Different terms for the same thing ...Friction and other types of bearings


As we ponder the various messages associated with multiple terms used to represent the same thing [ for example, "friction, plain, and solid" bearings, ] I would think that we should not be too surprised. Multiple terms representing the same thing is not uncommon, particularly in the railroad world. For example, no real Union Pacific "working railroaders" back in the 40]'s/50's would refer to a UP 4-8-4 as a "Northern". Instead, it was an "800". Similarly, a Challenger was a "3900", a 4-8-8-4 was a "4000"...not a Big Boy...and a 4-12-2 was a "9000"...not a "Union Pacific" type. If management wanted to describe such engines as Challengers or Big Boys...fine. But operations types called them 3900's and 4000's.

Regarding "friction bearings", the term actually has some support from the railroad industry. The book, The Steam Locomotive, written in 1942 by Ralph Johnson, Chief Engineer for Baldwin Locomotive Works, contains a chapter on "Resistance" [ Chapter 12 ] in which he writes about journal resistance. As Tony Thompson has noted, Johnson writes that ..."As the speed of a train increases, the difference in frictional resistance between the two types of bearings [ solid and roller bearing ] decreases rapidly , and above a speed of 10 mph the difference becomes very small". He adds, "In cold weather the starting resistance of a train with solid bearings is quite high and therefore the acceleration of a train with roller bearings is aided very materially". He continues, "The actual economy in the use of roller bearings is found in lower maintenance costs, reduced inspection, and these savings must be blanced aghasinst increased initial costs".

Interestingly, in this chapter, on pages 181 and 182, Johnson uses the term "friction bearing" although most references are termed "solid bearings".

BTW, for what its worth, the term "Turnout" is NOT a model railroad term. In a book titled "Elements of Railroad Track and Construction", published in 1915, there is a chapter titled "Circular Turnouts" and another: "Practical Turnouts".

Mike Brock

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