Opposed truck gears for better operation?

[sizemore]

Last night I was tinkering in the Lab to decompress from a very long day at work. I changed wheelsets on an Atlas GP9, plopped the trucks back in and threw it on the test track. In one direction smooth as glass for a loco that has been sitting for years. In the opposite direction it growled as bad as a Trix unit. I checked the trucks and noticed all the geared axles were on one side of the unit. "Hmmmm" so I flipped one truck so the gears were opposed between the two trucks. Threw it back on the track and it ran great in both directions. I looked at another locomotive that ran "OK", found all the geared axles were on one side of the unit, repeated the flop of one truck, and "blammo" it ran great.

I checked some other units in the fleet, all the latest Bachmann have the geared axles on one side while the WaLLyworlds I had on the bench were opposed.

Is this a eureka moment for me or is this one of those things I've forgotten *scratches head in contemplation of mental state*


The S.

[peteski]

Interesting.  If the trucks are truly symmetrical (the gear tower is centered in the truck and all of its features are symmetrical) their orientation (in relation to the chassis or to each other) should make no difference.  I'm surprised that it did for you.

Kato sometimes molds an arrow on the bottom of the truck gear cover to indicate which way the truck should be facing, but IIRC, those are only used on non-symmetrical trucks.

Have you tried to revert to the original orientation to see if the problem returns?  The problem might have been caused by something else being out of alignment.

[sizemore]

Kato sometimes molds an arrow on the bottom of the truck gear cover to indicate which way the truck should be facing, but IIRC, those are only used on non-symmetrical trucks.

Have you tried to revert to the original orientation to see if the problem returns?  The problem might have been caused by something else being out of alignment.

That's what I remember (arrows on the truck). I was on a high moment and didn't want to get into deep thought so I left it as it was and went to bed. Both trucks rolled freely when on their own, another reason why I didn't think twice about getting deep into the project. Maybe tonight if I ever leave my desk.

The S.

[kiwi_bnsf]

I have had similar experiences while working through a re-wheeling programme for my 4-axle Atlas locos (primarily Dash 8-40B/BWs).

There seems to be some variation in the meshing between the worms and the truck gears, and rotating the truck in some cases seems to benefit.

For me the result was not always consistent - sometimes the trucks ran better opposing, sometimes they ran better with oriented the same way.

I simply experimented with each loco as I put it back together, and found the quietest combination of truck orientation.

Cheers