When an occupant of specified or higher weight sits on the seating surface, the protuberances collapse and {HEAD ~ the force translation plates} activate {TAIL ~ the switch mechanism} 
activate
When an occupant of specified or higher weight sits on the seating surface , the protuberances collapse and { HEAD ~ the force translation plates } activate { TAIL ~ the switch mechanism }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL