Hi!

Welcome to the forum!

That sounds like analogue Märklin H0 (you put the question in General MRR without evening mentioning the gauge).

Reverse unit: very unlikely.
Gear: possible.

But most likely the collector plate of the armature is not in the optimal position.
Many locos have a slight difference of speed depending on the direction.

If the speed difference bothers you, maybe try to turn the collector on the axle or replace the armature.

The collector is the copper thingy on the armature (rotor) of the motor. The black thingy is the brush plate. The collector is hidden under the brush plate.

What Tom is describing is the timing on the motor, or more specifically, when a particular coil will turn on during motor rotation. If the collector is advanced (turned toward or favoring the direction of rotation) the motor will run faster in that direction. If it is retarded, then it will run slower in that direction. So you have a motor where the collector is not at zero timing which will make it run the same speed in either direction. Since it is faster running forward, determine the direction of rotation of the armature when the loko is running forward and then turn the collector slightly in the opposite direction on the armature (anker in German/Marklin speak). You will need to remove the armature from the loko to do this. Be careful, do not move it much.

No. Remove the brushes from the brushplate and then remove the two screws holding the brushplate to the loko frame. Lift the brushplate away as far as the connected wiring will allow and then remove the armature.

Sometimes the wires are tucked under the interference capacitors or any other handy object with the sole purpose of keeping the wiring tidy. You should be able to free it enough to remove the brush plate without desoldering.

On some locos, however, the screws for the brushplate are not accessible without removing some other part of the loco.

Interesting post. I have quite a few older locos that run faster in one direction than the other but have not yet taken any apart to really clean them and fine tune them. For example, the older 3000s including my original all seem to run faster in 'reverse' (cab forward) than with the tank in front. We ran the heck out of it for years mostly in the same direction. Others run better in one direction or the other due to the weight distribution. Be interesting to see what folks have to say.

My 3000 runs faster in reverse direction too. By the way, I managed to remove its rotor yesterday, I cleaned it and put it back, but I don't see any difference...(I didn't try to turn the collector as I didn't want to break it).
I think I'll buy a new one, I 'll keep you informed.

Hi,

I have a 3376 rail car that runs twice as fast on one direction than the other. It is an analog unit with an electronic reverse unit and I’m using a while transformer model 6646. The motor is DCM type. The fast direction is what I expect of Märklin locomotives and rail cars but on the slow direction is too slow in my opinion, plus the difference in speed is too much. With the transformer knob to full, on the fast direction the prototipical speed is about 160 km/h, but on the slow direction is about 80 km/h.

I own more tha 50 Märklin locomotives and I’m very familiar with their maintenance. I’ve opened the motor several time, cleaning everything and then oiling where it is needed. The gears turn freely as well as axels, on the first maintenance I put new rubber tires, I even replaced the electro magnet because I measured different values on the two coils.

Today I’ve been doing some test with the body removed and noticed some sparks visible through the brush plate when running in the direction it runs slow, but none whe running in the direction it runs fast. I’m thinking there might be some problem in the armature, probably in the drum collector.

Also, I’ve noticed that it sometimes doesn’t change direction on the first or second try and sometimes after a direction change I need to push the rail car to start moving.

Any suggestions are welcome plus I would like to get schematics of the electronics, does anybody knows where to get them?

Thank you in advance.

In all the Marklin locos I have come across, in the analogue locos, there is always a difference between forward and reverse speeds.
On some of the models there can be up to 4 intermediate gears and this in itself can create the difference. The gear train does wear over time and this can give a difference. There are many other factors, the moving of the brush positions for instance with the direction change. The best advise is that if it is running well in both directions, then not to worry.

The comment about excessive arching, this is a major issue. What happens is the edges of the commutator slots wear with arching and take the sharp edge of the off the commutator slots. Excessive running will also do this. Once the commutator is worn like this, the complete rotor has to be replaced. The commutator switching deteriorates and it will run poorly due to bad timing created due to the wear in this area.

With excessive brush arcing, one the most important things to do is to replace the brush springs. Arching creates heat and too much softens the brush springs and the motor goes slower due to less brush pressure. Brush pressure is very important. This maintenance point so overlooked.

David

I would inspect the brushes and the armature (commuter) when too much oil is applied over years the carbon brush will go softer and the graphite will deposit itself between the section of the commuter (3 pole) this will activate arcing as there is no longer a gap between the 3 poles, a good clean of the motor and a change of brushes will help

John