F7B slower than F7A

[ftauss]

Finally have a basic double loop with an up and over setup. Going to make a portable yard next to plug in. I've bought over the years 5 F7A and 4 F7B I believe they are all Spectrum or Plus, though I only have 4 of the pacages right now.

While testing/breaking in the engines I noticed that the F7A is noticeably faster than the Bs. When running 1 A with 2 Bs I got to a spot in the track that needs work and the A separated from the 2 Bs and just walked away.

Are the Bs supposed to be geared the same or are geared to be real helpers meaning lower ratios - less speed more power.

Come to think of it are the B engines physically diffferent from then As other than the shells and lights? I hadn't compared them side by side and I'm at work now so can't check.

I would think that if you put an A-B-B-A combo on the track uncoupled they should all move off in formation without running each oher down or pulling away.

Frank

[taz-of-boyds]

Frank,

I am with you Frank.  With just my little experience and from what I have heard from others, even identical loco's will run at different speeds (with the same gearing).  I don't remember the recommendations I have seen about putting the faster loco first or last, so maybe some of the others with more experience can contribute when they get a chance.

But one thing, I remember is if you want a loco consist, to keep those loco's together most of the time so they age together.  I have an F7A-B and I worked them together during break-in (which is about as far as I have gotten for now...).  I tried to work the slower loco a bit more to see if it could catch up in speed during break-in.  I think it worked.  From what I have seen, you need to speed match the loco's from the start.

As I have read, if you go with DCC you can program in speed calibration curves.  And then program the loco's to operate in a consist.  So I have a question too for someone please:

How stable is the speed calibration in DCC, do you end up recalibrating the loco's every so many operating hours?

Thanks,
Charles

[brokemoto]

One of the problems with the PLUS was that the gears cracked.  I suspect that B-mann used different gears in the SPECTRUM F-units.  I do not know if the gear ratio was the same or different in the PLUS and SPECTRUM, but if the gears are made using a different manufacturing porcess, that could account for the variation.

I have one A-B pair of SPECTRUM Fs and several of the PLUS.  The SPECTRUMs respond more readily to the throttle than do the PLUS. 

Still, there are always variations in throttle response amoung units of the same type and manufacture.