As the lifting rod operates the geared quadrants, moving inwards, they then effectively 'grab' the wire stopping it dead, which in turn pulls in the car safety gear. On older lifts they were knarled rollers that dug into the guides stopping the lift car. After a safety gear test, out come the big files to remove the rough indents left on the guides. I worked for 3 years with a company with the unfortunate name of Porn & Dunwoody Lifts, just around the corner from the Globe theatre and I think where taken over by Otis.