Quick and easy question; I have a Rivarossi Pacific with a cooked motor and an 0-8-0 Switcher that runs okay. Can I just use the 080 motor in the Pacific?
Not as-is. The 0-8-0 has a worm gear mounted directly to the motor shaft; the Pacific uses a coupling. The shaft on the Pacific’s motor is shorter too. I suppose the motor on the 0-8-0 could be modified to fit the Pacific; however, it wouldn’t be usable on the 0-8-0 ever again. May I suggest a look at Doug Gosha’s excellent study of first-generation Atlas products? Here is a link to his Atlas/Rivarossi motor page: http://www.irwinsjournal.com/a1g/a1glocos/motors.html (With thanks also to George Irwin!) Jim
This TrainBoard link might be helpful too. @mmagliaro provides rebuilt and improved Rivarossi motors. https://www.trainboard.com/highball...rivarossi-steam-loco-motors-available.137083/
FYI - Unfortunately he has run through his stock of parts to rebuild the Rivarossi can motors and he's not intending to do anymore
Seems like "quick and easy" is neither. One of the advantages of turntables with extra, exposed spoke tracks is they make great places to park a scenic yet immobile locomotive (aka "hangar queen".) Or you could remove the motor and gears, and use it as an unpowered helper.
You could try a 12 volt DC 12mm x 16mm coreless motor from China (aliexpress) or somewhere else like tramfabriek. You'd need to use probably a couple of styrene spacers to secure the motor in the frame. (just a thought). The one I'm thinking of has a double shaft but you'd cut one side off. However then there is the problem of securing the pin that the drawbar connects to which is on the RR motor. Could be a nice challenge.
Thanks Jim and this actually reminds me of a shortcoming on the Rivarossi motor page, I should have addressed the different configurations of the motor in the various locomotives with pictures. There's always something. If you were absolutely sure you would never want to reinstall the motor into the 0-8-0, you could cut the shaft off to the same length as the motor in the Pacific but, as Jim said, you'd never be able to use it in an 0-8-0 again. I know I would be reluctant to do that. Doug