Steam & Excursion > 765 mechanical issue

Surprised this wasn't posted here already but 765 had to go back to the shop due to a small mechanical issue. Here's what they posted on their Twitter. Looks like they're head to Cleveland later this week. 

"The hub liner on the locomotive trailing truck is running hot and we're not able to adjust it on the road. This is neither critical nor severe, BUT it does mean we're going to reverse back to our shop to fix."

Emmo213 Wrote:
-------------------------------------------------------
> Surprised this wasn't posted here already but 765
> had to go back to the shop due to a small
> mechanical issue. Here's what they posted on their
> Twitter. Looks like they're head to Cleveland
> later this week. 
>
> "The hub liner on the locomotive trailing truck is
> running hot and we're not able to adjust it on the
> road. This is neither critical nor severe, BUT it
> does mean we're going to reverse back to our shop
> to fix."

Interesting. Wonder what changed within the trailing truck from last year?

I believe they converted the trailing truck to roller bearings earlier this year.

Timken Tapered roller bearings do not use ‘hubliners’.
A ‘hub liner’ is specifically used in conjunction with plain-bearings, at the driver’s wheel-hubs.
The inside of the driver has a flat, circular bearing area called a ‘wheel hub’.
The actual axle bearing, riding on a film of journal oil, has a vertical, semi-circular, mating surface,
in close proximity to the driver hubs...at each end of the axles, hubs facing each other.
The hub and it’s liner only occasionally bump into each other...they should NOT be in constant contact.

The main challenge is that the bearing’s hub-liner only extends above the top-half of the axle... and proper lubrication can be difficult to achieve .

Timken’s use of tapered roller bearings, like their Series GG bearings, use tapered races and rollers in sets, with their narrow diameters facing each other.  This gives full 360-degree, ‘bearing protection’ to ‘roll’ the end-wise battering into the stronger frame structures.   Thus, lateral slamming and banging is ‘rolled’ into the structure of the journal box, and to the frame of the trailing, or pilot truck.   Locomotive pilot trucks and trailing trucks were some of the hardest bearings to properly lubricate, as plain bearings... 

Thus, in the 1930s, many railroads upgraded certain engines in their fleets with Timken’s tapered bearings
on the smaller axles, and stayed with plain bearings on the driving axles.

There is a form of roller bearings, specifically Hyatt’s, that are cylindrical bearings with no lateral restraints.
Hyatt limits the end-wise motions with the use of axle-end, flat bearings that are attached to axle end-caps ...
the flat part does not rotate, the axles batter and rub it as if they were the same as plain-bearing, non rolling-element bearings.

Somehow, 765 in recent trailer truck ‘upgrades’, either did not utilize Timken’s GG bearings, or some other reason continues to use hub-liners...or they’re not really ‘hub liners’.... perhaps incorrect terminology.
If they’re Tapered Roller  bearings, there are no hub-liners, per se.

Refer to Doyle’s recent(?) upgrades to rollers on ALL the SP 4449’s  trucks ( not the driver axles)  for proper application of GG bearings on existing locos.

Also, a year ago, or so, Scott Lindsay oversaw the application of modern GG bearings ( + new axles & wheel sets) on the pilot truck of the N&W J, #611.  That up grade was a wonderful success, and a modern improvement over the original arrangement.
​
W.

 



Edited 7 time(s). Last edit at 09/17/19 14:32 by wcamp1472.

Actually 765 did the same conversion as we did on 1225.  We used Timken bearings with the hub liners.  We had to use the hubliners cause of the conversion on the boxes could not just receive a regular bearing adapter.  The bearing adapter was modifided so it could float inside the box that way we kept the same laterial play on the wheel set so we still could go around a 20 degree curve.

Thanks for the clarification.

And, yes, the use of a properly shaped adapter is crucial. 
The use of devices to limit the ‘end-play’ is laudable and shows engineering expertise.

However, it’s also tue that these type of adaptations are, of necessity, ‘experimental’ in the early
development stage..a little more machine work may be necessary —- that’s to be expected.
Keep refining the adaptation,  until you get the system to function as intended..

Comgrtulations on a successful conversion .... the rewards are just around the corner.
 
Thanks again for the update...

​W.



Edited 1 time(s). Last edit at 09/17/19 18:21 by wcamp1472.

We would often "cartridge" the double roller sets, this in practice is similar to what could be accomplished
with the hub liner. As mentioned a bit of extra machining is required.

Out

765 is back on it's way to Ohio according to the Fort Wayne Historical Society social media

Fostoria as of 2:30.

fwrhs.org/track-765