Dr Yellow Visits the Doctor - 700 Series

[Guest Closed Account 1]

My Yellow HighLighter Train has an issue.

 

At very low speeds there is a definite grinding gear sound.

 

The driveshaft is definitely contacting the EM13 decoder. Tight clearance here.

 

I've swapped driveshafts & trucks.

 

Reworked the pickup strips to seat the decoder better.

 

Reworked the truck clip to gain some clearance. Didn't work.

 

Sanded the burr off the one driveshaft.

 

Even reinstalled the decoder.

 

Driveshafts are not bent. I've rolled them over white paper on a glass top.

 

Any hints?

[KenS]

No ideas. But can you take a photo showing the decoder and drive shaft in place? Maybe that would kick some neurons loose.

[Guest Closed Account 1]

Photo won't really help.

 

The fat square chip (term) is hitting the shaft.

[keitaro]

Web does the drive shaft move freely back and forth when it's attached?

 

If it does thats the problem.

 

I had with my kato ginza no decoder the trucks may be shifted forward a bit mine were.

I pushed them closer to the motor its only like 1mm or so and it stopped.

 

I also have this same issue on my 500 sayonara tomix

 

Except i cant move closer.

 

I notice once going fast it doesn't make noise anymore likely because the momentum holds it in place.

 

Hope this helps if not i have no idea why it would rub unless springs are allowing it to sag

[Guest Closed Account 1]

Back and forth between the motor and the yoke or horizontal play?

 

It does slip to adjust to the rocking truck.

 

Roller stands would be great for trouble shooting this.

 

Or a 9v battery and a ruler with the loco on its back. The ruler will keep the trucks in their natural position.

[keitaro]

Back and forth between the motor and the yoke

 

out of curiosity does it happen both directions?

 

mine was only 1 direction

[Guest Closed Account 1]

Yes.

 

Good slow grinding then an abnormal buzz at high speeds. Barely can hear the motor whine.

 

Ill slide the trucks and see if that does it. That would increase the drive line angle and increase the gap under the driveshaft.

[cteno4]

web,

 

are the wheels turning all the time at high and low speed if you put them under any strain? 

 

best way to check for stripped drive shafts is to run the train upside down with a power pack and a couple of probes on the wheels. its a little juggling but you can do that with one hand and then push on the spinning wheels to see if they stop under any pressure. if they do then its a stripped drive shaft, the nubs have gotten worn off just enough to catch when no resistance and turn the wheels but under resistance they just spin in the universal joint. Its hard to tell if the shaft teeth are stripped off by feel and even by finger turn.

 

the bit easier way to power is to clip to the motor leads if you have the top plate off.

 

thats a drop in decoder, correct? i doubt they would have gotten the decoder that close to the drive shaft that you could have it rubbing potentially.

 

stripped drive shafts will make the buzz at higher speeds as its a combo of one drive shaft slipping and the other truck still being powered but also slipping on the rails some i think. like ketaro said there is play in there and if partially stripped it will run for a bit but when it hits resistance it might slip for a big (and whine more) and then catch again so you can get some jerkyness in there as well. also carefully inspect the truck gears for any sucked in hairs or fuzz or even a bit of grit. that can also cause the resistance that starts slipping and eventual stripping of the joint. ive pulled apart truck gears that looked ok from the small hole in the bottom only to find a good bit of hair twirlled up in the middle of the gears around one or more of the shafts.

 

if there is too much play in the drive shaft you can always reduce this by sliding out the universal joint on the motor axle a tad on that side, you have a little play there.

 

jeff

[Guest Closed Account 1]

Problem solved.

 

There are 2 Universal joints per driveshaft to inspect for proper gap between the universal joint and the truck. 

 

In my case there was too much gap.

[cteno4]

You can move in or out on either end, doesnt matter which, just where you have room on the shafts the universal joint socket is attached to and room in the housing.

 

Glad it worked!

 

Jeff

Edited May 6, 2013 by cteno4