S e c t i o n 1 - P a g e 9 May 2013 bolt dollies have a 7 / 8 " hex shank and ar e only 3 1 / 4 " long. In addition to being the pr oper size for the r ock bolt head or nut, the dolly must also have suf fcient socket depth to allow nuts to be run onto the ends of TBE bolts. Pr oper T or quing of Bolts - T ypically , 3.5 tons of installed tension is r equir ed for a r ock bolt to set the anchor and tension the bolt to 50of the yield str ength. An appr oximately linear r elationship exists between the applied tor que and the tension in a for ged head r ock bolt. continued Installation Quality Guidelines continued DSI - Mining’ s T -Dome - for ged head r ock bolts have a special concave head design which when used in conjunction with T -Dome plates, work like a ball-and-socket and corr ect for angularity without r equiring extra washers. Rock Bolt Dollies - Rock bolt installation dollies should only transfer r otational ener gy to the r ock bolt during installation, not per cussive ener gy , when stopers and jacklegs ar e used. The shank end of the dollie must be short enough to avoid contact with the drill piston. T ypically , these r ock As TBE bolts turn at both ends during torquing, they generally apply more tension for the same amount of applied torque due to the reduced resistance to friction. However , as a generality: All mechanical rock bolts should be torqued to a minimum of 150 ft-lbs (per ASTM F432). www .dsiundergr ound.com