The D.C. & U.

A Gas/Steam Convertible Engine for the Oil Field


| January/February 2002



D.C. & U. convertible cylinder

An early ad for a Tillinghast-built D.C. & U. convertible cylinder.

This D.C. & U. was photographed in 1964, probably somewhere near McDonald, Pa., and likely when the engine was pulled from service.

This particular cylinder caught my interest while working with Joe Prinzinger on a historical document of the B.D. Tillinghast Machine Shop (see page 25 of this issue for the full history) in McDonald, Pa. While the D.C. & U. engine cylinder was one of the products that Tillinghast built, it was not of his own design. Tillinghast was the sole producer in building this unique and apparently once popular engine cylinder, and the patent rights belonged to three other individuals, Gustave Dahlberg, Jacob Clicquennoi and Ernest Uhlin. These three gentlemen all lived in the town of McDonald, and held May 1899 patent numbers 633338 and 633339 for their engineering design of this very unique cylinder.

The three inventor's relationship with B.D. Tillinghast is completely unknown. Were they personal friends, neighbors, or simply businessmen looking for the right partnership? What we do know is that their cylinder was extremely popular in the southwestern Pennsylvania and northern West Virginia oil fields.

The Convertible gas/steam engine is much different than your typical gas half-breed. As a half-breed simply turned an old steam frame into a gas-only pumping engine, the convertible cylinders could be used as a gas engine or a steam engine. The purpose behind such a concept was to allow an operator to use steam power when the gas reserves were not available, and the gas engine when the resources returned. It was much easier than constantly changing the gas and steam cylinders off of the well.

Although there were several companies that built and patented convertible engines, the D.C. & U. design seems to have stood out among the rest. The major noted factor was that the steam chest was used as a fuel/air mixing chamber, which allowed more room for a coolant chamber. Other designs used a separate charging area creating excess weight on the steam frames.

While studying the patents, I noticed some interesting facts. To begin with, the two patents that were registered show slight differences in design. The first patent shows the engine, although a 2-cycle, using an exhaust valve working off of the cross-head. The second patent shows a traditional ported exhaust, which appears to have been the more common of the two. The D.C. & U. cylinder also was built in a rotary steam valve configuration. An old price list is my only evidence to prove that this design once existed.