I recently purchased an ahm docksider in its rebuilt state with tender. the motor seems to be very jerky, particularly in reverse. while moving foward, the motion is very rough. I noticed that the valve gear is a little loose, could this be a problem? any help would be appreciated
This is probably due to 2 or 3 things. Dirty wheels/pickups, and also a dirty communtator on the motor. I would clean the wheels and then the communtator. I use lacquer thinner on a pipe cleaner to clean communtators and a paper towel with thinner to clean the wheels.
To clean the communtator, the loco needs to have the boiler removed from the chassis. If the motor is like I remember it, you can insert the pipe cleaner into the vent holes by the communtator and remove the dirt there.
To clean the wheels, moisten a small piece of the paper towel, and drape it over a piece of track. Run the loco on the towel, allowing the wheels to spin on it. This will clean the wheels quickly.
I would also clean the track as well.
I’m not sure which AHM engine you have as a dockide is an 0-4-0 with no tender. In any case I woulld touch leads directly to the motor. That will tell you if the problem is internal to the motor or between the rails and the motor.
thank you for the advice, I will definatly try this. I don’t believe that this is because of the track as I own another ahm dockside in tank engine form that runs just fine. it seems as if the motor has difficulty rotating fully. it will roll a few inches backwards, slow down to an almost stop, and then shoot back a few more inches. perhaps cleaning the communtator will fix this.
I think he’s referring to the B&O C-16a, which were converted from Docksides into shifters with tenders. I don’t know which version you have, but I’ve posted the exploded drawings from HOSeeker below for both square and round motored versions. The earliest square motors had ball bearings, which can become fouled with dirt or old lubricants. The best way to clean them out is to blast the brushes and bearings out with contact cleaner, like the stuff from MG Chemicals that should still be available at Radio Shack. After it dries out, re-oil the bearings sparingly. If it’s still noisy, the bearings may need to be snugged up a bit by carefully tightening the hex screw between the brushes until it stops rattling and runs smooth, then tighten the lock nut. It takes a 3mm nut driver. The worst case scenario with one of these is if someone tried disassembling the motor, and ball bearings fell out.
http://www.hoseeker.org/AHMRivarossiassembly/ahmrivarossi040class16aswitcherlubepg1.jpg
http://www.hoseeker.org/AHMRivarossiassembly/ahm040class16aassemblyinstrpg1.jpg
The round motors are much easier to service, but contact cleaner will work well for them too. Be very careful with lacquer thinner, because it will dissolve styrene plastic, including early versions of the ball bearing motor end bell. I’d stick with plastic safe cleaner, or 91% alcohol.
http://www.hoseeker.org/AHMRivarossiassembly/ahmbuildersbiblepage011.jpg
This sounds more like a drive wheel problem than a motor problem to me. Does the mechanism turn completely freely with the motor taken out? Slightly out of quarter drive wheels or possibly a bad gear could cause behavior like you’re describing.
upon further investigation, I have determined that the problem is not with the motor, I was able to run the motor disconnected from the frame and it runs fairly smoothly, the wheels, however have a difficult time turning with the motor removed. the valve gear is also very loose, I don’t know if this would be the problem. also, there is quite a bit of thick grease on the axle gear and the motor’s worm gear, could this be causing friction? on an unrelated note, what is the best method for installing a kadee coupler on the front of one of these models?
In most all cases in our models, you cannot reverse drive a worm and worm gear. That means you cannot turn an engaged worm by turning the wheels. If the worm was attached to the motor, and the motor has been removed, failure to roll freely is a real problem.
Both the grease and the valve gear and side rods could be problems. Since only one axle is driven by gears, the side rods must be reasonably tight and the quartering of the drivers must match.
I would start by cleaning all old grease and dirt out of the gears. Then test the mechanism without the worm engaged. If it rolls on a piece of glass, great. If not, remove valve gear and side rods a piece at a time until the problem is found.
just my thoughts and experiences
Fred W
Old grease can turn to a hard waxy substance, so that could certainly be the problem. I let the parts soak in alcohol and then clean them with an old toothbrush. If it still binds after being cleaned and lubed, then it’s a mechanical issue like quartering or linkage. Make sure the side rod screws are tight when you reassemble it. There will be a certain amount of slop in the valve gear from the rivets that hold it together, but the screws that suspend it from the valve gear hanger should be tight.