Mount Wilson Observatory Power House

Fairbanks-Morse - 50 Horse Power - 1911

According to factory records this engine was manufactured in mid 1911 and delivered to Los Angeles in December of that year. It was most likely installed in the Autumn of 1912. It is a twin Cylinder gasoline fueled engine directly coupled to a generator capable of producing 40 kilowatts of power at 125 volts D.C. To start the engine, compressed air is introduced into one cylinder to get the piston moving and the crankshaft rotating. Once the other cylinder starts to fire the air is shut off and the starting lver is returned to the 'run' position allowing both cylinders to operate normally. Instead of spark plugs, this engine uses mechanically operated contacts that extend into the combustion chamber. The contact assembly, called an igniter, is actuated by a push rod working off the camshaft just like the engine's valves. The electricity for ignition is provided by a 5 volt D.C. generator connected to inductive coils. A small 125 volt D.C. motor turns this generator. Gasoline is pumped from a supply tank on the floor to a sight glass at the level of the intake manifold near the top of the cylinders. From there it flows to the mixers where it is available to be mixed with the air that is being sucked in by the downward moving pistons. Excess gasoline drains back to the supply tank. The factory claimed 6 GPH fuel usage under load. Oil for lubrication is stored in a tank above the engine. It flows from there by gravity to a series of 13 adjustable drippers which in turn lubricate specific internal areas. Excess oil collects in the bottom of the crankcase and flows into a tank at floor level where it is filtered and then pumped back up to the supply tank. External engine parts are lubricated by hand with an oil can or grease cups. Water for cooling runs through water jackets surrounding the cylinders. This heated water was not wasted as it was piped to an adjacent shower room. Engine speed is kept constant by a rotating governor that controls the amount of air admitted for combustion.

Engine Specifications: Horse Power: 50 - Speed: 300 RPM Nominal - Bore and Stroke: 11 x 13 Inches (2,600 CU. Inches) - Shipping weight with generator: 22,000 LBS.