Abstract: A gouging cutter, includes a cutting element having a cutting end and a mounting feature displaced from the cutting end a cutter body affixable to a drill bit body. The cutter body has a corresponding mounting feature arranged to cooperate with the mounting feature on the cutting element to retain the cutting element to the cutter body so as to enable rotation of the cutting element therein. A drill bit may include a bit body having features to enable connection to a drill string and at least one of the foregoing gouging cutters mounted to the bit body.

Abstract: A roller cone drill bit includes a bit body adapted to be coupled to a drill string, a bearing journal depending from the bit body, and a single roller cone rotatably attached to the bearing journal. The single roller cone has a plurality of cutting elements, where at least one of the plurality of cutting elements is formed of an inner region that is at least partially surrounded by an outer region, where the inner region is more abrasive resistant than the outer region. Such an arrangement in a single roller cone bit allows the at least one cutting element to be “self-sharpening.

Abstract: When an interlock trip condition occurs, a back tracing of interlock logic occurs by examining input signals to an output gate of the interlock logic to determine which input signal caused the interlock trip condition. If the input signal is a predetermined interlock condition, that signal is deemed to be the cause of the interlock trip, saved and displayed. If the input signal is the output of another gate, then the inputs to that gate are examined to determine which input signal caused that gate to switch state. This process is repeated until a predetermined interlock condition is found which has switched state. By knowing the structure of the interlock logic and knowing the state of logic signals outputted from the interlock logic, the determination is made and saved such that even if the predetermined interlock condition that caused the interlock trip subsequently changes state as a result of placing the device in a safe state, the cause of the interlock trip is ascertained and saved by this method.