MTH smoke unit issue

Yep, the smoke impeller is slipping on the shaft.  When it's in idle mode and the motor spins continuously, it's fine, but when it's starting and stopping, the impeller can't change speed that fast.  Pull the impeller off and put a drop of CA adhesive into the hole and slide it back on.  Make sure you don't glue the impeller to the motor body or it won't work at all.

@gunrunnerjohn posted:

Yep, the smoke impeller is slipping on the shaft.  When it's in idle mode and the motor spins continuously, it's fine, but when it's starting and stopping, the impeller can't change speed that fast.  Pull the impeller off and put a drop of CA adhesive into the hole and slide it back on.  Make sure you don't glue the impeller to the motor body or it won't work at all.

Thanks John! Sounds easy, but I’ve never actually opened up a steamer before, so it should be interesting!!

Thanks again, John. As usual, your diagnosis was correct!

I wonder if you would mind if I picked your brain a bit. I know you have a lot of experience with both Lionel and MTH. Until recently, I ran only Lionel legacy, but I bought the new atlas premiere Amtrak P42s because Lionel does not have a scale model available. I’m quite pleased with the engines, but I have noticed that they just don’t have the low speed performance that Lionel Legacy does. I primarily make videos of trains entering or leaving the station and it requires extreme slow speed action. Is it just me or is this a known fact that Lionel has a better and smoother low speed operation? And if so, is there anything that can be done to improve the smoothness at low speed these atlas engines?

PS2 & PS3 only guarantee 5 scale MPH and higher operation.  Most of them will do better, but my experience is Lionel Legacy is still the creeping champ.

One thing you can do is do anything to reduce the drive line friction, though that's a pretty tall order.

One thing that Lionel Legacy does, at least for the RCMC and later boards, is tune the servo loop response to the specific model.  In addition, Lionel Legacy has back driveable gears that minimize the two motors fighting each other.

I'm almost certain that MTH doesn't do a similar thing.  I found that out putting Legacy hardware into upgrades, the very low speeds are hit or miss with the upgrades, and I was told that is precisely because of the servo loop response tuning to the actual Lionel model.  I is also noteworthy that I was putting the Lionel Legacy boards in MTH diesels.

Thanks John. It’s good to know it’s not just me. These Atlas P42s do smooth out around 3 or 4 smph, which is pretty good, but I’m used to Lionel Legacy engines starting and running very realistically smooth at speed step 1, which is 1.5 smph.
Atlas engines also lurch a bit when they first start to move. I’m guessing that’s because of the lack of back driveable gears. ( that also makes it much harder to clean the wheels!)

This is a good thread. I got a Dreyfuss Hudson PS3 and the smoke output is kind of weak. Not the jet I'm used to seeing. So clearly it's something to do with the blower and the lose impeller makes sense!

3-4 scale MPH is about right for a typical MTH diesel.

@Scott J posted:

This is a good thread. I got a Dreyfuss Hudson PS3 and the smoke output is kind of weak. Not the jet I'm used to seeing. So clearly it's something to do with the blower and the lose impeller makes sense!

The tell tale for this condition is ok smoke at idle, and either weak, or almost nonexistent smoke during chuffs. When idling, the motor spins long enough for the impeller to just come along for the ride,….when the chuff occurs, the motor gives a quick spin, and then brakes. A loose impeller never gets a chance to spin when the chuff occurs…Or it spins very briefly, giving a weak pathetic ooze out the stack,….

Pat

A burned wick can also reduce smoke output on that dreyfuss.  Pat's right on the sign.  Good at idle bad on chuff.  G