Engine "Slippery-ness"

NW Mailing List nw-mailing-list at nwhs.org
Wed Sep 16 12:14:40 EDT 2009



I witnessed a slip of a 1200 (class A) as a kid growing up in Circleville. In '52 or '53 westbound coal drags would periodically "set off" stock at?the cattle pens next to the local freight station on the north side of town.?They would stop the train south of town so as to not block all those grade crossings and?deliver the stock cars, maybe 3?or 4 of them?(and boy did they smell!), 2 miles to the pens and?run reverse?thru town back to the train. They would then start the train and accelerate with memorable stack talk thru town past my home. I saw this 3 or 4 times. On one occasion while I was watched from one of the grade crossings the engine returned to the train and started. To watch that alone was a sight to behold, but as the engine approached where I was - maybe 1500 or 2000 feet from where it started - with drivers turning at probably 60 to 80 rpm by then, the front engine broke and very rapidly spun up. I'm sure it was unexpected because it must have been turning 4 or
500 rpm (6or8 per second)?by the time the engineer got the throttle closed. This occurred on tangent track near the passenger train stop where the rail may have been oily. It is hard to imagine so much weight spinning so rapidly. It scared the devil out of me. But, it slowed quickly, regained traction and continued on it's way as if nothing had happened. What a spectacle! And to think the railroaders saw such things often. The recent talk of?the J's at 110 mph spinning so fast reminded me of what I had seen.



Ted Goodman, Columbus

-----Original Message-----
From: NW Mailing List <nw-mailing-list at nwhs.org>
To: NW Mailing List <nw-mailing-list at nwhs.org>
Sent: Tue, Sep 15, 2009 7:23 pm
Subject: Re: Engine "Slippery-ness"




I should have mentioned that one of the best examples of an A's performance
right on the edge of its max capability is on Winston Link's Mainline to Panther
album/CD.

There is one sequence where an A is westbound on Blue Ridge grade and manages to
keep moving with an overload down to about 10-12 mph. It holds the rail for a
considerable length of time, with the two engines going in an out of step,
sometimes staying one way or the other for sustained periods of time. It finally
slipped, reportedly on the turnout near the summit and was unable to recover.
Generally when one engine of a 4-cylinder simple slips, the throttle must be
shut off all the way until the slip stops. In the cited example there was one
slip with full recovery, and two additional slips in succession before finally
stalling. It's great example of a very skilled crew getting every last ounce of
low speed performance from an A.

BTW, the A's FA is 3.79 based on its RATED TE, which at low speeds is less than
what the locomotive actually developed during tests.

Dave Stephenson




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