A BALLAST TAMPER HAVING A TOOL SUPPORT OPERABLE BY A ROSONANT FREQUENCY POWER DRIVE. THE DIRECTION OF THE TAMPERING FORCE ON THE TOOL IS CONTROLLED BY PROVIDING A PAIR OF RESONANT FREQUENCY ACTUATORS, EACH OPERABLY CONNECTED TO A SEPARATE FORCE-TRANSMITTING BRANCH MEMBER OF A BIFURCATED TOOL MOUNTING STRUCTURE. THE OTHER ENDS OF THE BRANCH MEMBERS ARE CONNECTED TOGETHER TO A COMMON POINT ON THE TOOL SUPPORT. THE RELATIVE VIBRATION PHASE RELATIONSHIP OF THE POWER DRIVES IS CONTROLLABLY VARIABLE THROUGH ONE HUNDRED AND EIGHTY DEGREES WHEREBY THE RESULTANT DIRECTON OF THE FORCE ON THE TOOL IS VARIABLE FROM VIBRATORY VERTICAL MOVEMENT TO VIBRATORY HORIZONTAL MOVEMENT AND IN PASSING BETWEEN THESE LIMITS CAN ASSUME AN ELLIPSOIDAL ORBITAL CIRCUMFERENTIAL MOVEMENT WITH THE MAJOR AXIS VERTICAL TO ELLIPSOIDAL MOVEMENT WITH THE MAJOR AXIS HORIZONTAL PROVIDING IN THE INTERMEDIATE RELATIONS FORCES BOTH HORIZONTAL AND VERTICAL AND VARIABLE IN BOTH DIRECTION AND MAGNETUDE BY VARIATION TO THE RELATIVE POWER DRIVE PHASE RELATIONSHIP OF THE TWO ACTUATORS.