Was Re: Roller Bearings and the Y6-b, Now Y6b Development

[NW Mailing List]

So no opinions on what the result on N&W's operations would be if they had
one loco instead of having to use both A's and Y's?

John Rhodes

On Thu, Oct 10, 2019, 12:19 PM NW Mailing List <nw-mailing-list at nwhs.org>
wrote:

> All,
> N&W instead of expanding the speed capability of the Y Class they created
> the A Class to take care of Fast Freight, flatter districts and the
> occasional heavy passenger train.  Later they realized that a single engine
> type to do all freight jobs would be better for the railroad operationally
> and financially.  N&W started investigating the Y7 for this role, assuming
> larger drivers and abandoning compound operation was necessary to meet the
> objective of a general purpose freight locomotive.
>
> I propose that in about 1930, N&W could have sped up the compound 58"
> drivered Y Class to allow it to also do everything that the Class A did as
> well so that the Class A would have never been designed or built.
>
> There are 2 issues to a Y class doing the work of an A. 1. Maximum speed
> and 2. Drop off of drawbar pull at higher speed.
>
> With respect to 1. The size of the low pressure cylinders and lack of
> ability to balance them for 70 mph is the issue. Dividing the 2 huge lp
> cylinders into 3 reasonable sized lp cylinders on 120 degree separation
> would likely have allowed 70 mph balancing.
>
> Also the volume of the lp cylinders is driven by the volume of the hp
> cylinders. The hp cylinders size on the Y class is driven by tractive
> effort requirements for the 4 axles of the hp engine.  The lp engine due to
> size and the starting valve has no issue producing as much tractive effort
> as needed. Changing the wheel arrangement to 2-10-6-4 would have helped in
> allowing smaller hp and lp cylinders and balancing while keep TE high.
>
> Also the 3 cylinder  lp engine with less torque variation in a rotation
> should allow the lp engine to produce 25000 pounds of TE per axle vs 20000.
> So a 3 lp cylider Y class should have been capable of 180000 to 185000
> pounds of TE versus 160000ish pounds of rating TE for a Y5 Y6.
>
> The second issue is drop of of drawbar pull at higher speed.  This is an
> issue of steam flow and pressure drops. A 3 cylinder lp engine and also
> reducing the cylinder sizes in general will help this tremendously.  But
> having 2 piston valves per cylinder with the longest practical travel lap
> and lead will greatly improve middle range and top end power without
> hurting the low end.  High lead in valve gears can make a locomotive
> slippery at low speed so variable lead based on cutoff like DRGW did would
> be appropriate based on what the N&W did with the Y Class.
>
> The live and intermediate steam piping from the dome through the
> superheater throttle  and cylinder steam ports should have cross section of
> 25% of the cylinder faces not 8-10% on the Y class.
>
> Also the Y class need more  steam chest volume about 125% of the cylinder
> volume.
>
> More superheat like 850 degrees Farenheit would have helped but probably
> required saturated steam cooling of the valve liners.
>
> Also resuperheating of the exhaust steam to the lp engine would help.
> More feedwater heat extraction using a 2 stage setup with open and closed
> type stages. Basically adding a 2nd shell and tube stage to a Worthington
> FWH would work.
>
> When finished with this you would end up with a loco of similar weight and
> size but have 70 mph top speed 185000 pounds TE and likely 7000 drawbar
> horsepower on the same coal and water consumption as a Y.
>
> And in the end Stuart Saunders would have dieselized anyway.
>
> John Rhodes
>
>
> On Thu, Oct 10, 2019 at 8:10 AM NW Mailing List via NW-Mailing-List <
> nw-mailing-list at nwhs.org> wrote:
>
>> I'd like to throw another possible reason - roller bearing rods have
>> large hubs and may have interfered with the clearance limits on  the lower
>> part of the N&W's load gauge.  With the Y6's 58" drivers and 32" stroke,
>> there's not a lot of room  for a roller bearing rod hub.  IIRC, load gauge
>> interference was a problem with the P&LE's 2-8-4's and they had
>> conventional solid bearing rods and 63" drivers.
>>
>> Dave Stephenson
>>
>>
>>
>> On Wednesday, October 9, 2019, 9:58:26 PM EDT, NW Mailing List <
>> nw-mailing-list at nwhs.org> wrote:
>>
>> Bill
>>
>>       If you’re a Trainorders member (I am not)you can go back and read
>> Wes Camp’s writing on this subject recently . Very interesting  There were
>>
>> a lot of reasons why probably it never happened .
>>
>> Larry Evans
>>
>>
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