Patent ID: 8577562

Claim:
A construction vehicle, comprising: a power source; a travel device that comprises a modulation clutch connected to said power source, and that receives power from said power source via said modulation clutch and outputs travel drive force; a work equipment for performing excavation and at least one other type of task; a drive force setting device that sets a set drive force; and a controller that controls the degree of engagement of said modulation clutch, on the basis of said travel drive force outputted from said travel device and said set drive force set by said drive force setting device; wherein said controller comprises: a theoretical value determination unit that determines a theoretical value, which is a value that said degree of engagement must assume in order to make the upper limit value of said travel drive force be equal to said set drive force; an operational state determination unit that performs operational state determination by determining whether or not said work equipment is performing a task of a predetermined type and moreover said travel device is outputting said travel drive force in a predetermined travel direction; a drive force determination unit that performs drive force determination by determining whether or not said travel drive force is greater than said set drive force; and a degree of engagement reduction unit that, when the result of said operational state determination and the result of said drive force determination are both affirmative, reduces said degree of engagement so that said degree of engagement approaches towards said theoretical value, wherein when the result of said operational state determination and the result of said drive force determination are both affirmative, said degree of engagement reduction unit changes the rate at which said degree of engagement is decreased according to the magnitude of said theoretical value, so that said degree of engagement approaches towards said theoretical value, and when the result of said operational state determination and the result of said drive force determination are both affirmative, said degree of engagement reduction unit reduces the degree of engagement at a predetermined high speed rate when said theoretical value is greater than a predetermined reference value, while reducing the degree of engagement at a rate that is lower than said high speed rate when that is not the case.