Was Re: Roller Bearings and the Y6-b, Now Y6b Development
NW Mailing List
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Mon Oct 14 08:30:39 EDT 2019
Dave -
Again, you hit the nail on the head. As far as poppet valves are concerned, it must be remembered that N&W used factors of adhesion that were considered low. The J, in particular, was considerably less than 4.0. To apply poppet valves to a J would likely have resulted in excessive slipperiness, and the valving (and counterbalancing) of the J was so good that one official was heard to say that “getting a J up to 100 MPH was easy”.
N&W’s use of Baker Valve Gear might come into question, too. There were roads that would not use Baker because it had to be bought from the Pilliod Company where poor old Egide Walschaert’s patent had run out years ago and his valve gear could be applied without any other expense. But Baker offered a couple of benefits; all its connections were radial and could use conventional pins and bushings and later be adapted to needle roller bearings. Baker offered more precise valve settings that would last much longer with minimum maintenance than Walschaerts with its sliding link block. I believe that the experience with the ‘E-1 and M-1 engines soured the railroad on Walschaerts and made it a ready customer for Baker. I was told years ago that the design of the Walschaerts on the M-1s was such that it promoted undue link block wear, resulting in additional maintenance if you wanted to keep the valves square.
But N&W was, as you point out, an early desciple of th KISS principle of locomotive design.
Folks don’t realize that N&W might have been the most “studied” railroad there was. It knew exactly what it cost to store tidewater coal in hopper cars at Lamberts Poing versus designing and constructing a ground storage facility that could handle 250 classifications of coal. Similarly, it knew exactly what it cost to obtain a gross ton mile per train hour from its steam locomotives, and after the tests of 1952 it knew what it cost to obtain a GTM/TH from the diesels of the day. Labor costs were increasing during the 1950s which affected the steam locomotive more that it did diesels, and the efficiency of the diesels was improving steadily. When the cost lines crossed – when steam costs got to be more than diesel costs – the N&W dieselized and quickly. It was interested in net profit and kept its eye on the prize.
- Ed King
From: NW Mailing List via NW-Mailing-List
Sent: Sunday, October 13, 2019 7:15 PM
To: NW Mailing List
Cc: NW Mailing List
Subject: Re: Was Re: Roller Bearings and the Y6-b, Now Y6b Development
Overall, it seems that N&W did not like to get into overly complex design features. They avoided such applications as poppet valves of any type and tended to stick with highly focused and refined conventional locomotive designs. This simplified their operations and likely reduced their maintenance costs. The latter component was always a problem when comparing the total costs of steam vs diesel. Because of the forces on the loose within the steam locomotive, it tended to be self-destructive if not attended to fairly carefully.
Dave Stephenson
On Sunday, October 13, 2019, 9:01:02 AM EDT, NW Mailing List <nw-mailing-list at nwhs.org> wrote:
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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