f. Removing Steel.  verse the procedure used in adding steel (e above) to dismantle the string of steel with the following exceptions: (1)  Move the blow handle (fig.  2-1) to 1/4 "ON" position only when raising the bottom steel. (2)    Before  removing  steel,  always  make  sure the  steel  coupling  is  above  the  centralizer  and  that  the centralizer is in the closed position.  Neglecting to do this could result in loss of the remaining steels, coupling and bit in the hole. Section II.  OPERATION OF AUXILIARY EQUIPMENT 2-6. General The pneumatic rock drill can be operated with any trailer mounted  air  compressor  with  a  capacity  of  600    c.f.m. (cubic feet per minute). 2-7. Compressor Operation For    operation    of    the    air    compressor,    refer    to    the applicable  technical  manual  for  compressor  to  be  used for power. Section III.  OPERATION UNDER UNUSUAL CONDITIONS 2-8. Operation    in    Extreme    Cold    (Below    32F.) (0C.) a. General.  If the rock drill is to be operated in below  freezing  temperatures,  certain  precautions  must be taken to assure continued normal operation. b. Oil    Reservoir    Service.        Service    the    oil reservoir in accordance with LO 5-3820-241-12.  Use the grade of lubricant specified for the expected temperature. c. Hydraulic     Oil     Reservoir.          Service     the hydraulic oil reservoir in accordance with LO 53820-241- 12. d. Tramming Motors (2 ea used).  Open level plugs  and  drain  off  water  until  oil  appears;  close  drain plug. e. Air  and  Hydraulic  Systems.    If  operating  in sever cold (below 0°f.) (-18C.), complete the following:   (1)    Before  terminating  the  shift,  introduce one to two quarts of permanent  type  antifreeze  into  the main air supply line. (2)  Operate all air functions briefly, allowing the antifreeze to mix with any water that may be present in the air lines. f. Control  Station.    If  control  station  handles are iced up, apply heat to thaw the moving parts before attempting to operate. 2-9. Operation in Extreme Heat a. Refer  to  LO  5-3820-241-12  and  lubricate the equipment more frequently. b. Adjust the drop rate of the airline lubricator according     to     the     characteristics     of     the     oil,     the temperature, and the air consumption of the equipment. Always blow out the air supply line before connecting it to the rock drill inlet. 2-10. Operation in Dusty Areas a. Always  keep  hydraulic  oil  reservoirs  tightly capped. b. Service   the   hydraulic   oil   filter   at   more frequent intervals. c. Cover  all  ports  immediately  as  soon  as  a line is disconnected. d. Refer to LO 53820-241-12 and lubricate the equipment at more frequent intervals as required. e. Keep  the  equipment  clean.    Pay  special attention    to    the    condition    of    the    feed    chain    and sprockets,  machined  surfaces  of  the  hydraulic  cylinder rod, and the sliding surfaces of the drill carriage. f:  Take all necessary precautions to prevent dirt, dust,   or   sand   from   entering   the   pneumatic   system. Service the air strainer daily.  Cover the air inlet when not in use. g. Provide  maximum  protection  for  the  rock drill when not in use by storing it in a shelter or covering with a canvas cover. 2-11. Operation Under Rainy or Humid Conditions a.  Keep all exposed surfaces with preservative oil.  Pay special attention to damaged painted surfaces. Cover   all   paint   cracks   and   chip   marks   as   soon   as possible to prevent corrosion. b. Take  all  necessary  precautions  to  prevent moisture from entering the pneumatic system. c. Service    the    air    lubricator    (para    4-19). Cover the air inlet when equipment is not in use. d. Provide maximum protection for the equipment when not in use. 2-13