Drive Train Noise - Kato F7

[u18b]

I also bought those truck back in the day and re-fitted them to my locos.  Heck, I even adapted them to a GP50- though that required other adaptations.


When I placed these on an old F3, I did not not notice a ride height change.  Afterall, that's all Kato did.

Pete.  It's the same blue label chassis- unless he did some mods to it.

[u18b]

I tried that but the bearings won't come off the shaft.

Attached is a photo of what I have.  The trucks toward the top of the photo are the ones that came with the unit.  They made the ride height way too high and one side was higher than the other on one of them causing the unit to list to the right.  I also removed the rapido couplers in favor of body, or should I say, chassis mounting MTL 1015's.  I replaced those trucks with the 'revised' version, the set toward the bottom of the photo.  This brought the ride height down to an acceptable level plus they had no couplers attached.

However, this truck change did nothing to eliminate or reduce the noise.  As I mentioned, I searched TRW and did find the "beardenizing" fix for four-axel trucks but I am not able to remove the inner bearing block.  As can be seen in the photo, they do have the brass cups inside.  I don't know what this means as far as the noise is concerned but if it has any effect, I'd like to know.

Doug

p.s.  The paper insert inside the box is blue.

Doug,

I just realized there may be one other problem.  Looking at that photo I see the whitish rings between the motor and the flywheels.
Those are the motor mounts.

Well, those things degrade over time (30+ years).  Maybe Kato used a different material.... but I have seen U25Bs from that era have those rings crumble.

Point---- if one or both is damaged, the motor will not sit straight- resulting in noise.

[BCR751]

With the original trucks installed, there is a very noticeable gap between the top of the side frames and the bottom of the chassis.  With the 'revised' trucks installed, that distance is significantly reduced.  I didn't take any measurements but visually, it's a much better appearance.

The unit runs the same with both sets of trucks installed.  With the 'revised' ones, the little brass tab touches the frame in the same place the original ones did so electrical pick-up isn't compromised and the trucks swivel fine with no resistance.

peteski said:  "I suspect that the grinding noise is caused by the worm gear meshing too deeply with the worm. The worms seem to be larger diameter than the standard Kato worms used on most locos."  That's what I thought because, as I slowed the motor down, the grinding slowed as well.   I could see under the frame and noticed the grinding coincided perfectly with the main gear teeth meshing with the worm.  If this is indeed the cause of the noise, I doubt anything can be done to fix that.

I'll have a look at those nylon (I think) bushings on the the motor and see if they look bad.  Don't know if I will be able to tell.

I am the original owner of the unit.  I bought it a number of years ago but don't remember the year exactly.  I haven't taken it out of the box until this week.  The only modification I have done to it is to remove the rapido coupler pocket from the original trucks and mill out a pocket on each end of the frame to mount MTL 1015's  The original truck mounted coupler pocket put the replacement MTL's way too low.

I'm going to go now and close my eyes and try to pull off those u-joint thingys and hope nothing breaks.  I'll report back.

Doug

[thomasjmdavis]

I had a Con Core PA that started sounding like a coffee grinder when a bit of plastic picked up off the track (or so I think, couldn't find anything damaged in the truck or chassis).  Cleaned the trucks out and lubed the gears and I think it is good for another 40 years.
I have had an issue on old Katos with those bushings.  Some are green (don't know if they were made of different material or perhaps an interaction with a lubricant), and seem more brittle than the white ones.  Of course, it never hurts to count all the teeth on all the gears...

[peteski]

I had a Con Core PA that started sounding like a coffee grinder when a bit of plastic picked up off the track (or so I think, couldn't find anything damaged in the truck or chassis).  Cleaned the trucks out and lubed the gears and I think it is good for another 40 years.
I have had an issue on old Katos with those bushings.  Some are green (don't know if they were made of different material or perhaps an interaction with a lubricant), and seem more brittle than the white ones.  Of course, it never hurts to count all the teeth on all the gears...

The thorough cleaning advice is very good, but as I see it, if there was a missing tooth in any of the truck's gears it would likely cause a larger problem than just grinding.   Maybe if a gear was cracked and partially split (like gears in many Bachmann locos), that would cause a cyclical hitch and click.  Grinding noise to me is caused by something that spins the fastest in the mechanism (which would be the motor, universals, or worms).

[BCR751]

I closed my eyes and pulled and off came the u-joint !!!   Well, all I can say is WOW!!  The 'beardenizing' worked!  Thank you, Ron, for all the work you did toward solving this noise issue.

Not being able to take anything at face value, no offence Ron:), I closely scrutinized why this mod may have worked on my unit.  With the inner bearing block in place, the worm is held firmly between the two blocks.  If there is ANY resulting mis-alignment between the worm and the main gear, there will be added friction which can/will cause noise as the gear teeth try to mesh with the worm.  With that inner bearing block removed, it allows the worm to move back and forth along the shaft, thus allowing the gear/worm combination to find its own "sweet spot", thus eliminating, or at least reducing, the noise.  Although this may not be true of all noise issues, I believe it was the cause on my unit.

Another benefit of this mod was a significant reduction in current draw and a much lower starting voltage.  Although there's still work to be done on this issue, the mod has certainly helped.  I may be able to DCC this old girl after all.

I have a few other 4-axle locos that I will try this on should they exhibit the same noise issue. 

Thanks again, Ron, and all the others who provided suggestions.

[peteski]

I'm glad to hear that Ron's magical solution worked.    I also suspect that there might be a misalignment between the motor and worm shafts and some of the friction (and noise) was at the universal couplings.  But Ron's solution also alleviates that type of problem. I'm not a big fan of removing the worm bearing, but I have seen it work time after time.

[BCR751]

I do wonder if the removal of that bearing block will set up the possibility of excessive wear on the u-joint.  Only time will tell.

Doug

[mmagliaro]

I thought in all these types of drivelines (meaning Kato and Atlas diesels with the worms mounted between two bearings), the worm should always be able to move back and forth a little between the bearings.  If it can't, then I pull that little fork end out a hair so that the bearings and worm can slide back and forth.  It doesn't have to be much, but it can't be zero or the worm binds and makes a lot of noise.

[peteski]

I thought in all these types of drivelines (meaning Kato and Atlas diesels with the worms mounted between two bearings), the worm should always be able to move back and forth a little between the bearings.  If it can't, then I pull that little fork end out a hair so that the bearings and worm can slide back and forth.  It doesn't have to be much, but it can't be zero or the worm binds and makes a lot of noise.

I agree 100% - I don't know why I didn't mention in my response.    Both the motor shaft (in the motor housing) and the work shafts should nave slight lateral play.

[u18b]

I thought in all these types of drivelines (meaning Kato and Atlas diesels with the worms mounted between two bearings), the worm should always be able to move back and forth a little between the bearings.  If it can't, then I pull that little fork end out a hair so that the bearings and worm can slide back and forth.  It doesn't have to be much, but it can't be zero or the worm binds and makes a lot of noise.

Yep.  Not zero..... But not much.   This adjustment seems to be the tricky part for people who don't see good results.

[u18b]

I closed my eyes and pulled and off came the u-joint !!!   Well, all I can say is WOW!!  The 'beardenizing' worked!  Thank you, Ron, for all the work you did toward solving this noise issue.

Not being able to take anything at face value, no offence Ron:), I closely scrutinized why this mod may have worked on my unit.  With the inner bearing block in place, the worm is held firmly between the two blocks.  If there is ANY resulting mis-alignment between the worm and the main gear, there will be added friction which can/will cause noise as the gear teeth try to mesh with the worm.  With that inner bearing block removed, it allows the worm to move back and forth along the shaft, thus allowing the gear/worm combination to find its own "sweet spot", thus eliminating, or at least reducing, the noise.  Although this may not be true of all noise issues, I believe it was the cause on my unit.

Another benefit of this mod was a significant reduction in current draw and a much lower starting voltage.  Although there's still work to be done on this issue, the mod has certainly helped.  I may be able to DCC this old girl after all.

I have a few other 4-axle locos that I will try this on should they exhibit the same noise issue. 

Thanks again, Ron, and all the others who provided suggestions.

No offence taken.

In fact, all of what you said is in the article/PDF.

Glad it worked.

[ns737]

BCR 751 could you show a pic of how you milled the frame for the 1015 coupler. I have a f7A and b unit that have broken truck coupler pockets.

[BCR751]

BCR 751 could you show a pic of how you milled the frame for the 1015 coupler. I have a f7A and b unit that have broken truck coupler pockets.

Sure.  I'll try and get some photos tomorrow.

Doug

[BCR751]

I thought in all these types of drivelines (meaning Kato and Atlas diesels with the worms mounted between two bearings), the worm should always be able to move back and forth a little between the bearings.  If it can't, then I pull that little fork end out a hair so that the bearings and worm can slide back and forth.  It doesn't have to be much, but it can't be zero or the worm binds and makes a lot of noise.

So Max, are you saying you leave both bearing blocks installed and just fiddle with the u-joint to get the required "slop" in the worm gear?

Doug