Who knew little diesels needed a warm up?

[jagged ben]

Just to add, it's not only slow speeds where I see this.  In fact my most objective observations are at top speed, where I start my speed matching.  Almost all locos need at least a couple laps around my ~30"x36" test track oval before the speed more or less stabilizes. 

[sizemore]

While the great scientific debate on lube, delrin and chafing of parts has ensued, I switched out the DN163A0's (Series 3) for DN147A0's (Series 7). There was no hesitation in throttle response, they just crept along on the first notch (01) of the throttle. I then took the old DN163A0 decoder and put it in an early DCC ready GP-40 (pre-sound), and it did not exhibit the hesitation or sluggishness, it just crept along at the first notch.

Inspection of the motor between the GP-40 and the C420, the C420's show a greater skew of the armature. The winds of the armatures are almost indistinguishable without pulling it apart. I then compared it to Atlas GP-9's which had the same skew as the GP-40. At this point I am largely convinced this is a motor difference (not issue) and motor control capabilities of the old decoder. Given the change in decoders also changed the performance I am also leaning towards tehachapifan's point concerning the quality of the decoder.

Thanks All,
The S.

[peteski]

Thanks for the follow up S!

[MILWcoastdiv]

I definitely notice what is being discussed here mostly with older Atlas.  I have 3 Kato F units that have been in a consist for 3 years with NCE decoders, sit for months and start right up and all speed matching is perfect.  Same type of decoder in Atlas locomotives and it seems like I have to adjust speed matching everytime. I try to run them in consist and forward and reverse trim always goes out of adjustment.  ESU decoders run perfectly out of the gate and seem to remember speed match settings perfectly no matter how long they been sitting unused.   In my case, basement conditions, type of locomotives ect ESU is what I'm trying to standardize with.  I'm in the process of retrofitting older Atlas with with V5 decoders now so it will be interesting how the they run, remember speed settings and generally operate.

[jagged ben]

Most Atlas designed trucks have more gear friction than Kato.

[peteski]

Most Atlas designed trucks have more gear friction than Kato.

Probably due to loser tolerances and quality of the plastic used.  Best way to test this is to remove *ALL*  lubricant (including the axle bearing cups)  and then roll the trucks on inclined piece of track.

Since the plastic used for gears and the gear-case is very slippery, the only required lubricant should be oil in the metal axle cups, and maybe on the worm wheel since it meshes with a metal worm.

[MILWcoastdiv]

I'm amending my "ESU decoders run perfect" statement, went down stairs last night to relax after a hellish week of work and run some trains.  2 fairly new Intermountain SD40s in consist w ESU - both ran perfectly a few weeks ago, now one of them barely runs, spits sputters ect while the other is fine.  So now I'm down to just 1 class of locomotive that I own that I can say is reasonably reliable -  a 79.00$ Bachmann RS3.  That locomotive can creep around my entire layout and not stall on turnouts whether its been sitting for 6 months or not.

[peteski]

The wheels can be dirty, or some CVs in the decoders could have gotten corrupted. Or it can be something mechanical. I wouldn't jump to conclusions just on the initial observation of the problem.

[MILWcoastdiv]

I don't mean to belabor this topic but I just noticed something:  On my upper level the locomotive trucks are at eyelevel and noticed something new to me.  I don't normally run my intermountain SD40s up there because it's more of a branchline but with the slightest divot or un even track the trucks don't flex at all and the wheels go slightly airborne and loose contact and stall.  I wonder if the condition is a big source of my headaches on my layout.  I took a look at my 5 intermountain SD 40s and there is absolutely no side to side floatation.  The Atlas 4 axle locomotives all seem to have a bit of looseness, my Kato Fs don't.  Bachmann RS3 does.  This kinda all correlates to what locomotives seem to run better for me anyway.