Patent ID: 8718879

Claim:
A work vehicle comprising: an engine; a travel wheel rotatably driven by driving force from the engine; a power transmission mechanism configured and arranged to transmit the driving force from the engine to the travel wheel, the power transmission mechanism having a transmission and a torque converter with a lock-up clutch; and a control unit configured to control a shift in a speed gear of the transmission according to a vehicle velocity, the control unit being configured to control a connection state of the lock-up clutch according to the vehicle velocity when the vehicle velocity is smaller than a lower limit of a predetermined first range, the control unit being configured to determine whether or not an acceleration rate of the vehicle is equal to or less than a predetermined threshold, the control unit being configured to switch the lock-up clutch from a not-connected state to a connected state upon the vehicle velocity reaching a predetermined first range when the acceleration rate of the vehicle is equal to or less than the threshold, and the control unit being configured to maintain the lock-up clutch in the not-connected state even when the vehicle velocity is within the predetermined first range when the acceleration rate of the vehicle is greater than the threshold, wherein the control unit is configured to set a lower limit of the first range to be substantially equal to a first limit velocity, the first limit velocity being defined such that, during a state in which the speed gear of the transmission remains the same, a first driving force transmitted from the power transmission mechanism to the travel wheel when the lock-up clutch is in the not-connected state and a second driving force transmitted from the power transmission mechanism to the travel wheel when the lock-up clutch is in the connected state coincide when the vehicle velocity is the first limit velocity, and the second driving force is greater than the first driving force when the vehicle velocity exceeds the first limit velocity.