In this project, active HydroBalance weight control is developed. The HydroBalance weight control keeps the optimal machine height in optimal control so that 95% of machine weight is supported through the rear hitch of the tractor and the rest by supporting skids. Developed system can be used also in other similar implements, where weight balancing is required. Furthermore, the developed system utilizes the hydraulic facilities of the tractor. With the developed methods, the implement does not need its own hydraulic valves. The implement controls the hydraulic valves located in the tractor directly though the CAN-bus with standardized messages. The developed method can be utilized in wide range of implements where separate hydraulic valves in the implement are traditionally required.
The ELHO DUETT 7300 mower conditioner is designed to be used with a tractor equipped with reverse driving capability, for example Valtra TwinTrac. In this manner, the properties of self-propelled machines can be achieved with low-cost tractor-implement combination. Particularly the driver’s ergonomics and the agility of the tractor-implement combination are much better than for example with a trailed implement.
However, there are certain challenges when designing an implement for the tractor compared to the situation where the entire machine is designed at a time. The mower conditioner does not have its own supporting wheels. Instead, the cutter heads are supported by skids and suspended using hydraulic accumulators. In an optimal situation 95% of the machine’s total weight is transferred through the rear hitch of the tractor. Because the cutter head is located rather far away from the rear wheels, the lifting height of the mower conditioner in relation to the tractor is constantly changing due to slopes on the field. To achieve proper weight balance, the lifting height is actively controlled. With poor control, the cutter head scratches the surface of the field leading to impurity of the silage, increasing the requirement for power and could even break the machine down.
The ELHO Duett 7300 with active HydroBalance suspension has been used successfully in actual field work. The power measurements show that, optimally balanced, cutting head can save 20% of required machine power and fuel cost accordingly. Solely in Finland, potential annual savings can be up to 2 million euros and start-up costs are 10-15% smaller than with traditional solutions with separate proportional hydraulic valves.
Karl-Erik Häggblom, ELHO