EDUCATE YO MOMMA: Roller bearing trucks, and how they work

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jbaakko

Diesel Detail Freak
Never knew that? That "bearing failure" they talk about is why you head some nasty "thud thud thud thud..." coming from rolling stock.
 

RCH

Been Nothin' Since Frisco
jbaakko said:
Never knew that? That "bearing failure" they talk about is why you head some nasty "thud thud thud thud..." coming from rolling stock.
That thud you're hearing is more likely a flat spot on a wheel than a bad bearing. A wheelset won't last long with a bad bearing, but the flattened wheel can keep going for quite a while.
 

jbaakko

Diesel Detail Freak
Thats true, I thought of that after I posted and just didn't go through the work to edit the reply.
 

HaggisKennedy

Coal Shoveler
I've heard that friction bearings actually are a bit more forgiving at the point of failure. They're hard to get rolling from a start, but once going, they're OK. When the bearing fails, it's gradual.

The roller bearings start with way less friction, and roll well. But, it's said that when they fail, they fail catastrophically, and suddenly. There's not a whole lot of grace period. They can overheat and fail between hotboxes, while the friction ones will go by at least one hotbox before the axle is burned through.

Kennedy
 

HaggisKennedy

Coal Shoveler
jbaakko said:
Never knew that? That "bearing failure" they talk about is why you head some nasty "thud thud thud thud..." coming from rolling stock.
My Dad was an Ordnance Engineer for the Navy back during WWII. This came up during the war; battleship turrets were having a vibration as they rotated. At 15mi gunnery ranges, this could be bad.

Turns out that every time they fired a salvo from a turret, the recoil would put a microscopic flat spot on the turret bearings/race. Enough salvos meant that the bearings/race was filled with little dents, which meant that when the turret rotated, it'd bounce along (if only slightly).

They ended up going to a better bearing and more hard races...

Kennedy
 




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