Drive wheels

[Anonymous]

I have a 4-4-2 locomotive and if I push it by hand the drive wheels will turn. I just bought a 4-6-4 locomotive and the drive wheels do not turn when pushed. Is this ok or is there something wrong with one of them?

[spankybird]

It sounds like your 4-6-4 engine has a flywheel on the motor. The only way to turn the dirve wheels manully is to pull off the shell and trun the flywheel.

So it sounds like every thing is OK. It's made that way.

[Anonymous]

Thanks so much for the info.

[webenda]

That is an interesting observation (that it is the flywheel that causes the drive wheels to skid when pushed by hand.) I can see the reasoning behind the observation. Look inside any locomotive that skids when pushed and you find a flywheel. The flywheel will not turn when you pu***he engine, but, turn the flywheel and the drive wheels turn.

I do not believe that the flywheel is the culprit. It is the gear drive. Spur gears in the 4-4-2 can spin the motor when pushing the locomotive by hand. Worm gears (as on the 4-6-4) usually will not spin the motor when pushing the locomotive.

Imagine turning a screw while holding the nut. The screw pushes or pulls the nut along the length of the screw. Now imagine pushing or pulling the nut to turn the screw. It will not work.

As a child, I was very curious about this when I changed from O-27 to HO. HO engines had worm drives, O-27 spur drive. So, as Spankybird blames the flywheel, I blamed the worm drive. Over the years I found exceptions. Some drive wheels turn when the motor has worm drive. Whether the drive wheels turn when the locomotive is pushed depends on the pitch on the worm.

Anyone care to explain this in terms of friction differences between worm drive and spur drive?

Spankybird is correct. The behavior you discovered is normal.

[ben10ben]

It does have to do with the worm drive for the most part. I believe that whether or not you can turn a worm-drive motor with the wheels has something to do with the gear ratio as well as the angle of the teeth on the worm gear. I know that the postwar turbines and possibly a few others are worm geared and the wheels can still be pretty easily turned by hand, although not as easily as they could be on a spur-geared engine.

I've seen an excellent post on this subject either on this forum or the OGR forum, although I can't remember which.

[Dave Farquhar]

The first time I had an American Flyer postwar locomotive (with a worm gear), I thought I had something in really bad shape when I tried to turn the wheels and they wouldn't turn. Imagine my surprise when I put it on the track and it ran!

[spankybird]

Do not most engines today that have worm gears also have flywheels on the motors.

My answer was to try to offer a simple answer without getting to deep into the machinics of the engine drive system.

[brianel027]

joncoy, sounds to me like your 4-4-2 is one of the standard Lionel "Columbia" type starter steam engines that come with many starter sets. The other one, the 4-6-4 I'd be willing to be is a K-Line starter steam engine.

As mentioned above, the K-Line steamer uses a worm gear drive versus the Lionel spur gear drive. This means the Lionel one is pushed easily while the K-Line one is not. The K-Line steamer is a very nice loco for the money, and a little heaftier looking than the basic Lionel loco with a little more detail. But I do recommend the Lionel one over the K-Line one to young families with kids for this very reason. Young kids have an easier time getting the Lionel one on the track over the K-Line one.

[philo426]

Wow,I always wondered why some would turn when pushed and some would not.I guess you learn something new every Day!

[webenda]

Spankybird asked, “Do not most engines today that have worm gears also have flywheels on the motors?”

I believe that is true. Your statement got me to wondering about the K-Line Plymouth. So I looked inside...

Hey! Where’s the motor? Look how little it is. No wonder the Plymouth is so slow.

The real drive motor (under the floor boards) has worm gears on both ends, but no flywheel. No room with this layout.