B Smith posted:I'm not sure that sprung drivers make any real difference, in the absence of true equalization. If a 3-axle locomotive without springs encounters a vertical curve, then its weight on drivers will be transferred briefly to the first and third drivers when the center drivers rise above the rail head, presumably increasing the traction of the remaining four drivers that are in contact with the rail. I would like to see the quantitative results of tests to determine whether or not the tractive effort of the engine is actually reduced in this circumstance.
With a non-sprung (rigid) 2-6-0 locomotive, a vertically curved transition into an upward grade will cause the middle drivers to lose contact with the rails. To me, this is not acceptable because it looks unrealistic. With a downward transition, the front drivers will lose contact first. As the locomotive pitches downward, the rear drivers will lose contact. Does not look good. As for tractive effort, assuming the total torque delivered to two driver axles is the same as with three driver axles, the tractive force on each driver would be larger (by a factor of 3/2) when two sets of drivers are in contact, and the drivers would be closer to slippage, especially in an upward transition.
MELGAR
