Large Scale Central

Noisy Aristo BB truck (FA-1)

Problem Solving
#1

Hi all,

I recently swapped out a set of the newer Aristo power blocks from a used RDC into a locomotive. One truck is very smooth running, while the other is quite noisy. The sound appears to come from the floppy axle end of the truck. I opened up the block (and the floppy gear box) and found zero defects, or anything rubbing on the u joints. I applied Mobil 1 grease liberally to both gears and set it back together. The truck seemed quiter for about 20 minutes while pulling two cars.

When I added a second FA locomotive the noise picked up again. It actually continued onward after removing the second engine. I notice the wheel of the floppy axle has wear spots every ten minutes or so on the tread. This suggests to me, an internal alignment issue of some type. Its strange because the train pulls strong, and seems to run smooth (despite being noisy).

Not really knowing what else to try, (and a lack of gear wear) I figure I will just send it off on a three hour run with a passenger train tomorrow to see how it works.

Any thoughts?

#2

Try laying in on it’s back, power it, and then apply drag (your finger) to each axle and see how it runs, almost sounds like the power is cutting out intermittently and flat-spotting the wheels as they stop turning.

Also, putting drag on the wheels will point out if you have the problem where the axles turn in the “gear casting”, i.e. slip.

I’ve had locos with these trucks seem to run ok, only to find one truck completely not running at all, and the other truck pulling the loco apparently just fine.

(this happened after an RS-3 board burned out some traces from a derailment)

#3

Hi Greg,
I tried running the loco upsidown and found that the truck was powered. The solid axle powered through the resistance without any complaint, but the “rocking axle” made significant noise when disturbed. Still the gears were not slipping in either axle.

The loco is actually a battery powered unit by-passing all Aristo circuitry. Unless the motor has gone bad, I assume it’s a mechanical issue.

#4

I didn’t think to check if the worm or u-joints were slipping on the motor shaft at all. Is this a problem on the newer engines at all?

#5

The design and materials never really changed on these AFAIK.

The axles can slip within the gear “castings”, the gears can wear and pop out of mesh, the power pickup can become intermittent, and yes the u-joint can slip.

These trucks are far from bulletproof, but you will get some people arguing that. My explanation is that often a loco seems to be running ok, but some of the axles are really not “working”.

Regards, Greg

#6

Before going out on the train today, I ran the engine on the workbench and noticed that the gear box on rocking axle was vibrating in parallel with the motor shaft. I took some cardboard and jammed it into the case to dampen the vibration. This totally stopped the noise! After 3 hours running you could actually drive the motor by turning the wheels by hand. I think I may have found the problem, but I guess I’m not sure how to properly fix it yet.

#7

Wasn’t there some kind of fix, using a piece of foam to cushion the motor shaft? Or am I thinking about a whole different motor block, with a whole different problem?

#8

David, I think you are thinking of the prime mover drives where there is a piece of foam under the gearboxes.

Jeff, I cannot quite picture “vibrating in parallel with the motor shaft”… can you describe it a bit differently?

Greg

#9

And that is why I think that model railroading is such a good hobby. We end up learning basic mechanics, basic electrical, basic electronics, basic construction, some architecture, a bit of history, and we get to meet all kinds of interesting people.

Sorry, I digress. It almost sounds like there is a shaft wobble or some kind of gear misalignment or gear problem. If the end of the truck is wobbling in line with the shaft.

#10

When working on a friend’s FA-1/FB-1 set, I found the pivoting gearboxes in two of the ball bearing motor blocks were running lumpy. It appeared the worm gear shafts were bent. As it is chromed steel, it could not have happened when enclosed in a plastic case, or the case would have been cracked. I can only assume it was bent at the factory when the worm gear was pressed on. Fortunately new worm gear shafts were available.

More recently I was given a ball bearing motor block that was noisy at slower speeds. After taking it apart and lubricating it, the noise persisted. Further investigation revealed that an axle bearing was shot. The outer casing on the bearing could be moved from side to side with a finger. Although the axle appeared to roll smoothly, I assume it would jam and great noisy at certain speeds. As I have never run into this problem before, I had no spares to fix it. Hopefully Navin will have the bearings.

The next problematic pivoting axle case had a bronze bushing missing from the worm shaft. This allowed the worm gear shaft to move freely in the case affecting the way the worm gear and plastic drive gear meshed.