| Chicago Burlington & Quincy RailroaChicago Burlington & Quincy Railroad 2-10-4 Class M-4 6325 presumed at Philadelphia, Pennsylvania in April 1929, photograph by Baldwin Locomotive Works, print by H. L. Broadbelt, Chuck Zeiler collection. Number 6325 was built by Baldwin in April 1929 ( c/n 60770 ) as Class M-4, 4, rebuilt in September 1935 to Class M-4-A, sold for scrap in May 1961. The 2-10-4's were originally designed and built as drag locomotives, but by 1934 the Burlington needed faster locomotives. The driver diameter remained at 64 inches but the main driver was replaced with a Scullin cross-counterbalanced double-disc type. Roller bearings were applied to all running gear ( axles and rods ), and included the tender trucks. New one-piece cylinders were cast by General Steel Castings, machined by Baldwin, and applied by the Q. New light-weight rods were applied, and the limited cut-off was discarded in favor of full stroke. After tests, five more M-4's were upgraded, all but one were from the 1929 batch of locomotives. |