John Deere 840
Built: 1958–1960 · Series: 30
More machines from model year 1958
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
Technical data
Engine
| Fuel | dieselcorrect |
|---|---|
| Power | 70.6 hp (51.9 kW)correct |
| Rated speed | 1,125 rpmcorrect |
| Cylinders | 2correct |
| Displacement | 7,726 cm³correct |
| Bore | 155.58 mmcorrect |
| Stroke | 203.2 mmcorrect |
| Compression ratio | 16correct |
| Cooling | water-cooledcorrect |
Dimensions and weights
| Length | 3,861 mmcorrect |
|---|---|
| Width | 2,146 mmcorrect |
| Height | 2,057 mmcorrect |
| Wheelbase | 1,890 mmcorrect |
| Ground clearance | 549 mmcorrect |
| Unladen weight | 5,416 kgcorrect |
Drivetrain and chassis
| Drive | rear-wheel drivecorrect |
|---|---|
| Gearbox | 6 V/1 Rcorrect |
| Forward gears | 6correct |
| Reverse gears | 1correct |
| Front tyres | 8.25 x 20correct |
| Rear tyres | 18 x 26correct |
| Top speed | 18 km/hcorrect |
Working data
| Fuel tank capacity | 123 lcorrect |
|---|
Origin and approval
| Construction | unit construction (no separate frame)correct |
|---|---|
| Units built | ca. 883correct |
Where this model stands
Power-to-weight ratio: 9.6 kW/t (52 kW / 5.4 t)
Power class: Universal (40–100 hp)
Stronger than 49% of the tractors in the register — out of 15,663 models with a stated power figure.
Calculated from the documented figures above — not a rating.
Frequently asked questions
How much power does the John Deere 840 have?
The John Deere 840 delivers 70.6 hp.
How much does the John Deere 840 weigh?
The unladen weight is 5,416 kg.
What engine does the John Deere 840 have?
2 cylinders, 7,726 cm³ displacement, Diesel.
How fast does the John Deere 840 go?
Top speed is 18 km/h.
What are the dimensions of the John Deere 840?
3,861 mm × 2,146 mm × 2,057 mm.
When was the John Deere 840 built?
Production years: 1958–1960.
What to check before buying
- Check the hour meter against the service records — a replaced instrument is the most common gap.
- Compare the data plate and chassis number with the papers.
- Check the weights in the papers against the figures here — attachments change them.
- Check front and rear tyre sizes: mismatched pairs strain the drivetrain.
- Shift the gearbox cold and warm — jumps only show up at temperature.
- Load the hydraulics and watch for sag.
- Ask about parts availability for this build year — the running costs hang on it.
A general list for this type of machine — no substitute for an inspection or an appraiser.
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This page carries 27 individual figures for this model. They come from 2 recorded sources; every figure can be traced there. What we cannot document is not here — we leave gaps open rather than estimate them.
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Tractor in 3D section
Turn the model, look inside and click an assembly — each one is explained.