Abstract: A system for porting of hydraulic fluid in a hydraulically driven seismic energy vibrator of the reciprocating mass type. A mass is reciprocated relative to an earth contacting frame which includes at least two hydraulic piston rods coacting with internal cylinders within the mass. The piston rods, of the type having double rod ends, each include a single axial bore therethrough in communication with respective opposite sides of the piston ring assemblies, and cross porting is effected between opposite ends of the mass cylinders.

Abstract: Apparatus for truck-mounting of vibrational seismic energy transducers, particularly shear wave transducers, that provides improved vibrational damping and energy coupling into the earth. The apparatus consists of a four column, hydraulically actuatable suspension system operative from the truck or carrier frame as opposite side pairs to support a box frame under which the vibrator and earth coupling assembly is supported by a system of lateral and vertical springs. The vibrator assembly is entirely supported by means of left and right transverse springs to transmit reactive forces resulting from isolation through the box weldment and four columns to the vehicle body. Thus, the vibrator and its associated base plate structure is entirely supported from the vehicle and positioning assembly by resilient means having the requisite interactive constants.

Abstract: The present invention relates to an improved hydraulic vibrator of the type which includes a fixed double rod piston and a reaction mass reciprocally disposed around the piston forming a hydraulic cylinder therein so that when hydraulic fluid is introduced to the cylinder relative to the piston the reaction mass is reciprocated. By the present invention a pair of sleeves are slidably disposed on the piston rods, portions of which can be selectively moved into the cylinder to decrease the displacement of the cylinder and thereby increase the frequency range of vibrations producible by the vibrator.