atlas c30-7's

[Anonymous]

i have 2 atlas c30-7's, and both of them were bought new, and they have bad motors. they jerk back and forth, and it gets worse with higher throttle speeds. i gutted them, re-lubed all gearing, and checked for any frayed wires or loose connections, and the wheels are clean. what is wrong? i have modified both units to CONRAIL C30-7A specs. is it the motors, or something unseen?


crblues

[Anonymous]

i have 2 atlas c30-7's, and both of them were bought new, and they have bad motors. they jerk back and forth, and it gets worse with higher throttle speeds. i gutted them, re-lubed all gearing, and checked for any frayed wires or loose connections, and the wheels are clean. what is wrong? i have modified both units to CONRAIL C30-7A specs. is it the motors, or something unseen?


crblues

[jslean]

This is a common problemswith these units. Check all of the gears and drive shafts for flash. I believe that a cure was posted on the diesel list run by Andy Harmon several months ago but I can't remember exactly which part was causing the problem. Mine also jerks but it seems to be improving with age.

John Slean

[jslean]

This is a common problemswith these units. Check all of the gears and drive shafts for flash. I believe that a cure was posted on the diesel list run by Andy Harmon several months ago but I can't remember exactly which part was causing the problem. Mine also jerks but it seems to be improving with age.

John Slean

[wp8thsub]

Have you checked for burrs or other casting flaws on the gears? Although I haven't encountered the problem with Atlas units (I have several of their GE diesels and they run flawlessly) it does occur with blue-box Athearn mechanisms with some regularity. The fixes should be similar.

If I have a model that's exhibits jerking, I try to isolate the problem to one truck or the other by disconnecting the worm and shafts from one end at a time. If the problem really appears to be the motor, I try swapping with the motor from a unit that I know runs well. If the motor switcheroo cures everything I know it's the motor and not the gears. Sometimes you can tell by disconnecting both worms and shafts and running the original motor at speed to see if it vibrates. If that's the case, you could have deformed motor mounts or even something like bad contacts that are rubbing against the commutator (not usually an easy fix with a can motor).

If it's the gears, I work over the truck gear teeth with fine files and/or sandpaper to remove casting flash and other minor defects. Also check for burrs on the universals. With Athearn stuff, sometimes there are small burrs on the ends of the worm gears that catch and can cause jerking, plus if the worms don't sit tightly in their gearboxes they can slop back and forth. The latter problem can be cured with thin metal washers a la Athearn to shim the gear into compliance.

[wp8thsub]

Have you checked for burrs or other casting flaws on the gears? Although I haven't encountered the problem with Atlas units (I have several of their GE diesels and they run flawlessly) it does occur with blue-box Athearn mechanisms with some regularity. The fixes should be similar.

If I have a model that's exhibits jerking, I try to isolate the problem to one truck or the other by disconnecting the worm and shafts from one end at a time. If the problem really appears to be the motor, I try swapping with the motor from a unit that I know runs well. If the motor switcheroo cures everything I know it's the motor and not the gears. Sometimes you can tell by disconnecting both worms and shafts and running the original motor at speed to see if it vibrates. If that's the case, you could have deformed motor mounts or even something like bad contacts that are rubbing against the commutator (not usually an easy fix with a can motor).

If it's the gears, I work over the truck gear teeth with fine files and/or sandpaper to remove casting flash and other minor defects. Also check for burrs on the universals. With Athearn stuff, sometimes there are small burrs on the ends of the worm gears that catch and can cause jerking, plus if the worms don't sit tightly in their gearboxes they can slop back and forth. The latter problem can be cured with thin metal washers a la Athearn to shim the gear into compliance.

[Anonymous]

thanks everyone for your help, i'll give all these "cures" a try. i am now starting to think it is my power pack,(CMI 40V) that may be the culprit. tonigh, i ran 3 different brands of power, P2K, ATLAS, KATO. all of these units are exhibiting the "shimmy dance" now. i watched my P2K sd60m's do the "jerk", and they NEVER did this before tonight!! i think it is time for a new power source!

matt

[Anonymous]

thanks everyone for your help, i'll give all these "cures" a try. i am now starting to think it is my power pack,(CMI 40V) that may be the culprit. tonigh, i ran 3 different brands of power, P2K, ATLAS, KATO. all of these units are exhibiting the "shimmy dance" now. i watched my P2K sd60m's do the "jerk", and they NEVER did this before tonight!! i think it is time for a new power source!

matt

[Puckdropper]

Time to clean the track...

I'd put a light bulb on one set of the tracks wires and see if it changes in intensity or flashes without moving the knob on the power supply.

[Puckdropper]

Time to clean the track...

I'd put a light bulb on one set of the tracks wires and see if it changes in intensity or flashes without moving the knob on the power supply.