Work vehicle and control method for work vehicle

A work vehicle comprising:

• an engine;
• a traveling pump driven by the engine;
• a hydraulic circuit connected to the traveling pump;
• a traveling motor connected to the traveling pump via the hydraulic circuit;
• a rotational speed sensor configured to output a signal indicative of engine speed;
• a hydraulic pressure sensor configured to output a signal indicative of hydraulic pressure of the hydraulic circuit;
• and
• a controller configured to
• receive a signal from the rotational speed sensor and the hydraulic pressure sensor,
• determine whether the engine is in an over-rotation state based on the engine speed, the controller determining that the engine is in the over-rotation state when the engine speed is equal to or greater than a predetermined first threshold,
• determine an upper limit value of displacement of the traveling pump based on the hydraulic pressure of the hydraulic circuit, the upper limit value being determined such that an engine reverse drive torque transmitted from the traveling pump to the engine does not exceed a torque allowable value, the torque allowable value being a value of engine brake torque when the engine speed is a second threshold equal to or greater than the first threshold, and
• limit the displacement of the traveling pump to the upper limit value or less when the engine is in the over-rotation state.