Patent ID: 7866875

Claim:
A concrete agitating drum driving device comprising: a hydraulic motor connected to a concrete agitating drum; a variable capacity hydraulic pump which drives the hydraulic motor by supplying pressurized oil thereto; a hydraulic actuator which regulates a discharge flow rate of the pressurized oil discharged from the hydraulic pump in response to an actuator driving pressure; a load sensing valve which generates the actuator driving pressure by reducing a discharge pressure of the pressurized oil discharged from the hydraulic pump in response to a differential pressure between the discharge pressure and a load pressure acting on the hydraulic motor; a shut-off valve which shuts off supply of the pressurized oil discharged from the hydraulic pump to the hydraulic motor; and an unload valve which drains the pressurized oil discharged from the hydraulic pump when the differential pressure between the discharge pressure and the load pressure increases beyond a predetermined differential pressure.