A TELESCOPIC DATA COUPLER

A data coupler (30, 120) for use in transmitting data between mechanical parts (10, 20; 40, 50) which have a common axis and which are in relatively close engagement, said parts being adjustable on relative to the other along said common axis, and in which the data coupler comprises: an elongate housing (30, 122) having a longitudinal axis extending parallel to the common axis of said parts (10, 20; 40, 50) and which is intended to be mounted on and to extend between said parts so as to be slidable relative to said parts during adjustment of said parts; to a data source A and a data receiver B spaced apart lengthwise of said housing (30, 122); a respective axially short solenoidal coil (11, 103, 203, 160; 21, 106, 223, 162) provided at each of the data source A and the data receiver B; and an axially long solenoidal coil (32, 123, 230, 161) extending lengthwise throughout at least a major portion of the length of the housing and arranged, relative to the axially short solenoidal coils, to be one overlying the other, at least in part, throughout the range of relative slidable adjustment of the housing, whereby, upon energisation of the data coupler, data can be conveyed from the data source A to the data receiver B via the axially long solenoidal coil (32, 123, 230, 161).