I have no experience replacing either motor or gears.
When I look at possibly replacing a motor, possibly with something I have lying around, I wonder if the worm can be removed and used on the replacement motor.
One consideration is the shaft size of the replacement motor. It’s obvious that the worm cannot be re-used if the shaft sizes are different.
I also wonder how easy it is to remove a metal worm on a metal shaft. I was unable, with a press. I wonder if the worm was heated, expanded, before it was mounted to make a very tight fit.
and if the worm needs to be replaced, either because it can’t be removed or the shaft sizes are different, should the wormgear on the axle also be replaced as a set so that the spiral match?
if so, replacing a motor is more than just replacing a motor and the worm/wormgear may be more expensive than the motor.
It is very possible that the worm was heated before installation. Have you tried heating it before using the puller? If you have the space you might consider putting a heat sink on the shaft too. Small needle nose pliers with an elastic band on the handles work well.
Put the whole motor with gear on it, into Your freezer for about an hour…then use the gear puller to take it off…should come off a lot easier, if it got cold enough. Used to rebuild My own diesel Truck engines and that is how you put the connecting rod wrist pin, ( a 4lb stainless steel rod) into the Aluminum piston…put the rod in the freezer and then, used an arbor press to press it into the piston…worked every time! Taking it off the same way…but…You never re-use, a wrist pin. Made a couple good hammers out of the old one’s…just weld a steel bar to the pin…instant whammer! LOL
Heating and cooling affects the length or dia of a metal object as a percentage of that length or dia. So the larger the length or diameter, the greater affect you will see with temperature change. So on a 1/8 diameter HO motor shaft you will get very little benefit from heating or cooling.
Also heat shrinking can be very effective when assembling parts because you can cool or freeze the shaft, and heat the bore thus creating a significant difference in diameters. But when trying to seperate parts that are already assembled you end up heating or cooling both parts together, so unless the 2 components have radically different coeffients of expansion, the benefit for separation is negligible.
I admit that I’ve never done this on a Rivarossi. On some motors of other makes, I had to apply a LOT of pressure to get the gear off. In some cases, I had to cut the shaft off to get the gear in the puller. In only one case, I resorted to drill a hole in the gear… and it worked.
Well the armature shaft should be stainless steel…the worm gear, does not look to be metal, so it should work…if anything the change in temperature may ease their set grip. It would be worth a try! To Me, anyway. But then again were it Me, I would replace the motor with a can and get the proper worm.
I appreciate all the advice regarding removing the worm from the Rivarossi motor but I still have to wonder if this is the correct thing to do?
I thought I’d try removing the motor to find out how difficult it might be.
But since the worm on the Rivarossi motor is roughly the same pitch as the gear on the locomotive, I’m also considering swapping the motor/worm with the Rivarossi motor/worm. But I’m not sure if this wouldn’t wear out the gear prematurely or be noisy?
Even if I could remove and reuse the worm from the motor on the locomotive (not the Rivarossi motor shown), I would need to find a replacement motor compatible with that worm.
Would it be better to replace both the motor and gear set?
So, are you saying that your engine is not a Rivarossi, and that you want to use the Rivarossi motor and gear instead of the original? Might be worth posting more pictures… Or give more details about the engine and make. I’m no expert when it comes to combining various makes, but some of the folks here are.
I’m asking if people who replace a motors typically replace gears because the 1) worm on the old motor may not fit the shaft of the new motor, 2) it may be difficult to remove the worm and/or 3) you’re typically better off with a new gear set because they may be better made?
Ok, so in my case, I’ve always kept the gear because a) they are harder to find than a motor; b) because matching a motor with a gear is easy using NWSL parts (e.g. they sell motors and bushings to adapt to gears); and c) I’ve always managed to remove a gear from the motor. These gears rarely wear out, especially those made of metal.
