Introduced in 1903, the Bettendorf friction bearing truck was one of the first truck designs with one-piece cast sideframes and integral journal boxes. The original design used a sideframe with a "T" cross section. T-section trucks remained popular through the twenties, but were eventually phased out in favor of newer designs (and ultimately banned from interchange service in 1953). The Bettendorf T-section truck has never been modeled in N scale, so here's Kadee's HO version (hey, we can dream, can't we?) -
Significantly stronger trucks featuring a U-shaped cross section eventually superceded the T-section trucks starting in the 1920s. This style of truck, which is most identified with the modern steam and early diesel eras, has become generically (and incorrectly) known as the "Bettendorf" truck. The Bettendorf Co. widely licensed elements of its design, so many builders besides Bettendorf made trucks of this type (to the point that the U-section cast steel truck was eventually adopted as an ARA standard: the Type Y truck). Although each of these trucks (regardless of the manufacturer) follows the ARA/AAR standards, many have varying details (sideframe shape, spring size and styles, bolster design, journal-box lids, etc).
Starting in the 1930s, these trucks were upgraded with double-truss sideframes (with parts of the U-shaped section being filled in, creating a double-layer effect on the sideframes). Model-wise, these trucks are indistinguishable from the earlier U-Section / Type Y trucks.
Virtually every N scale manufacturer has offered up some sort of "Bettendorf" style truck at one time or another (and of varying quality). These are generally presumed to be 50-ton trucks, although Atlas does make a 40-ton version (for use on lighter cars such as reefers).
Athearn, Atlas/China, Atlas/Roco, Bachmann (new), Con-Cor, Fox Valley, Intermountain, and Micro-Trains 50-ton -
Arnold-Rapido, Bachmann (old), Life-Like, Lima, MDC/Roundhouse, Mehano, Model Power, Con-Cor/Red Caboose, Rivarossi, and Walthers 50-ton -
Atlas 40-ton -
The "coil elliptic" truck was a variation of the Bettendorf design, featuring a non-harmonic spring combination consisting of coil springs and an elliptic leaf spring. This arrangement provided good shock absorption and prevented rhythmic side-to-side sway on uneven track by using unequal damping control. 50-ton double truss trucks with this spring package were manufactured from the early 1930s to the late 1940s. Railroads that used these trucks on some cars included BAR, C&O, CGW, D&M, DT&I, Erie, LNE, LS&I, MRS, N&W, NP, TA&G, VGN and WM, and some AC&F tank cars built in 1937. A similar 70-ton version was used by B&M, CNJ, CRP, D&H, DT&I, Erie, LNE, MEC and PRR.
Micro-Trains makes the only N scale coil elliptic truck -
Bettendorf U-section trucks were ultimately banned from interchange in 1954. Starting in 1966, all new cars were required to have roller bearing trucks, and the old double-truss friction bearing trucks were gradually phased out as well (some were retrofit with roller bearings and the rest were scrapped when their cars were retired from service). Friction bearing trucks on cars carrying hazardous materials were banned from interchange service in 1991. All other cars equipped with friction bearings were banned from interchange in 1994. Cars with converted friction to roller bearing side-frames were banned from interchange in 1995. A few exemptions to these rules were granted for shippers who could not comply with the dates, so some cars did linger a little longer in interchange after the actual deadline dates. The converted trucks were ultimately banned because hot bearing detectors could not "see" them when they overheated.
Athearn 50-ton - wheelbase 10.7mm, frame width 16mm, wheel size 33", axle length 13.65mm
Atlas 40-ton - wheelbase 10.25mm, frame width 15.9mm, wheel size 33", axle length 14.25mm
Atlas 50-ton (original) - wheelbase 10.5mm, frame width 16mm, wheel size 33", axle length 13.6mm
Atlas 50-ton (revised) - wheelbase 10mm, frame width 16.7mm, wheel size 33", axle length 14.25mm
Intermountain 50-ton - wheelbase 10.07mm, frame width 15.93mm, Wheel size 33", axle length 14mm
Life-Like 50-ton - wheelbase 10.1mm, frame width 13.87mm, wheel size 33", axle length 13.9mm
Lima 50-ton - wheel diameter 0.201" (scale 32"), wheelbase 0.420" (scale 5' 7")
Micro-Trains Coil Elliptic - wheelbase 10.25mm, frame width 17.23mm, wheel size 33", axle length 13.7mm
Micro-Trains 50-ton - wheelbase 10.1mm, frame width 16mm, wheel size 33", axle length 13.7mm
Model Power 50-ton - wheelbase 10.4mm, frame width 17.23mm, wheel size 33", axle length 13.9mm