Noisy motors...

[Lek]

After deciding to rekindle this pastime, I've bought quite a few secondhand diesel locos on eBay. I've been going through them servicing each one as I buy them, but a couple are extremely noisy (and extremely slow), I've stripped the motors down, cleaned the commutators, oiled the armatures and put new brushes and brush springs in, yet they still seem noisy and slow. Spraying switch cleaner onto the commutator whilst running gives it a speed boost and usually fixes things as it lubricates as well as maintaining good conductivity, but the odd one or two quieten for a short period, but soon go back to being slow and noisy.

 

On the worst offenders, I've noticed copper showing through the commutator where it has worn against the brushes, so I'm assuming these motors have done many hours of service. What's the best thing to do in this situation? Is there a way to save these tired and worn motors, or should I look at a replacement motor / bogie? If this is the case, where do you buy replacement motors / powered bogies?

[RAF96]

Depends upon the actual motor, some are infinitely repairable and others are throw away.

There are several places that sell spares for most repairable motors and other places that will refurbish your motor. The same places will sell replacement throw away motors.

First you need to pull the service sheets for each of your locos and find out what the part numbers of the spares are you need and see where you can source them from.

[kevinlms]

These motors have slots in the armature. Have a look at them and see if there is brush dust in them, if so clean them out.

 

Perhaps the armature has gone open circuit on one winding.

If you have a multimeter, check the coil resistance, they should be the same between each pair. If one is higher, it has gone open circuit. It is possible to rewind them, or better still get it done professionally.

[ikcdab]

You say you have serviced the motors. Do they run noisy out of the chassis?

If not, then maybe it's a noisy geartrain.

If you haven't done so, try cleaning the gears and relubing those.

[WIMorrison]

An ultrasonic cleaner used with white spirit is about the best way I have found to clean gears and motors - you will be amazed how much crud comes out using one of these, best £25 I have spent in a long time.

[DCB]

Copper showing through sounds like Hornby.  Most others have copper coloured commutators.  The slowing could be brush spring tension or the lack of it.   The silly push on brush spring cap on some Hornby models is a really stupid idea 

Lima commutators wear away as does the plastic gear ion the armature so the armatures become scrap ,

Some motors run fine on smoothed DC and growl like a tiny bear on PWM so it could be your controller.  Not sure a spoak in white spirit is good for armature windings, I wouldn't risk it but the ultrasonic is a good tool for mechanical parts.

[SamThomas]

If you have a PWM controller & no smooth DC supply you could try a 9v PP3 (smoke alarm type) battery - can't get much smoother than a battery.

 

Also a good thing to carry to shows (when they start again) for testing used locomotives.

[The Johnster]

Some older motors and gear trains (especially gear trains on pancake motored models with spur gears) are noisy and there is not much you can do except live with it, but a modern mech with can motor driving through a worm and idler cog gearbox should be pretty quiet.  If one of these is noisy, it means that energy is going somewhere it shouldn't to create the noise, and you will find the loco to be a slightly (sometimes more than slightly) stiff starter and stopper.  I have a Silurian era Airfix large prairie with gets an outing occasionally, and the noise is not unlike a 37, but she is a very smooth runner for all that

 

Motors will buzz at low speeds with PWM controllers, as the current is repeatedly asking them to start and stop and they get confusticated, and start 'cogging'.  This generates excess heat and it is recommended to smoothly accellerate out of this rather than leave the loco running like this for any length of time, but sometimes a sustained crawl is needed, for instance propellling wagons into goods sheds.  The PP3 tip is a good one.

 

If you have a new loco that makes an unexpected noise, send it back for replacement.  Otherwise a motor hygiene regime and replacing the coloured grease lube with non-mineal fine machine grade oil applied as sparingly as you can manage is the best you can do.

 

Buzzes and motor cogging sound like an angry bee, a rapid brrrrrrrr suggests a gear train issue, and clicking, which may be more pronounced in one direction, suggests something fouling in the wheel spokes, usually a pickup.