Roger Long wrote:
The bigger the diesel, the more of a factor this is
which is why railroad engines are seldom shut down for maintenance.

Roger, I am under the impression that railroad diesels are run at pretty
high "idle". In fact when waiting for the various commuter trains to get
out of the way around here I get the impression of a pretty fast running
engine when they are stopped. They do not sound anywhere near idle. Is
this the case just when they are dropping off and picking up and/or is
there another time when they actually idle slower?
Red

On Sun, 25 Nov 2007 20:19:46 -0500, Red wrote:

Roger Long wrote:
The bigger the diesel, the more of a factor this is
which is why railroad engines are seldom shut down for maintenance.

Roger, I am under the impression that railroad diesels are run at pretty
high "idle". In fact when waiting for the various commuter trains to get
out of the way around here I get the impression of a pretty fast running
engine when they are stopped. They do not sound anywhere near idle. Is
this the case just when they are dropping off and picking up and/or is
there another time when they actually idle slower?
Red


I think that railway engines are basically generator prime movers and
run at a constant RPM all the time. At least that is the way a power
plant engine runs. It always runs at approximately rated RPM
and the governor makes small adjustments up or down to maintain the
proper frequency.


Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

"Bruce in Bangkok" wrote in message
...


I think that railway engines are basically generator prime
movers and
run at a constant RPM all the time. At least that is the
way a power
plant engine runs. It always runs at approximately rated
RPM
and the governor makes small adjustments up or down to
maintain the
proper frequency.


A train engine will increase RPM as the electric load goes
up.

On Tue, 27 Nov 2007 14:54:25 -0500, "Scotty" wrote:


"Bruce in Bangkok" wrote in message
.. .


I think that railway engines are basically generator prime
movers and
run at a constant RPM all the time. At least that is the
way a power
plant engine runs. It always runs at approximately rated
RPM
and the governor makes small adjustments up or down to
maintain the
proper frequency.


A train engine will increase RPM as the electric load goes
up.


I guess I assumed that because they drove a "generator" that they were
generating A.C. .
Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

On Wed, 28 Nov 2007 10:26:59 +0700, Bruce in Bangkok
wrote:

A train engine will increase RPM as the electric load goes
up.


I guess I assumed that because they drove a "generator" that they were
generating A.C. .

They probably are but then rectify it to DC at some point like an
alternator. If so, the RPMs/frequency do not matter.

On Fri, 30 Nov 2007 21:02:07 -0500, Wayne.B
wrote:

On Wed, 28 Nov 2007 10:26:59 +0700, Bruce in Bangkok
wrote:

A train engine will increase RPM as the electric load goes
up.


I guess I assumed that because they drove a "generator" that they were
generating A.C. .

They probably are but then rectify it to DC at some point like an
alternator. If so, the RPMs/frequency do not matter.


Years ago I had a train guy, who didn't understand it very well, try
to tell me about how an electric locomotive worked. He was a bit vague
about 'lectricity but did talk a lot about some sort of coils or
resistance grid on the top of the engine that got very hot under
certain conditions.

Bruce-in-Bangkok
(Note:remove underscores
from address for reply)