Identical locomotives....different speeds?

[Anonymous]

I just received 2 Proto 2K gp30s from Trainworld. They seemed a great buy. Out of the box they operate at very different speeds, so much so that I don't want to run them together for fear of screwing up one or both. Is this part of a break in period or a defect. Or was Trainworld unloading some substandard P2Ks?

[Anonymous]

It's been my experience that identical locos can run at near the same speed. I have four P1K F3, A-B sets
that are similar in speed and can run them as a A-B-B-A consist.

I also have three P2K- E7s older releases , where there is a 5% to10% difference in top end speed
and a 10% difference between the E7 & PA which have identical motor/flywheel etc.

Obviously you are not DCC. Perhaps you can determined the speed, the total feet start to finish,
achieved in seconds.

One of my E7s will do 40' feet in 19 seconds and the the other in 17 w/o cars.

Found a second P2K-PA and at the top end there's a four second difference in 40' feet

My GP 30 will do 40' in 22 seconds or 20' in every 11 seconds w/o cars
My GP 20 is about the same speed w/o cars

What will yours do? and then you may wi***o use that as a comparison.

[sparkingbolt]

I bought 2 P2K S1 switchers and they run at different speeds too, for no apparent reason. I posted a thread likt this one, and was informed that since both run smoothly, there would be no point in trying to get them fixed. So, yes, it does happen. I just don't double head them. Dan

[Anonymous]

There's ways to remidy it such that they run the same speed. If you're not using DCC (which really makes this easy), you can buy some resistors (someone with more expirience in this is sure to pop up), and wire one onto one of the motor leads on the faster loco. It may take some experimentation to find the right Resister value, but you can usually get the lcoo's to run realatively the same speed this way.

In DCC, you'd just have to play with the faster loco's speed tables a little to bring it down to the slower engines speed.

Jay

[cacole]

If you put the faster locomotive in front so it can help pull the slower one along, this should cause no harm to either locomotive unless the speed difference between the two is really drastic. After breakin, they might run more closely to each other.

[Wdlgln005]

I'd check that the contacts on the slower locomotive are clean & everything seems to be properly set. I'd also look for any burrs on the gears.

The second solution seems to be to try to run a wire from the frame of one to the other. Let's have real MU connections, so that you have 2 unit pickup, operating together.

[Anonymous]

I have 2 Athearn SD-45s, one of which goes almost twice as fast as the other. Repeated lubings and cleanings.... to no avail! One was built on Friday afternoon or Monday morning[:D], without a doubt!!

[Anonymous]

I had a very strange HO U33/36 C Atlas. After a few years I purchased a second one and it was 1/3 slower than the older one.

Not being DCC, couldn't double head so it got very little use.

A few months back, it got slower & slower.

An Atlasrr member suggested new brushes and did so.

WOW! Now top heavy in speed.

I still don't understand that one, premature ware out or ?

[Anonymous]

Well my question is, Is is better to push another loco or is it better to pull it, does one cause more damage over the long run? My locos are broken in and still run at different speeds.

[AntonioFP45]

Interesting, seems like this is quite common!

I have two P2K E7s that I purchased new. Yet, one will outrun the other. This is another reason why I'm looking forward to DCC as locomotives can be programmed to run at comparable speeds to each other when this problem occurs.

Cheers!

[NZRMac]

I have two BLI SD40-2 which run at different speeds, what CV's do I adjust? Vmax or something?

Cheers Ken.

[bogp40]

QUOTE: Originally posted by cacole

If you put the faster locomotive in front so it can help pull the slower one along, this should cause no harm to either locomotive unless the speed difference between the two is really drastic. After breakin, they might run more closely to each other.

For many years on a DC layout, I would set up MUed lashups w/ the faster locos in the lead. I believed that overrunning the gears on the slower loco(s) would cause the least harm. While (DCC) aquiring my locos for a consist, I realized that the faster loco was behind(coupled to a15 car train), with the slower one in the lead. They were still uncoupled and checking direction/headlight before mu-ing. I ran the locos after mu and noticed that they ran very close to the same speed. Apparently, the faster loco is slowed by pulling the train with the (was slower) one running along out front uncoupled. I experimented with other locos and this arrangement seemed to work better than running the faster in lead. If you have a drastic difference in speeds or are not pulling a good size train, I would not run them together. I am so skeptical about having problems w/ gear wear of constant plus or minus gear lash.
All I can suggest is to experiment w/ your various lash ups- coupled or uncoupled to see what works best for you situation.
Bob K.

[jsoderq]

If they do not run equally do not run them together. You will cause the faster loco to pull harder causing excess wear on things like wheel bearings, drive shafts etc and one or the other motor will generate more heat ( I foget which one) causing the magnetic field to deteriorate. Two LL locos are not necessarily from the same run and may not have the same gear ratio (same is true for Bachmann).

[Virginian]

I don't know, but I think the main causes of this are the motors. The old Canon can motors had an adjustable brush holder end, and by varying the timing just a hair you could radically alter the speed curve. Perhaps the assembly tolerances on todays motors or the way the brushes and/or holders are made yield the same result.

[AntonioFP45]

Since my units are earlier run P2Ks (1998) I'm going to replace the motors with Mashimas or Helix Humpers since for DCC recommendations, low-amp draw motors are recommended.

[siberianmo]

Interesting comments to a problem that I've accepted as commonplace .....

My inventory of HO loco's is rather extensive - all diesels and all from the leading manufacturers: Athearn - Walthers Trainline - IHC - Rivarossi and Bachmann. In EVERY instance where I purchased two loco's that were supposedly "identical" - one ran faster than the other .....

The "fixes" mentioned are worth looking into .....

See ya![tup]

[oleirish]

I have two athearns SD40's running togethor and have no problems with them.both are fly wheel ,stock motors .[:)]they are two years apart in age.By the way how do I change the engine numbers?They both have the same number on them.They are in SP colors#4823.
Jim[:D]

[Anonymous]

Jim, I think it's possible to buy "patch" decals to cover the old number, then put a new number decal on top. Not sure who makes these though.

Re: The different speeds problem. If one loco is a lot slower than the other then you should check that nothing's amiss - I have a Bachmann N F7A that arrived from the factory running very slowly and overheating, which I traced to a mangled pickup. I wouldn't have realised the problem existed were it not for my brother's F7A which he'd bought a few months earlier (which ran perfectly), and would probably have burnt the motor out before realising. I've had some surprising "matches" in loco performance under DC - managed to run a mixed Roco/Proto 1k lashup (Proto C-Liner A/B and Roco Sharknose A) without any problems. The problems came with DCC, or specifically with the cheap Bachmann decoders - avoid these if you can, as they have a speed curve more suited to a race car than a diesel loco!

[Don Gibson]

SOUND's LIKE ... two different production runs, or different motors..

For year's P2K's Geep's all ran at the same speed. (GP-20, GP-30, GP-9).They all had the same drive component's.

Call Life Like's service department. Maybe they'll swap one out for you.

I would.

[dave9999]

Sounds like a good excuse to get a DCC system[:-^][:D] Dave