TMCC engine speed limit setting

It could have TMCC with EOB in it and I believe the max speed setting takes different keys on the cab-1 or cab-2. Someone more familiar than me can chime in here.

Thanks, Ted, it does have EOB.  There's quite a discussion in the manual about how wonderful it is.  I had assumed that the Atlas manual that came with the engine was wrong on this  procedure.   Funny thing is that  when I use the sequence as in the manual, I get a single horn blow as if the thing took the setting.  But, no, it makes no difference. 

You might check the spacing and alignment of the tach sensor.      Check it's plug and whether all the wires are ok.          j

Thanks,  John.  I will look at that.   Incidentally, I have 2 other Atlas 3-rail engines and they all respond to the throttle exactly in the same manner, sluggish on take-off and can easily run away if you're not watching.  I have not tried to set maximum speed with the other 2.  

The "standard" TMCC speed limit setting only works on an engine running in 32 step TMCC mode.  If you have something like EOB or ERR cruise running with more speed steps, the speed limit setting will not work.

@Phil McCaig posted:

Thanks,  John.  I will look at that.   Incidentally, I have 2 other Atlas 3-rail engines and they all respond to the throttle exactly in the same manner, sluggish on take-off and can easily run away if you're not watching.  I have not tried to set maximum speed with the other 2.  

Phil, I have the same problem with an Atlas O GP-9 with EOB. Seems to run OK and then periodically it will just start running at high speed without any input. I've thought it was a problem with the EOB. I wonder if this is related to what you're describing, or if there's something wrong with the EOB.

Something wrong with the EOB, what we're talking about is simply setting a maximum speed that you can command.  If the engine just takes off without any change in command input, that's usually the tach reader or wiring.  Many times the wires break right at the tach reader board.

Well, Breezinup, what I was talking about was just the fact that I couldn't get the maximum speed setting to 'take.'  The engine responds to throttle commands just like 2 other Atlas 3-rail engines I have.  And, when I said that it can run away, what I actually meant was that the motor driver circuit ramps up suddenly after a sluggish start IF your speed control (throttle) knob is turned up too much at the beginning.   If you're not used to these engines you might turn that knob a lot more than needed while wondering what's wrong here, because it's starting out so slowly.    In that instance, after a sluggish start, the engine will rocket away.  When you're used to the sluggish start you realize that it's just how it is and the engine will behave very nicely.   I have Lionel engines with both TMCC and Legacy and I also have MTH engines with PS2 and PS3 and none of them behave like the Atlas engines.  If your engine is running along nicely and suddenly takes off at high speed I would have to think that there's an intermittent issue with the wiring to and from your tach reader at the motor or the main circuit board, whichever one it is.   Some of the engines just are so cramped for space it's almost a given that there will be wiring problems at some point.   Good luck with your engine.   I still am wondering why my engine won't take the top speed setting command, not that this is the end of the world.  The horn honks once at the end like it should but doesn't change anything.  It's good that I like puzzles.   

@Phil McCaig posted:

 I still am wondering why my engine won't take the top speed setting command, not that this is the end of the world.

I thought I already explained that, did you miss my previous post?

@gunrunnerjohn posted:

The "standard" TMCC speed limit setting only works on an engine running in 32 step TMCC mode.  If you have something like EOB or ERR cruise running with more speed steps, the speed limit setting will not work.

 Phil, I agree as to how EOB respond to throttle settings. They start out slow and ramp up to the last throttle setting. It’s just human nature as the engine is slowly accelerating to keep turning the knob trying to speed it up. I’ve had better luck running them with a DCS remote. Just a better feel with the smaller knob with detents. The speed steps are displayed on the screen. With practice you can just turn the knob and know which step to stop at.

I tried 100 speed steps set on my EOB boards and went back to 32 steps I think having the ability to set min and max speed as well as momentum ultimately gives me more control than having more speed steps. Set your momentum to  "L" and the loco will more closely follow your movement of the throttle.  You will have to simulate momentum with the rate you move your throttle but the loco will be less likely to run away on you. If after all this your locomotive just takes off without throttle input I would do a reset.  Oh and dirty track and wheels can cause erratic operation. I bought some passenger cars a few years ago which looked like new on the top but the lights flickered like crazy and that in turn drove odyssey crazy. I knew my track was clean as were the loco wheels so  I turned one of the cars over and took a look at the wheels and both the wheels and pickup rollers were coated with crud.  I cleaned the wheels on all the cars, the lights stopped flickering and the loco started behaving properly.          j

@gunrunnerjohn posted:

Something wrong with the EOB, what we're talking about is simply setting a maximum speed that you can command.  If the engine just takes off without any change in command input, that's usually the tach reader or wiring.  Many times the wires break right at the tach reader board.

Thanks, John. I figured it was something with the EOB.

It's an older engine, but never run before - the problem appeared during it's first operating session. I'll check the wires.

Check and see if the tach strip is falling off, the old glue may be giving way.

Hi, Gunrunner...sorry I missed your first post on this topic.  I offer no excuses, just hurrying.  The 32 speed step setting was no help but turning off the EOB system fixed both complaints I have about that system.   Now my top speed is exactly like I wanted it and the sluggish startups are gone.  The reason I was so concerned is that if the grandkids (or even adults unfamiliar with the way the engine was responding to the throttle)  were to run one of these engines it could easily have wound up on the floor.  Thanks for your help because it took me to the page in the manual describing how to set the desired speed steps and how to turn off EOB which seemed to be my last hope.

@gunrunnerjohn posted:

Check and see if the tach strip is falling off, the old glue may be giving way.

OK - I'll check that, too. Thanks.

 I still have a few engines with EOB. One thing I learned early on with a runaway at times engine. If you are running steam. Turn off the EOB. The engine should run okay. If the chuff signal is triggered by the tach reader.  If you notice it missing chuffs or no chuff at all at times. There is something wrong in either, the tach reader gap, the reader itself, or the flywheel tape. 
 My problem engine was the way the tach reader mounted to the motor.Ran fine most of the time. For some reason the gap didn’t stay consistent. Just adding the slightest downward pressure kept the chuff consistent. This was accomplished with a roller base.  A simple brace seemed to work to steady it and fixed the problem.

@Dave_C posted:

 My problem engine was the way the tach reader mounted to the motor.Ran fine most of the time. For some reason the gap didn’t stay consistent. Just adding the slightest downward pressure kept the chuff consistent. This was accomplished with a roller base.  A simple brace seemed to work to steady it and fixed the problem.

Mounting the tach reader properly would have fixed this properly and you'd never see the problem again.

 John, I thought I had something else going on. The engine ran fine for probably 6 months. I figured if it was the gap it would have acted up right away. It didn’t do it that often. I turned the EOB off while it ran at a steady speed on the roller base. Every now and then it would miss a chuff or not chuff at all for a bit. The  gap seemed okay. I think they provided a piece of styrene to check it. I adjusted a lot of points early in my career as a mechanic. It seemed right as it had just a bit of drag between the reader and flywheel tape. Your right bringing it closer would have solved it. It was a Weaver brass steamer. I remember it having a large can motor and a small flywheel. Rather than rip out what was there and try to re do it. A brace was fabricated out of brass and it seemed to add some slight downward pressure to fix it.