Mine shaft conveyance safety mechanism - Free-fall testing

All mine shaft conveyances in Canada and most of the United States that are supported by a single hoist rope or attachment point and used for transporting persons are required by regulation robe equipped with safety catches and mechanisms. These safety mechanisms, commonly called safety dogs, are designed to stop and hold a free falling conveyance, with a full personnel load in the event of a hoist rope or attachment component failure. The conveyance's safety mechanism must be tested under dynamic conditions before it is used to transport personnel. This paper will discuss free-fall testing and it's results on conveyance free-fall tests performed in the test tower at INCO limited Sudbury, Ontario. Topics covered will be free-fall tests on various wood types such as B. C. fir, Karri wood and Trusjoist MacMillan limited Parallam wood (PSL), comparison of deceleration rates versus free-fall velocity and the influence of safety dog tooth design on deceleration rates.