Upon his arrival on the farm welcoming our comparativeeach tractor (Deutz-Fahr 8280 TTV, New Holland T7.300 AutoCommand, John Deere 6R250 Autopowr, Case IH Puma 260 CVXDrive, Valtra Q305 Direct, Fendt 728 Vario, JCB 8330 Fastrac iCon et Massey Ferguson 8S.305 Dyna-VT) followed the same rigorous protocol. Its dimensions, first of all, were noted. We also measured its steering angle, although this depends on the tire fitment, the track and the adjustment of the stops made by each manufacturer on our test tractors. Finally, these were weighed, without their front masses, on the weighbridge of the local cooperative. Let us point out that some were equipped with wheel or ventral masses, which we did not remove.
Switching to the power bench
The nine tractors in the comparison passed the test of the power bench of the regional chamber of agriculture of Nouvelle-Aquitaine. These tests would not have been possible without the presence of Didier Langlois (CRA of Nouvelle-Aquitaine), assisted by Guillaume Rodriguez (Chamber of Agriculture of Deux-Sèvres). Before carrying out the power, torque and specific consumption measurementseach of the tractors was warmed up on a road trip to achieve optimal engine performance as closely as possible. The transition to the bench is carried out after deactivation of the air conditioning. The values recorded correspond to the OECD assessment protocol. This takes into account the efficiency of the transmission as well as the power consumed by the hydraulic pumps, the water pump and the fan, unlike the ECE R120 standard used by manufacturers in their brochures.
To measure the power, torque and consumption, with and without overpower, of the tractors concerned, we required the presence of a technician for each brand. In fact, the overpower is activated during transport or when taking power in particular, but the tractor must travel at a minimum speed, for example at 0.5 km/h for certain manufacturers. Since the transition to the bench is done statically at the power take-off, it is not possible to move forward unless the tractor is placed on blocks. The other possibility, simpler and more common, is to connect a computer to the tractor to simulate a speed and thus carry out the measurements without and with overpower. Thus, only the John Deere, Case IH and New Holland in our comparison were measured with overpower. Not having a technician, the Claas tractor was only measured without overpower. The Fendt, for its part, benefits from overpower that is automatically activated to respond to the energy consumption of the hydraulic circuit, air conditioning and fan. JCB, Massey Ferguson, Deutz-Fahr and New Holland tractors, however, do not have overpower.
Test in real conditions
For more precision, we wanted to measure the real consumption of tractors at work. For that, the diesel pump from the tank of each model has been diverted to an external 20 L GNR can. At each consumer workshop, the time of use was measured, and the can weighed before and after each sequence. These measurements make it possible to calculate consumption in kg/h. From the density of GNR (0.845 kg/m3 on average), we obtain consumption in L/h. One and the same person is assigned to the workshop in the field and on the road in order to have identical operation. For the field test, a Maschio Gaspardo Jumbo Isotronic rotary harrow with a working width of 7 m was attached to each tractor. Unfortunately, the rainy weather conditions did not allow us to use this data.
For the transport workshop, our nine tractors, to which we have attached a three-axle La Campagne tipper loaded with manure, completed the same 15.2 km route. The driver made the trip at a driving speed with “Cruise Control” set to 40 km/h. The transmissions of each machine were previously adjusted with a driving strategy (aggressiveness of the transmission) at 50%. The tires, all 710 mm wide, except those of the Massey Ferguson in 800 mm, have been inflated to 1.2 bar at the front and 1.5 bar at the rear.
