John Deere 20 Series

Farm Forum

The 20 series of John Deere tractors began with the introduction of the 420 Model in 1955.

The next year the 320, 420, 520, 620 and the 720 came along and in 1957 along came the 820.

The most common models within each series were the standard, row crop and utility. The other models included the orchard, hi-crop, crawler, single front, all fuel, LPG and the diesel.

Generally the 20 series tractors were rated with about 20 percent more power than the earlier John Deere tractors of the 40, 50, 60, 70 and 80 series.

Some of the added improvements of the new 20 series were custom power trol, power steering, new category three-point hitch, float ride seat and a new green and yellow color scheme.

The 20 series tractors were the first to be developed by the Research and Design Center at the John Deere operations in Waterloo, Iowa.

The John Deere 720 Diesel was test in September of 1956 and using fourth gear the tractor rated 40.41 drawbar horsepower. The fuel economy was rated at 16.56 horsepower hours per gallon of fuel. It was considered one of the most fuel-efficient tractors of its time.

The 720 two-cylinder diesel was rated at 1,125 RPM and achieved 116 percent of rated torque at 65 percent of rated speed. The engine had a compression ratio of 16.1 with a Cubic Inch Displacement (CID) of 376.

The tractor had a six and one-eights by six and five-eights inch bore and stroke. Starting of the 7820 Diesel was by a V type four-cylinder gas engine rated at 5,500 RPM.

The John Deere 720 Diesel was priced about $5,000. The gas model 720 sold for about $1,000 less.

The 20 series tractors were manufactured fro 1955 to 1958. In 1959 and 1960 the 30 series were manufactured. The 30 series ended the famous two-cylinder line of tractors.

The 420 series offered a number of new optional features like a five-speed transmission, a continuous running PTO and a three-point hitch for the crawler model.

An LP gas engine was also offered.

With the introduction of the 520 series all models and series had power steering and were painted in the new yellow and green combination. 0

The Model 620 Orchard was the last of the two-cylinder era of the 20 series. The history of the two-cylinder tractor was finally over after forty years serving as the power source of John Deere tractors.

The largest two-cylinder tractor was the 820 with a rating of 75.6 in the Nebraska test. Only the earlier 720 achieved a slightly better fuel economy rating.

The 830 series was the same engine size but offered a newer styling and more comfort. All two-cylinder production ended in 1959.

Written by Delmer Dooley

, an agricultural engineer, former high school ag teacher (Platte), expert on vintage tractors and farmer. The author lives with his wife on his parents’ homestead farm near Ramona in Lake County.