Re: philosophical topic: one loco, two motors
- From: "BH Williams" <bhwilliams@xxxxxxxxxxx>
- Date: Thu, 17 May 2007 11:40:03 +0100
"Sailor" <apeterabraham@xxxxxxx> wrote in message
news:1179397121.357542.134480@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 16 May, 22:47, "Tony Clarke" <a...@xxxxxxxxxxxxx> wrote:A friend used to have a couple of Triang-Hornby Hymeks which he'd fitted
I'm pondering upgrades to yer proprietary Brit diesel (any diesel)
and
keep wondering whether a motor per power bogie is a good idea or not.
Now, I know the best of all worlds is the way the Yanks do it, with a
big motor and flywheel in the middle, cardan shafts and a gear train to
all
axles in both bogies - it gives you true uniform drive. However, it seems
easier to put a motor per bogie, driving either one worm gear and a chain
of
spur gears, or two outer axles with the middle one loose or dummy (as in
the
Airfix 31 I've just bought, on the one driven bogie, that is).
Wise men tell me this is a no-no, though, as the two motors, however
they're wired - series, parallel, DCC controlled - will never run at the
same speed and/or "fight" each other so one is always dragging the other
so
rather than getting twice the power, you're lucky to get even once the
power
from your lead motor.
Has anyone anecdote or technical reasons as to why this is, if so,
and
what can overcome it? The only two-motor diesel I've seen in action is
the
Deltic that roars - and I mean ROARS; in a 100' long shed you have to
raise
your voice to maintain a conversation as it approaches - round Roy
Jackson's
Retford, which has two Lima power bogies in one chassis. Is the noise I'm
hearing partly the sound of overstressed gears in torment because
wheelslip
can't release the torque forces (it's well weighted too)? It seems daft
to
have a big diesel making traction on only six of twelve wheels, to the
possible detriment of working a scale-length train, but apparently for
ease
of use it must be so because some law of physics says so.
Enlightenment please, before I start doing things to
myWestern/Warship/31/whatever.
Tony Clarke
I modified several of the Hornby R8xx series units both 4 and 6
wheel bogies. Electrically things were fine (parallel operation)
but I found problems with making the 2nd unit a happy fit in the
modified chassis. This was due to the limited size of the bearing
quadrants and the lack of lateral strength after removal of the spacer
strut. Pulling power was indeed impressive (more than double) but of
course the trains ,if not handled properly, began to topple on the
curves when pulling hard. The newer X914 motors were best because
of their secondary pick-ups on the tyred wheels ( via the flanges).
The only time non syncronous operations gave a problem was when using
push & pull power cars on an HST 125.
Regards
Peter A
Montarlot
with double power bogies- they would pull the side off a house (or at least
40 wagons on a steeply-graded and sharply curved garden line). The major
problem with them was that the soft-iron wheels would develop a U-shaped
profile.
As regards the more recent Hornby/Lima bogies- the best means of ensuring
these pivot freely is to do a cut and shut job on a couple of underframes.
The rubber tyres are a bit of a nuisance when it comes to arranging
pick-ups, however.
The ideal, which I've done on a few locos, is to use the new-generation
centre motors and bogie assemblies from the latest Hornby/Bachmann offerings
within a modified chassis- these are available from East Kent Models,
amongst others.
Brian
.
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