The K3 Mountains

Tue Feb 10 10:53:40 EST 2015

To follow Ed’s comments.  If the K-3 had been a 2-8-4, there would not have been the rear axle of the lead truck behind the cylinders.  Without that wheel behind cylinder, the space from the cylinder to the throat sheet would have allow 69-inch drivers which would have been easier to counterbalance.  There would have been a corresponding shifting of the driving axles forward as well.

In my interview with C. E. Pond, I asked him if there were any concerns in 1937 with the proposed Class Y-7 having the same cylinder dimensions and driver size being used on the K-3s which gave problems.  He answered (and I paraphrase) – I think we knew a lot more about counterbalancing 10 years later.  There is a lot of truth in his statement when you consider the 58-inch Y-6s were worked at a higher speed then the K-3s were allowed which were known to kink rails above 35 MPH.

Too much emphasis is being placed on the main rod being connected to the third driver.  That was a factor but the driving rod was connected at the crossheads which were placed to the rear of the lead truck wheel behind the cylinder.  This required a shorter rod of almost three feet or so.

Bud Jeffries

From: NW Mailing List 
Sent: Sunday, February 08, 2015 10:28 PM
To: NW Mailing List 
Subject: Re: The K3 Mountains

adb - 

There was a general dissatisfaction communicated to the MP department, but the boss, Alexander Kearney, stayed put until he was thrown off a horse and met his demise.  That was when Russell Henley became Superintendent of Motive Power.

IMHO the K-3 was misconceived, but I have the benefit of 90 years of hindsight; it should have been a 2-8-4 instead of a 4-8-2 (it could have had a shorter main rod), but my guess is that Kearney didn’t want to go that way.  It was known, too, that 63”-drivered Super Power engines elsewhere were not known as particularly good riders or easy on track (T&P put disc main drivers on its 63” 2-10-4s to make them good for 60MPH which required a driver RPM of 320).  The K-3 was a fierce looking machine, though.

Notwithstanding the K-3, N&W’s experience in counterbalancing took a fantastic upturn, so that the Class A and the later Y’s were excellent at high driver RPM and there may never, anywhere, have been a steam locomotive as perfectly balanced as the J, which was completely comfortable at driving wheel RPM of well over 500.  The PRR people riding the 610 when it tested between Crestline and Chicago recorded a speed of 111 MPH, at which the drivers were turning at 532 RPM (assuming new tires; if the tires were worn the RPM would have been higher; one-half inch of tire wear, resulting in a driver diameter of  69 inches, would have meant an RPM of 540.5 at 111 MPH).  The PRR people stated (read Dave Stephenson’s story in the ARROW) that the only engine PRR ever had that rode better than the J was their 6-4-4-6, which had 84” Baldwin Disc drivers; the K4 Pacifics, M1 Mountains and even the T1 4-4-4-4s weren’t as good.  Not only did the J ride well, its valve gear was so well designed that it could attain that speed without resorting to the use of poppet valves.

Ed King

From: NW Mailing List 
Sent: Sunday, February 08, 2015 6:14 PM
To: N&W Mailing List 
Subject: The K3 Mountains

Internal politics tend to be covered up and generally linger on only in the fuzzy memories and often embellished tales of old men.

But is it known who, in the Motive Power Department,  took the heat for the design faults and the generally lackluster performance of the K3 class Mountains?

That is to say, was anyone's career "cut short" by the situation with the K3's?

-- abram burnett

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