mlehman As for reversing the rubberband drive with a flywheel, just doesn't work. Assuming the rubberband is tight enough to supply power to the flywheel to get it to spin, the the same thing will happen, other than brief slippage when the car slows. This would cause braking action, of a sort, but wouldn't give you momentum. Think dynamic brakes if you need a protypical example of what's happening. I think I mentioned a clutch would help with thie ideaa nbut still not sure it's practical.
As for reversing the rubberband drive with a flywheel, just doesn't work. Assuming the rubberband is tight enough to supply power to the flywheel to get it to spin, the the same thing will happen, other than brief slippage when the car slows. This would cause braking action, of a sort, but wouldn't give you momentum. Think dynamic brakes if you need a protypical example of what's happening. I think I mentioned a clutch would help with thie ideaa nbut still not sure it's practical.
There's theory and there's practice. I say rubberband drive will work in reverse for the same reason spur gear reduction can work in reverse. That is, in theory. There may be practical reasons it won't work.
The OP seems to have an incentive to make it work. Let's let him do his work and report back to us. There is a problem, of course, with proving a negative--just 'cause he can't make it work doesn't mean it can't. Maybe he's doing it wrong. But if he does, well, he did.
And, should anyone be wondering, I don't care enough about the answer to spend the time building something.
Ed
Indy Rail Hey folks! I had a great idea. Obviously mini air brakes aren't going to work but I thought what if I were able to install a flywheel into the freight cars and attach the flywheel to one of the axles with a rubber band? This would actually give the cars momentum instead of just simulating it. How would I jimmy rig something like this up?
Hey folks! I had a great idea. Obviously mini air brakes aren't going to work but I thought what if I were able to install a flywheel into the freight cars and attach the flywheel to one of the axles with a rubber band? This would actually give the cars momentum instead of just simulating it. How would I jimmy rig something like this up?
Indy Rail,
i think I understand your goal, but you have inadvertantly confused your question by intertwining the physical concept of momentum and applying "mini air brakes".
You want to simulate the slowing down of a freight car by braking by installing a mechanism that lets the car slow down slowly by storing inertia in a flywheel setup. Correct? In that way, the slowing down would (drum roll...) be like a miniature brakeman turning the HO scale brake wheel to slow and eventually stop the car.
True?
Let me know if I have read your mind correctly.
BTW, a nice idea for the novelty of it.
Joel
Modeling the C&O New River Subdivision circa 1949 for the fun of it!
If you want brakes, I would suggest using a servo to apply a brake shoe. A flywheel will just keep the car rolling.
If you have cabooses, then you could outfit them with brakes on all four axles. I would suggest rigging the brakes just like the prototypes did and instead of having a brake cylinder, just use a servo.
Im still not sold on the rubber band idea.
So i would like to offer this: Take a car, remove body and extras until your down to the trucks, couplers, and frame/floor. Get a couple of electrical pickups like the ones on Rivarossi tenders. Get a tiny patch of felt.
Attach a small piece of the felt to each tip of the pickup (the point where the pickup would normally rub the axle). Now mount the pickups upside down so that the contacts are on the bottom side of axle not the top side where they normally reside on the Riva. tenders.
Some slight bending of the tips may be needed so that there is the smallest of air gap between the felt and the axles (for those that want drag, skip the bending part and let them rub the axles as default). Now get yourself a magnetic core and mount it to the top side of the car floor (boxcars work best here! Cabooses too!) right above the truck.
Replace shell and other removed items.
In theory, when the magnetic core is activated, it should cause the tips of the pickups to be drawn toward the core (upwards), thus rubbing the axles, thus...... braking. De-energize the core and the tips return to normal position allowing the car to roll freely again.
This is a direct bolt on, make no mods to the car, and could be done in minutes. At the very least with band drive, you have to cut holes in your flooring and make mounts for flywheels and stubs to hold them, etc etc.
Just a thought.
PM Railfan
CandOsteam You want to simulate the slowing down of a freight car by braking by installing a mechanism that lets the car slow down slowly by storing inertia in a flywheel setup. Correct?
a flywheel would maintain speed, not reduce it
assuming there is a remote mechanism to engage a brake (dcc controlled servo), wouldn't it be sufficient to simply wrap a rubber band around a free spinning shaft in the car body and have the servo do something (lift the shaft) to creat tension on the rubber band which pulls the wheel axle up creating more friction between the wheel axle and trucks?
greg - Philadelphia & Reading / Reading
An apparutus for an HO car was availabe not that many years ago (not the one in the picture) to add momentum to your car. I'm thinking that a rubber band from the mechanism was attached to an axle. Does anyone remember that?
Victor A. Baird
Fort Wayne, Indiana
gregc CandOsteam You want to simulate the slowing down of a freight car by braking by installing a mechanism that lets the car slow down slowly by storing inertia in a flywheel setup. Correct? a flywheel would maintain speed, not reduce it assuming there is a remote mechanism to engage a brake (dcc controlled servo), wouldn't it be sufficient to simply wrap a rubber band around a free spinning shaft in the car body and have the servo do something (lift the shaft) to creat tension on the rubber band which pulls the wheel axle up creating more friction between the wheel axle and trucks?
gregc,
Yes, a flywheel continues motion when a motor spinning it hesitates because of power interruption.
But if you cut off that power input completely, the flywheel will slow and come to a stop as inertia is bled off by friction. This would simulate braking.
I think this is what the OP wanted to create. So to clarify my post, if power to a flywheel in a car is cut off completely, the car will coast smoothly to a stop. The trick is to figure out how to time this so that a locomotive "kicking" a car will "tell" the power driving the car flywheel to stop after couplers let go (this is another technical issue of how to do that).
Here is a thought: What if you had a train in motion full of these cars, the locomotive would have to deal with the tendency of the cars to resist change in motion if power is on to keep car flywheels going. If the locomotive slowed too suddenly, the cars would try to push it because of built up inertia in them. Mountain railroading would become more challenging, eh?
Hey guys, I was searching on this subject and came across this forum. I like to play with live-steam garden-railway equipment; my models are british and I have one steam engine and some freight and passenger vehicles.
The reason this discussion is interesting is that it occasionally emerges as a topic of discussion in the small-scale live-steam part of the community due to the behaviour of steam engines: they are very free-wheeling, and are quite powerful for their size. Therefore it is very difficult to get a small live-steam powered train to behave in a realistic fashion. A lot of guys will put radio controls on their engines, but this does not solve the basic problem of the train not appearing to have a realistic amount of mass. Uneven track, curves, or grades make it difficult to operate the train in a realistic-looking manner.
One solution that seems to offer a lot of promise is a flywheel mechanism either mounted in the locomotive frame or in a trailing wagon. There is a commercial version available called an "SSP Slomo" and it works very well. It gives the locomotive the appearance of mass and makes it very realistic to drive. However some people don't like to mechanically alter their steam engines, so a few of us have been experimenting with flywheels in training vehicles. I've just built a so-called "momentum van" for my train and it works very well. It makes starts and stops very realistic and since the geared flywheel is in the train, not on the locomotive, it makes the train appear to have a lot of mass, just like a real one, that the locomotive has to pull against and then deal with as it stops, as well.
I have already experimented with putting weight in a boxcar, and that makes the locomotive even more poorly behaved, because the extra momentum it gives still acts in the small scale. It makes the engine's tendency to race away on straight stretches or stall on curves even worse, and these are the two areas where momentum is wanted. On the other hand, having a geared flywheel will MULTIPLY momentum, rather than simply adding to it. If you double the weight, you only double the momentum. If you install a geared flywheel, you are giving the vehicle the momentum of the spinning flywheel, which is many times greater than a simple increase in mass.
If you put a flywheel in a model boxcar, it would make it appear to have a full-size mass. It wouldn't help with "braking" per se, but it would make it slow to react to changes. You would probably be able to perform a "run-around" or would allow you to let cars go during switching, the way they do on real railways. Your only challenge in your scale would be to make the mechanism small enough.
In HO scale too, your locomotives are geared, which means they are already much better behaved than a real stem engine. They already have some artificial momentum in their flywheels. While I built my momentum wagon to tame my locomotive, you guys would be using one to make the rest of your train more realistic for switching.
Here is a short video I made that shows the difference in behaviour the momentum device makes to my small manually-controlled garden locomotive. I put a "lump" in the test track to demonstrate the problems with "racing" and "stalling" that these engines have and how the momentum van solves these problems:
https://youtu.be/kkONOCJkqJ4
KELVIN,
Well done on using inertia in the flywheel car to counterbalance the abrupt changes of the steamer as it goes upgrade then downgrade.
Your demonstration reminds me of the observation that an OK running engine can become a great running engine when double headed for the same conceptual reasons. Any choppy slowing or running away tendencies are countered by the second locomotive with the net result of smooth overall running.
If you want momentum, try wrapping a layer of solder around the free axles of a car.
what if the coupler can be pulled out slightly, when there is tension on it, that relieves light spring loaded tension on the wheels?
think of the difference between a really free rolling car and one that doesn't roll as freely.
It's not enough tension to stop the car abruptly, but enough to prevent it from rolling on a marginal grade. There would be no drag when pulled by the train, but there would be when the train slows and coupler tension releases.
Yes, there would be drag when a car is pushed into a siding.
This would require that the coupler gear box can slide or the coupler itself if it were like the discontinued kadee #4