Test: John Deere 8335RT
While the John Deere 8335RT tractor is a big, heavy machine, it’s surprisingly light on its feet. It’s also extremely comfortable and an operator’s dream. Jaiden Drought headed to Hawke’s Bay to see it for himself.
The great part about this job is it allows me to get off the farm, travel around the countryside and meet a bunch of interesting folk. It's good to meet people who are often having the same battles as you (apart from Canterbury, which has been dealt three savage blows in the past month, no pun intended). Often those I meet on my travels have no grass or it's too wet or too dry etc. (remember it's a farmer's job to bleat about the weather). However, on a recent trip to Hawke's Bay it wasn't so much a case of having the same battles as, having had nearly 200ml of rain during the past week in Taranaki, I was surprised to find Hawke's Bay folk mowing and watering their lawns. Now, I'm not bitter and twisted about this, but I would need to develop some form of hovercraft/jet boat/lawn mower hybrid to even think about mowing my lawn, let alone water it — and to be honest, I would be more likely to water it with Roundup to ensure it never needs mowing again.
This month's test was situated just north of Hastings. Here I met up with Bill Barker from Cervus Equipment and the team at J.M. Bostock Ltd which had recently acquired a John Deere 8335RT and were willing to let me have a test drive. Now, it's not often you drive something that appears similar to other tractors in the cab and then turns out to be a very different concept to drive. You'd be forgiven for thinking these tractors work like a skid steer or normal tracked machine, like a digger or bulldozer. In actual fact, these machines have a cog in the diff to power one side or the other during turning. Technically speaking, a steering input device converts steering wheel position to an electrical steering command, which is received by a steering controller. The steering controller then calculates and transmits an electrical signal to the hydraulic steering pump controller. The pump provides proportional flow based on inputs commanded from the steering controller. The steering motor rotates the ring gears of the steering planetaries for differential speed control of the left and right-hand axle shafts. For a given steering motor speed, the speed of one axle is increased while the speed of the other axle is decreased to provide vehicle turning. The main benefit of this system is to significantly reduce scuffing during headland turns, which results in a very different driving experience.
When operating the 8335RT you must adopt a different driving technique to a normal wheeled machine and allow the steering wheel to centre itself (which it does automatically), rather than resting your hand on the wheel, particularly when reversing. It's hard to explain how it feels or what it actually does but you almost have to make little-and-often movements, because if you spun the wheel around with the palm of your hand like usual you would be facing the opposite direction before you knew what was happening. The steering wheel is very sensitive at low speeds and to be honest, this thing would be a handful on the road — which is the main reason a top speed of 35kph is the limit (thankfully) — but as the speed increases the steering sensitivity decreases to make for a smoother ride.
Unique features of the 8R tracked version
You may think the tracks are just another option you can tick when you order the tractor but this is not the case. For starters, you can only get the tracked option in the largest three of the six tractor line-ups and like the wheeled version, the 8360R and 8360RT are both standard with IVT, where as all other models have the choice of 16 x 4 speed power shift or IVT.
Because these machines are more likely to be used in a market garden/precision arable sense than their wheeled brothers, they do boast 1400kg higher linkage lift capacity with nearly 10 tonnes of lifting force and a massive 227L/min oil flow capacity from up to six SCVs. To spread out their massive 16-tonne weight (not including ballast), they have a huge undercarriage to cope with the large 'snozza' out front and one of the longest wheelbase tractors in its class, so it doesn't topple forward.
Often a new series of tractor has a few tweaks and some modern styling but often proven components remain relatively unchanged. This is generally the same for the new 8R series replacing the 8030 models, but the tracked versions (the track running gear in particular) has undergone a major revamp with operator comfort largely front of mind.
Firstly, the new AirCushion suspension system acts very much like the front suspension system on a normal wheeled machine, where you can have a smooth ride to maintain faster work rates without your teeth getting smashed out of your head. Not only does the AirCushion allow you to increase working speeds, it also aids traction to allow more power to the ground simply by having more track contact. The heavy-duty airbag and shock absorber allow the swingarm and walking beam to float on its own to give the beast traction, while the pressure in the airbag is automatically adjusted to keep the swingarm centred for the maximum suspension travel.
John Deere designs its tracks slightly differently to others. It makes the rubber ring out of soft rubber first, so it offers some give (because driving around on tracks is like driving on a flat tyre), and then it vulcanises hard cleats onto the rubber ring to give the smoothest possible ride with the hardwearing characteristics of the cleats. To help you keep the $25,000-odd needed for new ones in your bank account a little longer, John Deere has a nitrogen accumulator and a larger tensioning cylinder, increasing track tension to 14.5 tonnes. This is a 45% improvement over the 8030T Series and is all done with the aim of preventing track slippage, which directly results in increased track life.
You can have a variety of track spacing's from 1.8m to 3m with adjustment allowed at every four-inch interval. If you feel larger row spacing or stability on the hills is an issue, you can get an extension kit to allow track spacing out to four metres without the need for a separate frame. Vertical suspension travel is directly correlated to the track spacing with 24.5cm of travel at 1.8m, while out at four metres you get almost 52cm of travel, allowing you to tackle the toughest terrain you can point the 8R's nose at!
As I mentioned earlier, there are two options in the transmission department — unless you opt for the 8360RT, in which case the only option is the IVT. I personally think the IVT is the easiest CVT to operate. It isn't packed with buttons and sign language and its rugged simplicity means people who have never driven a CVT before can simply jump in and get it moving.
People may say that, with this size of tractor, you will lose a heap of power with a CVT. This probably is the case if it's going to be a tillage-only machine, so you may want to go for the power shift. For Bostocks however, this tracked machine is simply a finishing tool and will spend most of its life on the power harrow. Considerably-lower ground compaction and the ability to work through more challenging conditions make the IVT the perfect choice for Bostocks and the fact it is so comfortable and smooth to operate made the decision a no brainer. Speaking of compaction, it really is amazing what little footprint this machine leaves. It's as if they come with an invisible helicopter hovering above to hold up the tractor (our test tractor weighs around 17 tonnes with the front weights and with around two-percent wheelslip during the test, there are no ruts for the power harrow to sort out, that's for sure).
John Deere uses IVT 'auto mode' and 'field cruise' (each manufacturer with a CVT has a code name for the engine management system), where essentially there is constant communication between the transmission and engine allowing the tractor to automatically change transmission speed to keep (in the test) the PTO speed on the power harrow as consistant as possible, while varying the engine rpm and ground speed automatically to achieve this.
Another strange anomaly with this machine is that is only has two pedals, a clutch and a brake (no side brake). These machines come standard with right-hand reverser, although I am told if you order a 2014 model the left-hand reverser (LHR) is an option. This isn't a flaw, but given there is no accelerator, you have to do all of it via the IVT stick. This will take some getting used to if the rest of your tractor fleet is LHR.
These machines have the Tier II engine, which does away with the cooled exhaust gas recirculation or EGR and the particulate filter with the only downside being you don't get engine management or 'boost'. More importantly, this engine has the distinctive bark that John Deere's are known for.
If the bark in the Tier II isn't high on your priority list, you can still get the Tier 4, which uses the high common rail pressure. The ECU (engine control unit) on these machines senses engine speed and load changes at a rate of 100 times per second. This high-tech system allows the engine to instantly adjust fuel quantity, injection timing, air-to-fuel ratio and the amount of cooled exhaust gas recirculation — all the while with fuel economy in mind.
These days if you hop into a cab that is small and cluttered you feel robbed, given everything is becoming more spacious and luxurious, no matter whether it is a car, truck or tractor. The newly-designed CommandView II cab on the 8R is no different and is a considerable improvement on the 8030-Series it replaces. I always found it a little strange that the larger tractors (mainly the 8000- and 9000-Series tractors) were more basic in their cab technology levels than what you got in the smaller 5000-, 6000- and 7000 models. This is certainly not the case anymore, where there are now large screens on both the command-arm and the instrument display on the 'A' pillar of the four-post cab. Additionally, our test machine was running the GreenStar GPS system with the large display screen. There are two things you will immediately notice when you jump in the cab: firstly, the amount of glass in the cab and secondly, the large amount of glass which provides the best vision of any tractor I have been in. Why? It's easy: no front wheels blocking your view. Simple as that. The cab is genuinely massive with ample storage space behind the seat and, if you like your music, you can opt for the premium entertainment package with a subwoofer behind the operator's seat, which will take up a bit of storage space but you don't buy these tractors to sit in the shed so I'm sure you'll get plenty of time to enjoy it.
With most brands of tractors, you can find most of the tractor's functions on the armrest, but the 8R's command arm takes this to the next level with just about every function the tractor has being controlled off the armrest. The command arm can be adjusted up, down, forward and back to suit the individual operator with main tractor functions are at your fingertips. Attached to the side is a set of soft-keys, arranged with the most-frequently-used keys up front, while cab-environment controls are at the back. The GS3 Command centre is mounted on the end of the armrest. It's easy to use and is available in standard and touch-screen versions but I found (it may just be in this particular tractor) when you were facing forward, the Command centre monitor completely blocked your vision of the GreenStar display, so I had to have the seat swivelled to see both simultaneously.
The intelligent Total Equipment Control (iTEC) feature is purely an intelligent headland management function to lift the linkage and turn off the PTO at the headland once the linkage arms reach a certain height, and then do the same but in reverse when heading in the other direction. This function, along with the GPS guidance, will help save fuel and improve productivity. It is easy to set up and adjust on the move if need be and given you can store up to 20 functions for five different implements, you won't run out of computer space.
Operating the 8R really is a pleasurable experience, particularly with the iTEC and GPS features. Literally all you have to do is turn at the headlands and push two buttons, and you're off with centimetre precision.
Like most specialist machines, this one is packed full of sophisticated technology. The cab is both light and spacious and a very comfortable place to spend a day. It has an engine that sounds cool and allows you to actually blow black smoke. All of this, combined with one of the easiest transmissions to use on the market — what more could you want?
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