J Class Changes

NW Mailing List nw-mailing-list at nwhs.org
Tue Sep 2 14:14:43 EDT 2008

Dave is correct, there were four J's that got the redesigned single rods:
600, 605, 610 and 611. These were applied from 1952 to 1956-7 as needed when
a stress fracture appeared on a crankpin. This rod change involved replacing
the front, rear and intermediate side rods, the main and eccentric rods, the
intermediate driving wheels, and all of the crankpins. This was very costly,
therefore was only done when required. These rods were designed in 1952 and
were not interchangeable with tandem rods.

Other changes noticeable on the J's. Previously someone wrote about the
change in design of the steps on the pilot and this was done beginning in
1944. The bell was moved from the boiler top in the cowling to the pilot
deck in front of the left cylinder; this treatment was applied to the
streamlined K2's as well beginning in 1953. And the spoke pilot wheels began
being replaced in 1948 for the first 11 J's with solid rolled steel wheels;
the 611-13 get these as built. Beginning in 1953 these wheels were replaced
with cast steel wheels that were also solid.

One J, no. 602, was built in 1942 with a trailer truck booster which
required some external piping. This was removed in December 1945 along with
the piping.

Of course the six J-1's were built in 1943 with heavy non-roller bearing
rods and not being streamlined. From September to November 1944, the J-1's
were streamlined, received lightweight roller bearing rods and then classed
as J.

These were the visible changes. There were quite a few changes that were not

Bud Jeffries

----- Original Message -----
From: "NW Mailing List" <nw-mailing-list at nwhs.org>
To: "NW Mailing List" <nw-mailing-list at nwhs.org>
Sent: Tuesday, September 02, 2008 1:13 PM
Subject: Re: J Class Changes

> 610 also had its tandem rods replaced with single rods and larger hubs.


> I believe part of the reason was the long crankpin on #4 axle drivers.

> The new rods were closer to the surface of the drivers resulting in

> shorter crankpins and less bending stress.


> Dave Stephenson



> --- On Tue, 9/2/08, NW Mailing List <nw-mailing-list at nwhs.org> wrote:


>> From: NW Mailing List <nw-mailing-list at nwhs.org>

>> Subject: Re: J Class Changes

>> To: "NW Mailing List" <nw-mailing-list at nwhs.org>

>> Date: Tuesday, September 2, 2008, 7:37 AM

>> The "extra" side rods were removed on three

>> J's in their first life: 600,

>> 605, and 611. Actually, the rods on these engines were

>> completely replaced.

>> As I understand it, the reason had to do with a stress

>> failure of some kind.

>> Check out photos of the various J's and you will see

>> that the replacement

>> rods had much larger rod bearings on drivers 2 and 3. I

>> would call this an

>> ungrade applied as necessary, and only three engines got

>> it. 611 was the

>> last of the three to get the new rods.


>> Also 611 in its second life had two generators installed

>> instead of the

>> original one.


>> --Rick Morrison





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