Fluid Technology for Off-Highway Applications:

The hydraulic systems of mobile work machines are becoming increasingly intelligent

SYSTEMS & COMPONENTS exhibitors from the hydraulics sector continually redefine both efficiency and comfort in the daily work routine of construction and agricultural machines with modern drive, suspension and steering systems. The solutions that will be on display in mid-November on the trade fair grounds in Hanover provide improved handling and increased efficiency, seen through innovations such as hydraulic wheel hub motors as an additional drive. This is suitable equipment when the vehicle is primarily moved on paved roads and only temporarily requires increased traction on unpaved roads or a ramp approach aid at steep ramps. A press of a button in the cockpit is sufficient to activate the additional drive.

All-wheel drive at the press of a button

Hydrostatic gearboxes differ considerably from the permanent all-wheel drives with a cardan shaft, like the ones that are state-of-the-art for heavy off-highway vehicles where at the heart is a high-pressure pump connected to one or more hydraulic motors.

The mechanical power of the diesel engine is converted into hydraulic power by the pump and transmitted to the drive axles via differential gears. Here the latest developments combine two and three-stage planetary gears with axial piston engines to form individual and modular stepless drive packages for construction and agricultural machines. Depending on the driving situation, only as much torque as is actually required for traction is built up at the front axle. The basis for this kind of intelligent control system are sensors that detect the slip, weight and inclination angle of the vehicle. The optimum design of the high-pressure pumps and motors not only improves the efficiency of the drive, it also clears the way for downsizing the diesel engine. Depending on the vehicle configuration, the payload advantage compared to a conventional all-wheel drive is up to 750 kilograms. Added to this is fuel savings gained when the system is switched off and the non-driven wheels rotate freely along with the others.

Full power with less loss

The hydraulic system is also always in demand when mobile work machines are to become more economical. For this reason, the focus of many trade fair stands will probably be on the presentation of the latest generation of load-sensing technologies. The control principle stands for demanding hydraulic applications in an open circuit with which the oil flow is divided and exactly adjusted according to current pressure and volume requirements. Step by step the signal lines, which today are often still hydraulic, are being replaced by an electronic control system that dynamically adjusts the maximum pressure to individual implements and functions. As a result, no implements stop or operate in an unforeseen manner, even when the diesel engine is at full capacity. The driver can concentrate on the task at hand and define the characteristics of the working hydraulics by selecting the respective mode on a touch screen. This results in fuel savings and a higher handling capacity, which is especially apparent in machines with complex tasks and changing applications.

Yet this alone is still not enough. To ensure the high dynamics of driving and working hydraulics at reduced engine speeds, intelligent networking with the diesel engine control system via corresponding function modules is required. The hydraulic system signals the expected load requirement in advance to the diesel engine, which operates proactively and can avoid major fluctuations. This means both systems can work together to reduce consumption and emissions by up to 20 percent.

Digitalisation as driver for innovation

What does the future hold? The Internet of Things (IoT) is becoming increasingly relevant for mobile work machines which means the competition between electro-mechanics and fluid technology will continue to increase. Practically every exhibitor at this year's SYSTEMS & COMPONENTS is looking for ways to sound out the opportunities of digitalisation for themselves and their products. The technology suppliers are confronting this competition by capitalizing more strongly on the networking of hydraulics and electronics to increase the power density of the drives and to further optimise controllability.

Already today, hydraulic valves record their switching processes and pumps determine their load spectrum. In preparation for cloud-based services, machine manufacturers are integrating sensors that measure the pressure, volume flow and temperature. They not only support an exact remote diagnosis, they also serve to continually improve the components. In the future, electro-hydraulics will probably play a central role in many applications, like those used in powerlift control systems. The physical advantages of fluid technology are combined with digital control, while also forming the basis for assistance systems that decrease the strain on the driver and increase the safety of the vehicle. This enables manufacturers to reduce their development and assembly costs by shifting previously hydro-mechanical functions to the software. Furthermore, large parts of the hydraulic hose system are eliminated, which results in reduced maintenance costs and effort.

Showcase for off-highway innovations

When the quantity and diversity of the trade fair innovations presented at SYSTEMS & COMPONENTS are considered, it becomes apparent that fluid technology is a central topic in Hanover. Advanced modular drive technology, implemented in hydrostatic systems, forms the heart of stepless, power-split gearboxes for the off-highway market. Exhibitors score points with a broad range of hydraulic components and systems that promise added dynamics, reliability, operating comfort and productivity for mobile work machines like wheel and chain excavators or field choppers and combine harvesters.

The portfolio at the stands comprises pumps with even more compact dimensions and improved efficiency, hydraulic motors, valve technology, gears and electronics for open and closed-loop circuits. Here the diversified term of intelligent networking is applied to a large number of developments on the trade fair grounds. However, they all have one thing in common - smart components that communicate with each other and are the key to consistent system integration. Visitors can also learn what potential digital systems have and where the industry is today in the "Future Lounge", the trade forum of SYSTEMS & COMPONENTS in Hall 17.