Slow running Lima DMU

[drgj]

I have a very slow running Lima DMU. I have done all  the normal cleaning of the commutator,  axles, wheels and gears and then  relubing at the usual points.  I have not had this problem on any other Lima bogie. Would a new magnet cure it?

 

Thanks

Edited January 12 by drgj
More detail

[kevinlms]

4 minutes ago, drgj said:

I have a very slow running Lima DMU. I have done all  the normal cleaning of the commutator,  axles, wheels and gears and then  relubing at the usual points.  I have not had this problem on any other Lima bogie. Would a new magnet cure it?

 

Thanks

You've killed a Lima motor bogie?

 

I suspect that a winding segment is open. Have you got a multimeter to check the resistance between each leg?

[drgj]

Thanks for the reply. I have a multimeter with a continuity tester. Where shall I put the probes? One on a commutator segment and where would the other go?

 

Thanks

[kevinlms]

29 minutes ago, drgj said:

Thanks for the reply. I have a multimeter with a continuity tester. Where shall I put the probes? One on a commutator segment and where would the other go?

 

Thanks

There are 3 segments and you need to measure the 3 pairs of adjacent segments. Set your multimeter to about 200 ohms and the 3 pairs should be close to identical. 

[Elaine]

We had a Lima motor bogie where the plates on the commutator measured a high impedance, all the windings were fine, it didn't run hot., it just ran very slowly, we exchanged the armature and all good, if your windings are fine, consider fitting your slow armature into a Lima 09 for nice slow running.

[DCB]

I don't know if the affected loco  runs slowly consistently or just on a test plank.   My  lima locos take several yards to "Warm Up"  after a period of inactivity and are then fine.      I did have problems  years ago when running Lma locos on slow heavy trains.   If they didn't get a good high speed thrash they got slower and slower  the armatures ran   hot, the  brush holders came loose in the end cap and the temper went out of the brush springs.     I changed the end cap, brushes and springs to solve it.   I did have armatures fail with wear to the drive gear bit at least one eroded the commutator slots which are part of a PCB Disc.  I  went to CD Motors about 15 years ago for my garden line  but have a couple of surviving Lima DMUs which  don't give any trouble when run at scale speeds 30 +  mph .

Edited January 13 by DCB

[drgj]

I measured between commutator segments and the readings were just about equal. I took the magnet out and could lift it by touching it with a screwdriver and raising. Probably good enough?

 

My other Lima locos run pretty well.  They sit for just as long without use and are ok.

 

There are strong neo magnets available on ebay for about £12 plus p&p but I am not convinced they would make a difference.

 

I have just realised that there is no capacitor between the brush holders. Would this make difference to running as well as causing radio interference?

 

Dave

Edited January 13 by drgj

[cliff park]

It's not a capacitor, and no. It's a very small inductor and has no effect on the motor.

[Dagworth]

6 minutes ago, cliff park said:

It's not a capacitor, and no. It's a very small inductor and has no effect on the motor.

the one between the brushes on a Lima motor is a capacitor, an inductor connected across the motor would result in a short circuit.

 

Andi

Edited January 13 by Dagworth

[vikingsmb]

wonder if its worth setting up rewinding etc of lima armatures