Work vehicle

A work vehicle comprising:

• a power transmission device configured to transmit rotation power from an engine to drive wheels, the power transmission device comprising a plurality of hydraulic main speed change clutches for a plurality of speed change stages and a hydraulic Hi-Lo clutch having a high speed clutch and a low speed clutch and capable of changing a speed at a high speed stage or a low speed stage, and configured to transmit power via the main speed change clutches and the Hi-Lo clutch;
• control valves configured to adjust pressed states of the main speed change clutches and the Hi-Lo clutch;
• and
• a speed change control device configured to:
• control and change a vehicle speed in a multi-stage manner by the main speed change clutches and the Hi-Lo clutch, and
• perform a shift-up operation for changing a speed from a low speed stage range in which the low speed clutch is used to a high speed stage range in which the high speed clutch is used, wherein the speed change control device is configured to decrease a pressure of the low speed clutch while keeping a pressure of the high speed clutch at a first pressure higher than the pressure of the low speed clutch and keep a pressure of a first clutch of the main speed change clutches that is a speed change source, to transmit power by a combination of the high speed clutch and the first clutch, and thereafter decrease the pressure of the first clutch while increasing the pressure of the high speed clutch, which has been kept at the first pressure and increase the pressure of a second clutch of the main speed change clutches that is a speed change destination.