Test: John Deere 7550i Forage Harvester

When it comes to harvesting, everyone involved has high expectations. Farmers want a quick, tidy job, the machinery operator desires a comfortable, stress-free environment and the owner/contractor wants reliability, high output and low running costs. This month Jaiden Drought tests a machine sure to keep everyone happy.

As the worst drought in living memory takes hold over much of the country, it may seem hard to believe but, with the last name Drought, I have become even more unpopular and the butt of many jokes. The dry spell we’re currently experiencing is a real doozy and it certainly creates its fair share of challenges for contractors and farmers alike.

This month I decided to run an article  on the John Deere 7550i self-propelled forage harvester, kindly supplied by Gerald Davison and the team at Cervus Equipment here in Taranaki.

I actually tested it back in November  when we had grass on the farm. However, with most people around the country anxiously waiting for their maize to be ready, I thought now was a good time to give contractors something to ponder on the long nights harvesting.

This article will also be of interest to some farmers, not because they want to buy one, but because it might go some way to explaining the hefty bills they receive at the end of the job. Most farmers only see these big machines turn up on their farm, tear around eating everything put in front of them and never really understand what makes the forager tick.

With a lot of pressure on feed supplies at the moment, it wouldn’t surprise me if maize crops get harvested on the slightly lower side of the optimum dry matter (DM) percentage. Farmers may lose a bit of yield by doing so but it will at least give them some reprieve from the feed companies’ long winded excuses as to why their product prices coincidentally skyrocket every time the country experiences seasonal difficulties.

One contractor I spoke to recently described his new chopper as a ‘run-off’ on wheels. This is a great way to sum up the capital outlay required for one of these machines – and with that in mind, you’d expect to see high output.

Because there are a lot of components to a self-propelled forage harvester, let me outline for you the basics, including its ease of operation, key features and user-friendliness, which all current owners will agree is one of its major selling points.


It all starts in the clean and uncluttered cab. As with all John Deere cabs, the brown tones will hide any dirty fingerprints left from getting in and out all day. Given how noisy this machine is outside, I was pleasantly surprised by how quiet it was in the cab, with John Deere claiming 74dB(A) – 76dB(A). All the key controls are on the CommandArm, with the majority of operating functions on the ‘hydro handle’, including programmable header position buttons, spout rotations and header height controls, feed roll direction and an emergency shut-off. Additional adjustment buttons, such as chopping length and spout speed adjustment, are on the arms console. Machine instrumentation is on the ‘A’ pillar, the top display is devoted to machine functions, the middle panel is the performance monitor display and the lower panel shows such items as engine and cutter head speed and fuel levels. The metal detector, as well as some of the auto guidance functions, are located above your head. One thing is definitely noticeable about this chopper – it feels as if the cab has been moved back slightly and the pickup seems to be in clear view, without feeling like you are bending over. On the main joystick, as I mentioned earlier, there are programmable header functions set up, so by pushing button ‘one’ the header is dropped, while button ‘three’ lifts the front once out of the row -simple and easy to use.

Engine and drive

The 7550i sits at third in the six model line-up. However, it possesses the same 13.5-litre, in-line six-cylinder engine (with the usual VGT turbo and four-valves per cylinder) as the larger 7750 does. This thing is a big grunt box and  I’m not surprised given all of these ponies on tap, even though the cutter heads and feed rollers are only 20mm narrower than on the larger 7750.

John Deere’s engine-speed management works in conjunction with the stepless Pro-Drive hydrostatic transmission to match engine rpm and power to requirements under different conditions when running under a light load (both in work and at headlands), stationary or travelling on the road.

Because this machine is the 7550i, the ‘i’ (or ‘intelligent’) management package has three modes, all aimed at maximising harvester performance while also saving fuel:

  • Road mode – active between 1250 and 2100rpm, the system reduces engine rpm  to its minimum to maintain the desired forward speed. At the same time it provides up to 27% more torque to maintain forward speeds up steep inclines. Like an eco-box feature on a tractors transmission, fuel use in transport can be reduced by up to 10% in the case of the 7550i.
  • Field mode one – this is a headland fuel-saving mode automatically reducing engine speed once the machine is clear of the  crop. As soon as the forager enters a new swath, the engine speed is automatically increased to the rpm set by the operator.
  • Field mode two – during work this setting automatically maintains a constant load on the forager engine so it operates at its most fuel efficient speed of 1900rpm. If the crop thickens, the forward speed is pegged back but the engine rpm remains the same. This ensures the engine works at optimum economy. In light loads, the forager speeds back up to ensure a more consistent flow of crop into the chopping system. John Deere claims fuel savings of five percent can be achieved with this setting during a turn, or while waiting for a trailer FM2 does the same as FM1.

Dura Drum cutter head

The slotted knives push back if they hit a rock, minimising the damage and helping prevent costly downtime. The unique feed roll and cutter head transmission (IVLOC – I will explain further later on) lets you choose the exact length of cut you want from the cab. It maintains a constant speed to ensure you get the length you set. The reverse sharpening system strikes the heel of the knife first, drawing the stone across the face toward the edge. This hones the edge into a fine cutting point – maintaining the bevel on the knives gives you more efficient chopping for the entire life of the knife and ensures the knives stay sharper for longer.

Metal detector

These are often the things causing the farmer the most grief, with the little metal detector piles scattered around the paddock. Even the smallest pieces of wire or rocks can set the detector off, often leading to everyone huddled under the feed auger trying to find the culprit. This is extremely frustrating for the driver and often results in some form of colourful language, but it also provides extremely important protection for the machines internal organs. On the John Deere, the detector will stop the feed roller in just 40 milliseconds and, where a blockage occurs, the pickup can be reversed on the joystick.

A very clever feature is the light display in the cab showing in what area of the pickup the detector has spotted a foreign object, making it quick and easy to find.

Optional i-package

As I mentioned earlier, our test machine was the 7550i, not just the 7550, and this ‘i’ spec allows the machines to be fitted with Auto LOC, which links HarvestLab dry matter sensing with the IVLOC automatic length of cut transmission.


HarvestLab measures crop moisture using a near-infrared sensor. It can be used to help optimise the crop’s chop length in relation to its dry matter content – moisture content measurement of + or -2 points on the go for instant readouts. This is particularly useful for operators who are chopping maize for sale to various clients, as the HarvestLab and Harvest Doc will tell you when you have reached 100T/DM for example, filling their order.

Harvest Doc

Harvest Doc is the yield metering and crop recording system, permanently stored in the machines computer. This is a great tool for invoicing clients to let them know 10ha of their maize has been chopped, yielding 22TDM/ha, with attached map to prove it.

Infinitely variable length-of-cut (IVLOC)

This feature gives you an infinitely variable length-of-cut (IVLOC) from 4 – 19mm with 56 knives, 5 – 22mm with 48 knives and 6 – 26mm with 40 knives, all with adjustment increments of one millimetre. The knives can be sharpened by pushing a button in the cab, with this function able to be interrupted if required, although those who already run foragers will understand the fuel savings and increased output from running sharp knives.


The contractor I mentioned earlier, who had run every other brand of forager on the market and come back to a John Deere, said to me: “You send a technician to fix the other brands but you send a blacksmith to fix the John Deere.” Having driven the Deere, I can see what he means. It has all the technology you need and additionally offers some of the most high-tech crop assessment technology on the market, yet it feels like a hurricane of power is behind you, which come maize harvesting will be very handy. John Deere has been building choppers for 40 years, with the last 20 years at its dedicated plant in Zweibrucken, Germany. In total, it has produced well over 10,000 self-propelled harvesters and, judging by this machine, it must be doing something right. Owners, operators and farmers alike will not be disappointed by this machine’s throughput.


  • Clear view of the pickup from inside the cab, without leaning forward
  • Metal detector tells you what side has identified the foreign object
  • IVLOC on the move
  • Machine never felt like it was running out of power
  • Crop flowed smoothly through the machine and never felt like it was surging
  • Intelligent crop assessment technology, which is a great tool for invoicing customers
  • Programmable header functions make operating the front easy
  • Quiet comfortable cab


  • The 800/65 R32 tyres are too big, particularly for Taranaki gateways. Getting around the farm was an issue
  • The pick-up wheels need to be manually removed to get through some gateways, although the new pickups have a hydraulic folding feature


Model JD 7550i          


John Deere


PowerTech Plus



Displacement, L 



In-line six

Engine rpm/min on road mode (three speed GB)


Fuel system

Four valves + EGR + VGT

Cooling fan drive


Maximum power @ 1900rpm/kW (hp)

 458 (625)

Rated power @ 2100rpm/kW (hp)

  428 (582)

Extra power kW (hp)

30 (43)

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Photography: Jaiden Drought

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