Abstract: A distance measuring apparatus and method using an acoustic signal. It includes a transmitting probe for transmitting an acoustic signal from a transmitter, a plurality of receiving probes having resonance frequencies different from the central frequency of the signal transmitted from the transmitting probe, and a control circuit for controlling the functions of those probes. The acoustic signal is received by a receiving probe having a resonance frequency which provides the maximum received-signal sensitivity at the central frequency of the received acoustic signal under the control of the control circuit to thereby measure a long distance accurately.

Abstract: A guide rail apparatus for guiding a running body running around a pipe having a complicated form such as an elbow. The apparatus includes a guide rail secured to the pipe in parallel with the weld line or others and a dynamically stable holder by which the guide rail is fixed.

Abstract: An annular guide rail is detachably mounted in enclosing relation around a tubular member of piping to be probed for any flaws that might be present therein, and a flaw detecting unit, a circumferentially driving unit and an axially driving unit are movably arranged on the annular guide rail and interconnected by connecting means. The flaw detecting means includes an arm movable axially of the tubular member and supporting ultrasonic flaw detecting means. The circumferentially driving unit includes first driving means for moving the flaw detecting unit, circumferentially driving unit and axially driving unit circumferentially along the guide rail. The axially driving unit includes second driving means for moving the arm axially of the tubular member. A transmission mechanism is provided for transmitting the operation of the second driving means to the arm.

Abstract: A ultrasonic flaw detector driving apparatus including a driving apparatus which is equipped with an arm mounted respective side faces of a main frame of the ultrasonic flaw detector driving apparatus so as to allow the arms to move into an open and closed position. A resilient member provides a force which acts on the respective arms in such a direction so as to urge the arms into the open position. A ratchet prevents the arms from being opened by the resilient member as teeth engage with a pawl in a stepwise manner. Rollers are rotatably mounted to a tip of the respective arms and are in rolling contact with the guide rail on which the driving apparatus travels. The arms are moved to the open for mounting the driving apparatus to the guide rail and thereafter the arms are moved to the closed position. Thus, the main frame of the driving apparatus can be position movably fixed onto the guide rail.