One of the rarest oil field engines is the ‘Black Bear’
sold by the Oil Well Supply Co. of Pittsburgh, Pa. Of side shaft
design, Black Bear engines are very pleasing to the eye thanks to
their many moving parts while in operation.
Black Bear engines were ahead of their time with features such
as mechanically actuated intake valves, optional air starting, a
water pump and a triple-redundancy ignition system. Engines were
built in 25, 35 and 40 HP sizes.
One thing I don’t know for sure is whether Oil Well Supply
actually manufactured these engines, or if they were sourced from
another company. Existing engines are few, but I was fortunate to
track down a circa-1920 Oil Well Supply Co. brochure that describes
Black Bear Gas Engines
‘Black Bear gas engines are designed to meet the most severe
requirements in the oil country. All parts are made with a view of
exceeding the strength actually required.
‘The engine is of the four-cycle type with valve mechanism
operated by a camshaft driven by spiral gears from the main shaft.
Both inlet and exhaust valves are operated by the same cam.
‘Governing is effected by means of a Pickering governor,
which can be set to operate the engine at a fixed speed or can be
controlled by a line operated from the derrick floor.
‘The valves are of the poppet type. They are so placed as to
receive full benefit of the water jacket surrounding the valve
‘Ignition is effected in either of three different ways:
magneto and jump-spark system, hot tube or make-and-break system.
The design of the engine is such that all three ignitions may be
attached at the same time if so desired. Hot tube ignition is
sometimes desired, make-and-break ignition is recommended for power
house installations, magneto and jump-spark ignition for all other
‘A Wico magneto is furnished when the magneto and jump-spark
system is used. It is operated directly from the camshaft and is
mounted on a bracket.
‘Air starter provision is made on the cylinder head for
connecting an air starter.
‘Lubrication: The main bearings are provided with chain
oilers, which carry oil continuously from reservoirs in the bed
plate to the shaft. The crank pin is lubricated by means of a
centrifugal oiling system. The cylinder is lubricated by a sight
feed oil cup, as is the piston pin. The spiral gears driving the
camshaft operate in a bath of oil. Oil cups are provided for the
camshaft bearings, also for the rocker arm bearings. The Black Bear
engine can also be furnished with force-feed lubrication, if
‘The engine is built with a short crankshaft. On the pulley
side, there is a flange built as part of the flywheel hub. To this
flange is bolted the flange of a short shaft carrying either a
straight clutch or a reverse clutch.
‘An oil guard for the crank pin is furnished as standard
equipment with each engine. If preferred, a case to completely
enclose the crank can be furnished.
‘Water jackets are very liberal in size, and the circulation
of water is insured by a rotary pump, belt-driven from the
‘Flywheels are balanced to insure smooth running and are
extra heavy. This makes the engine give a very steady motion both
under light and heavy loads.’
As always, please call, write or e-mail if you would like a free
membership in the Oil Field Engine Society (OFES).
Contact the Oil Field Engine Society at: 1231 Banta’s
Creek Road, Eaton, OH 45320-9701, online at: www.oilfieldengine.com
e-mail at: email@example.com