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: An adjustable spirit level having a plurality of spirit levels therein. A first spirit level measures vertical orientation, a second adjustable spirit level is adjustable to a true horizontal position, and a third spirit level is adjustable to any desired position between vertical and horizontal. The second level may be adjusted with a rotatable cam-shaped end piece secured within the level body, while the third level is ratcheted to a predetermined angle. The third level may be held in place by a spring member biasing the level against the level body.

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.