References Queens Mine Design, https://queensminedesign.miningexcellence.ca/images/thumb/b/b7/Friction.jpg/180px-Friction.jpg     Web, April 2014 Hartman, Howard L. SME Mining Engineering Handbook. Littleton, CO: Society for Mining, Metallurgy, and Exploration.     1992. Print Chen, Gang. MIN301 - Introduction & Hoisting System Lecture Slides, 2014, Web. Wikipedia, Hoist (mining), http://en.wikipedia.org/wiki/Hoist_(mining), April 2014, Web. CEMI, HRMH - Koepe / Friction Hoists, https://www.minewiki.org/index.php/HRMH_-_Koepe_/_Friction_Hoists     April 2014, Web.