The Cummins NH220, a 6-cylinder engine displacing 743 in3, was introduced in the mid 1950's. The N Series engines experienced several modifications through the years.
In 1957, displacement was increased to 855 in3. Turbochargers and aftercoolers were added later on.
In 1961, the first NH engines equipped with a compression release engine brake were produced. The "Jake brake", manufactured by Jacobs Vehicle Systems, was one one the many great innovations of founder Jessie Cummins.