Kato 4 wheel chassis and Peco insulfrog points

[Justin Phillips]

I wonder if it is possible to fit a stay alive capacitor to get around this issue? I have Googled it myself but there does not seem to be anything about fitting capacitors, at least for Kato chassis.

[B.Meldon]

Reguarding the tighter curves, it is the coupling overhang that will be the first thing to give problems, not the actual locos.
With Meanderbahn that has 9 inch curves I only use locos with short coupling overhangs as well as almost every wagon and all coaches with couplings on bogies. 

[Hugh Norwood]

Stay-alives are really only for DCC.
(is the short answer).

[Graeme Dunbar]

Reguarding the tighter curves, it is the coupling overhang that will be the first thing to give problems, not the actual locos.
With Meanderbahn that has 9 inch curves I only use locos with short coupling overhangs as well as almost every wagon and all coaches with couplings on bogies.

Yes, with my oval of track in a boxfile layout (radius 95 mm) I was aware of the potential issues and it was interesting to see how it played out and was prepared to abandon the project if it didn't work with the track secured (really secured using a No More Nails equivalent) to an MDF track base and weighted down flat while the adhesive set. My quarry Hunslets had no problem pulling Peco skips round but my Minitrains loco just pulled them off the track.The Minitrains loco have rigid couplings on the buffer beams whereas the quarry Hunslet coupling is sprung and can swing just enough from side to side. Coupling height may have played a part too, but it has not been an issue on other layouts.

It is possible to push the limits of track and operation but I think it comes with selecting and accepting limitations on what will run. I suggest getting that bottom right curve laid and tested with your stock ASAP, especially if laying flexible track there 'free style' without tracksettas or printed/drawn curves. There is the added complication of a tight curve and a transition to an incline so extra care may be needed to avoid twists in the track which could also affect running, so early testing is key I think.

[cnw6847]

Analogue stay alives seem to be available from Hobby trax but i'm not sure they would be suitable for a Kato chassis.

https://www.hobbytrax.co.uk/products/dc-analogue-stay-alive

[Graeme Dunbar]

Analogue stay alives seem to be available from Hobby trax but i'm not sure they would be suitable for a Kato chassis.

https://www.hobbytrax.co.uk/products/dc-analogue-stay-alive

My opinion is that such things are largely snake oil. The main issue is that when they are most needed, that is when a locomotive is moving slowly they have have least effect. Moving slowly means of course the voltage on the capacitor is similarly low. The capacitor then contains only a tiny amount of energy. On the other hand when moving at high speed the capacitor is more fully charged and contains more energy. A lot more, as the energy stored goes up as the voltage squared.

The claims of an extra 46% coasting when the power is shut off may well be true but not necessarily useful if it is 46% of coming to an almost immediate halt. It should have a certain flywheel effect and that may be what is wanted if running vintage locomotives under trainset type operating conditions.

[Justin Phillips]

My opinion is that such things are largely snake oil. The main issue is that when they are most needed, that is when a locomotive is moving slowly they have have least effect. Moving slowly means of course the voltage on the capacitor is similarly low. The capacitor then contains only a tiny amount of energy. On the other hand when moving at high speed the capacitor is more fully charged and contains more energy. A lot more, as the energy stored goes up as the voltage squared.

The claims of an extra 46% coasting when the power is shut off may well be true but not necessarily useful if it is 46% of coming to an almost immediate halt. It should have a certain flywheel effect and that may be what is wanted if running vintage locomotives under trainset type operating conditions.

I am no expert, but I would imagine with some fancy electronics you could build some intelligence into it where current is stored and then released during times when it is needed most, i.e. low running speeds (I am thinking from a DC perspective, maybe DCC systems have that?). The stay alive advertised does not have any of that. So as you said, at best it will provide a small amount of simulated flywheel, but probably only for a second or two at best. But, then that might be enough to get the train over dirty spots on the track and prevent a stall. Its one of those suck it and see things.

[Graeme Dunbar]

My opinion is that such things are largely snake oil. The main issue is that when they are most needed, that is when a locomotive is moving slowly they have have least effect.
..

I am no expert, but I would imagine with some fancy electronics you could build some intelligence into it where current is stored and then released during times when it is needed most, i.e. low running speeds (I am thinking from a DC perspective, maybe DCC systems have that?). The stay alive advertised does not have any of that. So as you said, at best it will provide a small amount of simulated flywheel, but probably only for a second or two at best. But, then that might be enough to get the train over dirty spots on the track and prevent a stall. Its one of those suck it and see things.

What you say is true, but the 'fancy electronics' has to do pretty much all that either a DCC decoder with a stay-alive system or much of a radio control based system with added on-line battery charging - less the radio bit obviously. Instead, it needs sufficient onboard intelligence to take the voltage on the track whether it be the full 12 V or a slow running at say around 1 V. The track voltage is intermittent (the reason for it in the first place) and so it has to decide when it contains speed or stop information or is noise, and whether there is enough there to charge the battery and whether it can boost it to a charge value or turn off charging.

The solution is likely to be at least as complex and bulky  as either DCC or radio control, require modification to the locomotive with little if any benefit over either.

Also it is likely to work only with 'pure DC' controllers or be clever enough to work out what sort of controller (pulsed full-wave rectified such as Gaugemaster, PWM, feedback and so on) and interpret the waveform as speed information.

I have sometimes wondered about trying to do the calculations for how long a stay alive would keep a loco running. There are just so many variables. One thing though, with a simple capacitor stay-alive, because of the square law for energy on a capacitor, if it were possible to achieve 1 second's worth of storage at 12 V then at slow running, say a tenth of that then there is one hundredth of the energy stored. Let us say 1/100th the distance. If the suppliers of the capacitor that claims an extra 46% coasting over no capacitor, which is presumably when running at speed then one might expect 1/100th of 46% when running at 1/10th speed.

Such things can keep the Electronics SIG amused for quite some time.  ;D

[JulienW]

My own take on this is that the wheelbase of the Kato tram chassis should be more than enough to bridge the gap on an insulfrog (dead frog) point, so if the track and wheels are clean things should be OK.

Where there are likely to be issues are when the point blade itself is 'dead' due to an accumulation of crud (technical term) isolating it from contacting the stock rail, as this will make the dead section much longer than the chassis wheelbase.

The other issue with the older type of Kato 4 wheel chassis (the 11-103 and 11-104) is a lack of contact between the pick up(s) and wheel(s). Whilst the chassis will still run if it's only picking up from 2 wheels - not necessarily on the same axle! - when the a wheel with pick up hits a dead frog there's no current going to the motor.

[Justin Phillips]

My own take on this is that the wheelbase of the Kato tram chassis should be more than enough to bridge the gap on an insulfrog (dead frog) point, so if the track and wheels are clean things should be OK.

Where there are likely to be issues are when the point blade itself is 'dead' due to an accumulation of crud (technical term) isolating it from contacting the stock rail, as this will make the dead section much longer than the chassis wheelbase.

The other issue with the older type of Kato 4 wheel chassis (the 11-103 and 11-104) is a lack of contact between the pick up(s) and wheel(s). Whilst the chassis will still run if it's only picking up from 2 wheels - not necessarily on the same axle! - when the a wheel with pick up hits a dead frog there's no current going to the motor.

I have a Kato 109 chassis with no body that I use to test my track laying (it's the only functional "loco" I have at the moment) and it is a little sketchy even with "clean" track and electrofrog points. But then I realised of course it probably needs more weight! So I guess another aspect to this original question is how much is optimal weight to provide more adhesion, better electrical contact without putting too much strain on the motor?

[Graeme Dunbar]

I don't know the ideal weight but bear in mind that the chassis are from their Pocket Line range that have lightweight plastic bodies. I'm fairly sure there is no extra weight in them but I guess I could check my still intact tram. I put a diecast Chuggington Dunbar on the bogie version and it pretty much gave in, but that chassis is known to a more feeble than the four wheel version. I'd maybe try add weight bit by bit and see how much (or rather how little) it takes for reliable running.

I invested in one of the little electronic scales that are available. I was wondering why they were so cheap and readily available. Then the penny dropped. Fortunately I've not been raided. I've also got some tungsten putty as used by anglers which is convenient for adding weight temporarily but a bit expensive for general use.

[Justin Phillips]

I was wondering why they were so cheap and readily available. Then the penny dropped. Fortunately I've not been raided.

;D