Why does WBB wire dual motors in parallel?

It's not really the loco, it's transformers designed to work with PW type motors that didn't begin to move until there's 5 - 7VAC on the track. So the windings on the transformers were designed to put 5V out as soon as the throttle is cracked. The same thing also happens with other brands of conventional locos whose electronics aren't designed to slowly ramp up motor voltage at start up.

 

You can see it on some of the old Lionel transformers with multiple outputs. Usually in the form of A-U 5-16VAC, B-U 0-11VAC. The B-U posts were for better control of motorized accessories, with smaller motors and less weight to move. When B-U is used with PW locos, you have to push the throttle half way up before they move.

 

The problem is, with modern motors, and electronic E-Units that convert AC to DC and pass it straight through, 5V gets you straight to Warp-1. Using the B-U 0-11VAC posts on an old transformer with the new can motors will give smooth starts.

 

Unfortunately, newer transformers don't have that option. So rewiring the motors in series to split the voltage, instead of the current, is about the only option short of installing TMCC or DCS.

 

Lee:  This may be a difficult question to answer, but if it worked with this one, why didn't it work with the others?  Wouldn't all the same rules apply?  I don't have  sufficient electrical knowledge, but it just doesn't seem like it wouldn't work for all locos wired in series rather than parallel.  

 

Bob

Lee,

Bob has a point and I don't know, unless I'm wrong, but don't older motors differ from newer motors?

Ralph

Just took a closer look at the picture. That unit has the old style reverse unit, which had even less 'damping' effect than the newer Williams/WBB 'plug-n-play' units. Even they only cut the "jack rabbit" effect some without series rewiring.

 

Lee
Bachmann has it's own forum. Bachmann employees participate. Theis would be a great post to duplicate there. I couldn't agree more about the before, but I solved my speed with DCS, so my obs won't have the same meaning to Williams.

I was hesitant at first to series wire a WBB engine but, after taking the plunge, I was so pleased with the results I series wired all 26 of my WBB engines.

As Lee noted, it is a very easy two minute job and the engines run so much better afterwards it is amazing.  The engines definitely draw more power now than before but, that has the added benefit of making the headlights brighter.

Curt

It really is the loco. Jerry Williams developed this architecture before 1980 when we were all using postwar style transformers that work as you describe. All of his engines work this way.

 

The reason for not wiring them in parallel is to eliminate the differential effect that manifests in series wiring the motors and having to explain to the otherwise lay person what is happening when they observe, under certain circumstances, only one motor of the two running, and that this is "normal".

 

Dale Manquen has developed a circuit to eliminate this "open differential" effect for series wired DC can motors that would resolve the entire issue.

 

 

That should not be happening. With the bulbs, the engines should be drawing just a tick over half of what they were before.

I've done most of mine too. But the all time WORSE jack rabbit King was a K-Line F-7 ABA set I bought new. I could not run it on my Christmas layout at all......and it had 6 motors total so it did take me a while. But agreed......easy fix.

 

PS transformer affects it too.....high end MRC helps some.

Which is why I will not buy another Williams engine until they figure out how to make an engine so it is pleasant to run.  Can they not be geared lower?

Rob:

Before doing the series wiring, my WBB engines would operate at a "normal" speed around 8-9 volts on my Postwar ZW.  After the series wiring, a normal speed now pulls around 11-12 volts.

This extra couple of volts also makes the headlights brighter although, I have created small dish type reflectors that I add around the headlight bulb in my WBB F3's and FA's to enhance the brightness.

Curt

First off, all dual motored engines are wired in parallel, not just Williams. Motors do not act like light bulbs. Their effective resistence in not constant. As it speeds up its resistence APPEARS to get larger due to counter EMF. That means the voltage drop across it gets larger relative to the motor running slower. The motors no longer are sharing the load. The one slipping gets most of the voltage only making it it slip more.

The series wiring trick might work for light loads as long as the wheels maintain traction.

if you removed the traction tires you would see how quickly this scheme fails.

 

Pete

Wiring motors in series will allow the motors to see half the track voltage, to run slower and to develop only half the torque. You may not need the speed but you may need the extra torque.  My layout has some pretty steep grades and the engines need extra torque as they must run at 12V to make the climb.  Motors wired in series just wouldn't cut it, plus on the straight-a-ways where you might want 100MPH scale speeds for passenger trains, you would not be able to achieve it.

I have done the same thing with mine. The thing to watch out for with the newer ones is that the wire is not the same. When the motors were installed the second motor was put in facing the opposite direction. So when I did what lee did. the motors went in opposite direction (Yellow to Blue). So mine is now wired (Blue to Blue). I also have  thread about slaving a second unit. I am waiting for an answer from one of the techs. to confirm the capabilities of the 6 Amp board to support 4 motors which would eliminate the need to slave the second board.   

 

https://ogrforum.com/t...29#39441157801189429

 

When I have finish my first phase of testing of slaving the second board. When I finish I will post the results.

 

Doug

 

  

 

 

I think it is what Len2 alluded to, which I didn't know about.  This is a very old Williams unit - as I said it is old, and I am not the third owner.  The other two WBB un its I did that two are newer trianmasters and such, bought within the last three years.  The rewiring did make a difference, significant, too.  But not nearly as much as on this with the older circuitry.  It really was close to unmanageable as war.  

Excuse my manners Happy New Year Lee and every one else.

 

Doug

That's been my experience. If you have a long train behind a series wired engine will stall out on curves at some point.

 

Where series wiring has worked great for me are MTH Proto 1 Budd Cars and Doodlebugs. They run much smoother without a hint of a stall out. I also did a Kline GP-38 that pulls an ore car train with excellent results. 

 

For these examples I did the wiring change 5 years ago and it has stood the test of time.

I have wired all of my Williams locos motors in series, with thermistors between the motors.   Really nice running locos.   I have also done this with some of my Lionels (FTs in particular).   Every result has been good.  

 

The thermistors allow very gradual startup for a very nice effect (5 ohms initially, dropping to about .5 ohms as it warms up over 5-10 seconds or so.

 

I have never experienced the voltage problem on any locos under any load, where one motor turns and the other does not.  I am powering with Lionel CW-80s.   My layout is modest 6X12 so a 12 car train is a long train for me.

While some of you may need to re-wire your motors for WBB in series, it is more of a power supply issue as some have stated. I have noted that some Williams engines like the GP-9 before Bachmann starts to move around 5.5 volts and the SD-45 starts to move around 7.5 volts or higher.

I have not wired any Williams diesel engines in series. Just found a transformer that works with the Williams better then most other transformers.

The Troller Company TAC 2001 (a two train transformer)works great with all O gauge trains, as it has a switch for 0 to 9 volts & 0 to 18 volts, also has whistle and direction controls. I found this at a flea market in a box of 027 track and switches for $20.00. Now this transformer is one of my favorites for using with Williams engines.

 

Lee Fritz

I was having the same issue pulling 15 Atlas cars before the mod. Since the change I have not had that issue and I am able to run at lower speeds now. with the slave I have eliminated this issue with grade changes, Of course the lighter the load the slower I can run.

 

Doug

Series wiring is not just good for Williams. I have an early PS1 engine that I redid with a Dallee reverse unit. It was still jumpy and sensitive to small fluctuations until wiring in series, and now it runs great. I did the same with an old K-Line GG1, which also increased its draw enough to eliminate the clicking from its reverse unit relays.

 

With near-universal "cruise control" this is probably not an issue for newer engines.

The advantage to series wiring is slower speed but the down side is when one of the motors or trucks loses traction and uses all the power at that motor. The other disadvantage to series wiring is when you have a broken wire, the power stops at the break in the wire, won't happen in a parallel circuit.

 

So there is a definite advantage to running the motors in parallel, if one motor slips the other will try to go ahead and pull it until the slipping motor starts working again, this happens mainly with dirty track.

 

Lee Fritz

Curt, They don't draw more power, they need more in series.  When you had your motors in parallel both motors got the same 8-9V drop.  If that is your reference, when you series wired them, now the first motor dropped have the V, and the second motor dropped the other half.  So the same 8V track voltage results in each motor only seeing 4V and going much slower.  To get back to the original speed each motor needs more V so you find track voltage up at 12V or so.  Now each motor gets 6V and is running closer to your original speed.

 

The bulb is in parallel with track power so it now gets 12V and is brighter.

 

As Len stated, transformer and old e-units, with a better quality can motor that lets say a Lionel starter set causes this.

 

I run with Power Masters and the ZW-C.  I don't have this issue because track voltage ramps up from zero.

 

You can also do this wiring via switch so you can have a selectable series/parallel.  K-Line did that in some of there stuff.  G

If your light bulbs are getting too bright try using either 14 volt or 18 volt bulbs, there is also 24 volt bulbs but they may drain some of your power or look very dim.

 

Lee Fritz

Not power, just voltage.

If the motors are wired in parallel, and dirty track causes a problem, both motors stop, not just one.

If you replace the bulb with an LED power consumption drops significantly.

One of my train club buddies has converted his WBB engines to LED lighting and has been pushing me to do the same.  So far, the incandescent dinosaur in me has held out.  ��

Curt

A useful technique to adjust the "top end" speed of Williams engines that I have used is to wire several diodes in series with each motor.  This results in a reduction in the voltage applied to each motor. I use 6 ampere rated diodes.  Each diode that is added reduces the voltage applied to a motor by about 1/2 volt.  This process allows matching the top end speed of multiple coupled engines.

 

See attached diagram that shows the "typical" wiring for a Williams U33C diesel.

Then how do you deal with the brightness of the headlight when using LED's?

FYI; I am not into using electronics for everything, or in plain English I don't want to add any more parts if I use LED's.

 

Lee Fritz

 

I have found that for most LEDs the light intensity does not change significantly over a wide range of applied voltage. Note: Each LED circuit must include a series "dropping" resistor as shown. (Some LEDs can be purchased with a prewired resistor.)

Evan Designs makes LEDs with the necessary electronics already attached.  Installing them is simplicity itself:

 

http://www.modeltrainsoftware.com/ledlights1.html

 

 

Thank you! I will email them in a minute or so.

 

Lee Fritz

In my case, I removed the bulb and its housing and wired in a Evans Warm light LED right into the lens and as you can see from the first video nothing comes out of the cab widows. Now there was a post a couple of days ago about someone replacing the bulb with an LED bulb and had said he was happy with the results.. 1-DSCF2808.AVI

 

The second and third video show the FA running though my troublesome curves without stalling. Prior to the mods I needed more power to keep from stalling.

 

The last video shows the power draw on my Z4000 I need to get throught the troublesome curves otherwise with 2 powered units that are slaved I only need 7.0 , 4.0 to crawl with out stalling pulling mainly 15 Atlas cars. Now one thing to note is All my engines are DCS. So when the tree comes down I am going to add another power drop and see if that changes things. 

 

 

P=V*I so they are related. Just like a PM doesn't "draw" what it needs.  It passes what the load demands.   G

Even parallel wiring if Dirty track limits voltage to the Electronic board.  The output of the board goes down, both motor lose voltage.  Granted series wiring compounds the issue since the motors get half the voltage applied.  G

 

 

Except the I for the motors in series is half of that in parallel at any given track voltage.

Because they can? 

Lee,

 

Just some thoughts on your adjustment...

 

Most model train companies do not have electrical engineers on staff.  Many years ago companies like Williams relied on their OEM suppliers for help (QSI and TAS for example). 


The model you have is from a Sanda Kan build.  Sam Chan was the EE in charge; a great coder but not experienced with the simpler things. 

Also note that about 25 years ago QSI recognized the lack of engineering data available in this industry and published T.R.O.S.  (Three rail operating standards). It was a worthy effort but no one adopted it.

 I suppose this is somewhat of an obscure path but maybe it answers a bit of the question "why".

 

Lou N