Rural Retreat Depot is open today

[NW Mailing List]

Bud,

Thanks for the additional info.

Gordon Hamilton

On 10/15/2022 10:07 AM, NW Mailing List wrote:
>
> Gordon,
>
> Dave explained this in detail. I covered this on page 247 in the Giant 
> book revised edition. With this change, the rod between #3 and #4 
> wheels were the same as the front single rods. Louis Newton was the 
> one I got this information from and only four J’s were changed. They 
> were change only if stress fractures appeared on #4 four crank pins.
>
> Bud Jeffries
>
> *From:* NW-Mailing-List <nw-mailing-list-bounces at nwhs.org> *On Behalf 
> Of *NW Mailing List via NW-Mailing-List
> *Sent:* Saturday, October 15, 2022 6:19 AM
> *To:* NW Mailing List <nw-mailing-list at nwhs.org>
> *Cc:* NW Mailing List <nw-mailing-list at nwhs.org>
> *Subject:* Re: Rural Retreat Depot is open today
>
> Initially, all modern 4-8-4's in the 1940 era that were equipped with 
> roller bearing rods using the so-called tandem rod connection between 
> #2 and #3 axles. In addition, because of this configuration, all of 
> them had relatively long crankpins on #4 axle.  Because all railroads 
> used the same method (tandem rods), this was likely the industry 
> standard for handling the forces that had to be distributed through 
> the running gear, particularly between axles #2 and #3 of a 4-axle 
> engine set.
>
> N&W revised the Class J rods to do away with the tandem rod setup 
> between #2 and #3 driving axle on four locomotives  from about 1952 to 
> 1956.  From a side view, the change can be seen in a much larger rod 
> hub on #3 axle, because one rod bearing must carry the same load that 
> two smaller bearings carried before.  Also the hub on #4 axle is much 
> shorter (the rod is closer to the driver face) which reduced the 
> stresses that were present in the longer crankpin
>
> Dave Stephenson
>
> On Friday, October 14, 2022 at 10:41:35 PM EDT, NW Mailing List 
> <nw-mailing-list at nwhs.org> wrote:
>
> Dave,
>
> Pardon my ignorance, but what is the modification of rods on these 
> four Js?
>
> Gordon Hamilton
>
> On 10/14/2022 10:29 AM, NW Mailing List via NW-Mailing-List wrote:
>
> The four J's that I have for modified rods were 600, 605, 610, 611.  
> So with your photo, we've narrowed that to two.  Really does look like 
> 611 in the negative enlargement, but the top part of the second "1" 
> does look a little different  from the top part of the first 
> "1"............  Thanks for posting!!
>
> Dave Stephenson
>
>
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