Coolspring Spotlight: A 1925 175 HP Otto engine on display at the Coolspring Power Museum.
The 1925 175 HP Otto is likely the largest single-cylinder, conventional two-flywheel gas engine in the known collector’s world.
This display consists of a 175 HP Otto engine driving a Triplex 3-cylinder Worthington positive displacement water pump. These pieces of equipment have always been mated together and were installed in 1925 in the Brookville, Pa., water works, only 8 miles north of the Coolspring museum.
This engine includes a sideshaft that drives a governor and over and under exhaust and intake valves. The governor acts upon the stroke of the intake valve rocker arm, so it’s a throttling engine; it throttles by limiting the amount that the intake valve opens. It is air-started with a valve in the center of the cylinder head; a combustion air inlet and gas inlet form the mixer, which is where the engine gets its fuel. The exhaust comes out a water-cooled elbow.
The flywheel on the sideshaft is a normal flywheel, but the flywheel on the offside has a very wide rim, which drove a centrifugal pump that pumped water from a nearby creek into the treatment plant.