Stuying the pros and cons of both the FDL and HDL engines gave GE a good starting point from which to start on a new engine. Many of the pros from each previous design would be combined in the new GEVO engine, and many improvements were made as well. An example of improving on the HDL design is widening the main bearings. Sometimes redesigning one part has a domino effect on others. Widening the main bearings gave them "higher reliability, and when we did that , of course everything got wider with it. The bulkhead support to it, the main bearing cap, everything that goes along with it, the connecting rod witdh itself, so that was the core, basic structure that changed," explains Sue Napierkowski.

 

"The engine was designed in three dimensions, and at that time it was new to the engine group here. HDL was designed using a two-dimensional drafting system," says Napierkowski. Designing in 3D, on a computer resulted in increased accuracy, and outside vendors upgrades their facilities to handle the computer files instead of paper drawings that they had used before. Accuracy was so improved that many of the first components that wer cut, milled, or cast using it were actually the parts used in assembling the first engines. In the past there had been much trial and error involved with making parts so that often times many parts would be created before a usable one was completed.

GE decided to develop a 12-cylinder and a 16-cylinder GEVO engine at the same time. "We knew from the a design standpoint that the 16s and 12s are a little bit different," Napierkowski explains. "They have different vibration characteristics and we wanted to make sure we designed both of them at the same time so that we really could have that baseline done and do the fine details later.

With emission as a priority, the engine design team had to determine what was necessary in order to improve on that point in the GEVO. After much research it was determined that the firing pressure in the cylinder needed to be increased. But increasing the firing pressure puts more load on the main bearings - another reason to increase their witdh. "There's more pressure, more force, so with that you strengthen the structure all around it," recounts Napierkowski. "Everything got stronger structural components so you could have high pressures and still meet emissions now and in the future." As a result, the GEVO structure is beefier than previous GE engines, which also helps reduce vibrations and makes for a more reliable engine that has less effect on the rest of the locomotive and its crew.

From "GE Evolution Locomotives" by Sean Graham-White, ISBN 978-0-7603-2298-7

 

Pictures
top: Sue Napierkowski points out some of the GEVO features on a large cutaway drawing. She remembers, "to see it start from a pile of parts to a fully assembled engine testing in the lab was quite a feat."

middle: The GEVO crankshaft is a key component in the engine's success. It must be very strong to withstand the force of 12 connecting rods producing 4400 hp. In turn, it rotates the camshaft, water and oil pumps and the alternator.

bottom: A GEVO engine on the assembly line.

Questions
1) The ranks of women engineers have grown from less than two percent of all engineers in the United States in 1978 to nine percent of engineers today.
Can you think of reasons why there are so few women engineers?

2) What is a cutaway drawing and when is it useful?

3) List benefits and drawbacks of 3D designing.

4) What effect had the GEVO 3D design on General Electric's suppliers?

5) "... the firing pressure in the cylinder needed to be increased."
How can we increase the firing pressure in a diesel engine?