The end pieces of the Rotating Beam must be removed in order to slide the carriages onto the Rotating Beam.

Next, with the ruled side of the Rotating Beam facing you, attach the Counterbalance Carriage on the left, and attach the Sliding Carriage on the right.

Note that the Sliding Carriage should be oriented with the single bottom set of bearings sliding onto the Rotating Beam first, to allow the carriage to reach its maximum radius on the beam.