Thanks for the responses. I just checked things out. The dummy units roll fine. The wheels lock out when no power is applied, but I did try running with the shell off for a few minutes at full power with the engine upside down. Both motors seemed to run at the same speed through all voltages. There are no flywheels so I had to go by wheel speed. No binding of gears, wheels or motor shafts was found. Both motors were still cool. I did notice however, the four power transistors on the green circuit board were quite hot! These are located near the front motor (1" away) and have metal tabs on them to dissipate heat. Apparently this is where the heat has been coming from. I would guess this is normal and maybe just more noticeable on the PA-1 because the power transistors are located less than an inch from the inside of the roof. I should note, that due to the length of each unit(16"), I have only run this engine at the train club, which means operating sessions that can last for an hour or more. No damage visible from the inside to the shell so far. Seems like it can take the heat. Guess I'll be looking for a passenger set to go with the locomotives. I was thinking of getting a matching Williams set. Thanks again for the help.
You need to remove the cab from the chassis and run it a bit. Touch each motor after a while and see if either is uncomfortably hot. All electric motors get fairly warm after a bit of runnung but should not be blistering hot. Make sure the trucks and gears are well oiled and greased. Check to see that the motor flywheels are not rubbing aginst the wires that come up over the sides into the tops of each motor. This is somewhat common with some Williams and it will cause the motors to run hot. You can bend the motor wire tabs down to stop this. If one motor is running hotter than the other check for binding and lube. You could have one motor going sour.
Roger
If the motors are not well matched for speed, they will fight each other. Permanent magnet motors run at a speed proportional to the voltage across their terminals. If the motors are wired in parallel, as is usual, they both have the same voltage. So one of them tries to run faster than the other. The faster motor can draw a lot of current trying to get the slower one to go faster. See whether you can observe a difference when running the motors with the locomotive off the track.
Bob Nelson
Are the wheels in the trucks of the unpowered A and B units rolling freely?
Take the shell off and check to make sure that both motor shafts turn freely. Since the front motor seems to be running hotter, start your inspection there. The external gears can be clean, but if something (hair, dust, lint, etc) got inside the gearbox it might have ended up getting wound up on a motor shaft or axle causing it to bind.
I have an older Williams PA-1 ABA set that seems to run very hot without pulling any cars at all. These are long units with a lot of heft to them. There is only one powered unit with two motors. I can feel the heat by just putting my hand on the plastic shell above the motors(more in the front motor). It feels hot enough for me to wonder if the plastic could melt or become brittle over time and then crack. I'd like to get a passenger set to go with the locomotives but need to get the heating problem under control first. The gears are clean and lubed. Thanks for the help.
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