Abstract: In a method for preventing dust of a powdery material by mixing the powdery material with a polytetrafluoroethylene and subjecting the mixture to a compression-shearing action taken at temperatures from about 20.degree. to 200.degree. C. thereby the polytetrafluoroethylene is fibrillated to prevent dusting of the powdery material, the method is characterized by that polytetrafluoroethylene is an aqueous emulsion of a homopolymer of tetrafluoroethylene, the homopolymer has a specific gravity of not larger than 2.20 and an average particle size of 0.10-0.50.mu., and the emulsion contains a hydrocarbon-base anionic surfactant of not less than 1.0 wt % of the polytetrafluoroethylene as the emulsion stabilizer. The emulsion is highly stable and a less possible contaminant of underground water.

Abstract: An automatic steering device is presented for controlling the direction of travel of an asphalt finisher during a paving operation. The device is provided with a laser generator (18) which projects a laser beam of a slit shape on a series of objects along the roadside which is selected to served as a reference line (A). An image recording device (17), a CCD camera, is disposed on the vehicle member (2), which records the projected laser light illuminating the objects and outputs a generated image (Ba) to a master controller (22). The master controller (22) determines the current deviation of the vehicle member (2) from the reference line (A) by the changes in the position of the generated image (Ba), and operates the automatic control device so as to steer the vehicle member (2) in the correct direction to permit the asphalt finisher to follow the reference line (A).

Abstract: Efficient paving operation requires that the levelling operation of asphalt be carried out accurately along a reference line which follows a given direction along a roadside. A simple and effective automatic control device for controlling the steering direction in conjunction with adjustments of the screed for an asphalt finisher (shortened to finisher) is presented. The control device automatically regulates the extension or retraction of the screeds on both sides of the finisher in reference to a visual display of the reference line following some objects along the roadside. The visual detection system of control is simple and economical and provides an accurate control over the direction of paving.

Abstract: A measuring arm (12) is attached to a frame (5a) supporting a screed (5). Height sensors (13) and (14) are attached to the measuring arm (12), and a height sensor (19) is also attached to the arm (18) of the screed (5). The spacing must remain constant between the rear end of the screed (5) and the height sensor (19), between the height sensor (19) and the height sensor (14), and between the height sensor (14) and the height sensor (13). A distance sensor to calculate the travel distance is provided on the tractor unit (1). The relative height Ho of both height sensors (13) and (14) to the screed (5) must always remain constant, regardless of the tilt of the screed (5) and the measuring arm (12). The sensors (13), and (14), and (17) are connected to the arithmetic unit (30). The height sensor (19) is connected to the arithmetic unit (40). The arithmetic unit (30) receives an output signal from the height sensors (13) and (14) and calculates the thickness of the pavement.

Abstract: An access alarming method and apparatus for activating an alarm in the event of the access of a working vehicle, such as a road roller, to an object, such as a worker, in the same working area as the vehicle. An ultrasonic wave transmitted by a transmitter on the object is received by a receiver on the vehicle. The received signal is processed and used to determine the relative position of the vehicle with respect to the object. An alarm is activated, and/or the vehicle is braked when it is judged that the object is within a hazard area determined in relation to the position and course of the vehicle.