From: pierson@cimcad.enet.dec.com (Dave Pierson)
Subject: Re: Diesel vs. Electric Locomotive Maintenance
Organization: Digital Equipment Corporation
Date: Tue, 6 Oct 1992 17:53:17 GMT

In article <35601@cbmvax.commodore.com>, grr@cbmvax.commodore.com
(George Robbins) writes, in part:

>In article <1992Oct5.233132.27383@s1.gov> lip@s1.gov (Loren I. Petrich)
>writes:

>> 	I have seen it claimed that electric locomotives usually need
>> much less maintenance than diesel ones. Is there any truth to that
>> claim?
	Yes, tho I haven't numbers, nor do i know off hand where to find any...

>Well, the are a couple of problems with your assertions.  First of all
>electric locomotives aren't particularly simple.  In the case of the
>diesel locomotive, you can regulate power output simply by changing
>the engine speed and simple switching of the traction motor series-
>parallel arrangements.

>An electric (we'll deal with a powerful AC one) has to in effect
>have a power sub-station
	Consider that most power substations are expected to operate unmanned,
	24 hours a day 365 days a year.  Such subs are highly reliable.
	Bouncing them around a railroad will cut into that, but not a lot.

>to step down the 11-50KV power from the
>overhead to a lower voltage ~300-600 Volts that can be used in brush
>type DC traction motor or handed economically by solid-state rectifiers
>and switching circuits.  In addition there either has to be fairly
>complex switchgear for selecting different effective voltages for
>different speeds/power outputs or fancy solid state inverter/chopper
>circuits for newer equipment.
	Similar swirch gear is need on some diesels.  Many modern ones use
	solid state gear, just like the modern straight electrics.  I recently
	toured a "receiving terminal" for a +/- 500 KV, 500 megawatt (?) dc
	link (the one from Hydro-Quebesc to Littleton, MA) as part of an IEEE
	tour.  If memory serves, they spec less than 10 minutes a year outage
	for the whole thing, choppers included.  No vibration to hurt, but the
	voltages are higher....

>All of these needs to be cooled and controlled so you have quite a
>pile of auxilliaries
	So does a diesel prime mover.  Needs rather more cooling, in fact.

>Second, the maintenance requirements for diesel locomotives aren't all
>that demanding.  The locomotive style diesel is rugged and subject to
>periodic oil and filter changes runs (guessing a little) hundreds of
>thousands of miles before requiring major maintenance or rebuilding.

	Soundslike a pretty close guess, but consider that the transformer
	it "replaces" has NO moving parts bigger than an electron.  (OK, mild
	poetic license...   8)>>)  It has cooling, but so does a diesel.
	Call it a wash.

	I suggest that the diesel electric and the straight electric are nearly
	the same except:
		Diesel engine has MANY more moving parts.
		Diesel engine dissipates more waste heat on unit.
		(some side issues also, not relavant to maintenance...)

>> 	I think that it is a significant issue in evaluating the
>> merits of electric (flat-road) cars, since one of their (purported)
>> merits is low maintenance costs, 

>Well, for railroads electric propulsion seems to make economic sense
>in areas with high traffic density, cheap electricity or expensive
>fuel.  For just about anything except the Northeast Corridor and
>commuter rail, the diesels have displaced electric traction, even
>where the fixed plant is paid for and there is an effective fleet of
>locomotives.  The first to go were the short tunnel electrifications,
>followed by the mountain divisions and finally tearing down the wires
>over the PRR/PC/Conrail feight only track.

	This is a complex bit of history.  If the rest of the system had been
	electrified, CR would have used it.  It was a combination of high
	AMTRAK imposed line charges and short runs for the Electric Power.
	PLUS, the US has a habit (driven by many things, including high crew
	wages) of running infrequent, long trains.  This is the antitheses
	of succesfull electric operation.  (I WILL try to find some numbers
	to go with this, but no promises....)

	It is also US based history.  In much of the rest of the world
	Straight Electric is growing steadily.  Across many economic systems
	and many sets of fuel costs and railroad administrations.

>As far as electric autos - there may be some opportunity for short
>distance urban commuting if the technology catches up, if not the
>only thing that will have it happen is coersive fuel prices or public
>policy.
	Largely agree.

(Private note to James S, Michael S, et al.  Mail keeps bouncing....)

thanks
dave pierson			|the facts, as accurately as i can manage,
Digital Equipment Corporation	|the opinions, my own.
200 Forest St			|I am the NRA.
Marlboro, Mass		01752	pierson@cimnet.enet.dec.com
"He has read everything, and, to his credit, written nothing."  A J Raffles