Actually, Skonk....

The 315 had a higher boiler pressure on the D&RGW than her sister engines in the Class C-18, like 318, which had its pops set at only 145 psi. The 315 received a new firebox in 1924 and it had more lateral braces (from the firebox to the boiler barrel) installed than the other 5 engines in the class. Reasons for the slight reduction in pressure on 315 are not known, but the C-class engines and Rotary OM ran at 160 psi, which may have been a standard pressure for older boilers. We were happy to get the locomotive recertified at 160 psi, because it will give it enough power to hoist at least 3-4 cars up grade.