I have a pair of old DC power Athearn BB S12's that I want to MU. Both have identical motors/flywheels/gearing, but there is some push/pull between the two when slow switching.
Would electrically linking their - and + pickups help smooth out the jerkiness, or is that an exercise in futility? I do like the dualing "growl" these old athearns produce.
The fact that they are DC makes it harder. A drawbar might help in conjunction with conjoined wiring; may not be prototypical (early Fs were joined with drawbars, don't know about switchers).
My Athearn PA1 A/B are drawbar connected and electrically tied together. They also supply power for all the lighting in the nine Rivarossi coaches they pull.
It is very easy to do.
The slight jerkiness in the couplers is just nature of the beast. It will not cause any problems.
-Kevin
Living the dream.
It might be worth a trial. I don't see that anything will change, including the slight bucking of the hesitant drive. It's the same voltage, after all, and except for very slight grade changes for the leading or trailing unit, the rails are the same. While the drives are also ostensibly the same, one of them has a hitch in its giddyup. The only difference might be where one of the two derives its power, and the drawbar if you go that route.
Same, same, AFAIAC.
tin canA drawbar might help
If they run back-to-back be sure the drawbar is insulated.
Good Luck, Ed
tin canThe fact that they are DC makes it harder.
On all the speed matching threads, the DC and ex DC guys tell it's no big deal with DC.
If connecting the 2 motors electrically makes a difference, that means there was probably some tune up you could have done on one of the locos to improve electrical conduction. There is an Athearn BB tune up page somewhere on the Web, I never bookmarked it.
Henry
COB Potomac & Northern
Shenandoah Valley
gmpullman tin can A drawbar might help If they run back-to-back be sure the drawbar is insulated. Good Luck, Ed
tin can A drawbar might help
Kadee makes a plastic drawbar version of their couplers which is ideal for this circumstance.
Rio Grande. The Action Road - Focus 1977-1983
Thanks, I forgot the frames of Athearn BB are energized. I'll either have to swap the trucks in one or make a plastic drawbar. I may trial a pair of jumper wires to see if they equalize the voltage between the motors in case of dirty spots on the track or wheels or pickup contacts.
My guess is that if your Geeps are still using those metal wiper bars for current distribution from the trucks to the motor, you may get better operation by replacing them with wired connections, rather than wiring the two locos together.I did all of my Athearn diesels, and got vastly improved performance.
The picture below, of an Athearn switcher pretty-well illustrates where to solder the wires on the truck. I ran them to a small piece of circuit board, using rail joiners, so that I could easily remove the trucks for servicing. You could wire them directly to the motor, though, from both trucks.
Wayne
doctorwayne My guess is that if your Geeps are still using those metal wiper bars for current distribution from the trucks to the motor, you may get better operation by replacing them with wired connections, rather than wiring the two locos together.I did all of my Athearn diesels, and got vastly improved performance. The picture below, of an Athearn switcher pretty-well illustrates where to solder the wires on the truck. I ran them to a small piece of circuit board, using rail joiners, so that I could easily remove the trucks for servicing. You could wire them directly to the motor, though, from both trucks. Wayne
That's a great idea using some kind of connector to make removing the trucks easier. The switcher chassis is what I'm using and the wired pickup is on the to-do list.
I've seen situations where two engines with the same motor (and everything else) would not run at the same speed. As suggested by Wayne, it's important to check whether differences are caused by electrical contact problems or other mechanical failures. I would certainly use polished wheels - depending on the age of the locos, the old BB locos had cast wheels that get cluttered with crud very quickly.
Simon
Worse than cast - if they were cast you could at least polish them. They're sintered - powered metal put in a press under high heat and pressure. Best upgrade to old Athearn locos you could do was replace those wheels, NWSL used to have the ones to go to, but newer Athearn wheels are at least plated if not turned like the NWSL ones. This made even more difference than getting rid of the big metal strap across the top and replacing it with flexible wire. (which you should definitely do as well)
--Randy
Modeling the Reading Railroad in the 1950's
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