When the load of an actuator consists of mass and Coulomb friction for a valve-controlled hydraulic device, the correct responses are obtained analytically for rectilinear inputs. As any type of inputs can be approximated by a connection of straight lines, the responses to various types of inputs are analyzed. As an application of the analysis, the responses respectively for either a step, or ramp or sinusoidal input are obtained and are approximated by the equivalent transfer functions. The effects of the dither applied to the spool are also clarified by this approach. The validity of the analysis is verified by experiments. The equivalent transfer function is considered very useful to design more complicated servomechanism.