GT I drive is the closest I can understand.
My thoughts: Main swing arm (single pivot) begins swing then large pivot actuates in a forward and upwards direction resulting in a wheel path that is initially slightly backwards and up wards getting more vertical as the travel progresses.
Ahhh. My brain hurts.
EDIT. I think the BB is mainframe mounted. The pivot would be to VPP (not Santa Cruz) and closer to maestro wheel path.