Test Drive tractor MF 7720 Dyna-6

We tested the MF 7720 Dyna-6 tractor from Massey Ferguson, recently nationalized, together with the MF 713 Seeder, to prove the efficiency of integrating the engine with the Semi-PowerShift transmission in jobs that require efficiency.

25.08.2017 | 20:59 (UTC -3)

We tested the MF 7720 Dyna-6 tractor from Massey Ferguson, recently nationalized, together with the MF 713 Seeder, to prove the efficiency of integrating the engine with the Semi-PowerShift transmission in jobs that require efficiency and versatility from the tractor.

Taking advantage of two days of sunshine and mild temperatures, we had the opportunity to test the new Massey Ferguson tractor model, the MF 7720 Dyna-6. Inserted in a family of four models, this is the second in maximum engine power, with 210 hp. This family was presented at the last Agrishow, in Ribeirão Preto, in May and is already being sold through the MF dealership network. Production begins in September. The MF 7700 family is made up of four models, MF 7719 Dyna-6 (195hp), MF 7720 Dyna-6 (210hp), MF 7722 Dyna-6 (230hp) and MF 7725 Dyna-6 (250hp). The first two models have 6,6 liters and the MF 7722 and MF 7725 models have a volumetric capacity of 7,4 liters, all with six cylinders in line.

It is noted that the Proconve MAR-1 regulations revolutionized the market for tractors with power greater than 100 hp. Within this new generation of tractors, this is another of the brand's models with electronic injection.

As has been common in the MF tractor line, this is a model that follows global projects, with the tendency to manufacture the same models here in the country that are produced in the most important industrial centers. This model is the same one originally produced in the tractor factory located in Beauvais, France. Even with this international project, which represents an evolution of the Series 7000 Dyna-6, the model sold here in Brazil is manufactured at the Canoas (RS) unit, with the engine coming from the AGCO unit in Mogi das Cruzes (SP), and maintains the transmission of the international model, manufactured by Gima, of French origin.

As we said, with this globalization, the models acquired a global identity and, in this series, the main points are the new aesthetic lines, the possibility of having a three-point lifting hydraulic system and front PTO, the presence of suspension on the front axle and the Dyna-6 transmission imported from France.

Due to all these issues, relating to the technology applied to these models, the manufacturer will not exceed the production of 100 units this year, even with demand pointing to a higher number of sales. Only the Redemaq dealership, which serves the region where the test took place, has already sold three units and will not plan any more sales, although interested parties exceed this volume.

MOTOR

The MF 7700 family tractors are equipped with an AGCO Power six-cylinder in-line engine, with an electronic fuel injection system, Common Rail. All engines in the range are supercharged by a Schwitzer turbocharger, associated with an intercooler to cool the incoming air.

The fuel injection system has three filters. The first has a translucent housing for viewing water settled at the bottom and checking for system pressure irregularities. The second filter presents the system's air removal mechanism, consisting of a manual pump and bleed screw. The third filter, with a finer mesh, complements the function of the others.

There are sensors throughout the engine structure that monitor the presence of water in the injection system, engine temperature, fuel temperature and pressure, minimum and maximum speeds, inlet air temperature and lubricating oil pressure. Failure of one of these parameters will result in engine power being cut and the engine entering safety mode, aiming to preserve its integrity.

The engines of these tractors have an idle speed of 850 rpm. However, when the tractor is in idle condition, that is, stopped and without request from the hydraulic system, the parking brake located next to the reverser is activated, and the idle speed increases to 750rpm. This system called “Idle Stop” helps reduce fuel consumption.

In order to comply with legislation relating to emission levels from agricultural and road machinery, Proconve MAR-1, the line's engines are equipped with an EGR (Exhaust Gas Recirculation) system. The engines carry out recirculation internally, this procedure is carried out by modifying the valve control. During the combustion gas expulsion stage, the intake valve allows a portion of these to return to the air collector, to be admitted into a new cycle. This system is called iEGR.

The presence of already burned gases in the admitted air reduces the maximum temperature in the combustion chamber, thus reducing the levels of nitrogen oxide emissions, which are harmful to human health and the environment. With the use of iEGR, the use of the selective catalyst system in conjunction with Arla 32 fluid is not required.

To facilitate the diagnosis of faults that may occur during engine operation, taking advantage of its electronic control condition, the manufacturer has provided an identification system, using a monitor report, which presents error codes, facilitating the identification and correction of faults. problems such as clogging of filters, lack of fuel, insufficient pressure, etc.

STREAMING

The MF 7700 family tractors use a Dyna-6 transmission with 24 forward and 24 reverse speeds, resulting from the combination of four groups of speeds with six gears and a reverse system. The range of speeds achieved varies from 1,5km/h to 40km/h. The transmission is of the Semi-PowerShift type, which allows gear changing with the tractor under load. It should be noted that it is a transmission that presents total engine/transmission interaction, facilitated by the use of electronics.

The transmission features two modes of operation, work and transport. In work mode, the sequential change of gears between different groups is blocked, this occurs to protect the integrity of the transmission system. In transport mode, there is no such restriction, and the entire gear shift can be used sequentially.

As the tractor does not have a gear selection lever, forward and reverse drag gears are configured. The reverser, positioned to the left of the steering wheel, has the function of selecting the direction of travel, sequential gear changing and the clutch function. The clutch also has sensitivity adjustment, allowing it to be smoother or more aggressive.

Also related to gear shifting, there is a “T" lever to the right of the console. Both this lever and the reverser are used without the aid of the clutch pedal, as this is only mandatory when starting the engine, for safety and security reasons. compliance with standards.

As a transmission configuration, the MF 7700 line also features automatic mode. In this mode, a limit gear is selected for displacement and the speed is configured to carry out the change. In this way, the tractor automatically changes gears when it reaches the selected speed, repeating this feature until it reaches the selected limit gear.

In addition to manual and automatic transmission modes, there is DTM (Dynamic Tractor Management) mode. In this mode, the working gear and the maximum and minimum engine speeds are selected, thus the system will automatically adjust the engine speed depending on the load demand of the implement, keeping the operating speed constant.

When the rotation change is not sufficient to meet the load requirement, the system will automatically downshift. DTM mode will always aim to work at the lowest engine speed, aiming for lower fuel consumption. You can also change the motor's response speed to overloads encountered.

For use in special operations, the transmission has the Creeper system as an option. This system is a super-reducer that provides speeds ranging from 0,33km/h to 2,21km/h at 1.800rpm, distributed across 12 forward gears and 12 reverse gears. In this way, the transmission system can result in 36x36.

The electronics on board the tractor also allow the memorization of two working gears in the system, activated by buttons on the console. The clutch and transmission systems are electro-hydraulically actuated. Therefore, there are no mechanical links between its mechanisms and the controls that activate them.

Of the 24 speeds available in the standard version, the transmission has 11 speeds in ranges commonly used in field work (4km/h to 12km/h). The scheduling also presents overlapping speeds between the groups, preventing them from changing during work.

The final reduction is of the epicyclic planetary type, with rim fixation via a through shaft. This system allows for better adjustment of the wheelset gauge, both with single and double wheels. The service brakes work in an integrated manner with the pneumatic system, when the tractor is equipped to transport sugarcane wagons.

POWER OUTLET

The power take-off is available for operation at conventional speeds of 540rpm with a six-spline fixed shaft and 1.000rpm using a 21-spline flanged shaft. The movement transmission passes through the independent clutch on the engine flywheel, enters the gearbox through speed selector gears to the output shaft.

To select the speeds for using the PTO (540 and 1.000rpm), electro-hydraulically activated switches are arranged in the column to the right of the operator. The tractor also has a switch to activate the PTO on the left rear fender, used after programming the working speed on the integrated information monitor (SIS) screen. The MF 7700 line has as a factory option the use of a 1.000rpm front PTO, with anti-clockwise working direction.

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