John Deere 30
1 model in this series
John Deere 30 line, Model 840: a classic two-cylinder engine of 7,726 cc, 51.9 kW at just 1,125 rpm, and a weight of 5,416 kg, built from 1958 to 1960
With its 20 and 30 lines, John Deere built the final generation of its classic two-cylinder tractors before switching to four- and six-cylinder New Generation engines in 1960. The 840 belongs to the 30 line and was built from 1958 to 1960, right at the close of that two-cylinder era.
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The two-cylinder engine of 7,726 cc produces 51.9 kW (70.6 hp) at just 1,125 rpm. That combination of very large displacement and very low speed is the technical hallmark of the classic John Deere twins. At 5,416 kg, with a wheelbase of 1,890 mm and a width of 2,146 mm, the 840 is a heavy, powerful field tractor for its time.
The low rated speed combined with large displacement delivers high torque from a standstill, which is what made these twins valued for heavy pulling work such as ploughing with multi-furrow ploughs. With a top speed of 18 km/h, the 840 sits clearly in the slow tractor category.
Buying such an old twin means paying particular attention to the crankshaft bearings and cylinder bores, given the high running hours on many surviving examples. The pulley, starter motor and the ignition and fuel systems of an engine this old should also be checked closely before any long-distance driving is attempted. Thanks to a large collector base, an active parts market exists for the classic John Deere twins, including reproduction parts, which keeps most of these tractors serviceable decades after production ended.
Sources: SpecCodex-Register: Kennwerte des Modells 840
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