Adjusting the top end speed of Williams Engines

I've always believed that using diode strings on twin-motored engines is a better way to "slow em down" than wiring the motors in series as is the typical mod.

 

While being a quick and easy fix, the problem with series wiring is that it can create an open differential effect on twin-motored engines.  That's where the torque transmitted will be equal at both motors (and thus, at the wheels) and will not exceed the threshold of torque needed to move the wheel with traction.

 

So in other words, with series-wired engines, if the set of wheels tied to the front motor starts to slip and loose traction, the other set of wheels tied to the second motor will just sit there and do nothing instead of continuing to rotate and help push the first motor wheelsets out of its slipping state.  This can be especially problematic for those that run long heavy trains, have grades on their layouts, uneven trackwork, and if the track isn't kept clean of accumulated oils and grease.

So in other words, with series-wired engines, if the set of wheels tied to the front motor starts to slip and loose traction, the other set of wheels tied to the second motor will just sit there and do nothing instead of continuing to rotate and help push the first motor wheelsets out of its slipping state.  This can be especially problematic for those that run long heavy trains, have grades on their layouts, uneven trackwork, and if the track isn't kept clean of accumulated oils and grease.

 

On the other hand, as long as each truck has intact traction tires (as nearly all 3-rail diesels do), wheel slippage is a non-issue.

 

That's like saying that wheel slippage is a non issue with automobiles since they have tires.

 

Traction  tires don't prevent wheel slip; they just reduce the chances of it happening (increasing adhesion limits).   You can still get wheel slippage with traction tires.  In fact, that tends to be the primary reason traction tires get thrown and need to be replaced.

 

TMCC has a function to limit the top speed of a loco. It works OK but if you change the load( number of cars) it needs to be reset. Just mentioning this to suggest that the number of diodes you use may depend on the length of your train. All IMO; Don

It is 99.9% of the time, unless you are a race car driver.

 

Or if you run model trains on steep grades, pulling very heavy cars, have uneven track, and haven't cleaned your track in a while.

I have had no issue with series wireing....but how about a how to on diode method??? With the what part #'s and how???

Explained here

 

www.jcstudiosinc.com/BlogShowT...=488&categoryId=

 

Dale H

so I can't help but wonder why Williams can't manufacture the engines to run slower in the first place?

wb47 I agree!!  They did a great job with the new 4-6-0, so it's not impossible, but I'm not wild about the pre-WWI look of that particular loco.  They need to redesign the "Golden Memories" Berks, Hudsons, etc. along similar lines.  If they did, I would buy two of each

 

"Great performance without gimmicks, it just runs better because it's made right"

"It's the toy that runs like it's scale"   

I must be missing something here.  Yes, the Williams locos can run very fast, but even with my semi-prehistoric TMCC set-up I can set the locomotives to run very slowly.  Why is that not an option as compared to undertaking these alterations?  The series wiring has always seemed problematic to me for the reason mentioned above, and while the diode method seems more prudent, any of these modifications will void the warranty -- which is, IIRC a limited lifetime warranty on the powered units for the original owner. 

The second reason that I am installing diodes is to achieve "directional" constant intensity lighting.  I will be replacing all the conventional light bulbs with LEDs. I will "tap" the diode string for use in powering LED lighting. The front and rear headlights will then change from "bright" to "dim" when the engine changes direction.

This is what the Bachmann now says about their warrenty for Williams engines; "One Year."

The former Williams made when Jerry Williams was the owner was limited lifetime.

Not anymore as Bachmann has basicly chopped off the warrenty to one year.

 

Lee Fritz

As at least one other persson mentioned, why do we need to slow down our Williams engines? I too have no problem with running my Williams engines with a post war Lionel ZW transformer or an MTH Z-1000, GP-9, SD-45's and F-7's. I had to add more power to an F-7 set of ABA diesels, now I have two powered A units that can pull a nine car passenger train.

Buy a cab-1 or other power control unit like a command control and you can control track voltage very easily.

My need was for more power! Not less.

 

Lee Fritz

I am with you Lee. A transformer that starts at zero volts plus actually pulling rolling stock will give prototypical speeds.

 

Pete

PW-V-150,  I can get the lights on at 5v,and begin the pull at 7v, at a snails pace!

I find better control, of them with the V, as opposed to the MTH, z-750 

Lee, fwiw I checked the website and the warranty is a year.  After one year, there is what WBB calls a "nominal service charge" of $30.00.  Not trying to be nitty, just want folks to have the facts.  While I prefer Williams' old warranty, this new one is not worthless either and provides me with some incentive not to screw with the trains too much.  

 

As to the original point, I think there is a phenomena on the internet where people talk each other into thinkinng something is a problem that "needs" to be addressed.  If folks want to modify these locos, that is all well and good but I would respectfully suggest it is far from necessary.  

Hi All,

I understand the potential issue with wiring the motors in series, and before doing this myself was cautious about the idea.  Here is my data: over the last 4 years, I have wired seven locos in series:  5 Williams and 2 Lionel.  For some locos, I also added a couple of diodes pairs.  I also added thermistors to all but one.  These locos experience substantial run time pulling long and short trains, fast and slow.  I also added sound systems to some of the Williams locos.

 

I have yet to encounter any problem doing this in the real world of my layout, and have never seen a situation where one motor pulls and the other either spins or does nothing.  None of the motors have failed.  None of the mechanicals (gear train) have exhibited a problem.  All traction tires are fine.  I have no oil slicks on the track.  I have a 3% grade, up to a mountain return loop which does not cause a problem, but otherwise the rest is level.

 

I understand the theoretical potential to have uneven resistance between motors in series resulting in unequal application of power and voltage to the motors.  But I have not seen it.  Has anyone had a actual problem with series wiring of dual motors in locos?  Just curious.

 

There are other aspects to the series wiring vs diode chain not yet mentioned: 

*  The series voltage drop is greater than just a few diodes, though certainly a long set of diodes can drop the voltage any amount needed.

*  Depending on whether the transformer is deliverying AC or chopped sine waves:  The diode drop results in an exaggerated pulsed sine wave, as the first X-volts are needed to enable the diode string to pass current.  I don't see this a problem since the motors are small DC motors, but it is interesting.  The series wiring reduces the amplitide/voltage applied to each motor, not the width of the pulse.  So if your transformer generates AC sine waves, then the diode-dropped chopped power waves could potentially be an advantage for motor control, like pulse width modulation, allowing higher voltage pulses to deliver more motor torque at lower average voltage (note average, since the power will be delivered in 60 rounded spikes/humps per second.)

*  The series wiring divides the transformer voltage applied to each motor in half, so that you need to work more of the handle in controlling the loco (almost twice the handle movement) for the same loco speed range.  The diode chain forces you to move the handle farther to enable the diodes to pass current, but once you reach that level, then the motors respond over nearly the same voltage range and handle movement as an unmodified loco.

*  I have noticed that for a given speed I am applying more voltage to the track, that my trains run better over less than perfectly clean track.  My theory is that the increased voltage overcomes the resistance of the dirty spots, kind of like diodes - once enough voltage zaps the dirty spot, it passes the rest of the voltage without resistance.  What do you think - does that theory seem plausible?

*  Like the kid says in Terminator 2 to Arnold the cyborg:  "And you can do combinations!"  I have a Williams BL2 with the motors in series, also in series with the motors are two pairs of diodes and two thermistors!   And I installed a sound system and LED headlight - very nice running loco.  The sound and headlight come up before the motors start, then pushing the handle forward, the loco gradually accelerates.  It took a lot off the top speed of course, it tops out at around 70MPH - still fast enough, but no longer the rocket it once was.

 

 

My experience:  no real-world problems with series wiring - its quick, easy, and works, with larger handle movement range and range of speed control.  The diode chain has the potential to result in slightly better performance, but I have not demonstrated it "in the lab" (on my layout that is).

 

Fun discussion. 

KEN,

 

let me ask a question off topic,

Can I put a " sound system, and LED', in a Williams SD90,  I dont want to mess the train up!!!??

thanks

I have another transformer that I got at a flea market and it has very low voltage settings that can be used with any AC powered model train set. Starts at almost zero and goes to nine volts, that is the first setting. The second setting gives you zero to 18 volts and has two adjustable outputs for two different tracks, along with whistle control. The transformer is a Troller Company model TAC 2001.

When I use it with my Williams I get a super slow turtle that barely moves when at low power.

To me I can not see wiring the motors in series with any Williams, just get a lower volt transformer and be done with it.

 

As for the person who asked about putting a sound system in a Williams. First you will need to remove the True Blast 2 sound board and speaker then put your new sound system inside. LED light should be able to be added or changed over to, even if you have to change out the light socket.

LED's use less power then incandescent bulbs even in O gauge.

 

Lee Fritz

Lee and Pete,

I'm sure they are fine when pulling trains.  But when you try to do realistic switching with the loco by itself, one or two cars you will notice somewhat abrupt starts and unrealistic slowing down for curves, grades, etc.  If a long train uncouples, the locomotive will accelerate to high speed and leave the platform incurring damage.  If the factory had used a larger motor and/or a numerically higher gear ratio, these things wouldn't happen.  The manufacturers use the current design because it's rugged, and very cheap to build and assemble.

 

All vertically-motored diesels use small Mabuchi motors and a gear ratio of 10:1 or less.  These motors are good for 9000 RPM, which equates to a top speed of 120 scale MPH.  Diesels couldn't go that fast in real life.  Given the short straights and sharp circular curves on a typical home layout, designing for an absolute top speed of 60-70 mph would give more pulling power, a wider range of throttle positions and smoother low-speed performance.

 

There are TONS of fast-running locos currently available, and they will be circulating in the aftermarket for the rest of our lives.  It's about time for someone to make trains that run slowly and smoothly without gimmicky electronics.  The new Williams 4-6-0 is one example, but I'm not wild about the prototype.

 

Believe me, this thread wouldn't even be here if the factory performance was beyond reproach!

I have experienced issues with series wiring,especially on longer engines on curves.  I had a Williams GG1 that would not run correctly on series wiring and several E series locos. One motor turns faster than the other and resistance becomes unequal as does voltage distribution.  The the series wiring amplifies the problem. If one motor stalls or slows,the other speeds up.  

 

I take out E units all together on some Williams then use 2 diodes instead of a bridge rectifier for uni directional operation. Each motor gets half of the sine wave (one the top and one the bottom) and and voltage distribution is not a problem.

 

different transformers start at different voltages but there is an advantage of the PW type 6 volts at start. Smoke unit and lights are at full brightness and the train can be stopped and remained lighted if the diode string is used. Many PC boards do not work well with chopped sine waves. 

 

Lots of ways to do things and each methosd has drawbacks.

 

Dale H

You can adjest the proformance of W/WBB with TMCC in Conv.

Dale, thanks for the comments and your experience.  What diameter curves are you using, perhaps that makes a difference:  I am running O-48 minimum with Lionel Fastrack, with sectional easements and O-60 minimum turnouts.

I have 2 WBB diesels, a GP38 and an Alco A-A pair. I series-wired the Geep and left the Alco powered unit alone, as it seemed to run a bit slower out of the box. Even so, I can't imagine it running smoothly with a transformer that starts at 6 volts. It may RUN well when moving, but I'm not crazy about jackrabbit starts or hard stops that pop cars off the track.

If you're using a CW80, MTH Z-series or other electronic power supply, it may be different.

On my home layout O 81 Atlas. On my new layout,O 96 up to O 120 K-Line shadow rail. Some diesels are a lot more touchy than others.

 

Dale H

Using a number of diodes in series with each individual motor is the preferred solution to adjusting the top end speed of Williams engines and increasing the starting voltage for the engines..  What may not be clear is that I am not only lowering the top speed but I am also adjusting the speed for all the engines that I operate in a lash up so they all run at the same speed.  A side benefit is that I now also have constant intensity and directional lighting using the same diodes.

 

For example I may add 8 or more diodes in series to each motor depending on the top speed that I want.  For my NW-2 switchers I may use 10 diodes in series.  For my passenger (GG-1s) I will use fewer diodes in series.

 

Remember I am adding these diodes to achieve a desired speed depending on the particular engine (FAs, GPs, Es, PAs, GG-1s, NW-2s etc.,).  My MTH DCS system allows me to use the variable TIU output and exactly set the voltage for starting and running Williams engines.  Since I may run conventional and PS-2/PS-3 engines at the same time on the same track the higher "starting" voltage allows me to place up to 18 volts on the track.

 

I do not wire the two motors in series. I use separate strings of diodes for each motor. For the motor that tends to run faster I will add an extra diode in series.