Abstract: A trencher for mounting on a conventional three point hitch of a tractor. The trencher is driven from the power takeoff of the tractor and uses the hydraulic system of the tractor to operate a hydraulic cylinder for raising and lowering the boom and digging chain of the trencher. A power transmission system is provided using interchangeable belts and pulleys for selectively changing drive ratios for driving the digging chain. The boom is telescoping and can be lengthened to achieve a deeper digging depth through turning of an adjustment rod. The boom is spring-loaded for absorbing shocks delivered by the chain to the boom.

Abstract: A separator is provided for use with a ditching machine to segregate rocks and coarse aggregates from the material excavated by the ditching machine s that the excavated material may be used as padding to protect the pipeline or other item positioned within the excavated trench. The separator comprises a plurality of rows of blades mounted on a rotatable drum. The spacing between adjacent blades within a row allows passage of the fine excavated material between the blades but prevents passage of the rocks and coarse aggregates. The rotating blades then deposit the rocks and coarse aggregates in a row beyond the row of fine material deposited along the trench.

Abstract: An excavator for constructing an underground continuous wall includes a traveling trolley movable on rails and having a sprocket in mesh with a rack extended parallelly to the rails and a hydraulic motor for driving the sprocket. The trolley further includes an upper frame arranged thereon and having a tiltable frame tiltable relative to the upper frame and a saddle provided on the tiltable frame slidable on the tiltable frame in directions substantially perpendicular to the rails. An extensible guide post is provided upward and downward movably relative to the tiltable frame. An endless chain extends around a chain driving wheel provided on the saddle and a chain sprocket provided at the lower end of the guide post, and a number of cutter bits and a number of agitator bars are alternately arranged on the endless chain to form an endless chain cutter. A chain driving device is provided for driving the endless chain.

Abstract: An automatic evacuation drilling bucket comprises a follower formed with a working space for receiving a blade member which is capable of coming in contact with an osculating arm, the working space having upper, lower, transition and receiving compartments. If the blade member is located in the upper and lower compartments, the blade member is engaged with the follower when a drive shaft member is rotated in the normal and reverse directions. If the blade member is urged to move into the receiving compartment through the transition compartment, the blade member comes in contact with the osculating arm when the drive shaft member is rotated in the reverse direction.

Abstract: A trenching apparatus having a digger arm operative to form a trench along a trench line includes a lower end which mounts a digging and propulsion unit having an upper and lower group of sprockets which are vertically spaced from one another and carry chains having digger teeth mounted thereto. Structure is provided to increase the relative spacing between the upper and lower sprockets, while the chains remain in engagement therewith to increase tension in the chains as they wear and a number of scraper blades are mounted in position relative to the sprockets and the shafts which carry them to prevent the buildup of soil, concrete, rocks or other foreign material thereon and thus ensure smooth operation of the digging and propulsion unit.