THE EMD 567 SERIES TWO-CYCLE UNIFLOW ENGINE, AN INSPIRATION: PART 1

The boys worked all night and hoped the engines would run all the next day. It was no fun but we learned fast and a new design study was soon underway at Winton. To mention the parts with which we had trouble in Chicago would take far too much time. Let it suffice to say that I do not remember any trouble with the dip stick.

E.W. Kettering, Chief Engineer, EMD

Predecessor to the 567 Series:  The Winton 201

It’s 1930, the Great Depression is deepening and gasoline prices are rising.  The railroads, recent adopters of gasoline-electric powered railcars for local passenger service, are screaming:  “Gas prices are going up!”

GM had just recently purchased the Electro-Motive Corporation, an early builder of gasoline-electric rail cars and the Winton Engine Corporation, builders of the engines that powered Electro-Motive’s rail cars.  The new division of GM, Electro-Motive Division (EMD), was set to task building a new engine to run not on distillate or gasoline, but diesel.

Up to this point, Winton’s largest 4-cycle gasoline railroad engine made 400 horsepower from 1,184 cubic inches.  Winton’s early solution to the problem of making more power with cheaper fuel was their 900HP distillate engine.  The engine, plagued with problems, made 900 horsepower when it could be kept running.  EMD realized that the future of railroad combustion engines was more power, LOTS more power.  This would allow the combustion powered train to haul much more weight and take to the main lines.

To build a more powerful engine, General Motors Research concluded the solution was a compression-ignition 2-cycle uniflow engine burning cheaper diesel fuel.  This engine would use Winton’s recently developed (but far from perfected) unit injector.  The 2-cycle engine, by it’s very nature, allows a higher volume-specific power output than a 4-cycle engine because it fires every revolution of the crankshaft, rather than every other revolution.   A course of research and development began with the construction of several single-cylinder test engines.  As problems were solved in the test engine, an 8-cylinder inline engine began to take shape, soon to be called the Winton 8-201.

“..I do not remember any trouble with the dip stick.”  Such was the story at the GM Building during the 1933 World’s Fair.  A pair of new engines of unconventional design, just recently assembled and still relatively untested, were on trial before the world.

Called the 8-201 because if their inline 8-cylinder configuration with a displacement of 201 cubic inches per cylinder, they would be discovered at the World’s Fair by Ralph Budd, president of the Chicago, Baltimore and Quincy Railroad.    The 8-201, redesigned immediately after the World’s fair and designated the 8-201A, would power his groundbreaking new train, the Pioneer Zephyr.  “Dieselization” of America’s railroads had begun.

winton worlds fair

The Winton 8-201’s at the 1933 World’s Fair.

The Winton engines were unique in many respects.  Beyond their novel fabrication almost entirely from welded steel plate, “powerpack” construction and unit injectors, they were one of the first uses of the poppet valve uniflow scavenged 2-stroke cycle.

The Winton Engine Corporation unitized injector, U.S. Patent 1,864,860. Filed Feb 11, 1931

Winton fabricated engine construction, U.S. Patent 1836,189. Filed Feb 14, 1930

One of the major issues to be solved in developing the 201 engine involved cooling the piston crown and ring belt.  Winton’s solution to this problem is instructive as it is a problem I expect to face as well.

winton piston

An early Winton 201 series piston. Not the large number of compression rings, heavy wall crown and ring belt. Also note the even temperature distribution between the crown and ring belt. lllustration Credit: “History and Development of the 567 Series General Motors Locomotive Engine” Page 11.

Initial development in the single-cylinder test engine concluded that conventional piston design was not appropriate.  As power approached 82 1/2 HP per cylinder, the piston rings began sticking, presumably due to oil coking.  Piston seizure soon followed after about 100 hours of operation.  It was discovered that increasing the cooling oil flow to the piston crown did not necessarily reduce ring belt temperatures and that the piston shed almost 70% of it’s waste heat to the cylinder liner through the top ring.  EMD’s solution to the problem was the heat dam piston.

late winton piston

A revised Winton 201 piston design. Note the much lighter construction, higher crown temperature and lower ring belt temperature. Illustration credit: “History and Development of the 567 Series General Motors Locomotive Engine” Page 13

The heat dam piston reduces the ability of the crown to transfer heat to the ring belt by limiting the area of metal connecting the two surfaces.  This substantially reduced the ring belt temperature, but increased the crown temperature.  A material change to cast iron was made at that time, presumably for it’s lower thermal conductivity and it’s capacity to resist the higher temperatures in the crown area.  Piston cooling oil was used to cool the underside of the piston crown.

While the 201 and 201A series engines were variously plagued with problems related to piston cooling, crankcase stiffness and coolant leaks, the lessons learned from the Winton 8-201 and it’s larger cousins the 12-201 and 16-201 would directly produce the engine that finished “Dieselizing” the railroads of the world.  It’s an engine which can still be heard running the iron today:  The EMD 567 series.  It is this engine that first introduced me to the 2-cycle uniflow design.

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