The Mighty 175 Otto Engine

This 175 hp Otto engine is one of the largest single-cylinder gas engines in the world and one of only five built.

| April/May 2016

1925 Otto 175 hp
Manufacturer: Otto Engine Works, Philadelphia, PA
Serial no.: 14247
Horsepower: 175 hp @ 180 rpm
Bore & stroke: 21in x 30in
Engine weight: 49,000lb
Flywheel diameter: 17-3/4in x 1-3/4in
Ignition: Magneto and igniter
Governing: Throttle

Of all the wonderful engines displayed at the Coolspring Power Museum, my favorite will always be the 175 hp Otto and the Worthington water pump, which were originally located at the Brookville, Pennsylvania, waterworks. Brookville, only 10 miles from Coolspring, seemed such an unlikely place to find one of the largest single-cylinder gas engines in the world. Amazingly, Otto only built five of these monsters: one going to an ink factory in Brooklyn, New York; three going to China; and one going to Brookville! I can still recall the summer evening in 1968 when John Wilcox and I drove to Brookville to peep into the waterworks, not knowing what we would find. He seemed to go berserk after looking in through a window, and soon was running around to all the windows and doors for a better look. A bit later, he explained to me the significance of the jewel we found.

John quickly investigated with a call to the Water Board and found that the engine and pump, on standby since 1945, were to be replaced with an electrically powered pump. Successful in obtaining the retired unit, he spent most all of 1969 dismantling the 25-ton engine and the 20-ton pump single handedly. He hauled all the parts to his location in Ohio on his 1952 L140 2-ton International truck. Only the engine main frame needed special trucking. A monumental feat! He meticulously maintained all the parts, but did not have the opportunity to assemble them. About 35 years later and health declining, he sold the Otto engine and Worthington pump to me. This is the story of its return home.


Looking back into history a bit, in 1911 Brookville built a beautiful new waterworks as shown in Photo 1. It was located on North Fork Creek, which provided unlimited pure water from a watershed of many thousand acres of pristine forest. The new waterworks replaced an older steam plant that could no longer provide the town’s needs. Note the room on the right of the building; it housed an 80 hp Otto. Fifteen years later, it would be the home of the 175. 

In 1925, the waterboard recognized the need for a larger pumping unit. Borough engineer Fred Sayer applied for engine bids of a 175 hp unit. He considered a Worthington and an Otto. Photo 2 is the engine contract dated Nov. 2, 1925, for the 175 hp Otto, at a cost of $7,590. It is the 1912 model, which replaced the highly successful 1893 Columbian model. A catalog picture is shown in Photo 3. Although still available, it was essentially obsolete in 1925! The huge single-cylinder, 21-inch bore and 30-inch stroke, two large flywheels, 9 feet 1-inch in diameter, and simple two-piece main bearings betrayed its earlier design. 

An undated picture from the waterworks file, shown as Photo 4, is the Otto and its pump during its working years. It was meticulously maintained and operated by plant engineer Reuben “Rube” Ferringer. Its location was in the side room of the waterworks, as mentioned above. Note the flat belt over the flywheel extending into the basement. This powered a centrifugal pump that brought the water from the dam into the sedimentation basins. There the water was filtered, with the Worthington triplex pump finally pushing the water uphill some 300 feet to the town’s reservoir. Gravity delivered the water to all the users. The engine ran 24 hours a day from Monday morning through Saturday afternoon; the reservoir supplied Sunday’s needs.