pressures.
The gas/gasoline engines of recent time past were all low
pressure naturally-aspirated engines. Today they are being
supercharged and cylinder pressures are approaching that of
diesels. This supercharging first made its appearance on 2-cycle
gas engines and soon became universal. These high pressure

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