In reading through the Central Division timetables that have been posted recently (and thanks again, Richard), I became very interested in the Bridge Class of Engines table in TT 35C. What got my attention was the fact that the Maximum Bridge Class of Engines between Monett and Paris was 53. The most commonly used locomotives between Fort Smith and Monett were 1305-class 2-8-0s, 1040-class 4-6-2s and 4000-class 2-8-2s. What is interesting is that each of these classes of locomotives had individual locomotives of differing Bridge Class. In the case of 1305s, some were rated 50, some 53.8 and some 55. Similarly there were 4000s rated 53, 53.5 and 53.8. With the line limited to 53 it would seem to have meant that some 1300s and 4000s were permitted and others were not. As late as 1959 the Maximum Bridge Class was still 53. Yet I know from first-hand knowledge that specific 1300s and 4000s (including 4003 now preserved in Fort Smith) having a Bridge Class greater than 53.0 operated into Fort Smith. So several questions: 1. I am not aware of significant differences among individual 1305 and 4000 locomotives, such as some having boosters and some not, so how did they come to have different Bridge Class ratings? 2. To have gone to the detail of rating individual locomotives Bridge Class 52, 53, 53.5, 53.6, 53.8 and 54, it must have been felt that this was a significant difference. But if so then why were locomotives of greater than Bridge Class 53 allowed to operate south of Monett? 3. What probably should have been question #1 -- how is Bridge Class calculated. I'm confused (a frequent occurance). Gordon
Gordon, Here are a few bits from Trautwine http://www.frisco.org/vb/showthread.php?3474-Bridge-class&highlight=cooper
Another source of Coopers Info you might consider is Design_of_Steel_Bridges (free download from Google Books). It's a large volume and very technical but even I could wade through most of the Coopers information which began on page 10. For those interested in older Frisco bridges in the St. Louis area, Google offers another free download. Washington_University_Studies Vol 1 (July 1913 Apr 1914). The article which begins on page 105 was a study of loading on Frisco bridge 18.2 at Valley Park, MO. It includes a few photos of Frisco locomotives and parts of the bridge and drawings of the bridge. John
