It is an LCI slide mechanism
(this manual should be in your documentation package). The extend/retract motor acts on one end of the slide through a long threaded rod. On the bottom of the support arms, which slide in channels through the frame, are gear racks and there are pinion gears riding on each that are connected together via a square tube to transfer the position of one arm to the other.
However, it has been known for the pinion gear to fracture or lose a tooth or two - they are made via a compressed metal powder method and not machined from billet. I haven't heard of too many failures recently but it was a topic a year and a bit ago... a search may turn up more threads.
2015 Rockwood Signature UltraLite 8282WS Platinum, GY Marathon LRD, TST 507RV TPMS
2005 GMC 2500HD CCSB D/A, Curt E16, Prodigy P2, Garmin RV760LMT w/BC-20 b/u cam