The invention provides apparatus for shaking structures such as fins in a fluid agitator, shaking tables, shaking screens, conveyors, or the walls of bins or hoppers. The apparatus is driven by a hydraulic driving system in which high pressure pulses are generated by repeatedly creating water hammer within a conduit. The high pressure pulses are directed to a chamber where they act against a wall of the chamber to periodically push on the structure. Preferably, the structure is spring-like so that after a high pressure pulse has passed the wall of the chamber is returned to its equilibrium position. In one embodiment of the invention a water hammer pressure pulse is directed into a reinforced hose in contact with a surface to be vibrated. The high pressure pulse causes the hose to expand and move the surface to be vibrated. Water hammer pulses are generated periodically so that the surface is maintained in continuous vibration.