Help with a Bachmann Can motor

[xdford]

Hi all,

A friend of mine has a Bachmann British 4-6-0 with a motor where the motor brush on one side is apparently sticking and needs to be pushed firmly onto the commutator using a pin. Obviousy this cannot continue. It seems that this problem occurred with his last motor as well.

Is there a way of tensioning what I presume are springs within the brush cavity to maintain tension or a trick involved with these units please?

TIA for sharing

regards

Trevor

 

 

 

[tinman1]

I'm thinking that what you are experiencing is a worn brush. The brush has a braided line embedded into it from the side, which typically exits the brush holder through a slot on the  side. The brush holder is just a square tube or other means to hold the brush from twisting or otherwise trying to rotate and also contains some sort of tensioning spring and retainer. When the brush wears over time, the mesh wire on the side can hit the bottom of its slot and prevent the spring from pushing it any further. Arcing starts following, which further eats up the brushes. The "fix" would be to replace the brushes, and make sure to clean and burnish the commutator well. 

 If the brush is long enough and you are experiencing a weakened spring, I would pull the brush and gently stretch the spring a bit. Don't get crazy or too much pressure will be applied.  Still, other methods use the brush holder itself to transfer power to the brush and the spring has some sort of limiting factor to prevent it from hitting the motor.

Short story,--- you're probably looking at replacing the motor, since replacement parts are non-existent anymore.

[xdford]

Hi Tom,

Interesting as this motor has not been run for more than an hour absolute tops. The motor on this unit has a sort of brass cap which does not take kindly to manipulation as we found out with the previous motor which had also not been run very long. We actually had to send to England to get this particular motor as the local agent did not have it at all. The first one we thought was our fault. The second time now makes us sure we were not at fault. I could write to Bachmann in England and request a new motor... we don't need a new loco but thought there may be a trick to these brushes

Thanks for your note and I will check in to see if anything else comes up!

Regards

Trevor

 

 

 

[tinman1]

Unfortunately, not many things are made to be repaired anymore. Everything is throw-away nowadays, but with some of the "better items", at least there's sub-assembies that can be had. As such, they are not meant to be disassembled either. Kinda stinks, but thats the way the manufacturing world has turned in the last 20yrs

[richg1998]

I had a two motor HO 44 ton that did that. It finally cracked one gear so I sent it in with a check and got a single motor 44 ton, DCC ready.

You might try a tiny drop of Rail Zip on the brush assembly. It is a contact enhancer.

In the past I have used a CRC contact cleaner product that works. Cannot remember the particular number on the spray can.

In both cases, a tiny drop. More is not better.

Rich

[SteamFreak]

Trevor, the Bachmann can motor used in a lot of Spectrum locos has very small diameter brushes, and I've found the commutator to be prone to fouling with oil or brush dust that seems to cause intermittent stalls, ie. you switch it into reverse and suddenly only the headlight comes on. The cap you're speaking of is made of phosphor bronze, and can be pried off carefully with a jeweler's type screwdriver, but if you attempt it I recommend you do it inside a plastic bag so that the spring doesn't go sailing into the stratosphere.

I generally cut one of the ribs out of the plastic endbell on the brush end of the motor so that I have access to the commutator and can clean the slots between the plates.  The easiest thing to try first would be to blast the brushes and commutator out with a plastic safe contact cleaner. Radio Shack carries a good one from MG Chemicals, which is what I use. After spraying it let the motor dry out, and lightly re-oil the bearing on the brush end.

I had one of these motors in a K4 I'd gotten secondhand that got sluggish and occasionally stalled, and I couldn't figure out why. I polished and cleaned the commutator, but it was still flaky. When I finally looked at the brushes I discovered how much they were worn, so I just stretched the springs a bit and it runs perfectly. If your motor is new, this isn't likely to be the problem, unless there's a burned or flattened out spring that's not tensioning the brush.