Brooks was the builder of choice for the U.P. in the early 1880s. The Utah & Northern and the Kansas Central were both Baldwin lines until the U.P. aquired them and they starting receiving Brooks 2-6-0s and 4-4-0s.
Even if the DSP&P had remained independent their days of buying Mason bogies may have been near the end. The DSP&P leased the four AT&SF narrow gauge 2-8-0s in 1879 and promptly ordered eight Baldwin 2-8-0s of their own as well as the four Mason 2-8-6T locomotives. Baldwin could deliver more locomotives quicker and the DSP&P could mount the big wedge snow plows on the Baldwins, but not on the Masons.
Wallace gives the tractive effort as being 7,628 lbs for the newer 2-6-6T Masons and 11,250 lbs for the 2-8-6T Masons. Those numbers were calculated on 120 lbs steam pressure at 75% MEP. I don't know the exact boiler pressure of the Baldwins as built, but it probably 130 psi at 85% MEP like the similar D&RG class 56 locomotives, which gave a tractive effort of 12,450 lbs. This made the Baldwins in theory 10% more powerful, but in actual service they probably pulled the same. By the C&S days the 2-6-6T was rated at 10,806 lbs T.E. using 150 psi at 85% and the Baldwins were rated at 13,901 lbs T.E. using 150 psi at 85%. If the pressure on the 2-8-6T Masons was also bumped up to 150 psi at 85%, then their tractive effort 15,938 lbs. They would have slipped more as their driver weight was 50,600 lbs compared to the Baldwins at 53,748 lbs, but they could have been more powerful.
It is interesting to noted that the "standard" narrow gauge bogies built after the DSP&P purchases, had larger diameter boilers and larger fireboxes on the 2-6-6T locomotives, with smaller 13x16 cylinders compared to the 14x16 on the DSP&P. The Denver, Utah & Pacific 2-8-6T Masons had smaller 15x18 cylinders compared to the DSP&P 15x20 cylinder. This was on locomotives weighing the same as the DSP&P 2-8-6T locomotives. Did use on the DSP&P show that despite the free steaming of the Masons, a larger boiler capacity was needed to make up for steam and pressure losses in steam feed piping with all the bends and joints?
Dave
