to expose the couplings 190 195 and 205 at the same time as arms 225 and 226 are retracted with the end wall the entire slave transfer assembly is pulled into contact with the seal tube such that couplings 190 195 and 205 engage corresponding couplings 240 246 respectively for continued transfer of the various functional rotary motions thus manual z motion coupling 190 in the seal tube engages coupling 240 in the transfer assembly azimuth coupling 191 engages azimuth coupling 241 right and left elevation and twist couplings 192 and 193 engage couplings 242 and 243 respectively tong coupling 194 engages coupling 244 y motion coupling 195 engages coupling 245 finally motorized z extension coupling 205 engages coupling 246 locating pins 228 and 229 engage sockets 247 and 248 in the slave transfer assembly to insure proper engagement of the various couplings couplings 240 246 are each connected for rotation of horizontal shafts 250 256 respectively as in the case of the seal tube couplings slave transfer couplings 240 246 are splined to be rotatable with shafts 250 256 and longitudinally movable with respect to those shafts the couplings are spring loaded and provided with ratchet lock means for maintaining the proper orientation of the couplings and shafts when the.