Abstract: Apparatus for remote disconnection and short-circuiting of a pair of conductors, such as those comprising a telephone line, consists of a switching unit and a probe unit. The switching unit is capable of generating a tone and the tone may be sent down the pair of conductors, where the probe unit is used to identify the pair. The probe unit is also able to send bursts of a signal along the pair, upon receipt of which the switching unit switches sequentially from a first mode (when the tone is applied to the conductors) to a second-mode (where the conductors are disconnected) to a third mode (where the conductors are short circuit). The apparatus is useful in line fault location and telephone apparatus installation.

Abstract: A position indicator for monitoring movement of one part of an assembly relative to another--e.g., for monitoring the relative positions of the movable and fixed jaws of a gyratory crusher. The position indicator has a body which is fixed to a probe suitable support and a variable capacitor which responds to movement of the member to be monitored to adopt a capacitance value which is characteristic of each position of that member relative to the support. The capacitor is connected into an electrical circuit operative to generate a signal which varies according to the capacitance value and therefore provides an indication of the position of the member being monitored. The probe body includes at least two telescopic tubes arranged so that the body extends and contracts in accordance with movement of the member being monitored and conductive parts of the variable capacitor are connected to the tubes, so that their relative positions change with extension and contraction of the probe body.