The electric drive system puts out a great deal of power and is very beneficial when it comes to automation and autonomisation – and it’s available now. It’s ready to use in the field. What would be possible if we also had high-performance batteries as large as shoe boxes? This is the thought experiment I invite you to participate in. Let’s completely rethink the tractor!/p>
If we can do that, many components will no longer be necessary: The cabin will disappear because the vehicle drives itself. Because it is electrified, the tractor will no longer need a diesel engine, exhaust system, or fuel tank. If we take it a little bit further and get rid of the wheels, front axle, and main frame, all that is left is the heart of the tractor: Its rear axle. With that, we retain an efficient transmission that drives the rear axle using electric machines. We also keep the rear hydraulics, the PTO shaft, and the standardised implement interfaces.
The tractor – redesigned
Let’s build our new tractor on this basis. Let’s first consider putting the tractor onto caterpillar tracks. Then we add a reduction gear and two electric motors to the design, and the mechanical portion of the drive train is done. While the speed of the diesel engine and hydraulic pumps is always interdependent with classic tractors, we will separate the two systems in our tractor in order to make the drive train even more efficient. This means that one of the engines is purely responsible for the traction drive, and the other is responsible for the rear PTO and the hydraulics system. Each of these machines puts out 250kw of power. This makes the performance of our tractor comparable to tractors from the 7000 or 8000 series. In this compact space, this is only possible because the electrical components are so compact and powerful, allowing us to stop worrying about the power supply. How is this supposed to work? We will get to that in a moment, be patient for a little longer!
How to get power to the ground
Our tractor has a John Deere inverter to supply power and control the electric machines. A second inverter enables us to offboard power to an implement. The next step is to then clad the drive train. Underneath the chassis, there is a new brake system, various cooling circuits for the electrical components – among other things, as well as control components.
We can attach different weights so that the tractor drives its power into the ground. For this, we have developed a ballast system for both the basic vehicle as well as the track. This allows us to decide if we want to make the vehicle heavy or if we need a lighter machine, depending on what the focus is: Heavy tillage or lighter tasks.
Without a front axle, the wheeled version of the tractor might tip over. To prevent this, the tractor forms a symbiotic relationship with the implement when balancing. Here, the additional axis is used as a second axle for the tractor.
This creates a form of articulated steering. Conventional machines can be used as implements; only the interface needs to be adapted.So far so good. Now there is just the question of where the power for the tractor comes from? After all, the assumption we made at the beginning of this article about a battery the size of a shoe box is still a long way off.
Power from the edge of the field
The solution for our prototypes is a power distribution vehicle based on the model of our GridCon tractor It is powered from the edge of the field using a cable. The power is then distributed to the autonomous tractors from this vehicle using a cable. Tractors, as in plural? Exactly! Because this concept works very well when the tractor works in a swarm with other units.
This means that the power is used efficiently over a larger area once it is brought to the field. Thanks to advances in steering and autonomous driving, there are also no problems with turning or driving on the field. And, in our vision, there is always a person standing at the edge of the field supervising what is going on.
Our swarm tractor is certainly not a technology that will go into series production within the next few years. That’s because there are still a few hurdles to clear, for example in the areas of infrastructure, farm layouts, energy provider billing models, and laws and regulations.
Developing electric vehicles more freely
Still, the project is very valuable to us. After all, the cable technology enables us to test electric vehicles in the field over long periods without being slowed down by a dead battery. With these vehicles, we can theoretically work 24 hours a day in the field, gaining insight the entire time. It is astonishing to see the ideas that come to you when watching from the edge of the field as a swarm unit drives over it.