Outdoor Track Powered & Non Track Powered Loco's

Discussion in 'Gardeners World' started by CME & Bottlewasher, 24 May 2013.

  1. These posts were moved from there original location in my layout thread as they may be of interest to a wider audience:).........

    Hi Phill:)

    Are flywheels really needed?

    I have been told that flywheels only really work at high revs - and thus are almost useless for slow speed work and only used where 3 pole/cheaper motors are used.:)

    .....Thus with quality 5 pole Mashimas you/we shouldn't need flywheels.

    What are your thoughts/views?

    Kind regards,

  2. Who told you that?
    A balanced flywheel will always add a little smoothness to the performance of a motor, and the impression of a bit more mass and momentum to a model. An unbalanced flywheel will simply make things worse. It is true that the momentum effect is related to the square of the rotational velocity, but that does not mean a flywheel at slow revs is worthless.

    If a modeller like Trevor Nunn, who earned his crust as a mechanical design engineer in the medical instruments industry before retiring (and therefore really knows what he is on about), uses them whenever and wherever he can, on 5-pole and coreless motors. (As an aside, as the only mechanical engineer in a company dominated by electronic engineers, he chose to have the job title "Chief Mechanical Engineer" for a laugh!)

    What is silly, is boring out flywheels of the size we use on models: whilst this might concentrate the mass which is present in the flywheel further from the radial centre, the total amount of mass is reduced, sufficiently so that the effect of the flywheel is reduced.

    This comes from an incomplete understanding of physics: a "hollow" flywheel will have more momentum than a solid flywheel of the same dimensions and mass. Keeping the dimensions but reducing the mass negates this.
    Phill Dyson likes this.
  3. Hi Simon and how are you?:):rolleyes:

    I'm not telling you who told me! (suffice to say such came from two reputable engineers):p:))

    I never mentioned the issue of balanced vs un-balanced, I stated 'flywheels', that refers to flywheels in general, in that they only really work at an optimum rpm and most never get up to such in model form (ie within our models). Also most railway modellers use such to 'improve slow speed running':rolleyes:

    I have used flywheels in the past and such have 'appeared' to smooth out motor function, yet my guess is that such is just down to pushing the magnet around that little bit further:)

    Kindest regards.

  4. Phill Dyson

    Phill Dyson Western Thunderer

    I agree with Simon :).........no idea regarding DCC, but for DC they always improve performance in my experience :thumbs:

    That's very interesting Simon, I am very impressed with Heljan flywheels .........I thought it was the huge size of them that made these loco's run so sweetly, but they are hollowed out as you suggest..........

    Heljan Flywheel.JPG

    Cheers Phill
  5. Phill,

    They are hollowed out to fit around the motor, and to increase the mass of the flywheel within the confines of the body shell. They have not been hollowed out due to a miss-understanding of physics, and the use of them is entirely consistent with what I said. The alternative would have been a simple, flat, disc. It would probably have worked perfectly well as a disc, but this way they have given the flywheel a bit more oomph.

    I am fine thanks, Martin.

    I know you didn't mention balancing, I mentioned it solely because an unbalanced flywheel (or a balanced one on a bent shaft - been there, got the t-shirt!) is a poor advert for flywheels. I mentioned it as additional information.

    Your engineer friends are not wrong, but there are at least two reasons for having a flywheel on a model, and they are addressing one of those. Whilst I agree that on a model, flywheels rarely get up to an "optimum" speed, that is only true if the desire is to create a lot of over-run and create the impression of more momentum. Adding extra mass to the rotational parts of the motor will always improve its smoothness (providing it is balanced, of course!)

    My point was - and you seem to be agreeing with this - that the aim is to add more mass to improve the slow-speed running.
    Phill Dyson likes this.
  6. Hi Phill & Simon:)

    I understand what you are saying Simon (and yes bent shafts, poorly balanced flywheels will all cause problems/more harm than good)...

    .....The Heljan flywheels seem to be almost fitted for 'show' if, that is the info I have received is correct - and I believe that it is....

    .....It certainly seems to me that the smaller fly wheels that I have used with Mashimas (for both 4mm and 7mm) have helped running - yet how much I cant quantify - and it would be good to know if these smaller types were fitted to a Heljan loco, if they would have the same effect as the Heljan flywheels or not....

    .....I must admit that my Heljans have run superbly straight from the box (even with - allegedly - unmatched motors etc. etc.):) .

    I also have a suspicion that the quality of the gears/gearing/gearbox and the use of a quality 5-pole motor would have more 'effect' than just sticking a flywheel onto eg. a 3 pole motor fitted with an el-cheapo gearbox.

    Simon, yes at higher speeds one has to presume that a flywheel adds both momentum and then inertia (replicating speed, braking and/or a heavy train slowing etc.), yet at slower speeds I have been told that flywheels add very little, if anything, to performance and that the quality of components (motor and gears) is more important than using a flywheel. This of course could relate to the issue that <perhaps> the motors and gears that we use vary, greatly in quality and therefore a flywheel could either help or hinder!:confused::(:eek:

    It would be good to bottom such out as there must be a definitive answer:);) .


  7. iploffy

    iploffy OC Blue Brigade

    You forgot to add the additional current draw at starting. Maybe they work on the premis that even though the motor is working slowly it would benefit from the additional mass to smooth out the initial choppy ness of the forces created. It is only my take on things and if I am wrong I am wrong
    CME & Bottlewasher likes this.
  8. Phill Dyson

    Phill Dyson Western Thunderer

    That's what I tend to find;) & flywheels seem for me to keep a loco running smoothly over a bit of track where current pick up is less than perfect..........I know in an ideal world we would not have dodgy bits of track:oops:.......but gardens are probably not really the perfect environment for a train set! ;) :D
    CME & Bottlewasher likes this.
  9. Phill Dyson

    Phill Dyson Western Thunderer

    Perhaps the only way to prove or disprove this would be to have a couple of Heljan's (one with flywheels removed) & run them both for comparison, I'm not removing the flywheels from mine though!!! :D As Withercombe operates the 'If it ain't broke don't fix it policy':D;);)

    Phill :)
  10. This is where on-board battery power will take over from DC. You could use the rails to trickle charge the batteries, indeed, just do this where motive power typically stands still, and then use some form of wireless control to tell the train what to do. (Look at Protocab for a glimpse into the future, be nice to see some movement here!) You could also use DCC with "stay alive" circuits.
  11. SteveO

    SteveO Guest

    Does a well-programmed DCC chip perform a type of electronic flywheel in that it smooths out jerky acceleration and deceleration?

    For example, on a good chip, if I were to open the throttle to halfway, the acceleration algorithm would provide a smooth transition of speed from stop to half speed. A DC equivalent would just zoom off with very little time to reach half speed. Whereas, a DC + flywheel of adequate mass would perform closer to the DCC model. Is that right?

    If you've got the space I think flywheels are worthwhile, and more so if you operate DC with a track that may not pass on 100% its current 100% of the time.
  12. lancer1027

    lancer1027 Western Thunderer

    Good point there Simon.:thumbs:.

    This is something i have been toying with for sometime. I do like the general idea of radio control and i will be asking Tony lots of questions and seeing his progress at Telford:thumbs:

    Jordan likes this.
  13. Jordan

    Jordan Mid-Western Thunderer

    Me too, as we've discussed elsewhere here. It would be Radio Control that would tempt me into the garden - so that track could just do the job it's meant to.

    :eek: I would do - that IS my ideal world!!! :rolleyes: :D :thumbs:
  14. Yes, but if you hit a dead spot, it is still a dead spot unless you have fitted a stay alive capacitor or similar.
  15. Of course it's a good point. ;)
    By using Standard wireless protocols and having a concentrator, he has solved a lot of issues. I am waiting for an iOs version, and for the ability to link up with existing DCC loco modules: too much already invested, plus I want the sound features of my Tsunamis.
  16. Steve Cook

    Steve Cook Flying Squad

    Better late than never....
    Cheers Phill :) I'd be tempted with a short siding myself, if for no other reason than a 'dead' bit of stock could be left out all year round - watching it change throughout the seasons would add just another bit of interest (not that you are lacking in that department if I'm honest :D ).
    You might even need scissors to keep the lonicera behind the platform trimmed...... :p :))
    lancer1027 and Phill Dyson like this.
  17. When you say, "we ", please exclude me. I can never understand why people would "save" money by buying cheap gears and motors, but I suppose it is the same mentality that would rather have 60 locos at £50 each than maybe a dozen at £250.

    I carried out some controlled "experiments" nearly 20 years ago, with a small 0-4-0 chassis, powered by a Mashima 1620 (back in the days when they really were 1620s, and not a re-labelled 1420!) coupled to a two-stage DJH gearbox.
    Voltage (about 8v, IIRC - once set, the controller was not touched, merely switched on or off) was applied to the rails, and the loco ambled along until it had passed over a gap in one of them, cutting the power.
    4 different configurations were tried:
    20mm dia x 10mm long solid flywheel;
    20mm dia x 10mm long flywheel, recessed for 6mm of it's length to a diameter of 10mm;
    20mm dia x 4mm long solid flywheel;
    No flywheel.

    The results were interesting, and partly surprising.
    Firstly, a flywheel absorbs some energy, so the motor running without one accelerated faster, went faster, but covered the shortest distance when it ran out of juice.
    The 20mm x 4mm solid flywheel was indistinguishable from the semi-recessed version - running was a bit slower, acceleration slightly move sedate, and there was a little overrun; I was surprised at how little benefit was obtained from the extra mass of the hollow part of the semi-recessed flywheel.
    The 20mm x 10mm "solid" flywheel really tamed the motor, but it ran superbly. It still does, as Adrian can vouch for it is in the Drewry 04 shunter that appeared on East Lynn Quay at Railex some years ago. Overrun was about 50% more than for the recessed or thinner flywheels.

    Sorry, I no longer have the results of the rather unsophisticated "test", and there were not many repeat runs, but I was satisfied that a flywheel is a benefit, even where slow running is the order of the day, but that a recessed flywheel may as well have the recessed portion removed completely.

    Hope that helps - it is by no means definitive, but it would be very easy for a doubting Thomas to repeat the exercise and get the definitive answer, if still required. Frankly, I have other calls on my time.
  18. Hi Fella's,:)

    What a great discussion.:)

    The issue of having track-power in the garden, especially, seeing how successful the H&BLR has been (Battery and Live-Steam), still jars with me a little. Although I have a wonderful DCC set up waiting for me to fit, RC is still something that I know and I am comfortable with (I am even considering fitting such into one or two road vehicles).

    The last time that we discussed RC on WT, I mentioned the issues surrounding battery size/power relative to eg. Heljan diesel outline locos power 'needs'. Mike has also - for DCC decoder fitment - very kindly took amperage readings of Heljan locos for us and Steph is refining that level of research too (both aspects of which could help with battery specs for a RC Heljan loco).

    Also, in addition, it has come to light, that RC receivers from the likes of Deltang et al, are getting ever smaller and ever more cost effective, the same too with batteries (with the advent of such things as i-phones/i-pads et al.) and a lot has changed/become available - at reasonable prices - in the past year. I very much liked the red-arrow RC system yet the batteries required were too big and, also, required a lot of fitting into a Heljan loco (battery size is of course relative to loco/motor size/numbers of motors fitted etc etc. in whatever scale), yet as battery technology/prices improve maybe such is on the change thus making this method of control more viable. So perhaps now, as garden railway modellers, using locos designed for indoor track-power we have a better chance of using RC in them and being more successful with such.

    The issue of 'glitching' needs looking into, as railway lines tend attenuate RC signals and can then cause issues such as 'the rusty bolt effect' (worse with damp/wet rails). I also have a suspicion that every-time, although such shouldn't, we are exposed to the introduction/update of the likes of WiFi, 3G/4G et al. such interferes with the then current ranges of RC kit, RC frequency ranges plays a role in such of course. The latest batch of RC kit has, by and large, overcome such things, for the time being that is, whether or not such technology now irradiates yer dangly bits is another matter though and this may not be known for the next 20 years or more!:eek::)

    DCC 'electronic flywheels' (capacitors) can also help ease challenges for DCC users in the garden though, so all is not lost (with plenty of feeds, jumper wires, or a BUS).

    Simon, the Protocab system looks v'interesting:thumbs:

    And I agree, Simon, less is more, I use, by and large, Canon's, Mashimas et al. I have seen those with eg. 120 Lima Cl37's in 4mm (all fitted with pancake type motors), yet less is more in terms of 7mm and quality, and VFM is a better approach in my book. 'We' all have to accept though what we are given/purchasing - unless we re-motor - with a purchase of a eg. RTR Heljan loco (and now possibly Dapol too). I have heard from various traders/retailers, that motor quality could be better in Heljan's in terms of amperage, efficiency and 'motor-matching' etc., yet mine all work well and I accord with Phill, if it aint broke, then dont fix it - life is too short ;)

    As I have yet to lay and wire track in the garden RC is still an option....I hope to have at least on RC controlled loco.

    I also have a few ideas for a different form of point control - details to follow, slowly, in due course though:D


  19. taliesin

    taliesin Western Thunderer

    Hi, I am no expert but from what I have seen the modern 2.4G radio control sets are glitch free and the rusty bolt effect is a thing of the past. Recently I noticed in the local RC shop that so called Lipo battery packs have seriously dropped in price, cheers Rob
  20. I have been told that 2.4GHz is not compatible with DCC, but cannot vouch for that either way.

    Most systems seem to be on North American/Australian frequencies, or using network protocols similar to those for wireless home networks. Bluetooth is, apparently old-hat, although I would have thought it ideal for this purpose.
    CME & Bottlewasher likes this.