"OP" engines (WAS Re: Arrow Train Master article)

[NW Mailing List]

I read somewhere that the cranks were timed so that most of the horsepower came off the lower crankshaft; perhaps that meant that lower crank also had to be the "exhaust" one.

Perhaps some folks know that British Railways' early top Diesel express locos had "Deltic" engines, which were opposed piston engines with three crankshafts arranged at the corners of a triangle, with the cylinders constituting the "sides" of the triangle.  I think that they were higher-speed machines with smaller cylinder displacements than the FMs. I think that they were pretty successful and ran flat out for much of their lives.

Maybe the "Deltics"  were mentioned in the Arrow article - I haven't had time to read it carefully.

pete groom 
On Jan 20, 2013, at 7:09 PM, NW Mailing List <nw-mailing-list at nwhs.org> wrote:


> Good questions Jimmy.  I'm traveling without my reference material (listed at the end of the article) but I'll try to answer anyhow.  You are correct, that the FM doesn't have a cylinder head.  I don't know where I got that terminology, but I think I got the major point: a lot of regular maintenance required taking off the top of the engine and removing the upper crankshaft, which was, I assume, a lot more work than was required on a "conventional" layout.  Now to your second point: I meant the lower portion of the combustion chamber, and I can see how that could have been clearer.

>  

> Further, thank you for your comments on the tendency of diesel engines to be "smokers".  I would guess that the reputation of FMs (and Alcos)to make more smoke than "average" has some basis, but I haven't seen the hard data.  To be Frank (intended), I'm always open to supplementation and correction; we want to get the best possible information and get it out there.  And in answer to your final question about intakes, I'm sure that FM had some reason for doing it the way they did, and, if I had to guess, I'd speculate that it's related to the engine's marine history.

>  

> Frank Bongiovanni

>  

> 

> 

> On Sat, Jan 19, 2013 at 12:11 AM, NW Mailing List <nw-mailing-list at nwhs.org> wrote:

> Maybe Frank could comment on a couple of things in his Train Master article. 

> 

> On page 23 it states: 

>     "Much routine maintenance required removal of the upper cylinder head and crankshaft".

> 

> The FM engine doesn't have a head.

> 

> "There are also reports of incomplete fuel combustion (causing blue smoke) in the lower combustion chamber."

> 

> There is only one combustion chamber, rather than an upper and lower as the sentence would suggest. 

>    

>      Just for information, it is very common for diesels to put out a lot of smoke when not up to operating temperatures. Back when we had GP9's, sometimes a consist would be setting around for hours idling waiting for an assignment and a lot of carbon and unburned fuel would collect on top of the dished piston head. We would get them off of the outgoing track and baby them down to the train. After pulling the train past Randolph St. Tower the engineers would open them up and look back to see a pretty good smoke screen being laid down. Usually by the time we got to North Roanoke the smoke had cleared up.

>     Try and start up a cold four axle GE unit in the middle of Waynesboro, Va. and see if people don't call the law on you! Yikes!

>     With emissions what they are today, it is sometimes hard to see smoke from the diesels. Good for the air, but now it can be very hard to look back and tell which unit just shut down you.

>     One other thing in looking at the way FM designed their engine is that I wonder why they put the cool intake air coming in at the top and exhaust going out the bottom. Seems to me they would have breathed a little easier with the cool intake air forcing the hot exhaust out the top. Maybe they didn't realize that hot air rises.

> 

> Jimmy Lisle

> 

> 

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