Ding... The traction motor technology was such that they were huge
back then. Like the GE 44 Tonner started out as a side rod loco. Then
as they developed better traction motors, they were able to put 2
motors per truck.
But ... one does not always WANT two motors per truck, if ONE will do!
The additional motors are just added cost, complication, and
maintenance. The 44 ton loco did not 'replace' the 45 ton loco, but
supplemented it. Each has it's place.
p.s. ... the one ton difference in weight is not a reality, but a
subterfuge to avoid certain regulatory issues. Either loco could be
orderd ballasted to any reasonable weight the buyer wanted.
Largely true as stated, but siderods are still around.
Early traction motors were too large to fit between locomotive frames
(or axles), so had to mounted on top the frames. These were inherently
high torque low "RPM" motors, and no gear reduction was neccessary or
desired, so a direct siderod drive made lot of sense. As motors got
smaller, and increased in speed, gear drives became more competitive,
and eventually won out.
For applications requiring relativly high tractive effort compared to
horespower (switchers and industrial locos for instance) often one motor
is sufficient, but you want to power several axles. You could use gears,
or chains, or siderods. While ALL these systems were and are used, it
turns out that siderods are a very simple and effective way to do this
at low speeds. Probably the best exampel of this type are the GE-45 ton
center cab locos. They look almost like the popular 44 ton models, but
(usually) have siderods (a few have chain drive, like the "Steel Mill
Specials"). The 44 ton locos have four motors (one per axle), while the
45 ton have only two motors (one per truck). With all axles being
powered, and comparable weights, they both have similar pulling power.
The 44 ton can potentially operate at higher speeds (more motors, better
balance), but is more complicated. If only low speeds are needed, the
simpler 45 ton loco is more suitable.
Also, siderods can have some advantages over even gears. A properly
phased and balanced set of siderods (usually three at 60 degree phasing)
can transfer rotary motion from one shaft to another *VERY* smoothly,
and with almost no backlash. Chains and gears always introduce harmonic
distortions. While this is of little importance for the case at hand
(locomotives), don't write off siderods from a performance standpoint.
Like all such things, they have their advantages and disadvantages.
That's used on diesel locomotives with hydraulic transmission to get the
power to the wheels. More modern locomotives usually have cardan shafts
instead. Dieselelectric locomotives typically have one traction motor
Siderods are usually found on older shunters (up to the 1960s), not on
locomotives for higher speeds, as they will run more smoothly without
weights moving up and down.
tobias benjamin köhler ____________________________________ firstname.lastname@example.org
._______..__________.._______.._________. <>_<> <>_<>
Yes, it is higher speeds that have made the siderod drives less
deisrable in today's operation. Siderods have balance issues at higher
speeds that are difficult to overcome. Changing times, changing
requirements. However, many can still be found in service that is
inherently low speed (mostly industrial operations).
Well . . . . <doubtful voice on> you could, assuming you can find siderods
with the correct hole spacing. <doubtful voice off>
Don't forget to rotate one wheel on each axle 90 degrees so you don't bind
them. Oh, also don't forget to take into account the weight of the
I think that is all. I am sure that others will add more if I forgot
Please support the following train meets if you can
Gratiot Valley ( www.gvrr.org ) in Macomb Michigan in March and November
On 27 Jan 2006 09:29:46 -0800, email@example.com wrote:
They still do all around the former British Rail network.
There were a few variants . One was a higher speed version so they did
not spend as much time occupying main trackage.Another was two units
permanently coupled together only one having a driving cab. used only
in one location at a hump yard.
The Netherlands railways also used them in large numbers and may still
have some in use. An HO Model is avaliable , by Roko I think.
A handful were also used in Australia by Victoria railways,yet another
variant as these were 5ft 3" gauge.
Another mob that used the Eng. Elec. 350 h.p. 0-6-0 side rod d.e.
shunters was the KTM (Malayan Railways). They got 20 of them in 1948, metre
gauge. They had a more rounded body than the British locos.
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