Abstract: A vibratory earth penetrator employing a high pressure air distributor and an oscillating mechanism has the ability to dig down to underground utilities and contact those utilities without damaging them. The invention includes a hollow elongated tube having a plurality of air lances at the bottom end thereof. The air is preferably distributed to the air lances by an air distributor in a criss-cross sequence. An oscillating eccentric weight is synchronized with the air distributor to enhance the digging effect of the device. The penetrator is supported by a boom which includes an automatic tension device for providing sufficient upward force to keep the penetrator in the vertical attitude while allowing the weight of the penetrator to provide enough force to permit the device to dig into the ground. Since the digging action is accompanied by very little downward force, it is possible to contact underground utilities without hurting them.

Abstract: A tunneling machine is described which uses an array of impact tools for cutting a deep kerf that defines the wall of the tunnel. The impact tool provides impact blows through drill steels to which drill bits are attached. A substantial portion of the drill steels extend through webs which provide bearing support and alignment for the drill steels and bits on a dynamic basis while the kerf is being cut and the webs also permit the drill steel to bend; thus providing clearance between the impact tool and the wall of the tunnel. The webs also provide control of the sideways motion of the bit, while at the same time, providing for full impact blows to be delivered to the working face.

Abstract: Impact tools are described which are capable of developing percussive forces for rock drilling and other repetitive high force applications. A hydroacoustic oscillator contained in such tools includes a hammer and a valve mechanism which is actuated by the hammer for controlling the flow of pressurized fluid so as to establish pressure variations which sustain the oscillation of the hammer. A number of alternative valve mechanisms are disclosed, each including a valve element, the motion of which is controlled by controlling the flow of fluid with respect to the valve element as the hammer and valve element move relative to each other. Such flow control is afforded by chambers defined by the valve element; hydraulic fluid flow with respect to which is controlled so as to determine the deceleration of the valve element and the motion of the element in its actuation by the hammer.