Here we go again, a Norfolk Southern train derails, only this time it's in Alabama...

[FacEngrPE]

The journal bearings used prior to roller bearings were in my opinion awful, but railroads ran on them successfully until the modern roller bearing replaced them.
The journal boxes have no seals and relatively large clearances. They seem to always be rather dirty.

Journal Boxes And Their Inspection By Heritage Rail News February 7, 2016Features

If you find technical details interesting these documents are full of them.
SKF Railway technical handbook Volume 1
Axleboxes, wheelset bearings, sensors, condition monitoring, subsystems and services
SKF Railway technical handbook Volume 2
Drive systems: traction motor and gearbox bearings, sensors, condition monitoring and services

 

[spsalso]

Plain bearing railroad trucks were banned in 1994 in interchange service. There were NOT very many in 1994. They could still be used on a single railroad, and likely were under maintenance rolling stock.

So, unless you've been visiting a railroad museum, you likely haven't seen any of these "live".

The journal box DOES have a spring loaded cover which keeps the majority of "stuff" out. What does get through wears the bearing until it needs replacing.

As far as clearances, I'm not sure there ARE any. The journal should be round and smooth. The bearing should roughly conform to the journal. Is there anything else? Well, the bearing has to actually fit into its mounting. I suspect that was what was so "elegant" about the design: NO tight clearances. Yet it still worked.


spsalso

 

[FacEngrPE]

I spent a few months during my apprenticeship servicing locomotive cranes, so I worked on a few car trucks.

The short line at work converted all of our flatcars to roller bearings sometime in the late 1980's, the messy task of servicing journel boxes is long gone, along with the considerable maintenance labor expense.

The large clearances I called out above are on the back side where the axle enters the journel box. The backside clearance is large enough that the car can be jacked up enough that the journal bearing can be pulled out of the truck with only pulling out the keeper wedge. It seems a bit crude, bit it is a simple and elegant design.

The babbit lined bearing only covers a bit more than 1/4 of the journel circumference. They were machined to a slightly larger diameter than the axle, and then wear to fit. After a while in service the entire contact surface will take on a burnished appearance. We used wool mops manufactured for use as oil feeding wicks to keep the journel well lubricated.

The journel box doors mostly did have spring closures and could be ordered with seals, but many did not have seals, and some boxes never had springs. The only time I remember the inside of a journel box being "clean" was just after we serviced one.