Re: Branchline reefer rolling resistance


Denny Anspach <danspach@...>
 

There are so many variables to contend with according to your post that it is impossible to render any single bit of advice as to how to proceed.

Probably the most productive place to start is determining the length of the axles. The most important thing to keep in mind is that model trucks are most distinctly NOT precision assemblies (we could not even begin to afford them if they were!), and that within wide parameters, they are for the most part designed only to roll above a certain minimum standard. For those widely interested in increasing truck rollability, this standard is commonly found to be relatively low, while for the general market, the standard is widely accepted as OK.

Most mass produced trucks are sized to routinely handle axle sets nominally of 1.015" length. Because of the natural variability that occurs in the plastic injection process, however, two trucks from the same batch with the same wheel sets may vary considerably when it comes to rolling ability. If a given axle/truck fit is not optimal, no amount of other changes will improve things.

Maximum rolling ability often clashes with another issue: minimum axle end play- an issue ever more important with the increasing use and acceptance of scale-sized couplers. Although not too often- but often enough- maximum rolling ability is accompanied by the truck sliding/ rocking from side to side like a drunken sailor because of excessive axle end play. No wonder these cars will not couple easily!

1) The Branchline metal wheel sets had axles that routinely measured 1.018" in length, versus the long-time popular Intermountain sets that most commonly measured 1.012" (nominal 1.015"). This excessive length can and has caused problems, sometimes with Branchline's own products.

2) The shape and contour of the axle ends make a difference, as does the material with which they are made. The thin needle-like axle ends of the Reboxx , Intermountain, and Branchline wheel sets offer the best rolling potential. The wide axle ends of the otherwise beautiful NWSL wheels turn out to be a significant relative disadvantage when measuring comparable rollability. The plastic ends of the high quality Kadee wheels ditto (all of Kadee's own trucks gain added rollability when fitted with measured Reboxx wheel sets). For reasons that I cannot explain, the Reboxx wheels of the same nominal length consistently out-roll the Branchlines.

3) Over the past year or two, IM has changed the China sourcing for their wheels, a change that I and others have discovered has resulted in a reduction in routine axle length from 1.012" to 1.007", albeit with some perceived smoothing of the axle tips. This is a significant change- not for the good- that has caused at least one premium aftermarket truck manufacturer to change metal wheel suppliers (although IM and Reboxx are owned by the same entity, Reboxx wheels are still sourced from their original factory, and in my experience still maintain their very high quality).

As has been pointed out by many on this list over the years, the limited "science" that can be applied to this rollability issue has itself to be applied with a large dollop of art because of the composite nature of so many variables.

Denny

Denny S. Anspach MD
Sacramento

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