Abstract: A seismic vibrator system for imparting compressional and shear wave vibrations into the earth has an earth contacting base with a vertical post. A tubular hub is slidably received on the post in a piston/cylinder relationship. Spaced apart horizontal top and bottom plates are secured to the hub. A mass is slidably supported between the plates. Pistons interconnect the hub and the mass. Hydraulic energy is used to reciprocate the mass vertically on the post and horizontally between the plates.

Abstract: A broad band seismic vibrator includes a hydraulically-operated actuator with a piston shaft depending from the actuator. A spherical member or ball is secured to an end of the shaft and received in a socket provided in an anvil. The spherical member or ball is securely clamped to the end and in its clamped condition affords the sole support for the actuator. Hydraulic means is provided for unclamping the spherical member to enable the positioning of the actuator in selected degrees of inclination from vertical and azimuth.

Abstract: The method and apparatus for generating seismic vibrations in a liquid includes an electronically controlled, hydraulically powered generator that includes a piston assembly reciprocally mounted on a cylindrical post in a generator housing. The control apparatus includes a control valve that is located very close to the piston assembly thereby reducing the volume of the passageways extending to the piston assembly so that the cyclic rate of the piston assembly can be very rigid and can be changed accurately and quickly. An extended life is provided by releasing the high pressure fluid driving the piston assembly prior to impact between the piston assembly and the post and by providing a trapped volume of fluid in the chamber to damp the movement of the piston assembly toward the post.

Abstract: Described is a method of driving a seismic vibrator with a control signal to produce an output signal having minimized harmonic distortion. The method includes the steps of producing a plurality a harmonic distortion signals related to a fundamental frequency of the control signal. The phase and amplitude of said harmonic distortion signal is varied to produce with the vibrator suites of variations of the distortion signal. From among suites of variations there is selected that harmonic distortion signal having phase and amplitude values which produce a minimum value in harmonic distortion signal amplitude. The steps are repeated for different fundamental frequencies and the selected signals are summed with their related fundamental frequencies to produce a vibrator sweep control signal. The seismic vibrator is driven with the control signal to produce an output in which harmonic distortion is significantly attenuated.

Abstract: An improved vibrator system for seismic geophysical prospecting, comprising a sealed chamber having two parts which reciprocate axially with respect to each other providing a sealed space between the two parts. One part connected to a baseplate, the other part connected to a reaction mass. Means for injecting into the sealed space a pulsating flow of high pressure fluid in response to which the two parts will vibrate with respect to each other. At least a single output opening comprising a valve, the cross-sectional area of which is a function of the displacement between the two parts of the vibrator.

Abstract: Mounting structure for a marine seismic vibrator comprising at least three acoustic isolators equally spaced apart about an upper housing of the vibrator. Each of the isolators comprises a pair of spaced mounting pads mechanically secured to the housing. A U-shaped bracket having a base and depending spaced leg portions is attached to the mounting pads by way of a low-pass acoustic filter. A rectangular shaped bracket has a base, a top and a pair of spaced vertical sidewalls. The rectangular shaped bracket is located between the spaced leg portions of the U-shaped bracket and a resilient means is mounted between the bases of the U-shaped bracket and the rectangular bracket to provide a high-pass acoustic filter. Means mechanically connected to the top of the rectangular brackets to the tops of the mechanical brackets secure all the isolators to a common point at the center of the housing.

Abstract: An over-the-road type vehicle for transport and powering of a seismic hydraulic vibrator which is adapted to operate in either one of two modes of operation. A first mode is the conventional mode wherein the vehicle is operated over large distances at varying road speeds, obtained by use of multiple gear ratios, and varying engine speeds. The second mode of operation is in a single gear ratio, with engine under control of a governor, to operate at constant high speed, and the movement of the vehicle is by successive short traverses. In the second mode of operation the single engine alternately powers the hydraulic vibrator, then with the engine still at high speed, moves the vehicle to a new vibration point a short distance away.

Abstract: An over-the-road type vehicle for transport and powering of a seismic hydraulic vibrator which is adapted to operate in either one of two modes of operation. A first mode is the conventional mode wherein the vehicle is operated over large distances at varying road speeds, obtained by use of multiple gear ratios, and varying engine speeds. The second mode of operation is in a single value of road speed, with engine under control of a governor, to operate at constant high speed, and the movement of the vehicle is by successive short traverses at constant speed. In this second mode of operation the single engine alternately powers the hydraulic vibrator, and with the engine still at high speed, then moves the vehicle to a new vibration point a short distance away. A high energy efficiency is provided by the use of a mechanical, rather than hydraulic drive system, and a high time efficiency is provided by a novel style of clutch that can start the vehicle from rest with the engine at maximum speed.