54044Re: [HOn3] enough of the locktite, geeze! any what HOn3 brass is good?
- Jul 1, 2008
--- On Mon, 6/30/08, Rob <rdressel@...> wrote:
From: Rob <rdressel@...>
My requirements for good running include:
1. realistic speeds for the engine modeled.
2. Flywheel included? nec for smooth operation.
3. all wheel pickup?
4. slow speeds.
5. good pulling ability.
6. good details or better.
7. reliable non rubber band drives?
8. reasonable running on Model rr curves?
Micro Motors with gear-heads will remedy items 1, 2, 3, 4, and 5 almost by them selves with major plus to number 4. Item 6 is a function of the when the model was produced, with the best detail being from the last ten years or so. 7 has never been observed by me in my 50 plus years and 8 is only a problem of you start going below 22 inch radius with 2-8-2’s or larger wheel bases.
Item (2) really catches my eye though!
I know that there are those here that will strongly disagree with this point and have all sorts of trick ways to overcome the problems involved. I can almost hear the keyboards warming up now, but here goes. This little exercise involves physics that can not be argued with and a little trip to visit a guy named Newton and one of his laws of motion, namely; A body in motion tends to stay in motion and a body at rest tends to stay at rest. Gravity and friction have profound effects on bodies in motion. With these laws of physics in mind, it is best to put that flywheel on a double shaft micro-motor with a gear-head on the opposite shaft to whatever final drive to the drivers you have in place or in mind.
Here is why. Mass and motion are what makes the fly-wheel do it’s work. In our case, instead of work being defined as horsepower it is much more relevant to have our work expressed as ounce/inches. This is not very much work to begin with. So having a high efficiency motor with a low drag and no clogging of the winding segments while in rotation, or what it is referred to in the industry as magnetic-detent, removes much of the drag to the centrifugal force of a fly-wheel in motion than less efficient types of motors would exhibit. The flywheel must also at least equal or better the mass of the motors windings if it is expected continue to spin the drive shaft after power is cut or interrupted for any useable amount of coasting.
Old Pitman style iron-core motors have too much internal drag and detent to make a flywheel with anything less than the core and windings total mass worth the time of adding a fly-wheel. Many can motors (which also have an iron-core) also share this problem. You need very large fly-wheels to even begin to get effective momentum with these motors. With HOn3 space is always at a premium, so large fly-wheels are push out of the picture from the get-go! Very small open frame motors (Pitman style) and small can motors have so little oz./in. torque at the output shaft and so much proportional friction to their size at the bearings, that they can scarcely power their own cores through even a portion of the windings revolution after power interruption. Putting a fly-wheel in this situation only marginally improves the motors momentum after power is cut or interrupted. There is also the problem of matching the fly-wheel to the motors work capacity and not over
matching it’s capacity.
All of these kinds of things are why a little German fellow invented the Micro-Mo in the first place! He quite correctly concluded that friction at mini and micro sizes in electric motors was the most problematic to motor efficiencies at low RPM. The corless motor solved part of that problem. The motor still had nominal and maximum output efficiencies that had to be dealt with and these motors do their most efficient work at higher RPM’s. This is where mating a coreless with a gear-head came in. By mating a gear-head to the coreless motor, the motor was able to be powered up to it’s most efficient RPM and the output shaft could be made to work at a slower RPM than the motor would normally work at efficiently. These a ranges of RPM’s at the output shaft are far slower than Pitman’s and can motors ever imagined working at.
In our little RR worlds all one needs to do is use one of these high-efficiency coreless motors with a gear-head added on to the main output shaft. The motor will now operate in more of it’s most efficient power range and may not even need a fly-wheel to correct momentary power interruptions. But, by adding a nominally sized fly-wheel to the opposite output shaft, the higher RPM of the un-geared end to the motor can utilize those RPM’s and convert them into centrifugal motion and that in turn into coasting motion when power is momentarily interrupted.
Putting a fly-wheel in the mechanism just for the sake of having it there will not improve a poor running motors efficiency. Its more like just putting lipstick on a pig. It’s still just a pig.
I have a pretty firm grasp of this material and am not looking for or needing any criticism here. I just want to help get some facts on the subject out there to help.
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