This was 30 pound iron rail in the early 1870's, remember, not steel rails. Period sources of the time rated iron rails as good for a practical maximum of about 224 pounds per wheel per pound of rail, and steel rails for about 300 pounds per wheel per pound of rail**. Lower values than those maximums were *strongly* recommended to prolong rail life, especially on 6- and 8- coupled locomotives. As a rule, the more axles, the lower the suggested individual axle load. For 35 pound iron rails (a common size on narrow gauge lines), Baldwin usually recommended 4-4-0's of about a 12,500 pound axle load, or Moguls or Consolidations of about a 11,000 pound axle load. 4-4-0's were heavily favored during the days of iron rails in part because their balance, smooth operation, good tracking, high flexibility, and relatively low hammer blow didn't harm the rails as much as the other classes did. The North Pacific Coast railroad (laid with 35 pound iron rail) was of the opinion that its 4-4-0's of roughly 14,000 pounds axle load actually wore the rails less than its Mogul of ~11,000lbs axle load! It was far from alone in that opinion, and a great deal of bias existed during the late 1860's and early 1870's against the Mogul and Consolidation type locomotives.

In the early days the D&RG attempted to stay within manufacturer guidelines for axle loads on given rail sizes. Baldwin generally recommended 35 pound iron rails for the class 10-22-E 14x16 2-8-0's. Axle load of these locomotives averaged about 11,500 pounds. Since the D&RG was laid with 30 pound iron rails, it used lighter machines. The standard locomotive classes the D&RG used in those early days was the class 25 9x16 2-4-0 with a 10,000 pound axle load, and the class 35 11x16 2-6-0 also with about a 10,000 pound axle load.

A few years later on, the D&RG began buying heavier locomotives and simply accepted the increased maintenance of way costs until it was able to renew with heavier and/or steel rails. The class 40 Moguls were noted to throw the track out of line more than the earlier locomotives did. Their axle load was on the order of 11,000 pounds.

Speeds were not high. The class 25 locomotives ran roughly at speed and were usually kept to 15-20 MPH. The heavier class 37 and 38 4-4-0's of the mid-late 1870's were usually kept to about 20 MPH although they were known to be capable of running faster if desired. Freight trains were usually held to about a 10 MPH average.

The very long rigid wheel base of the early 10-22-E 2-8-0's would not have been popular on the D&RG, either. The Class 56 and class 60 locomotives had the rigid wheelbase reduced by more than a foot compared to the earlier 2-8-0's, despite being larger machines.

The class 60 2-8-0's usually had about a 13,000 pound axle load. This was near the practical maximum for the 30 pound iron rails then in use and must inevitably have caused significant wear even if run only at low speeds. Notably the D&RG purchased only a *single* class 60 locomotive during the 1870's; all subsequent 2-8-0's ordered during the 70's were of class 56 plan with axle loads reduced by about a half ton.

**Note: These values--commonly quoted in 1860's through 1880's engineering journals--are rather conservative to modern eyes and reflect the state of manufacturing quality control of that era. Permissible weights increased as quality control improved and experience demonstrated that heavier loads were permissible.



Edited 2 time(s). Last edit at 04/19/2014 02:24AM by James.