US Patent 7559271 Working machine

Of a plurality of hydraulic signals output from an operating device, a hydraulic signal is input into a control valve serving as a hydraulic control device without conversion, and particular hydraulic signals are converted into electric signals corresponding to their hydraulic pressures by signal converting devices, such as pressure sensors, and are then input into a controller. The controller controls the drive of an electric actuator, such as a rotating electric motor, on the basis of the electric signals. Hydraulic fluid flow paths communicating to the pressure sensors are connected to each other via a throttle, and air in one of the hydraulic fluid flow paths is removed using the other hydraulic fluid flow path.