These photos show a standard drilling rig utilizing a
single-cylinder, two-stroke gas engine manufactured by Bovaird
& Seyfang Manufacturing Co., Bradford, Pa. The rig was located
in the Bradford Oil Field, and the photos were probably taken in
the late 1920s or early 1930s. These photos are from the archives
of the Coolspring Power Museum.
This particular Bovaird & Seyfang engine is a 40 HP Class AJ
and has a 12-1/2-inch bore by 14-inch stroke. It was fitted with
the lighter 900-pound flywheels used for drilling. The pumping
engines used 1,200-pound flywheels. The flywheel diameter was 66
The engine was self-oiling, with the exception of the cylinder,
which was equipped with a Manzel mechanical lubricator. Ignition
was either by a Wico magneto or hot tube. Like most early Class
AJ’s, the water pump was a plunger type. Also, no governor was
used: The speed was controlled by a telegraph wheel and line to the
derrick floor. The forge blower was run by a friction wheel that
contacted the clutch side flywheel face. The clutch was of the
The rig clearly shows the engine in operation, and one can only
imagine the sound coming out of that straight 6-inch exhaust stack
pointing at the ground. Note the clutter around the rig. This was
typical when the early oil fields were being developed.
Contact engine enthusiast Michael Fuoco at: 656 W.
Washington St., Bradford, PA 16701.