Abstract: In one embodiment, network node-to-node connectivity verification is performed in a network including data path processing of packets within a packet switching device. In one embodiment, an echo request connectivity test packet, emulating an echo request connectivity test packet received from a first connected network node, is inserted by the packet switching device prior in its data processing path prior to ingress processing performed for packets received from the first connected network node. A correspondingly received echo reply connectivity test packet is intercepted by the packet switching device during data path egress processing performed for packets to be forwarded to the first connected network node.

Abstract: A self-propelled all terrain track driven trench box carrier, comprising a main frame, a pair of side frame members, a pair of transversely adjustable end wall frame members and detachable attachable extension structure members. A cat-walk, hand rails, access ladders and safety rails. A pair of adjustable hydraulic wheel track assemblies mounted along the two sides, supporting the apparatus, and allowing the trench box carrier to be propelled along the ground. A pair of detachable attachable extension structure members, for adjusting the width of the trench box carrier, to accommodate different widths of a trench. Adjustable wheel track connectors are detachably attached with an extension axle, to increase the overall wheel base of a trench box carrier for work on oversize trenches. A plurality of hydraulic cable wenches for controlling a trench shield. A main engine power supply for operating a self-propelled all terrain trench box carrier.

Abstract: Transmitting/receiving apparatuses are installed in a base station and a mobile station, respectively, to perform mutual transmission and reception by using a plurality of spreading codes. The transmitting/receiving apparatus installed in the base station has a block for designating to the mobile station the kind and the number of spreading codes used in a reverse link from the mobile station to the base station through a forward link at the time that communication with the mobile station is started. The transmitting/receiving apparatus installed in the mobile station has a block for transmitting a signal to the base station by using spreading codes of the designated kind and number.

Abstract: An underground continuous wall building method and apparatus in which a chain cutter 2 provided with excavation blades is obliquely mounted on a running carriage 1. Slanting continuous trenches G1, G2 are excavated by moving the running carriage 1 in a transverse direction while rotating the cutter 2 with the cutter 2 obliquely placed in the ground, and a water cutoff material is poured into the excavated continuous trenches G1, G2 and solidified therein to build slanting continuous walls R1, R2 in the ground.

Abstract: An overload protector mechanism provides protection for an excavating wheel shield mechanism so that if a large foreign object becomes lodged between the excavating wheel and a portion of the shield arrangement the shield mechanism can move out of the way and the wheel may be stopped. The overload protector mechanism includes a release mechanism connected between the shield mechanism and a wheel frame. The release mechanism includes a linkage arrangement having first and second links pivotally connected to one another and releasably biased to a set first position. Once the release mechanism trips, the shield mechanism pivots away from the wheel in order to prevent damage to the shield mechanism or to the excavating wheel and allow the wheel to be stopped and the large object removed.

Abstract: A method of installing a groundwater containment system is provided utilizing a powered trenching apparatus. The apparatus includes a boom at an end thereof; a trenching tool coupled to the boom; and frame structure mounted with respect to the boom. The frame structure is separated into at least first and second adjacent compartments. Each compartment has an inlet opening and an exit opening. The method includes advancing the trenching apparatus to create a single trench with the frame structure being disposed within the trench. Filter material is fed through the inlet opening of the second compartment. A first, impermeable wall panel is inserted through the inlet opening of the first compartment.

Abstract: An excavator for forming an underground continuous wall includes a traveling trolley movable on a ground and an upper frame constructed on the trolley. The excavator further includes a guide post vertically extending and vertically movably provided at one side of the upper frame on the trolley and variable in length by supplementary extension guide post members detachably connectable thereto through flanges. Chain sprockets rotatably provided on the guide post at its upper and lower ends and at one end rearward of the chain sprocket at the upper end of the guide post, respectively. An endless chain extends around the chain sprockets to be driven by rotation of at least one of the chain sprockets. A number of excavator buckets are provided on the endless chain therealong spaced at suitable intervals to form an endless chain bucket type cutter.

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 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.