Running a train too slow....... Bad for the motor???

[92hatchattack]

just asking cause im wondering ... for o gauge, is it bad to run them really slow?? does it put alot of strain on the motor??? does it depend on what type of train it is and the quality of the motor??? thanks guys!

Joe

[eZAK]

With motors HEAT is the problem not speed.

If a motor is repeatedly getting hot to the touch this will shorten it's life.

[92hatchattack]

ok, so then what kind of conditions creat heat with these toy train motors???

[SPFan]

Current through the motor is what causes the heat. Slow speed, long trains, and climbing hills all increase current flow. The two main components that are affected by heat are the the wire insulation which starts to break down between 300 and 600 F depending on the quality of the coating and the oil used to lubricate the bearings which begins to break down about 220-250 F depending on the formula. If a motor case is too hot to touch (~150F) the bearings and windings are probably much hotter than that.

Pete

[spankybird]

Joe,

It does depend a lot on the type and year of the train. New trains with speed control, such as the MTH PS2 engines can run a 2 to 4 scale miles per hour without any problem. So can the new Lionel’s with speed control.

tom

[lionelsoni]

The motor heating is proportional to the square of the current through the motor. The current through a traditional universal motor is proportional to the square-root of the torque produced by the motor. The current through a permanent-magnet-field "can" motor is proportional to the torque produced by the motor. More torque will make the train move faster, less will make it run slower. Therefore, it is easier on the motor to run slow than to run fast with the same train.

This does not mean that you cannot overheat a locomotive by making it pull such a heavy load that it runs abnormally slow even with normal voltage from the transformer. (In that case, it would still be worse if you were able to turn the voltage up even higher.)

[92hatchattack]

ok cool guys.... so pretty much as long as im not running a big load( i usualy run about 6 or 7 cars) i should be ok to run her pretty slow???

[lionelsoni]

If it's safe to run fast, it's safe to run slow.

[ben10ben]

The only real danger with running slow is stalling. Remember that when a motor stalls, its current goes through the roof. If I remember correctly, a motors stalled current is something like two to three times the current with a moderate load. That much current for more than a few seconds at a time can fry your motor to a crisp.

[laz 57]

As SPANKYBIRD says it is ok to run the engines in slow speeds as long as they have the cruise controll. I have not had any problems.
Laz57

[FJ and G]

I run all my trains slow incl MTH and Williams. Haven't had any problems ... yet. Hopefully, running my conventional locomotives slow won't harm the motors; yet another thing to worry about!

[lionelsoni]

Don't worry, Dave. It won't.

[Anonymous]

I have done allot of machining on mabuchi motors as they are so cheap and built to handle a ton of current.
!st the armatures are wound with 16 gauge electric motor wire so heat is not a problem.
The reason they get noisey is the bearings are cast and have excess play in them.
Out of a box of 25 at our local axman store we were able to find 4 that would run at 12 volts and feel smooth. The rest had quite abit of vibration in them, which wobbles the flywheel at speed and makes a loud growling sound.
We use those motors for trued flywheels done on the motor in the engine and the others we convert to ball bearings. We use the 3/8 diameter with 1/8 hole 25,000 rpm bearings Make a press bearing assemble for the front bearing and just mill out the rear hole to allow a 1/1000 press fit.
I then take the armature and balance it on a two razor blade assb making sure every thing is level. This gives a statice balance of the armature like the old bubble balancer for car tires.
Now with the motor assembled in the engine and flywheel pressed on, (we press .025 hole to .025 shaft) and this is a nice and easy press.
Now the big trick, prop your engine up with some solid blocks so you can run the motor mtg in the engine connected to the drive train at about 12 volts.
I now take a flat meduim file about 1/2 inch wide and gently lay it on the spinning flywheel. Then I stop the motor and take a look at all the high and low spots on the flywheel. Then I keep doing this until I can find no more high and low spots.
Then with the flywheel spinning I start with 600 grit to smooth the flywheel ending up with 2000 grit.
I then take a dial Mic and put it on the wheel and it will show a run out of +- 0/1000
Just did this to my MTH Greenbrier and low and behold the loco now coasts when power is shut down, growl is gone and when running it with sound off all you hear when the engine goes by is a faint whirring sound.
Current of the engine dropped by 1/2 an amp.
If you enjoy this type of work it is neat to have them run that great.
Dave. email me if you have any specific questions "[e-mail]"
I was blessed with a fellow friend with his DR. degree in electrical engineering and another fellow with his Dr's degree in Mechanical engineering. They where both in model railroading and took me under their wing and were willing to answering my 1001 questions one at a time.
Dave. Ps was even shown how a pure DC sine wave can have an AC properity to it, both on paper with math and on a very neat O scope with a super sensitive time base.
Hewitt Packard to be presise,.

[Anonymous]

One more thing, pittman motors are built to withstand 300 degrees centigrade and the mabuchis with the heavy wire will go super hot also. Not to worry with these motors.
Tiny can motors with tiny aramaure will fry on 24 volt spikes of cruse contorl.

[thor CNJ]

Running fast is good. Most people who run slow are people who are too chicken to run their trains.[:P][:P]

[sulafool]

DC sine wave?? HAHAHHAHAHAHAHAHA !!! Good one, Northern 1 !!!

[FJ and G]

northern1,

I enjoyed reading your explanation but I'm now satisfied that my motors won't burn up. Your comments go to show that you can take model railroading to any level you like and continually grow in the hobby.

I don't know how anyone can get bored with so many things to do and learn.

Dave

[Anonymous]

Thor, good point. Im the same way. Thats what magnetraction is for anyway!!!