Patent ID: 8504257

Claim:
A work vehicle, comprising: an engine; a drive unit configured to be driven by driving force from the engine for causing the work vehicle to travel; a hydraulic pump configured to be driven by the driving force from the engine for discharging hydraulic oil; a work instrument configured to be driven by the hydraulic oil from the hydraulic pump; a work instrument load detecting part configured to detect a work instrument load information pertaining to a load of the work instrument; a torque converter unit including a torque converter and a lock-up clutch, the lock-up clutch being configured to be switched among a coupled state, a slippage state and a decoupled state in accordance with a lock-up hydraulic pressure indicating a pressure of the hydraulic oil to be supplied thereto, the torque converter unit being configured to transmit the driving force from the engine to the drive unit through either the torque converter or the lock-up clutch; a control unit configured to control the lock-up hydraulic pressure for switching the lock-up clutch, the control unit being configured to execute a lock-up slippage control for switching the lock-up clutch into the slippage state when the work vehicle starts moving, the control unit being configured to control the lock-up hydraulic pressure based on the work instrument load information during execution of the lock-up slippage control, an engine speed detecting part configured to detect an engine speed; and an accelerator operating member to be operated by an operator, wherein the control unit is configured to set the target engine speed in accordance with an operating amount of the accelerator operating member and control the engine for regulating the engine speed detected by the engine speed detecting part to approach the target engine speed during execution of a normal control without execution of the lock-up slippage control, and the control unit is configured to modify the target engine speed based on the work instrument load information and the operating amount of the accelerator operating member such that a modified value of the target engine speed increases as the load of the work instrument increases, and to calculate a command value of the lock-up hydraulic pressure for regulating the engine speed detected by the engine speed detecting part to approach the modified target engine speed during execution of the lock-up slippage control.