Abstract: According to the applicant's invention a load detector is used, in which a load sensor and a vibration sensor are combined using an AND gate. A load signal from the load detector is used for the feedback control of the cutter drum height and double ranging drum cutter running speed, so that a person who is not skilled can operate the double ranging drum cutter while preventing overload acting on the cutter drum.

Abstract: A double ranging drum cutter for long wall type machines for coal extraction is disclosed, which comprises a drum cutter body, a television camera mounted on the drum cutter body for picking up an image of a coal layer cutting portion of a lower bedrock being cut by a cutter drum, a television camera mounted on the drum cutter body for picking up an image of a coal layer cutting portion of an upper bedrock being cut by a cutter drum, and a video image processing unit mounted on the drum cutter body and connected to the television cameras, whereby the boundary between a coal layer and bedrock can be readily judged to permit extraction of much coal without cutting much bedrock and also the ratio of the area of a bedrock to the area of a coal layer in a portion of the bedrock being cut can be readily detected.

Abstract: A pressurized aeration tank is provided which comprises an inner barrel arranged on the tank axis and an axial-flow impeller of optimum characteristics mounted therein, the inner barrel and the outer barrel or body portion of the tank being particularly proportioned and arranged relative to each other to define in the tank a circuitous flow passage of minimal total resistance loss. With this tank structure, a highly improved plant efficiency of BOD removal is readily obtainable with the use of concentrated activated sludge and aerobic microorganisms, mainly of the Opercularia group, in a specified range of tank pressure.

Abstract: An arrangement is described for controlling a winch used in mining machinery, wherein the direction of operating a winch and speed thereof are controlled by changing the position of a control element of a fluid pump for supplying a fluid into a fluid pressure recirculating circuit, by a device incorporating the fluid pressure recirculating circuit and a control circuit. The arrangement is characterized by feeding ON/OFF signals for giving instructions of a position to a control element, by a bi-polar pulse generator. Pulse from the bi-polar pulse generator are fed to a reversible BCD counter by pressing push buttons, and comparing a voltage generated via a D/A converting circuit from the reversible BCD counter with a voltage generated from a potentiometer coupled to the control element according to the position of the control element to be selected, thereby controlling the instruction of the position of the control element; and setting a speed of the winch by pressing the push buttons.