Shuttles are probably the most simple and cheapest option to improve the efficiency of hydraulic off-road machinery. As it promoted these devices at bauma 2022 in Munich last week, Innas highlighted that users could save up to 2,000 liters of fuel in an average off-road machine.
Shuttles increase the efficiency of hydrostatic pumps and motors. When applied in a conventional slipper type machine, the peak overall efficiency increased from 91.4% to 96.4%. At speeds below 1,000 rpm, the efficiency at some points increased by more than 30%-points.
The importance of improving pump efficiency becomes clear when calculating the effects on fuel consumption: the shuttles can save up to 2,000 liters diesel per year in an average mobile machine.
Shuttles do not demand a completely new pump or motor design. Only a rather small adaptation is needed. The cylinder block or barrel needs to have some extra connections between the cylinders, allowing the small ceramic shuttle balls to be installed. Furthermore, the valve plate design becomes more simplified, eliminating any silencing grooves or pressure relief grooves. The valve plate for a motor will be identical to the valve plate for a pump. Shuttles can be applied in both fixed and variable displacement pumps and motors.
The results are impressive. For many decades, the overall efficiency of conventional slipper type pumps has been limited to around 91%. Simply by means of applying shuttles and changing the design of the valve plate (to match the shuttles), the overall efficiency has been increased to 96.4% in the best point. In the range between 500 and 3,000 rpm, and between 100 and 400 bar, the average overall efficiency has increased to 94.3%. At operating speeds below 1,000 rpm, the overall efficiency has been increased by more than 30%-points. For instance, at 100 rpm and 400 bar, the shuttles have increased the overall efficiency from a value of 49.6% to 75.3%, an increase of 33.5%-points.
The technology can be implemented in all piston-type pumps and motors and is made available through licensing to manufacturers of hydraulic equipment.