High Iron PRR K4 Initially Struggles to Move

Stephen,

Your engine may not have a problem if everything else seems to be working correctly.  This engine has a Train America Studios (TAS) Engineer on Board (EOB) cruise control.  This board naturally starts the engine very, very slowly, which is not liked by many folks.  There is nothing you can do to help the acceleration other than to replace the EOB with an ERR board.

Yes, the EOB electronics contain a high degree of momentum.  There is no way to turn the momentum off.  Engines with EOB start and stop very gradually on their own.

Have you set the stall speed?

That could make a difference.

Happy railroading,

Don

"the engine kind of shuddered and struggled"

Not sure about the above part of the issue, but, yes, if you have EOB you will have to live with this unresponsive behavior. EOB is not a linear device and is quite maddening. I have a couple. It can usually be turned off (through commands in the manual) and a loco with good gearing can live without it.

Switcher behavior especially suffer from this feature; on a road loco (minimal starts/stops) I have found it tolerable. It makes all locos act as if they are starting 100-car trains - even when they are running light.

I almost said that you could upgrade it with ERR Cruise Commander, but, well...those days are over, at least for now. 

Thanks for the suggestions, gentleman. This is my only engine with EOB installed, so I wasn't sure what behavior to expect. It's comforting that this sounds like normal behavior.

@D500 - Yeah, bad timing. I ordered a few ERR cruise M sets when I read the announcement for some long-delayed upgrades, hopefully I got my order in in time. But I wasn't counting this engine among those, so I'll have to see if I can either live with EOB (either on or off) or sacrifice one of the cruise M boards for this...

My High Iron K-4 was sluggish initially, too. After an hour or so of running it loosened up and now runs beautifully. Yes, it does have a lot of momentum built in.

I have one of these and actually put EOB back into it so I could free up the ERR cruise board for another project. Like mentioned above, the built in ramp to setpoint can't be disabled and EOB does not respond to TMCC stall nor momentum. I'd make sure it is in 128 step cruise mode (DIR, AUX-1 three times, keypad 2), then you can use boost to start it at lowest speed step.

You can figure out if something mechanical (drivetrain/rods/brake shoe hangers) is causing jerky behavior by putting it into 'open loop' (cruise off) by doing the above sequence and hitting 3 on the keypad. Keep in mind that EOB puts a fairly high starting voltage to the motor in this mode but it should help you figure out if something is hanging up/rubbing, etc. 

I always like to check the encoder by turning the motor by hand and making sure the LED lights up for each black stripe. The only other thing you can do to improve low speed performance is to adjust the background pulse but this usually ends up giving you a higher start speed.

These engines top out at maybe ~50-55MPH for some reason, probably due to the pulley/gear ratio.  

I just got a 3rd Rail L3b with factory EOB and I was pretty stoked that it worked. I also run a 3rd Rail M1a with factory EOB and it runs well. My only gripe with EOB is the lack of a ramp to the first speed step. They sort of start 'smartly'.

I had a 2-rail version loaned to me from a friend and we found 2 mechanical problems.    the belt connecting the sprocket on the axle to the motor was too tight causing very hard starts with no electronics at all.

the second issue was that the trailing truck spring was too strong or hard.    basically the trailing truck was lifting the rear drivers and possibly the middle ones off the rails.    Essentially it was a 4-2-2.   

Sunset provided a new belt and we took a couple of loops out of the trailing truck spring.    the hardest part was getting the boiler off to change the belt.    There 6-8 small bolts on the back of the cab that hold the back of the superstructure on.   these are very soft metal of some kind and the heads tended to crush when we tried to remove them.

Thanks for the additional suggestions, guys!

@Norm Charbonneau I saw those different settings in the EOB installation manual posted by GunRunnerJohn in the manuals reference thread. In my visual inspection nothing looked like it was impeding anything, but checking the encoder would be a good confirmation. I noticed its speed sort of maxed out when I hooked up a 4 GGD coaches to it; besides still having that sluggish start, it didn't seem to have any issues hauling them. Does your have any issues traversing your Atlas #5's? Each leg is wired but this engine still seems to lose power momentarily while going over them.  

@prrjim I'll keep the belt tension issue in the back of mind to check after I play around with the electronics a bit more.

I don't have any issues traversing my #5s with this engine but I don't normally run it very slowly over switches. I can't remember if it has a tender pickup roller.

Keep in mind some of these TMCC/EOB 3rd Rail engines have fully insulated tender wheels so the  whole tender (including truck sideframes and axles) can be used as an antenna. These engines can suffer a bit for a good ground if you have insulated rails for signals and accessories. Be mindful of this if you ever install Kadees.

Antenna issues can also cause jerkiness. The old TMCC mind meld (hand over the engine) trick is good for checking this. Look closely at the tender and make sure the previous owner kept the electrocoupler insulator in place.

I seem to remember having a collapsed spring or two in the drivers. I think these shipped with some spares but I may be wrong.

These engines also had the adjustable reverse arm in the valve gear. I think if it's too far out, it can cause some binding.

I suggest removing all the electronics and testing the loco on straight DC to determine if there are any mechanical problems.    IF there are none, then the focus can be on the electronics.

Easier to desolder the motor leads and put a DC power supply to it while up on Jak blocks if you wanted to go that route. Sounds like it runs and drives though, so a few simple checks and tweaks might be all it takes to get it figured out.

From everyone's comments, it sounds like this is typical EOB behavior; if not, I have a few things to check that are less drastic than gutting the electronics to test for any the mechanical issues. It didn't have any issue running at high speeds.

I played around with it for a few minutes last night, nothing mechanically. It seems to start better after setting it to the 128 step cruise mode. I also noticed too that it responds better when using my Cab-2 than with my Cab-1L, for whatever reason.

(And Norm, there is not a pickup roller on the tender. As it crosses my Atlas #5 it momentarily losses power, which at a high enough speed is not a problem, but I still might look into adding an additional roller there.)

I looked mine over a couple nights ago and noticed that too. In any case, here are some vids of my K4 (the 1737) and a pal's (1361) I fixed up. Please note that I neglected to adjust the fireman's side eccentric on the 1361 after some other minor running gear fixes. Last vid is my 1737 on my old layout with ERRCo cruise and no sound.

Thanks Norm, especially for the first one. That initial movement from a dead stop seems similar to mine.

It's me again. I finally found some time to take the locomotive shell off. I have a couple questions based on what I've seen. Please see the attached pictures.

(1) There was a wire with heatshrink that had been rubbing up against the tach strip. This left a series of black marks across the tach strip. Will this impact performance of the EOB tach sensor (might explain my issues)?

(2) There are two wires disconnected, one red and one green. I'm assuming that the detached red wire goes to the connector with the red wire attached and the green wire goes to the connect with the red and brown wires (whose mate has a full set of green, red, and brown wires)? Any one know what these power? The left marker light on the pilot is not lit, but it's hard to see up into the engine shell where these wires run. I haven't used the smoke unit, so no comment if that works.

As always, any comments / suggestions are welcome!

The black marks could be an issue. To check, apply power and spin flywheel very slowly with your finger. The red LED should blink with every black bar. Also if you have the instructions you may need to reset the pulse width modulation for the motor. I’m going by memory, I think that’s what they called it. I can make copies and email you if need them. That of course is if they used the same boards they offered to the public.The very slow speed up is momentum built into the unit. Nothing you can do about it. Sent GRJ an email. He may be able to shed some light on this for you. 

Link to 39 page EOB installation instructions.  From the forum TMCC/Legacy Control reference section.   Includes a lot of adjustments via the handheld Cab1 remote.  Some of the adjustments may improve performance.  Adjustments and setting begin page 27.  

You can fix up the encoder with White Out and a Sharpie. I would not adjust the pre pulse and chuff until you do so. Cleaning up the encoder will probably cure all the stuttering at low speed. That green wire looks like it came out of the plug (smoke unit or lights?) and the red wire probably snapped off a switch.

Thanks for the suggestions. I'll try cleaning up the encoder before fiddling with the settings, hopefully that'll take care of it.