Some frequently asked questions on EMD Roots blowers:

Question: Why does the parts list for blowers in catalog 301 have four blower part numbers and four columns for different applications but all the individual component part numbers of the items in every column are the same?

Answer: Because all four of the blower types listed have exactly the same parts. The difference between them is in how the parts are assembled. Unfortunately the parts list does not explain that.

Question: Did EMD write a Maintenance Instruction on Roots Blowers?

Answer: Yes, the Maintenance Instruction is No. 430 covering 567 engines and 430A covering both 567 and 645 engines. They were for internal use and were not widely circulated, these are very hard to find in print.

Question: If I have a blower sitting on the floor and do not have access to a parts book, how can I tell visually if it is for left bank or right bank use on the engine?

Answer: The blower is not symmetrical. On the air outlet (bottom) flange you will see it has a long foot on one side and a short foot on the other side. The long foot always goes toward the center of the engine. Visualize that you are standing where the engine would be and looking at the blower. If the long foot is on the right, the blower is for the right bank side of the engine. If the long foot is on the left it is for the left bank side.

Question: Why do the 567U and 567V have different blower part numbers from the other 567 series engines?

Answer: The Roots blowers for the 567U and 567V engines are assembled differently, thus a different part number. They have the drive quill shafts installed on the inboard rotor of the blower. The Roots blowers for the later engines have the drive quill shafts on the outboard rotor of the blower.

Question: Can I convert a blower for a 567A or later engine so that I can use it on a 567U or 567V engine?

Answer: This is done by changing the side of the blower that the quill shaft is installed on. This is a relatively simple change done by removing the end cover and swapping the quill shaft with the gear cover on the opposite rotor.

Question: Can I convert a blower from left bank to right bank use on the same type engine?

Answer: Yes you can, but this requires disassembly of the blower and buildup with the long foot side of the housing facing the other way. In other words, if you visualize the blower with the drive end bearing support and the outboard end bearing support, the cover, and the rotors all staying in the same orientation, then the center section of the body has to be turned 180 degrees so the long foot of the bottom (outlet) flange is facing toward the other side of the blower. Also, the quill shaft has to be changed to the other rotor lobe, assuming you are going back onto the same type of EMD engine the blower came from originally.

EMD printed references, when and where you can find them:

EMD MI-430 - 567 engine Roots blowers
EMD MI-430A - 567 and 645 engine Roots blowers
EMD GSB-416 Rev. A – Converting 567A blowers to 567U or 567V use
EMD Parts Catalog 301, List A385 - 567 Engine Roots Blowers

Their Address:
EMD / Progress Locomotive
9301 West 55th Street
La Grange, IL 60525

The remaining fleet of 567 engines is declining rapidly in all industries. If your museum intends to have a 567 engine locomotive operating far into the future they need to be paying attention to its condition and planning for increasing difficulty locating parts.

PC

A little OT but look what some red neck did with a root blower

Explained a little more here, for the interested:

https://www.youtube.com/watch?v=v0qeYd5gcnQ

Apparently a hilbilly, not a redneck. Interesting to see what will happen with that much positive displacement and no blowoff valve or wastegate equivalent; interesting too that he has not apparently even considered how much underdrive (perhaps with multiple reduction belt and pulley sets!) he would need to avoid overspeeding the rotors and gears in that blower past their design speed.

As a note: the 'traditional' drag-racing blower isn't called a 6-71 blower for nothing...

Are there Roots-blown 710G's?

Almost certainly not. It was my understanding that EMD made a conscious choice not to offer a Roots-blown version of the 710; Mr. Cook will have a much more thorough explanation of the technical reasoning, but it made better sense to provide the clutched direct turbo drive for low-rpm operation.

I think all the derated locomotives use 645 power assemblies on a compatible block. The 710ECO (8-cylinder) 710 was and is turbo only

http://www.progressrail.com/en/products/locomotives/repowered.html

The 710 engine was developed at a time when EMD was in a very critical fuel economy competition with other builders, and when demand for the 645 Roots blower engine was already declining. They consequently continued production of the Roots Blower 645 into the 1990s but did not develop a Roots blower version of the 710 engine.

ASME Technical Paper 85-DGP-24 provides a more detailed explanation of 710 engine design considerations.

PC

How does the turbo interact with the roots blower? I think I heard depending on the rpm the engine switched beyween the two.

Systems with a turbocharger providing inlet air in series with a Roots blower were used by Detroit Diesel and Cleveland Diesel on two-stroke cycle Diesel engines. EMD designed a turbocharger for their 567 series engines that was assisted by the engine gear train and did not require series operation with a Roots blower. This was introduced in production in the 567D engine series and developed further in the 645 and 710 series.

PC

Remember that the Roots blower isn't a 'supercharger' in the usual sense; it's a scavenge air blower. It is also a positive-displacement device so the scavenge air flow is proportional to engine rpm even at idle. Boosting/intercooling ahead of the Roots blowers, as in early practice, does what the LP turbo in a set of twins does: it increases the effective air density going into the positive-displacement volume. I'd think to make this work you'd have to intercool aggressively, throwing away potential regeneration heat, and then you have the increased work and heating running the denser charge through the rotors turning at a 'fixed' speed relative to the crankshaft.

I also know of no system that allowed 'clutching' of the internal gear drive to the Roots blowers, so there would be no point in 'switching over' from Roots to turbo at higher rpm, and the fuel and even if 'bypassed' and not compressing air a considerable portion of the work to drive a Roots blower is required if it is being driven by the gear train -- Mr. Cook will know just how much.

At low crank rpm, a straight turbocharger won't provide enough scavenge air, for the same sort of reason an Alco throws black overfuel smoke. So EMD drives the blower of the turbocharger via a mechanical drive that is fitted with an overrunning clutch, so the delivered charge air is the 'greater' of what the geartrain or the exhaust turbine can deliver.

The 710 was designed so that the "turbocharger" develops the right overpressure at any speed and load, so there is no need to run a pair of positive-displacement geared blowers for low-speed scavenge or be limited by corresponding positive-displacement charge air mass flow above Run 5 or so.

Those interested in the performance curves for the EMD turbocharger, there is ASME document 60-OGP-7, "Design and development of Turbochargers for the General Motors Corporation Series 567 Engines" by Albert "Norm" Addie, submitted February 1960. That paper essentially duplicates an EMD internal slide presentation from June 1958.

The practical and economic issues of turbocharger vs. Roots blower EMD engines as they pertain to equipment preservation were covered in a clinic on engines that was done for an ATRRM meeting about ten years ago.

PC