Atlas Engine with PS2 Jackrabbit Speed

I was under the inpression it would run smoothly and the accelaration would be as linear as the MTH engines.  This engine on the other hand at 5 smph flys around the layout like one of my MTH engines at 25 smph.

Most likely it's either a problem with a wrong or damaged tach tape, or a mismatched sound file, since that's where the speed parameters (driver size, gear ratio, etc. ) are.

It could also be a mis-spaced tach reader.

The easiest thing would be to contact the seller to see if he has any clue what might have been done during the upgrade to throw off the speed.

Most likely the issue. Since MTH motors will not work in the Atlas engine. He had to mount the tach reader on the Atlas motor. Its an easy fix.

I have converted atlas to PS-2 and they are smooth.  I agree with possible too large a gap on reader.  Since 5 is like 25, versus full speed at 18V.  G

Depends on if he used the kit or a donor engine. Did they use a zip tie on the motor?

That will help a lot.

Can I rule out the battery?

Absolutely.

The tach reader is the device pointed at the striped flywheel.  Hard to tell if it is too low and misreading, or if the gap between sensor and flywheel is more then a dime in thickness.  Also is the tape on the flywheel damaged or dirty?  G

G, 

 I saw that too with the tach tape. I would clean it then test it before anything else. Hard to tell but it doesn't look like it is sitting to low.  A side shoot would have been better. But if he uses a dime to check the gap. He could quickly determine if that is the issue. Isn't it normal to have the Tach reader in the rear, not the front of the engine?

From the look of the third photo, There is too much gap between the fly wheel and the reader. Also wipe the residue of the tap. At speed the residue would look like a white streak. I had an engine do the same thing. The fly wheel had been rubbing on a wire. and had put worn marks into the tach tape.. Just enough at low speed it worked fine. At 7 SMPH it took off like a jackrabbit. 

Too much gap. Its some what of an easy fix. Can you do one more thing?  Trace the wires from the tach reader to the connector. Then un plug and reconnect them. Also have you done a engine reset factory specs ?

Doug

It is the gap.  For that smaller flywheel they should have used the 1.5mm spacer tach reader.  Your option is to use a knife or dremel cutoff and remove the tach reader and cut into the tach reader bracket so the reader can fit closer to the flywheel.  After the mod a small amount of epoxy to lock it in place.  G

Another option might be to use a plastic wire tie to pull the top of the reader over  or a shim shoved into the bottom of the reader holder forcing the top of the reader over a bit. Maybe a little of both.  Whatever you do don't try to   remove and re-solder the reader. That's for guys like George.

Everyone agrees on that one. American  dime.

You can just slide the tach reader board up out of the holder.  You need to move the wires out of the little clamp before you try to remove it.

Well, really in a couple of flavors.  There is the one for Pittman motors and one for the Mabuchi motors.

The real cure would be to get the proper tach reader with the spacer behind the sensor, that would fix it.

Send me an email and I'll hook you up.  I have several in stock.

Another option is you can order the reader from MTH with the spacer already installed.

P/N AG-0000041.

Chuck, you want the AG-47 with 1.5mm  The 41 is too thick.

It is not the holder, the tach reader itself comes in 3 variations, no spacer, 1.5mm and 2.2mm spacer.  Unfortunately the diesel kit comes with only the no spacer version.

I keep them in stock also, plus just the reader so I can build a custom one if needed.  G

OK, I was going by the space in JD's pictures.

Chuck, I have done several locos that have the 27, 27.7, or 28mm flywheels and have found the 1.5mm version is a better fit. 

Unfortunately I have also seen variations in the tach reader bracket that can cause a mismatch too.  G