Revolution Offering Mk5 coaches

[Graham]

OK so here are this afternoon's results.
@jpendle and @njee20 as promised, here are some pics of how I added weight to the 92's. I probably should also add these to the 92 thread.

1. here is a 92 straight out of the box, this one is sound fitted, as can be seen 74g


2. this is after I have added the weight. non sound. and as you can see 86g


3. lastly this is all the weight added


all the weight added is basically lead sheet cut and hammered down to the size required then covered in Kapton tape to eliminate any shorting issues, on the large piece which sits on the top I have 3 layers of Kapton tape.

[Graham]

basically I am just filling holes with lead to help with the traction. It does help.

[Roy L S]

I am wondering what the impact of all that extra weight will be on the longevity of the drivetrain as it will be under considerably more load. I do appreciate that the to some extent unavoidable drag caused by the internal bearings currently used on the Mk5 coaches requires a solution that will allow a full length "Caledonian Sleeper" to be hauled and this is one such, my concern is that the loco isn't designed to be that heavy so while obviously an individual choice, I would be pretty wary of adding that much weight personally.

On the subject of the Mk5 coaches, I haven't seen the bearings used but the cause seems to be the inevitable additional friction over that of a pinpoint bearing and presumably to some extent this will be impacted by the surface area involved. Appreciating that a secondary and complicating factor is providing adequate contact for the lighting pickups, nonetheless I am curious to know, have RevolutioN (or their designers in China) tried experimenting by using a much smaller internal bearing surface?

I have no "skin in the game" so to speak as I do not model the modern era, but they are lovely coaches so it would be great if a more effective solution could be found for the "drag" issue and I hope my thoughts/suggestions are take constructively as I intend them.

Roy

[Graham]

I added the weight pretty much within 3mths of receiving the 92's and they have run a lot since then with no problems.
When I mean a lot, to do a full circuit of the club layout takes approx 40mins at a scale 60mph, and these would have run for many hours on the layout. I would normally run 2 or 3 circuits on a club night so I think this speaks volumes for the reliability of the loco's and motors used.
cheers
Graham

[Roy L S]

I added the weight pretty much within 3mths of receiving the 92's and they have run a lot since then with no problems.
When I mean a lot, to do a full circuit of the club layout takes approx 40mins at a scale 60mph, and these would have run for many hours on the layout. I would normally run 2 or 3 circuits on a club night so I think this speaks volumes for the reliability of the loco's and motors used.
cheers
Graham

Here's hoping that continues and of course your choice to do so. All I am suggesting is that others should think very carefully before doing the same, and regardless of how "good" the motor may or may not be the model was not designed for that extra weight to be added and greater load will inevitably be put on it, very likely reducing motor life and potentially extra wear the entire drivetrain.

[ntpntpntp]

I have no interest in the Mk5 coaches, but with this talk of drag from internal bearings it's interesting to note that my Kato ICE 4 12-car set has internal bearings on some of the coach bogies (not all), and those coaches are perfectly acceptable free-running. Stub axles with live bearings ready to take light bars if desired.

[njee20]

I think you're crediting them with overly fine engineering tolerances. Let's not pretend they're calibrated to 74g and any deviation from that will cause failure. You hang a couple of hundred grams of train behind them anyway. It is a disappointing failing of the 92 that the haulage is poor, so Graham's solution seems good!

[jpendle]

I have no interest in the Mk5 coaches, but with this talk of drag from internal bearings it's interesting to note that my Kato ICE 4 12-car set has internal bearings on some of the coach bogies (not all), and those coaches are perfectly acceptable free-running. Stub axles with live bearings ready to take light bars if desired.

Thanks for that, but for a mechanical numpty like me, what's a stub axle and what does it look like inside the box that the axle is in?

Thanks,

John P

[woodbury22uk]

I have no interest in the Mk5 coaches, but with this talk of drag from internal bearings it's interesting to note that my Kato ICE 4 12-car set has internal bearings on some of the coach bogies (not all), and those coaches are perfectly acceptable free-running. Stub axles with live bearings ready to take light bars if desired.

@ntpntpntp

The Kato inside bearing bogie augurs well for the forthcoming 9 car Class 800 where some of the extra cars have them. I be interested in how the brass pick up strip is designed, and whether the axle passes through a hole in it. Stub axles would facilitate that.

[ntpntpntp]

@jpendle Kato typically uses two half-axles (stub axles) pushed into a plastic centre which keeps them isolated from each other.  This then allows each wheel to be live as a pickup, with power transmitted through the pinpoint axle ends to phosphor-bronze axleboxes and then up to the mechanism. It's a reliable method which has much less drag than wiper pickups, and all wheels can pick up (some older designs of bogie pickups  eg. older Fleischmann, Minitrix have only one wheel live to the metal axle, with a wiper contact to the axle. Thus only 2 wheels of a bogie pick up power)

Here's an example of the pinpoint axle version


In the case of these ICE 4 inside bearing wheels there are obviously no pinpoint axles, but just behind the wheels you can just about see they're supported in thin metal strip bearings.    I would imagine the separating collar is different to that of the pinpoint axle version, given that there needs to be some bare metal axle for the bearing.  I expect it's still a plastic tube but with a definite plug in the middle to maintain separation and to keep the required back-to-back distance.

I've not actually had a bogie apart to see the full arrangement, and don't intend to fiddle unless something misbehaves in the future. For now they are running nicely - not as freely as pinpoint axles do but definitely much better than other brands of coach which still use wiper pickups.  Give one of these a gentle push and it glides for up to a metre without any obvious  immediate friction effect.




It stands to reason you won't want to be lubricating these bearings as you'd risk the build-up of non-conductive crud as we see in locos with stub axles and chassis bearings.

[Roy L S]

I think you're crediting them with overly fine engineering tolerances. Let's not pretend they're calibrated to 74g and any deviation from that will cause failure. You hang a couple of hundred grams of train behind them anyway. It is a disappointing failing of the 92 that the haulage is poor, so Graham's solution seems good!

Not sure if this response is directed at my comment but here's the thing. As matters stand with the weight of the loco as purchased, hooking it up to anything like a full Caledonian Sleeper train will, from all that I have read, even with traction tyres as fitted cause a break in traction - the wheels will slip, immediately relieving much of the load on the motor and drive-train. With extra weight and less or no propensity to lose grip the load of the train and all the friction in the bearings remains on the gears and more specifically on the motor and I would be very surprised if the motor didn't get hot which is from all I have learned especially undesirable for a coreless motor (which I understand to be fitted) as there is no iron core to dissipate heat.

I an simply expressing a view and concern, but with (as I have said already) no "skin in the game" as far as 92s or sleepers are concerned it does not affect me personally and people will of course make their own choices. That said, I doubt there would be much sympathy from RevolutioN if burnt out motors are the result.

Regards

Roy

[njee20]

Yes, it was aimed at your comment and mild prophecies of doom. I'm not really talking about the mk5s specifically, just in general - any loco will be at risk of motor failure if you attach a train to it. Sticking a few extra grams in the loco isn't going to change anything IMO.

[Graham]

As an aside to this I have added weight to the Dapol 66's and 68's, and they all run and operate so much better. I consider myself fortunate to have the fleet I have and service each loco every year, regardless of if it has run or not.
I also found on my Farish 319, as the pickups and decoder are in the adjoining coach to the motor coach, by adding a bit of weight in this it aided reliability.
I am sure we could argue the merits or not of my actions for a long time, but they work for me. Especially on the club layout which takes one hell of a pounding with most of the modellers running US outline with up to 4 locos on long trains, and some of it being over 20yrs old.

[Roy L S]

Yes, it was aimed at your comment and mild prophecies of doom. I'm not really talking about the mk5s specifically, just in general - any loco will be at risk of motor failure if you attach a train to it. Sticking a few extra grams in the loco isn't going to change anything IMO.

You are entitled to your opinion as I am mine, but bottom line is that once you have added weight in such a way any warranty is quite reasonably void.

[njee20]

Your ability to claim for a burnt out motor may be compromised, but it's not as clear cut as saying it voids any warranty. In the same way that weathering a loco modifies it but doesn't void a warranty. I think everyone understands that you think it's a bad idea. Again, pulling trains puts undue stress on models, but we all do it. I have eleven 92s, I'll happily add weight to some and compare longevity. Could even remove some, they'll last forever then!

IME models have a very extreme bathtub curve failure rate. If they work out of the box they'll likely be fine for ages. I don't believe you get many failures 9 months in, even if you add 10g of extra weight.