Improving the new u33's
truck power pickup
Stuck on the Frogs!
Click on images for larger view
|How can a loco with 12 wheels get stuck on
insulated frogs? I assumed all 12 wheels were supposed to be able to
pickup power from the track and therefore would easily bridge insulated
frogs. I only had this problem on ladder track turnouts on the layout. All
track work was powered like it should be and it was clean and so were
the locos wheels. A close look at the problem reveals that:
1. The rubber traction tired wheel-sets do not pickup very well if at all due to the larger diameter of the rubber tires.
2. The middle wheel-set was not touching the track at all by design!
3. When the outer wheel-sets both were on the frogs it lost power due to.1. and 2.
This is the spot that the second generation AF u33 has trouble getting through.
|This is the first generation u33 truck. It has a
blind middle driver. It does not have any pickup problem on the
layout. There is no wheel suspension equalization on these trucks.
||Here is the latest generation u33 truck. It is
quite a bit different than the first generation. It has a flanged middle
driver. The outer wheel-set has sprung journals. The good part is
the great new low speed gearing.
|Here you can see the gap on the middle wheels.
No traction or power pickup here! Even though the outer wheel-set has sprung journals they do no allow the middle wheel to touch the track when the loco's weight is on them.
|Here is the detail of the springs of the outer
wheel-sets. DO NOT LOSE the springs! There is no part number for them
yet so getting them may be difficult of you loose one.
|This is the middle journal pocket before
||Here is how I modified the journal pocket. I
drilled holes for the new springs. The springs I used are Kadee S
gauge coupler pocket springs. They are 1/16" x 1/4" and are
larger than the original Lionel springs but it is what I could find to
use. Note that I doubled the springs to get the tension I needed.
I found springs at Lionel that work better than the Kadee springs.
Lionel part number 6408036055.
|Here is the truck bottom cover that need to be
||A pocket need to be filed into the middle wheel-set
position so the journal can match the travel of the outer wheel-set
The pocket is .020" deep
|There are spacer sticker shims that need to be removed on the middle wheel-sets journals for maximum travel||When reinstalling the middle wheel-sets turn the journals so the non flanged portion of the journals is next to the bottom truck cover.|
|I also turned the rubber tires down a few thousandths
on the lathe closer to the non tired diameter
The middle wheels now are equalized and provide traction and electrical pickup after these modifications.