Large Scale Central

Steam Locomtive drives

General Discussion
#21

Ok, Geoff, is that wheel slip under load on the flat, or on a grade? If on a grade, what grade, and how long is the grade? There are lots of variables in your proposal.

The knowledge that a locomotive will operate at full slip in the hot sun at 100+ degrees F for X minutes before it melts down will tell me a lot. I recognize that that test will possibly destroy the drive and the motor, and will deform the track, but it is done by the manufacturer, not me, and only once.

If your test is done on a 2% grade and my ruling grade is 4%, your test doesn’t tell me much that is helpful.

#22

Steve, What I just mentioned as a definition for full load works on any grade. On the flat a given engine will haul a number of cars without slipping, less on a 2 percent grade and even less on a 4 percent grade ( just like the real thing).

If it could be stated that an engine will run all day in a given temperature range without damage if load limits are not exceeded that would be great. The challenge for the manufacturer would be to clearly communicate the limits of an engine. Few would spend the money on a scale to measure drawbar pull, even less would take the time to actually measure. Wheel slippage is easy to observe and by establishing that as the load limit a manufacturer could control expectations. A manufacture could spec the number of axles in an acceptable load, but now you get into what kind of bearings, weight of the cars and so on…

#23

When a prototype engine’s wheels slip they add sand to the rails. Does that exceed the load limits?

#24

Interesting point. If the wheels are slipping on dry rail, I would think they are exceeding the design limitations.

#25

Joe Zullo said:

When a prototype engine’s wheels slip they add sand to the rails. Does that exceed the load limits?

The amp gauge on the locomotive determines the load limit. The more amps you pull, the shorter the continuous time you have before the you start burning out the traction motors. I can’t remember the exact numbers of the top of my head right now, but it’s something like 15 min, 10, and 5 min amp readings if you red line the amp meter in any of these areas it’s continuous time. So say something like: 1800 amps at 15, 2000 amps at 10, and 2200 at 5 min. Each locomotive is rated different based upon a couple of factors; weight, traction type (AC or DC), and horsepower rating.
Sand helps grip the rail, but just because you use sand doesn’t always mean your over the amp rating. A good example of this was when I was switching in the yard with a SW1500.When kicking cars I would have to throttle up into notch 8, with full sand. Sometimes I would hit the max amps, but as soon as I got the train moving the amps would die down a bit.

Craig

#26

Max. grade on our layout is 3.5%. We have two steamers, the Brawa G4/5 (Consolidation) and a LGB G3/4 (Mogul). Both work flawlessly straight out of the box; excellent running characteristics, more than enough power for a prototypical train. No tinkering necessary!

Since we’re running DCC we adjust the CVs to the behaviour curve of the protoype.

#27

On that full load bit; the prototype designates full load depending on grade percentages i.e. shorter trains for 2% (or whatever) grades. But here comes the BIG difference, steamers have full torque at near zero speed, electric motors (the DC variety) don’t. But a high quality DC motor will take quite a bit of punishment, the problem is: most LS mfgs don’t use high quality motors. That includes MLGB’s E10, with a patently ridiculous drive to come in at a certain price point.

#28

Geoff Ringle said:

Steve, What I just mentioned as a definition for full load works on any grade. On the flat a given engine will haul a number of cars without slipping, less on a 2 percent grade and even less on a 4 percent grade ( just like the real thing).

If it could be stated that an engine will run all day in a given temperature range without damage if load limits are not exceeded that would be great. The challenge for the manufacturer would be to clearly communicate the limits of an engine. Few would spend the money on a scale to measure drawbar pull, even less would take the time to actually measure. Wheel slippage is easy to observe and by establishing that as the load limit a manufacturer could control expectations. A manufacture could spec the number of axles in an acceptable load, but now you get into what kind of bearings, weight of the cars and so on…

So, are you expecting the manufacturer to provide you with the number of cars to wheel slip for each half percent of grade? And how long is the grade? What kind of bearing on the axles? Whose cars? I understand what you are trying to say, I’m just not convinced that you will be able to convince the manufacturer to do it. I do know that Dave won’t do it, any more, and I certainly have no interest in doing it for the same reason as Dave.

#29

Steve, I am just trying to communicate that the circumstances do not matter. If the wheels slip (you are exceeding the limits of the toy engine), take a car or two off the train.

#30

While not part of the ‘drive’, the type of track used plus the material used on the driving wheel tread are important in gauging the amount of slip/resistance and when it will occur.

I use stainless rail and I believe its coefficient of friction (if that is the term), means with a given wheel tread material (stainless, brass plated, potmetal), the wheel will slip before the same wheel used on brass track.

We know battery users do not regularly clean their railheads, so is tarnished brass more ‘sticky’ than clean/polished brass rail? Also, with the introduction of aluminium rail, where does it fall in the ‘slippage resistance’ table.

One cannot quote a loco will slip with a given load unless track and wheel tread materials are factored in. Thus a manufacturer may quote a loco is good for ten cars maximum load to remain in a ‘safe’ operating envelope (wheels commencing to slip), whereas an operator may find his motor self destructing because his track material will only allow slip with a higher load.

#31

Stan Ames said:

I would add … items to the list.

  1. Good top speed at 24 V

Stan

It’s a good thing I’m retired and don’t give a rat’s hindquarters anymore about this. However, the to-be-expected response has shown up. Typically, when one asks a question knowing what answer they want, when that answer is not forthcoming, they add it as 'concensus".
And probably publish it as such.

I read all the prior responses three times, even did a search…you are the only one to drag Accucraft/Bridgeworks 24V supply into the conversation.

Now everyone knows where you’re headed.

Next generation of Bachmann locos will require a Bridgeworks or more space for 24V of battery?

Say it ain’t so, Stanley!

TOC

#32

Geoff Ringle said:

Steve, What I just mentioned as a definition for full load works on any grade. On the flat a given engine will haul a number of cars without slipping, less on a 2 percent grade and even less on a 4 percent grade ( just like the real thing).

If it could be stated that an engine will run all day in a given temperature range without damage if load limits are not exceeded that would be great. The challenge for the manufacturer would be to clearly communicate the limits of an engine. Few would spend the money on a scale to measure drawbar pull, even less would take the time to actually measure. Wheel slippage is easy to observe and by establishing that as the load limit a manufacturer could control expectations. A manufacture could spec the number of axles in an acceptable load, but now you get into what kind of bearings, weight of the cars and so on…

I used to do that in reviews. Fish scale, both on the loco at full slip, and pulling cars on level track, to give you some idea. However, one issue that you need to watch on wheelslip, since it IS the only safety valve to prevent motor burnout, is wheel plating. Bachmann stuff has…oh, shoot, can’t say lousy, that will get deleted…questionable? wheel plating.

To give you a real-time idea, original (and later) 2-truck Shays. Up my 150’ of 4%, a new set of wheels will pull 12 cars max on my aluminium rails. Once the plating is into the copper (or the base metal, even), 28-34 loads unassisted in dry weather. So, your wheelslip calculations on fresh plating on more slippery rails go out the window on worn wheels. I’ve rebuilt my trucks at least 4 times, ALWAYS put the old wheels back on.

I used to do full-slip current readings, too. K and 3-truck both pulled 5 amps at full slip…and that was fresh plating.

In the old days, would I have paid more for stainless tyres? Not on your life, as the worn plating gives me better operational characteristics.

In fact, I often use a sanding drum on my Dremel to “help” the plating to go away while running the drivers at low speed…of course, since I don’t care about track power pickup at all.

Dang, it’s a good thing I retired…this would certainly get me jumping up and down…but, I’m still calmly sitting here…

TOC

#33

Curmudgeon mcneely said:

Stan Ames said:

I would add … items to the list.

  1. Good top speed at 24 V

Stan

It’s a good thing I’m retired and don’t give a rat’s hindquarters anymore about this. However, the to-be-expected response has shown up. Typically, when one asks a question knowing what answer they want, when that answer is not forthcoming, they add it as 'concensus".
And probably publish it as such.

I read all the prior responses three times, even did a search…you are the only one to drag Accucraft/Bridgeworks 24V supply into the conversation.

Now everyone knows where you’re headed.

Next generation of Bachmann locos will require a Bridgeworks or more space for 24V of battery?

Say it ain’t so, Stanley!

TOC

Dave

Prefer Stan

Since you misread the intent, it clearly is worded incorrectly. There are 3 common speed values that I generally like to know. Slow speed (less then 1mph) 14-16 volt speed (good normal or realistic speed), and 24 volt which is high speed. I have locomotives which at 24 volts DC are relatively slow and well below the rated top speed of the locomotive. Some standard gauge locomotives also suffer from requiring a lot of volts to get a realistic speed.

The counter is that a lot of folks like to run their locomotives very fast (when compared to prototypical speed. You might not, I might not but the market clearly desires this.

Clearly better wording is needed, perhaps Greg would have a suggestion.

We all want good running locomotives. Achieving a better concensus of what we actually mean by this is I think a useful exercise. And if we can achieve a useful concensus perhaps Kevin and others could start using the criteria when locomotives are reviewed.

Stan

#34

Where did a 24v high end marker come from? While some manufacturers state they can handle 24v, that’s with the 5v drop on the input to allow lights and sirens to come on…and, the torque curve stops before you get there.

16VDC is about the max you ever need, 18 would be a push.

You start throwing 24V into calculations for motors…I do recall first run Accucraft K with 24V motors…and with a full charge of batteries at 24V read on the meter, you could walk at a normal pace, get to the next set of steps, sit down and wait for it to arrive.

Knowing how this process has worked in the past, any time I see you throwing numbers like that out, we can only surmise you are planning on motors that will not achieve maximum speed until 24v of input.

Go ahead.

With the complaints about pricing, and probably the sales to reflect it, adding a 24V motor to the next generation is sure to bring everything to a stop.

Doesn’t bother me.

Barry will have a field day replacing motors for folks…maybe even Rodney.

But not me. You cannot accuse me of having vested interests any longer.

Somebody else can take up the flag.

You push 24V motors and it might be pitchforks.

But not me. I’m just watching. Far be it from me to try to influence anything for the good of the hobby anymore.

Keep it up! It’s good reading!

I’ve printed off the page, I’ll show it at the next ops session.

TOC

#35

Dave

I never ever recommended 24 volt motors in Large Scale. I have no idea how you could reach that conclusion from anything I have ever posted. Most 24 volt DC motors simply do not have good speed performance at lower speeds.

But like it or not LGB and others in DC have promoted 24 volt DC for years. It is the generally accepted maximun track voltage in Large Scale.

You do bring up a very key technical point and that is motor winding.

I think we can agree that 12 volt motors in large scale while common are simply asking for problems.

And I think we can agree that most 24 volt windings also do not work well. Pittman years back recommended 19 volt windings for their motors. Different motor types likely will require different windings values but clearly this is a design constraint manufacturers must consider.

Stan

#36

Stan Ames said:

  1. A Standard Gauge locomotive of say 2-8-0 size should be able to handle 10 cars and a caboose without wheezing.

Stan

Oh, and this answers another question of recent events. Since Bachmann doesn’t do Standard gauge locos…one now wonders (aloud) which company will be bought or absorbed by Kader and then offer standard gauge locomotives? Williams by Bachmann is an example…add to that the high speed of 24V, and one begins to see into the darkness so carefully hidden.

Gawd, I’m glad I don’t do this anymore.

Can you imagine a review…“The locomotive runs at 90SMPH at 24VDC of input. However, those of you running 16VDC power supplies may find the speed is a close cousin to a sow bug”.

You had it all laid out in this direction with 14.5:1, even without 24V input.

Then there’s the need to make certain you cater to the 24V available (more or less) in dcc…are you trying to make these new engines only friendly to Bridgeworks or dcc?

Did I say I was glad I didn’t do this anymore?

TOC

#37

Stan,

with the hobby direction more to ‘large’ locomotives and possibly higher haulage capacity, is a 24 volt motor capable of higher amperage tolerance than a lesser voltage motor? I assume Accucraft went to a higher voltage to haul their heavy brass bodies around. With the trend to battery operation are DCC friendly voltages still a requirement for our hobby?

If speed is a prerequisite then one sacrifices low end smoothness. A possibility considering the use of radio control is a two-speed gearbox. As drives are more engineering examples these days than the plastic chassis of days gone, could not a variable speed gearbox using today’s cheap multi-channel radio control systems handle both low speed operation to suit the enthusiast and a high end gearing to satisfy the “need, the need for speed”? Tamiya have been using multi speed gearboxes for many years in their very large truck models. I am sure the tecnology has advanced to the point that a gearbox would be a reliable addition to a drive.

Case in point is the venerable old Bachmann Annie motor. It seems around 14 volts was a maximum without encroaching the point of no return. These locomotives did however, have a good turn of speed at lower voltage thus a higher voltage was not needed. On the other hand an Aristo C-16 running on 18 volts was very limited in its top end speed. At 18 volts it was quite slow.

#38

TOC,

The 24V marker is one of those LGB legacies, it was dumb in the first place and it hasn’t improved. The same cr…utch was carried over to LS DCC; still dumb!

#39

Tim Brien said:

Stan,

with the hobby direction more to ‘large’ locomotives and possibly higher haulage capacity, is a 24 volt motor capable of higher amperage tolerance than a lesser voltage motor? I assume Accucraft went to a higher voltage to haul their heavy brass bodies around. With the trend to battery operation are DCC friendly voltages still a requirement for our hobby?

If speed is a prerequisite then one sacrifices low end smoothness. A possibility considering the use of radio control is a two-speed gearbox. As drives are more engineering examples these days than the plastic chassis of days gone, could not a variable speed gearbox using today’s cheap multi-channel radio control systems handle both low speed operation to suit the enthusiast and a high end gearing to satisfy the “need, the need for speed”? Tamiya have been using multi speed gearboxes for many years in their very large truck models. I am sure the tecnology has advanced to the point that a gearbox would be a reliable addition to a drive.

Case in point is the venerable old Bachmann Annie motor. It seems around 14 volts was a maximum without encroaching the point of no return. These locomotives did however, have a good turn of speed at lower voltage thus a higher voltage was not needed. On the other hand an Aristo C-16 running on 18 volts was very limited in its top end speed. At 18 volts it was quite slow.

Tim

I am not a motor expert. Barry might be a better one to answer your question. As I understand it the winding is the voltage the motor is designed to operate at. Most motor manufacturers all for over voltage with no ill effects.

You mention Pittman. They offer stock motors at 12 and 24 volts. You can also order 15 and 19 volt windings but you generally pay more for these and you must special order them. The Amp and torgue curves for the Pitman motors does not vary much between the 12, 15, 19 or 24 volt winding.

I believe Barry uses 19 volt windings and Bachmann started using 19 volt windings starting with the K27.

Speed range is always something the manufacturers need to consider when designing their locomotives. Clearly there are some out there with very poor performance.

And max voltage has absolutely nothing to do with DCC operation. WIth DCC, the greater the track voltage, the greater the maximum speed. No different from battery operation or DC.

Stan

#40

(Donning flame proof suit)

Unfortunately there are some locos that need 24 volts or even more.

Never seen a NG loco that needed it, but many SG units. One that readily comes to mind is the 3 axle diesel truck in Aristo products. An Aristo e8 will not be able to achieve prototype passenger speeds with any form of remote control unless you feed it about 24 volts, and to make matters worse, when you speed match diesels, you loose some top speed in the matching process, (you match to the slowest loco for example)…

Many 1:29 SG locos are way too fast on “normal” voltage, like 18 volts, but there ARE exceptions.

You don’t really have any disadvantage to supplying this higher voltage, but it’s sad that some locos need this voltage for prototype operation. Poor choice of motors and/or gearing.

Greg