If the modern era did not have roller bearings

@CALNNC posted:

Just pondering if the roller bearing had not been invented, and freight cars still had friction bearings

The proper technical term is Plain Bearing.

and oil chests, how much locomotive would be required to start a 3 mile long train or would 2 and 3 mile trains even be possible?

A lot depends on the weather, i.e. the temperature. The colder the bearing temp., even for cartridge roller bearings, the more difficult it was/is to start a train moving.

As a side note, Harley Davidson in the late 30's and early 40's experimented with using all ball bearings in the 45 flat head motor.  What they found was that it only made a difference in the friction encountered at start up, and that once the motor was running, the pressurized oil system they used allowed a level of friction-less shaft rotation that was as good as a ball bearing.

Your theoretic question is a good one to discuss.  Railroaders look at it entirely differently than railfans.

Are we to assume that modern hot bearing detectors had also not been invented or adopted?  15,000 foot trains, no matter which kind of bearings were in use, are not safe to operate without that technology.  The train length exceeds the distance at which visual inspection from the head or rear end could be effective.  

As far as starting the train, there would not be a lot of difference to the Engineer.  If there is enough horsepower to run over the district at reasonable speed, you can bet there's enough tractive effort to get the train moving.  In winter, factors other than cold axle bearings are of much greater concern in initiating movement.  Two examples: brake pipe leakage and ice.

Handling a 2 or 3-mile long train with solid bearings over a district, is only part of the picture.  In pre-roller bearing days, trains had a mandatory 500 mile inspection in which car inspectors were required to open the journal box cover, inspect and lubricate each bearing on the train, and repack any which needed it.  Delay, delay, delay.  Money, money, money.

It would surprise me greatly if a 15,000 foot train with all cars equipped with plain bearings, could make it 500 miles without an unplanned stop due to one or more hot bearings.  So, the plain bearing train would have more unplanned delays as well as long delays for train yard 500 mile inspection.  As far as the added friction, it would not likely be a problem except in extreme situations where the locomotive could just barely pull the train to the top of a grade.  In that case, there would be a slight disadvantage if the train had solid bearings.