This report presents a fundamental consideration on the performance of recently developed rotary spool valve type hydraulic vibration exciter. First, a method was derived for analyging the frequency characteristics of a valve-controlled hydraulic actuator, consisting of rotary type four way spool valve with unmatched lap, hydraulic cylinder, and mechanical load. The effects of inertia load, supply pressure, piston area, valve orifice area, axial eccentricity of spool, etc. on the frequency characteristics of output amplitude and drift were clarified theoretically by using the above-mentioned method. Experimental results showed good agreement with the theoretical values, even in the frequency range where cavitation occurs in the cylinder chamber.
It was confirmed that this hydraulic exciter does not matter in practical application in so far as frequency, output amplitude, output waveform, durability and control are concerned.