total defence day block 522 ang mo kio avenue 3 sigma elevator lift b traction Published 8 months ago • 27 plays • Length 0:30 Download video MP4 Download video MP3 Similar videos 0:12 tripping the governor on a elevator full load safety test. 2:20 elevator modernization metric 1:56 why does the elevator need a counterweight? 0:55 manual handling - what is the power zone?