Tony Thompson wrote:
The MCBA adopted the automatic coupler in 1887 as standard with further details adopted in 1889 and 1893, and modified in 1909. The coupler was replaced by the Type D in 1918.
The original Type D was adopted as standard in 1916 and was modified in 1918 to the No. 10 contour replacing the former MCBA standard.
All freight cars built new and used in interchange were required to be equipped with Type D couplers cast with 6 inch by 8 inch shanks as of November 1, 1920. Rebuilt cars were to be so equipped on, and after July 1, 1928.
The greater number of early MCBA standard couplers were required to be replaced as of January 1, 1929 due to deficiencies in dimensions and riveted or pinned connections between the coupler and yoke.
The general demise of the early MCBA standard couplers was due to attrition and lack of available replacement parts. The prohibition of cars of all wood construction as of January 1, 1935 would have been another major blow to this coupler design as well.
All new cars built on, and after August 1, 1933 were required to be equipped with Type E couplers. Cars rebuilt on, and after August 1, 1937 were required to be equipped with Type E couplers though exceptions were allowed for cars which would not accommodate larger coupler shanks. Those were still required to be equipped with Type D or E couplers cast with dimensionally smaller shanks.
Type D couplers cast after August 1, 1936 were prohibited, effective January 1, 1937. The AAR required all Type D manufacturers to certify all castings and related equipment was destroyed.