|The following list provides basic details of the
most important tractors in the Marshall - Field Marshall Range.
|Marshall Model 15/30
||February 1931 to December 1932. Prototype
first appeared at the National Tractor Trials in 1930. Three
forward and one reverse speed. 550 r.p.m. engine of 8" bore
x 10.5" stroke
|Marshall Model 18/30
||December 1932 to January 1936. Basically as 15/30 with
|Marshall Model 12/20 & Model M
||January 1936 to June 1945. Increased power from 700 r.p.m.
6.5" bore x 9" stroke engine.
|Field Marshall Series I
||June 1945 to September 1947. Further increase in power.
Engine speed 750 r.p.m.
|Field Marshall Series II
||September 1947 to March 1950. As Series I but with improved
exhaust arrangement and other minor improvements.
|Field Marshall Series III
||March 1950 to June 1952. Dome Top pre-cleaner introduced.
Also six speed gearbox.
|Field Marshall Series IIIA
||June 1952 to 1956. Further improved by revisions to piston
design. Early versions still in green livery but the vast
majority were in the new house colour of orange.