| 摘要 |
PROBLEM TO BE SOLVED: To reduce drag torque by efficiently warming hydraulic fluid with a simple configuration.SOLUTION: A crane 100 includes: an oil passage selective valve 142 disposed between a control valve 141 and a tank 119; a cooling oil passage 182 connecting the oil passage selective valve 142 and the tank 119; a heating oil passage 184 connecting the oil passage selective valve 142 and the tank 119; a relief valve 145 disposed in the heating oil passage 184; an oil cooler 170 disposed in the cooling oil passage 182; and a temperature sensor 171 detecting the temperature of hydraulic fluid. A controller 120 of the crane 100 determines that hydraulic fluid is in a low temperature/high temperature state. When it is determined that the hydraulic fluid is in the low temperature state, the oil passage selective valve 142 is operated so that pressure oil discharged from a first pump 111 is introduced into the heating oil passage 184. When it is determined that the hydraulic fluid is in the high temperature state, the oil passage selective valve 142 is operated so that pressure oil discharged from the first pump 111 is introduced into the cooling oil passage 182. |
