Abstract: A balanced transmission device having a pair of impedance element mutually of an equal value and connected between a pair of connecting terminals and an earthing point of an apparatus for superposing alternating signals on a direct current source and transmitting them through parallel two-wire cables. A transformer inserted as a high impedance source with respect to the apparatus for superposing and the transmitter, whereby the device can restrain any noise influence to realize smooth superposed transmission, with simpler arrangement but without enlarging it.

Abstract: A drum assembly for carrying a plurality of rotary recording and reproducing heads of a magnetic recording and reproducing apparatus recording and reproducing a signal on and from a magnetic recording medium in a rotative manner.

Abstract: A pump for use in a paint application apparatus which is so constructed that there is provided a clearance between an appropriate portion of an internal surface of a casing of the pump and an external periphery of protruded portions of a rotor of the pump, and there is provided another clearance between an internal periphery of the protruded portions of the rotor and an external periphery of a cylinder section of a grand box of the pump. Further, in the pump, an appropriate portion of the internal surface of the casing of the pump, the external and internal peripheries of the rotor of the pump and the external periphery each of the cylinder section of the grand boxes are made hard by quenching, applying thereto an extremely hard alloy or spraying thereonto a hard material such as molybdenum.