Anyone who buys a new machine in the municipal sector is always faced with the same question: What type of drive system do I use? Because each of them has its advantages, but also its disadvantages. While a mechanical travel drive impresses with its high degree of efficiency, the machine with hydrostatic drive can be maneuvered very sensitively thanks to its stepless drive. The Swiss company Aebi has now tried to combine the best of both travel drives and therefore equipped the MT740 and MT750 implement carriers with semi-hydrostat. In order to show the advantages for the user, Sales Manager Charles Boné and Product Manager Philipp Hohl invited the editors of Bauhof-online.de to their stand one day before the opening of demopark 2017 and demonstrated the MT740 with semi-hydrostatic transmission.
The idea itself is nothing fundamentally new. There are already trucks in which the semi-hydrostatic drive is used. Aebi has now also equipped its two implement carriers MT740 and MT750 with it. “The semi-hydrostatic drive is the ultimate in municipal technology,” says Boné. The hydrostat is used for slow journeys, such as winter service, mowing or cleaning delineator posts. “From 0 to 20 km / h it is steplessly driven,” explains the sales manager. The driver of the machine does not have to spend all the time coupling or shifting gear, but can concentrate fully on the work ahead. “The hydrostatic driving mode also protects the transmission and thus reduces wear,” Boné lists other advantages. With the help of a hydraulic booster pump, a total output of 70 liters is achieved at an operating pressure of 220 bar. However, if you want to change location quickly, for example, the hydrostatic drive is switched off again and the mechanical drive is used instead. "A speed of up to 89 km / h is then possible here," says Boné. And that with a much lower fuel consumption than would be the case with a fully hydrostatic.
Relaxed driving with minimal background noise
When entering the driver's cab of the MT740, hardly any change in the interior reveals the new equipment with semi-hydrostatic transmission - apart from the small black box on the ceiling, the size of a navigation system. To make operation easier, there are instructions for the users of the transporter that describe in a simple manner how to use the new drive system. Boné starts the MT740. With the help of the joystick, the sales manager enters the desired direction of travel and the appropriate work program, which is displayed on the dashboard. He then activates the hydrostat on the black box and selects the appropriate speed. Since a flail mower head is attached to the implement carrier for the demonstration, Boné opts for 1500 revolutions - precisely the number of revolutions at which the entire hydrostatic power of the engine is achieved. "Each level can still be regulated, depending on which implement is connected," reports Boné. Then it starts. A light press of the accelerator is all it takes to set the machine in motion. Thanks to the stepless driving, Boné can now fully concentrate on maneuvering the mower.
The MT740 runs very quietly when performing the mowing work. What is particularly noticeable here is the low volume. Despite the driver's door being open, you can talk to each other without any problems. The activated torsion frame also stabilizes the machine when mowing. Boné demonstrates the difference by temporarily deactivating the frame. You immediately have the feeling that the machine is sagging forwards. Then we switch from the hydrostatic drive to the mechanical one. To do this, Boné removes all previously entered programs. The aisles are now free again. “Now you can switch gears again and drive mechanically to the next site,” he explains, adding: “It's like normal driving.” He steps on the accelerator and the MT740 instantly accelerates. Winter service is a very good example of use, says Boné: “If you clear a parking lot where you have to drive a lot forwards and backwards, the hydrostat is switched on. However, if you then have a distance of 15 kilometers again, where you simply have to clear and spread in a straight line, a hydrostatic drive would be nonsense. ”On the one hand, the hydrostatic would lack the power, on the other hand, the fuel consumption is enormous. “We don't have any of that with our semi-hydrostatic drive,” reports Boné proudly. “It couldn't be easier.” Another very user-friendly feature of the machine is that all functions are controlled via the joystick. “There are no frills in the vehicle,” says the sales manager.
Close-to-series installation of the semi-hydrostatic travel drive
The semi-hydrostatic drive was specially developed for the Aebi MT implement carriers. In the two models MT740 (109 HP) and MT750 (156 HP) with 4 and 6 cylinders each, the new drive could be installed very close to series production without the need for major modifications such as an additional oil tank or cooler. In addition to hydrostatic and mechanical driving, the two vans also have a third mode: the mechanical crawler gear reduction, which is used when driving slowly over rough or steep terrain. In combination with its four attachment areas, the Aebi MT equipment carrier can be used in a multifunctional manner and is also very economical. Boné: "You can drive what you want with it, adapted to the respective work."
Text / Pictures: Jessica Gsell - Redaktion Bauhof-online.de