Plain -v- Roller bearings (Was-Stock car reloading )


John H <sprinthag@...>
 

Tim,

I don't know that there was any changing of the lubricant in journal boxes by season. What about a B&M car that had a load bound from fridgid Maine to, say, hot Arizona? And if there were spikes due to temperature changes it would be much more likely in the spring than in fall. I could be wrong (Often am) but I think those stories are akin to changing the air in your tires.

So far as friction with cold lube, probably less than with hot lube. Cold oil is thicker than warm stuff. It also is quite resistent to movement. Try pushing your car when it is zero and hasn't been moved for some time. And your car has roller bearings. I think it has to do with the cohesivness of the oil. But once it gets moving, the oil will heat up on its own. Probably due to molecular action.

John Hagen

--- In STMFC@..., Tim O'Connor <timboconnor@...> wrote:

Frank

I have heard many times that starting a train was harder in very cold
weather, and that the oil needs to warm up a bit. In other words if there
were NO friction in a plain bearing, then the oil could never warm up! So
paradoxically it was necessary for journals and bearings to get a little
bit hot just so they could warm up the oil which then coated the journals
and bearings sufficiently to reduce friction and rolling resistance to an
equilibrium. Most hot boxes occurred when contaminants (especially bits of
rag) got loose and got in between the journal and bearing and caught fire.

Tim O'Connor


Tim O'Connor
 

So if your theory is correct that oil heats up with movement,
if I pour a can of oil off a 1,000 foot tower in a perfect vacuum,
the oil will be hotter when it hits the ground?

So far as friction with cold lube, probably less than with hot lube. Cold oil is thicker than warm stuff. It also is quite resistent to movement. Try pushing your car when it is zero and hasn't been moved for some time. And your car has roller bearings. I think it has to do with the cohesivness of the oil. But once it gets moving, the oil will heat up on its own. Probably due to molecular action.

John Hagen


John H <sprinthag@...>
 

No.

"Probably due to molecular action." I.e., the molecules are in movement within the lubricant. Not a blob of oil moving through the air.

John Hagen

--- In STMFC@..., Tim O'Connor <timboconnor@...> wrote:


So if your theory is correct that oil heats up with movement,
if I pour a can of oil off a 1,000 foot tower in a perfect vacuum,
the oil will be hotter when it hits the ground?


So far as friction with cold lube, probably less than with hot lube. Cold oil is thicker than warm stuff. It also is quite resistent to movement. Try pushing your car when it is zero and hasn't been moved for some time. And your car has roller bearings. I think it has to do with the cohesivness of the oil. But once it gets moving, the oil will heat up on its own. Probably due to molecular action.

John Hagen