John Hagen <sprinthag@...>
I don't see how the immersion in oil could have much of affect on increased
resistance. Oil is less viscous than grease at all temperatures so I don't
understand how they would add resistance. Trucks use oil immersed bearing
for reliability and less resistance. I always thought (when I thought about
it which is all that often) that the reason railroads don't use oil bath
rollers bearings the susceptibility of the housing/reservoir to damage from
all the crap that ends up on the right of ways.
Brock" <brockm@> wrote:
tothis subject so why not me?
frictionalone equipped with solid bearings is eight to one in favor of the roller
above 10resistance between the two types of bearings decreases rapidly, and
themph the difference becomes very small. In cold weather the starting
ofacceleration of a train equipped with roller bearings is aided very
Mike,roller bearings, the journal friction will be reduced 50% at starting,
I hope my latest post does not drive you beyond a six pack....
This seems like a good starting point for 1942. What surprised me from
reviewing the car builder's cyclopedia was the immersion of roller bearings
in oil. This would no doubt significantly increase the friction of roller
There has been significant progress in reducing roller bearing friction
since then - not sure where things stood at the end of this group's era
(1960), but roller bearing friction today, at speed, is much less than the
JOURNAL bearings of old. Friction that results from trucks tracking through
curves is also reduced (by a combination of better bearings and better truck
geometries), such that the old curve compensation standard for laying out
right of way may be out of date (note - this is a theory based on some
analysis of a very complicated subject a few years ago that I am not going
to get into again - not worth my time.)
One 2003 engineering report I have from a prototype truck manufacturer
indicates that rolling resistance of modern freight car trucks on tangent
track is only 1.8 pounds per ton of car weight - without any speed
dependency. The increased car resistance with speed is now mostly
aerodynamic. Tapered roller bearings have come a long way.