cutoff with 1/4-in lead, 3/8-in lap. Data for 1927 (6312); tractive effort is usually given as 90,000 lb because the Burlington later reduced the cylinder size to 28" in diameter when they rebuilt ten of the 18 as M-4; see Locobase 5475.
Firebox heating surface included 43 sq ft of arch tubes and 107 sq ft of combustion chamber.
The Burlington called these Texas-type locomotives "Colorados".
These are the 10 M-4 Colorados (first described in Locobase 96) that were modified in the late 1930s-early 1940s to improve reliability. The big change was to drop the cylinder diameter to 28", which lowered tractive effort to 83,000 lb and reduced all the demand factors commensurately while raising the factor of adhesion to 4.00. At the same time the railroad fitted disk drivers with better counterbalancing and installed Timken roller bearings on all driving axles, the main rod, and the leading truck bearings.
See Corbin & Kerka (1960, p 133).
| Specifications | ||
|---|---|---|
| Class | M-4 | M-4A |
| Locobase ID | 96 | 5475 |
| Railroad | Chicago, Burlington & Quincy (CB&Q) | Chicago, Burlington & Quincy (CB&Q) |
| Whyte | 2-10-4 | 2-10-4 |
| Road Numbers | 6310-6327 | 6311-13, 6315-20, 6322 |
| Gauge | Std | Std |
| Builder | Baldwin | Baldwin |
| Year | 1924 | 1939 |
| Valve Gear | Baker | Baker |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 22.33' | 22.33' |
| Engine Wheelbase | 45' | 45' |
| Ratio of driving wheelbase to overall engine wheebase | 0.50 | 0.50 |
| Overall Wheelbase (engine & tender) | 95.96' | 95.96' |
| Axle Loading (Maximum Weight per Axle) | ||
| Weight on Drivers | 353000 lbs | 333430 lbs |
| Engine Weight | 512440 lbs | 504570 lbs |
| Tender Light Weight | 385700 lbs | 385700 lbs |
| Total Engine and Tender Weight | 898140 lbs | 890270 lbs |
| Tender Water Capacity | 21500 gals | 21500 gals |
| Tender Fuel Capacity (oil/coal) | 20 tons | 20 tons |
| Minimum weight per yard of rail on which locomotive could run | 118 lb rail | 111 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 64" | 64" |
| Boiler Pressure | 250 psi | 250 psi |
| Cylinders (dia x stroke) | 31" x 32" | 28" x 32" |
| Tractive Effort | 102106 lbs | 83300 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.46 | 4.00 |
| Heating Ability | ||
| Firebox Area | 492 sq. ft | 492 sq. ft |
| Grate Area | 106.50 sq. ft | 106.50 sq. ft |
| Evaporative Heating Surface | 5914 | 5914 |
| Superheating Surface | 2487 | 2487 |
| Combined Heating Surface | 8401 | 8401 |
| Evaporative Heating Surface/Cylinder Volume | 211.56 | 259.32 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 26625 | 26625 |
| Same as above plus superheater percentage | 34613 | 34613 |
| Same as above but substitute firebox area for grate area | 159900 | 159900 |
| Power L1 | 29340 | 35964 |
| Power MT | 916.20 | 1188.96 |
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