HAND-HELD ROTARY ROCKDRILL/JACKHAMMERThe hand-held pneumatic rock drill/jackhammer(fig. 14-15) is a piston rotary unit that is designed mainlyfor use as a hard rock drill; however, it is equallyefficient in soft and medium formations.The components of the drill are shown in figure14-16. The drill consists of a back head group, cylinderunit, and front head group. The back head groupconsists of the four-position throttle, handle, and live airinlet. The cylinder unit consists of a cylinder with areciprocating piston. The front head group consists ofthe chuck, retainer latch, and anvil. The drill designdirects air through the drill, down the drill steel, and intothe bottom of the hole to blow out rock cuttings.Four classes of rotary rock drills/jackhammers areas follows:. The first class is a light drill, weighing about15 pounds. This class is used for drilling shallow holesin quarry operations.l The second class is a light drill, weighing 25to 40 pounds. This class is used for light work, such aspotholing and drilling concrete.. The third class weighs from 40 to 50 pounds.This class is used for drilling in limestone and other softrock.. The fourth class is a hand-held drill, weighingfrom 50 to 65 pounds. This class is used for drillingholes up to 6 feet during quarry operations.NOTE: All of these drills use hollow drill steel andare built with automatic rotation.Figure 14-15.—Hand-held rotary rock drill/jackhammer.Figure 14-16.-Components of a hand-held rotary rockdrill/jackhammer.14-12
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business