Anspach Denny <danspachmd@...>
This lively subject has a lot of tentacles (or arms and legs); and in the end, there is less science than there is art and judgement in determining ideal roll ability.
As Jon Miller surmised, I do indeed use a Reboxx Rolltester to test trucks. This is an elevated vertically-curved track segment about 24” long 4” high on each end and about 1” high in the middle. I simply count the number of times any given truck will roll back and forth -no matter how small the movement- until it stops. I test each truck three times, and record the results.. As I test various brands and axle length wheel sets, my own benchmarks (which have served me well) are:
· Unsatisfactory: 0-5 rolls
· Poor: 6-10 rolls
· Acceptable/Good: 11-15 rolls
· Very Good: 16-20 rolls
· Superior: 21 and up.
This is not the only thing that I rely on, however.
Occasionally, placing a lead weight (from a defunct N gauge diesel) on the truck will alter the rollability, but not often enough to be a routine, nor to be of perceived overall significance..
Sometimes the highest roll ability is only attained by accepting excessive axle end play, an important issue re: wobble, and -most importantly for me- creating big time centering/coupling problems with the “scale” couplers common to my rolling stock (Accumates and 150 series Kadees). In these instances I make note of where the best balance might be. The ideal for me is the highest roll ability and least end play.
Here are some selected rounded/averaged SAMPLE Rolltester results, wheel set brand and/or axle length or type, and numbers indicating counted rolls:
Accurail Bettendorf: OEM 11; Reboxx 1.010 -1.020” 21; NWSL 10; IM 1.012” 20; JayBee 12; Kadee 0.088” 20.
Branchline Barber S-2: OEM 18; Reboxx 1.0
Central Valley Arch Bar: OEM 7; Reboxx 1.025” 10.
Kadee AAR (sprung): OEM 10; Reboxx 1.020” 17.
Kadee Barber S2b (new) : OEM 11; Kadee 0.088” 12; Reboxx 1.020” - 1.025” 12/13
Silver Streak AAR metal: OEM 5; Reboxx 1.045” 12.
Tahoe Dalman two level: OEM N/A; Reboxx 1.005”-1.010” 22/23; IM 1.007” 19; IM 1.012” 21.
Walthers Archbar leaf spring caboose: OEM 6; Reboxx 1.030” 18; 1.035” 12 (the former had excessive end play).
Although out of scope for this list, there have been some near-spectacular results with the occasional brass passenger truck, and even greater results in bringing the venerable still-fine Central Valley three axle passenger trucks back into modern life.
With reference again to the excellent Tahoe trucks, it was Brian Leppart who in a phone call brought to my attention his finding of the unnoted diminished IM axle length, which I subsequently confirmed.
Keep in mind that none of these trucks, nor the wheel sets that we install, are precision instruments or assemblies. If they were, we would not be having this conversation, primarily because not a one of us could afford them.
Denny S. Anspach MD