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Consisting + BEMF?

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  • Member since
    January, 2014
  • From: Chicago area
  • 280 posts
Consisting + BEMF?
Posted by Arto on Monday, January 07, 2019 1:06 PM

I have three BLI E8 all from the same manufacturing run pulling a California Zephyr (12 cars). Currently all three loco are assigned the same address.

 

When the train comes rolling into the station, slowing down (most of the train is still on a downhill grade on a curve) the locomotives "buck" each other - jerky kind of speed.

Will consisting these three loco together eleminate the "bucking" and make for smoother performance? Or is this some other kind of issue requiring adjusting of individual CV in each loco?

  • Member since
    February, 2002
  • From: Reading, PA
  • 25,632 posts
Posted by rrinker on Monday, January 07, 2019 3:14 PM

 It's likely as much gear lash figting the BEMF on the dongrade as it is anything else.

I never had a problem running locos together that had BEMF, even when the locos were different maufacturers and the decoders were too. But I didn't have any grades, and neither does the club layout.

                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    November, 2013
  • 710 posts
Posted by snjroy on Tuesday, January 08, 2019 4:54 PM

They should run at the same speed. To check, I would place them on the track a few inches apart and turn the throttle. If they don't run at the same speed, you might want to reset the decoders. Make sure the wheels and track are clean. It is unlikely to be a BEMF problem, but you can turn that off and see what happens.

Simon

  • Member since
    December, 2015
  • 4,885 posts
Posted by BigDaddy on Tuesday, January 08, 2019 6:31 PM

Arto
Will consisting these three loco together eleminate the "bucking"

Well, they are consisted, old style.  Advanced consisting, without playing with any other settings doesn't seem like it would solve any problem.

In theory they should run the same, but one could have been assembled on Monday and the others on Thursday.  Randy could be right, but I'd see how closely they are speed matched.

Henry

COB Potomac & Northern

By the Chesapeake Bay

  • Member since
    December, 2012
  • 114 posts
Posted by Redvdub1 on Friday, January 11, 2019 1:51 PM

You might check the E8s speeds and then see how many cars you need to attach to the fastest one to match the speed of the unloaded (slower) engine.  It should be 1-4 cars to get the speeds matched.  At that loading, say 2 cars, both locomotives when consisted are pulling a share of the load..on level ground or on uphill grades.  Downhill may cause the consist to buck..then you probably need thrust washers on the armature shafting and/or on the worm shafting.  If that doesn't work satisfactorily the next step is to take apart the gear train and center the gears to improve the meshing for the worm gear, any reversing worm gear, and the axle gear. 

  • Member since
    January, 2014
  • From: Chicago area
  • 280 posts
Posted by Arto on Sunday, January 13, 2019 3:36 PM

Redvdub1

You might check the E8s speeds and then see how many cars you need to attach to the fastest one to match the speed of the unloaded (slower) engine.  It should be 1-4 cars to get the speeds matched.  At that loading, say 2 cars, both locomotives when consisted are pulling a share of the load..on level ground or on uphill grades.  Downhill may cause the consist to buck..then you probably need thrust washers on the armature shafting and/or on the worm shafting.  If that doesn't work satisfactorily the next step is to take apart the gear train and center the gears to improve the meshing for the worm gear, any reversing worm gear, and the axle gear. 

 

Same as the old days Geeked

Now that you've mentioned getting the slack out of the drive train, there seems to be (to me) way too much slack in the coupler knuckles.

These are Broadway Limited locos. I haven't had any issuses with their "Kadee compatible" couplers in the past but I'm not a fan of so-called "Kadee compatible" in general. Maybe a change of couplers is also a good place to look after the speed tests?

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