Planetary Gear PTO Unit with a Hydraulic Control, Work Vehicle Comprising the Same and PTO Torque Estimation

A working vehicle comprising a power take-off (PTO) unit comprising;

• a planetary gear having a first shaft for connection with an engine of the work vehicle:
• a PTO spline connected in power transmission to the planetary gear and defining a gear ratio with the first shaft;
• a hydrostatic transmission driven bv the planetary gear to control the gear ratio;
• a pressure sensor unit for sensing a diffrential pressurec across a loop ol the hydrostatic transmission:
• and
• a control unit programmed to calculate:
• a diffrential pgressure drop in the loop on the basis of an actual kinematic status functioning of the PTC) spline:
• and
• a PTO spline torque from a farther mathematical model based on the pressure drop, on pressure signals from the sensor unit and on kinematic or hydraulic factors of the planetary gear and the hydrostatic transmission.

A method to estimate torque at a power take-off PTO spline of a PTO unit for a work vehicle comprising:

• a planetary gear having a first shaft for connection with an engine of the work vehicle;
• a PTO spline connected in power transmission to the planetary gear and defining a gear ratio with the first shaft;
• a hydrostatic transmission driven by the planetary gear to control the gear ratio;
• and
• a pressure sensor unit for sensing a differential pressure across a loop of the hydrostatic transmission,
• wherein the method comprises steps of:
• calculating a differential pressure drop in the loop on the basis of an actual kinematic status of the planetary gear and from a first mathematical model representing an unloaded functioning of the PTO spline;
• and
• calculating the PTO spline torque from a further mathematical model based on the pressure drop, on pressure signals from the sensor unit and on kinematic/hydraulic factors of the planetary gear and the hydrostatic transmission.