George.....as others have suggested, replace the brushes AND the the brush springs. Clean the gunk out the brush tubes while you are at it. If you really want to be thorough, clean the commutator and the gaps between the commutator plates. A vintage Berk is a beautiful thing to waste.
Jack.
IF IT WON'T COME LOOSE BY TAPPING ON IT, DON'T TRY TO FORCE IT. USE A BIGGER HAMMER.
Thanks to all for the replies. Last night, I turned the power on with the 736 on the track and pressed one of the brushes with the point of an ink pen. It took off and ran well for a while. I did this again and the same thing happened, so I am going to replace the brushes.
George
Have you checked the brushes and springs for proper tension on the armature plate? Sometimes a brush will have a very deep pit(you can sand that down if needed) and that can cause it to run hot or overheat. If you can get the motor to turn again check for sparks inside the armature area, use a toothpick to push on the brush holder(one at a time) and if it runs you have a spring tension problem.
Lee F.
When you lubed the engine, did you oil the motor bearings? There is an oil hole in the top of the motor housing that needs several drops of oil to lube the motor bearings.
The oil will run out past the bearings, and just make a mess. It's better to apply the oil directly to the bearings.
[quote]And it is not the brushes [/quiote]
Bad (fouled) brushes / dirty commutator are the most common problem, and will make a motor run hot / poorly.
As far as bad winding go.... it does happen, but not all that frequently.
If the field winding is shorted, it will probably also be discolored due to the heat generated. It may also smell like it is burned.
It is also possible that you have a wire broken inside the loco, and/or a wire shorted against the inside of the shell.
Bruce Baker
Among the many possibilities is shorted turns in the field winding. This would manifest itself as slow running and overheating. A good test for this problem is to run the locomotive on DC, to see whether the performance improves significantly. Unfortunately, it seems like something has burned out, preventing running at all. You can test the field winding for continuity; but, if it is open, the only cure is to rewind it, which would not be fun.
Bob Nelson
When you lubed the engine, did you oil the motor bearings? There is an oil hole in the top of the motor housing that needs several drops of oil to lube the motor bearings. Also, when you had the engine apart, did you turn the armature to check for free running? This engine should not take more than 10 volts to run, and if it is taking more than that, something is not lubed properly. And it is not the brushes. You should be able to turn the wheels and back drive the motor, and the wheels should turn relatively easily. The motor is a worm drive, so the wheels don't turn as easily as they do with a motor driven by spur gears, but they should turn.
Where on the inside of the boiler did you find the tape. If it's near the front, did you check the wire leads to either the smoke unit or the headlight. Do either look like they could be touching the inside of the shell. If the tape is near the back of the boiler, check the motor field brushes where the lead wires are connected. Are they sticking upwards to where they could be touching the inside of the boiler. Electrical tape is thin enough that sharp contact or solder joints could easily pierce it and cause a short circuit. The engine symptoms you described sure imply some sort of chort circuit problem. I hope these suggestions are helpful.
There are a couple of common problems that might be causing your operating issues.
Were the engine mine, the first check would be the brushes, springs, commutator plate. I'd make certain the brushes were clean, that the springs were OK, and that the brushes were able to slide back and forth freely in the tubes.Be aware that sometimes people clean oil-soaked brushes and re-use them. I find that when this is done, the brushes work OK for a little while, and then they get fouled.I think the oi must soak in deep. The cleaning gets the oil off the surface, but then more makes it's way to the surface. There have been a number of times where I had to re-do another repairman's work because of this.
Sometimes everything looks nice and clean, but the brushes still aren't making good electrical contact with the brush holders. I have to say, I don't have a fix for this (after trying to clean the brush holders again), other than to switch to brushes with pigtails.
Next stop: the e-unit. I just make certain all the contacts are clean, and that the "fingers" have the proper tension against the drum.
After this, the work gets a bit more complicated. I've run into issues with the berkshire style motors that had old, dried out grease in the motor casting. Cleaning out the old grease and re-lubricating the motor solved that problem. I think that's enough for one post, there are other things to check if none of the above resolves the problem.
I was running my 736 post war Berkshire two nights ago when I noticed it was very hot to the touch and it was running slowly, even though I had the track voltage up to 14 volts. I had bought this engine second hand from someone who said it had just been overhauled. I took the boiler off and added some grease to the gearbox even though it was not dry. I also oiled the bearings. When I took the shell off, I noticed someone had put some black electrical tape on the inside of the boiler. Anybody know why? I put it back together and tried running it again. It needed a small push to get it started but it seemed to do alright. After a while, it simply quit on me. No noise, no response to the track voltage other than the head light comes on.
Can anybody speculate on what has happened? Has the motor faulted open? I am afraid this isn’t going to end well.
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