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From: johne@haddock.UUCP
Newsgroups: net.railroad
Subject: Re: Orphaned Response - (nf)
Message-ID: <24@haddock.UUCP>
Date: Mon, 2-Jan-84 23:41:32 EST
Article-I.D.: haddock.24
Posted: Mon Jan  2 23:41:32 1984
Date-Received: Wed, 4-Jan-84 02:55:31 EST
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#R:dciem:-58500:haddock:15300002:177600:1809
haddock!johne    Jan  2 17:47:00 1984


  The throttle of a Budd RDC operates directly on the governors of the
diesel engines, by means of solenoid-operated pilot valves within the
governors, which are (presumably) hydraulic devices.  MU is accomplished
electrically, as usual.  Each RDC has two Detroit Diesel "truck engines"
of about 300 HP; each engine drives the inboard axle (only) of the adjacent
truck through an Allison torque convertor (GM again) and conventional
gearing.
  Now, the torque convertor is a device whose intimate acquaintance I have
yet to make.  I have always envisioned it as a fluid transmission with a
continuously-variable ratio, consisting perhaps of opposing "fans" moving
within a compact and pressure-tight enclosure so designed as to allow a
finite amount of fluid to circulate other than through the vanes, thus
allowing only a finite amount of slip.  Perhaps someone can clarify this.

  On the subject of MU, it is interesting to note that while the electric
transmission itself showed up pretty early on (notably, in gas-electric
cars, precursors of the RDC), practical diesel-electric MU had to await
the development of automatic load regulation mechanisms which could match
the electric transmission with its inherent overload tolerance to the
finite power output of internal combustion prime-movers.  Early gas-electrics
had generator excitation controlled manually by the engineman; this worked
fine as long as that person was sitting next to the prime-mover and could
guage its loading by ear.  When a cab was added at the other end, however,
and the prime-mover was out of earshot, embarrassment, rather than
acceleration, was often the result of over-enthusiastic rheostat operation.

  This is a fascinating topic and I look forward to further discussions.

					      John Ewing
					      Boston, MA