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From: chaltas@uiucdcsb.UUCP
Newsgroups: net.railroad
Subject: Re: trucks
Message-ID: <11100032@uiucdcsb.UUCP>
Date: Fri, 7-Dec-84 22:50:00 EST
Article-I.D.: uiucdcsb.11100032
Posted: Fri Dec  7 22:50:00 1984
Date-Received: Tue, 11-Dec-84 03:53:44 EST
References: <147@decwrl.UUCP>
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Nf-ID: #R:decwrl:-14700:uiucdcsb:11100032:000:1986
Nf-From: uiucdcsb!chaltas    Dec  7 21:50:00 1984


hmm...I don't have any firm dates, but here goes, more or less chronologically.

Arch bar trucks are no longer found outside of a few relics.  They have not
been permitted in interchange for many years -- I think they were banned in 
the 20's.  Their frame is fabricated from steel bars -- roughly in an arch, but
with straight lines rather than curves.  They were prone to failure and had
bolts and such that could come loose.  

Andrews trucks were designed to ease the financial pain of having to junk the
arch bar trucks -- they have a cast frame, much like the Bettendorf design,
but use the journal boxes removed from arch bar trucks.  Bettendorf trucks are
what most people think of as a "normal" truck. (This would be much easier 
with pictures).  Arch bar, Andrews, and Bettendorf trucks are all friction
bearing trucks -- the journal boxes were packed with oily whatnot.  Roller
bearings were used in locomotives in the 30's, but didn't become popular
for freight car trucks until the fifties.  They have much less friction
(rather like ball bearing, but capapble of a much heavier load) and are
less prone to overheating (a "hotbox").  Timken is a manufacturere of such
bearings as was (is?) Symington.  Most trucks now in use have exposed axle
ends which you can see turning.  The Symington (sp?) design did not.  I have
recently seen coal hoppers on the ICG that have Bettendory-style trucks that
have had their friction bearings replaced with roller bearings.  The lid is
removed from the journal box and you can see the axle turning inside.

There was also an archaic truck design by Fox, which was banned even before
the arch bar.  It had rigid frames and sprung journals.  All the above designs
have journals rigidly fixed in sprung frames.  I'm told that modern
trucks have NO fasteners of any kind in them (nothing to work loose), being
held together by gravity.  This makes them hard to lift, so spares are often
bolted together.

	George Chaltas
	uiucdcs!chaltas