Stepless transmissions with a hydrostatic-mechanical power split have been used in agricultural tractors for over 20 years. Up until now, additional generators for electric
drives with a higher power requirement were installed on tractors (fan, compressed-air/
air conditioner compressor, etc.) or on implements. The eAutoPower gearbox
for the new 8R large tractors from John Deere represents the first electro-mechanical
power split gearbox in agricultural technology. Technically, the hydro unit (pump/motor) is
completely dispensed with; instead, two electric motors are used as a continuously variable actuator. The electric motors have been specified so that they not only supply the drive, but can also provide up to 100 kW of electric power for external consumption. The resulting
possible tractor-implement electrification is demonstrated with a system solution for spreading manure developed together with Joskin, where two axles on a tridem
spreader are electrically driven.
On the tractor side, this electrical integrationresults in improved gearbox efficiencies and reduced maintenance costs. In addition, the surplus power flows occurring at certain operating points can be “tapped” when utilising electric power for external electrical components, which further improves the overall efficiency. Used in combination with an axle drive on a manure spreader, the results in practical use include, among other things, higher traction, reduced slip and improved track guidance on side slopes.
