Restore & Respect

Cooper-Bessemer engine becomes an homage to a departed brother

By Scott Hollis

The green beast quietly lays in wait. Quickly, Dean Unruh jumps on the 18-foot trailer. He positions himself near the 4,500-pound 1937 Cooper-Bessemer's broad base and reaches toward the apex of the engine to open an air valve to the cylinder head. With a glance at a check valve and a notice of a petcock, everything looks ready to go as he gives a nod to his buddy below.

Perry Hildebrandt turns a valve extending from an air tank to introduce 160 psi of air into the engine's cylinder head, while Dean nimbly jumps down to the ground to roll the engine's big 910-pound flywheel over top dead center. A cam off the crankshaft in time with the pistons introduces the pressurized air needed to start the lumbering two-cycle engine. Throngs of people have gathered to witness the rare upright 65 HP oil field engine run at the 2004 Oklahoma Steam & Gas Engine Show in Pawnee.

“The engine will easily flood if you don't watch what you're doing,” Dean says over the din coming from the Cooper-Bessemer. “The carburetor just can't adjust.” The crowd looks on in amusement, cluelessly taking the difficult start-up for granted. Dean walks around the engine, inspecting all things large and small on the engine and trailer for problems. It takes an eagle eye, and it's a duty that only comes with years of experience starting the engine.

Dean knows the subtle intricacies on his Cooper-Bessemer Type GSD, serial no. 39852, because he's been exhibiting it at Pawnee and other nearby shows for almost 15 years. It's his largest and favorite engine in his collection, but sadly the Cooper-Bessemer holds deep sentimental ties since his brother Marlin, who helped him restore and show the engine, passed away three years ago.

“That was our favorite engine … we had so many memories and hours on that engine,” the Enid, Okla., native affectionately recalls about his time spent with Marlin restoring the engine..g engine upon start-up. “The engine will shake for a minute at a low rpm until it gets up to speed. Once it gets past that critical speed, it balances out real good.”

Also added to the trailer is a unique, adjustable resistance plate that puts pressure on the flywheel to create simulated work. “It's a smooth-running engine, but the two-cycle wants to pull something or it runs uneven.” The resistance plate consists of nothing more than an oak brake plate and two water spigots to reduce the temperature and friction. Once adjusted, the resistance is set just right, and the engine seems to settle down as if it were a workhorse comfortably harnessed to a plow.

Tribute to Marlin

This Cooper-Bessemer is now a complete, self-contained unit that travels exceptionally well behind Dean's 1/2-ton pickup. Over the years, he's added an original Cooper-Bessemer logo, a wooden placard with restoration pictures, an air horn just for giggles and a few sundry personalized add-ons like a monogrammed plate and faux moonshine bottle below the water tank. It's obvious that Dean has fun with the setup wherever he goes.

The Cooper-Bessemer Type GSD is Dean's crowning achievement, but it's also a tribute. A plaque for Marlin, centrally positioned in his honor, reads, “In Memory of Marlin Unruh – The Cooper-Bessemer was his pride and joy.” It's a fitting tribute for Marlin wherever the engine travels. It's probably safe to say Marlin wouldn't have it any other way.

Dean Unruh is looking for other collectors who have information about Cooper-Bessemer Type GSD engines. Contact him at: Route 3, Box 429, Enid, OK 73703; (580) 234-0151.