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Author Topic: A Thought  (Read 4638 times)
wb2002

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« on: March 27, 2013, 01:37:32 PM »

While looking at my HO setup the other day, I thought why the loco manufacturers have not considered using small D.C. motors on each axle just as traction motors in real life? I know there are small and very small motors now that are powerful enough now. I was thinking of the diesel electrics I have such as the U33C's, C30-7's and SD's could be fitted with motors like these.

Just A Thought

wb2002
« Last Edit: March 27, 2013, 01:39:05 PM by wb2002 » Logged
richg
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« Reply #1 on: March 27, 2013, 03:02:12 PM »

Cost. Take some time to think about what is involved with this size motor if you any experience in manufacturing tiny efficient motors.

Rich
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Desertdweller

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« Reply #2 on: March 27, 2013, 06:48:34 PM »

I'm sure a single large motor with a fat armature would produce more torque than several small motors.

If the small motors were axle-hung, as in the prototype, they would drive each axle through armature-mounted pinion gear and axle-mounted spur gear.  The gears are always in mesh.

This could create a problem slowing the train.  It would coast instead of suddenly stopping as with a worm-gear drive.  This could actually add to realism.

Actual dynamic braking could be effected by shorting across the counter-current generated by the spinning motors while coasting (some slot car controllers work this way to slow the cars when the throttle is released).
This should work pretty well with the entire wiring circuit to dissipate the heat (no dynamic brake resistor grid and blower needed in the loco), but, since you would be using permanent magnet DC motors, some weakening of the magnets would eventually result.

If you tried this with DCC, it would probably hopelessly scramble the entire system as locomotives started feeding power back into the system.

Les
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wb2002

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« Reply #3 on: March 27, 2013, 07:31:20 PM »

I don't believe it would create any electrical problems which could not be easily solved. I also have some of these motors - some even with reduction gear mechanics (also miniature) that I considered using to simulate hydraulics for pistons on model construction vehicles.

I can easily believe the biggest factor for this implementation would be the almighty $. One could sell 3 or 4 of the present concept we have now as oppose to selling one with the technology of each truck axle with its own traction motor. I wish I had the skills, and equipment to build one. I have purchased motors of this size/power for about $12 - $18/piece. I might add that they produce quite a bit of power especially ones with reduction gearing. They also can be used for moving train signals. These motors and controllers for them are mainly used now for robotics and other applications.

Perhaps 20 years from now this will be the norm.

Just A Thought . . . . .

wb2002
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jward


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« Reply #4 on: March 27, 2013, 08:47:48 PM »

the gear reduction would be a major issue. and gear reduction is what makes our trains run like trains not slot cars.

truck mounted motors were the norm in train sets years ago. ahm, tyco and Bachmann all used truck mounted motors. the results were not impressive.
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Jeffery S Ward Sr
Pittsburgh, PA
wb2002

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« Reply #5 on: March 27, 2013, 09:19:10 PM »

I doubt gear reduction would be any problem.  Significant improvements in this area would allow for this as well as the torque of the motor output. The motors/gearing is small enough to fit on each individual axle (that would be 6 or 4 axle) trucks. I don't think when this was tried, as you mentioned, that the technology was not as advance as it is today. Of course I am speaking of HO and larger gauge.

wb2002
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NarrowMinded


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« Reply #6 on: March 28, 2013, 01:17:09 AM »

The answer to me is simple, there is no good reason from a manufacturing aspect to  go to a more complicated multimotor unit when theres free space inside the shell, the $$$ factor will always come into play either from assembly or parts cost, I'm sure we will see improvements in the drivelines but I would bet we will never see scale traction drives as the norm.

NM-Jeff
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J3a-614

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« Reply #7 on: March 28, 2013, 02:11:20 AM »

Such things are available, you just have to go to O scale:

http://www.nwsl.com/NWSL_Online_Catalog.html

Scroll down to Page 15:

http://www.nwsl.com/uploads/cat_chap2_for_web_3-01-13.pdf

Just don't look at the price list, or at least try not to look at it and then calculate what four or six of the things would run. . .
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Doneldon

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« Reply #8 on: March 28, 2013, 06:47:02 AM »

If the small motors were axle-hung, as in the prototype, they would drive each axle through armature-mounted pinion gear and axle-mounted spur gear.  The gears are always in mesh. This could create a problem slowing the train.  It would coast instead of suddenly stopping as with a worm-gear drive.  This could actually add to realism.

Les-

It could also add to train wrecks.

                                         -- D
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Doneldon

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« Reply #9 on: March 28, 2013, 07:04:31 AM »

wb-

Cost (read, outrageous cost) probably is the main obstacle to mounting miniature traction motors on our locomotives but there's an even better one: It's a terrible idea. Keeping locomotives with one or two motors tuned up, properly aligned, lubricated and functioning well can be a problem at times. Why would we want to go to four or six motors per engine? We would likely multiply component failures with exceedingly difficult repairs due to the tiny size of the new parts. And for all of that (not to again mention the cost, which could easily be as much for the exotic motors as we now pay for a whole loco) we would gain what? A well-functioning, slightly more prototypical model? Of course we already have that without the added cost, complexity and reliability problems. My locomotives look and run great, and I'm pretty sure that no one can tell from looking that I don't have a motor on each axle. Or, to put it in contemporary argot, if it ain't broke don't fix it.

                                                                                                                                                                    -- D
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Desertdweller

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« Reply #10 on: March 28, 2013, 11:02:13 AM »

I work in N, not HO, so I really don't keep up with HO developments.  But I do remember in HO there were self-contained, small power trucks available that did not include large motors (like the Tyco and AHM ones did).
I think NWSL and Bowser offered them.  The idea was that they could be used under things like self-propelled passenger cars without intruding into the interior.

This idea would allow a model in HO or larger to use a heavy frame (lead? Depleted uranium?) while keeping the interior open to hold scale model internal parts.

Les
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Doneldon

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« Reply #11 on: March 29, 2013, 05:58:44 AM »

Dd-

Those power trucks are still around. They would be completely different, however, from what's being talked
about on this thread. The power trucks have one motor mounted atop the truck and powering all axles. This
thread is talking about having individual tiny (scale?) motors on each axle.
                                                                                                                 -- D
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Desertdweller

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« Reply #12 on: March 29, 2013, 10:57:08 AM »

Don,

Then how about this idea:  mount the motor in the conventional way.  Make it small enough to fit inside a model of the Diesel prime mover.  The armature shaft would be hidden inside the generator and electrical cabinet at the front end of the loco, and drive the front truck through a gear tower under the cab floor.

The armature shaft at the rear end of the loco would be exposed (as is the driveshaft on a full-sized locomotive) and would drive the gear train at the rear of the loco, concealed inside the air compressor.

Printed circuit board could be concealed under the roof of the locomotive.  Weights could be mounted inside the frame and in places like inside the nose, the rear sand box, internal water tank, etc.

On cab-type units, the interior could be lighted, allowing details to be seen through the portholes.  The engine rooms were lighted on the actual units.  On hood units, the hood doors could be hinged to open to show these details.

Les
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Jhanecker2

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« Reply #13 on: March 29, 2013, 07:26:57 PM »

Making  products more complex garaunties   significantly  higher prices  and less reliability .    Every  extra part  means  more money for engineering & manufacturing and then has to be assembled  .  Are their any  real benefits  to doing this ?  J2
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Doneldon

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« Reply #14 on: March 30, 2013, 01:50:53 AM »

Then how about this idea:  mount the motor in the conventional way.  Make it small enough to fit inside a model of the Diesel prime mover.  The armature shaft would be hidden inside the generator and electrical cabinet at the front end of the loco, and drive the front truck through a gear tower under the cab floor. The armature shaft at the rear end of the loco would be exposed (as is the driveshaft on a full-sized locomotive) and would drive the gear train at the rear of the loco, concealed inside the air compressor. Printed circuit board could be concealed under the roof of the locomotive.  Weights could be mounted inside the frame and in places like inside the nose, the rear sand box, internal water tank, etc. On cab-type units, the interior could be lighted, allowing details to be seen through the portholes.  The engine rooms were lighted on the actual units.  On hood units, the hood doors could be hinged to open to show these details.

Les-

Hiding all of those components would be a lot of work, would require lots of new tooling, and would drive the price way up. I think I have a more economical idea:

Let's just get a really tiny replica of the prime mover, only a real one, not plastic. And instead of building a whole new expensive pair of gear trains, have the mini diesel spin a mini generator which can run the tiny electric motors on each axle. Yes, those motors are expensive, as I mentioned before, but all of the money we'd save by not casting plastic mechanicals to conceal the diesel and generator would cover that cost. Plus, leaving doors and portholes open would let guests to our pikes view actual mechanicals, not cheap plastic imitations. We'd gain additional savings by not paying for electricity to run our trains. Some of those savings could be used to acquire radio controls so we could sell our now antiquated DCC systems on eBay, which would give us even more money to pay for simulated control equipment in the cab, as well as an animatronic crew.

The engineer could have a Z-scale decoder in his chest which would tell a servo motor to lift his foot off of the dead man (or ignore the auditory safety signal on later prototypes) based on a random number generator. This would periodically present emergency situations which would cause the locos to shut down, giving the dispatchers for our railroads realistically difficult situations requiring adjustments throughout the railroads. It's true we'd have to purchase diesel fuel for our locos but that would be cheaper than the gasoline we use in our cars as well as cheaper than the expensively generated electricity hiding in the walls of our train rooms. As a last financial benefit, the weights of the prime movers and generators would be much greater than plastic replicas, giving us awesome traction and yet more savings since we won't have to add any non-prototypical weights to the locos.

Now there is the question of where to conceal the radio receivers and servos needed to operate everything, particularly since we will illuminate the insides of the locos and encourage viewers to look inside.  I struggled with a solution for this dilemma for a long time until one of those really easy answers popped up, you know, the kind of thing that's so obvious that you just don't see it right away. And that answer is ... we put the radio equipment inside the loco with the propulsion system but wrap it in a piece of Harry Potter's invisibility cloak. We'll have functioning radio control on board but no one will be able to see it when they look inside.

What do you think? Too simple?
                                                       -- D
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