Dual drive arrangement for the drive of a vehicle hydraulic pump and method of controlling the same

A method for controlling a dual drive arrangement for driving of a hydraulic pump for a vehicle having a gearbox driven by an internal combustion engine, the gearbox having an output for mechanically driving driven wheels of the vehicle and the vehicle having an auxiliary electric motor for driving the hydraulic pump, the arrangement comprising a three way power split system converting input rotation from the gearbox output and from the auxiliary electric motor into an output rotation driving the hydraulic pump, the method comprising:

• setting a minimal flow value Qm to the hydraulic pump;
• sensing the vehicle speed;
• processing the sensed vehicle speed where the processing comprises comparing the sensed vehicle speed with a reference speed value to thereby determine whether die vehicle operates in a first operational mode I where the speed vehicle is too low to drive the hydraulic pump alone up to the minimal flow or in a second operational mode II where vehicle speed is sufficient alone to meet at least the minimal flow value Qm;
• controlling the operation of the epicyclic gear system so that the auxiliary electric motor drives the hydraulic pump in combination with the gearbox output when the vehicle runs under the first operational mode I and at least the gearbox output drives the hydraulic pump when the vehicle runs under the second operational mode II.