arm and attach the ring end to a tractor tow hook. Push with the tractor until the operating gear linkage unlocks. WARNING Once  the  emergency  lowering  device  is installed,  all  hands  shall  stand  back  at  a  safe distance  from  the  JBD  and  around  tractor.  As the   JBD   begins   to   lower,   the   emergency lowering device will be dragged out of the JBD pit by the tractor utilizing reverse gear. 5. Adjust the panel lowering speed by opening/closing the emergency bypass valve. 6. Once  the  strut  is  over-center,  the  JBD  panels will  fall  under  its  own  weight  until  it  is  flush with the deck. Inoperative Deckedge Control Panel or Portable Electrical System Control Box In the event of an emergency where the chestpack or  the  deckedge  control  panel  cannot  be  used,  the auxiliary control panel becomes operational. 1. Station   a   crewperson   at   the   flight   deck   or deckedge to man the phone and relay instructions to the auxiliary-control-panel operator. WARNING The crewperson, acting as a safety observer, should ensure that the area around the JBD is clear of aircraft, support equipment, and personnel. 2. With the transfer switch in the AUX position, the auxiliary-control-panel operator shall operate the panel by the instructions relayed to him  or  her  from  the  flight  deck  or  deck  edge personnel. CAUTION Repair and checkout of the faulty panel or control box operation shall be accomplished at times when the raising or lowering of the JBD would not be prohibited by aircraft movement on the flight deck. 3. Continue   operation   of   the   auxiliary   control panel  until  the  faulty  chestpack  or  deckedge control  panel  is  completely  checked  out  and restored to proper operating condition. WARNING Prior  to  returning  control  back  to  deck operation,  verify  with  the  flight  deck  safety observer that the area around the JBD is clear of aircraft, support equipment, and personnel. 4. Return control of the JBD to the chestpack or deckedge operator. MAINTENANCE This   section   contains   preventive   and   corrective maintenance   information   and   procedures,   some   of which  are  general  and  apply  to  various  items  of  the system  and  others  which  are  specific  and  apply  to  a particular part of the equipment. Planned Maintenance The   planned   maintenance   system   furnishes   all vessels  and  stations  with  MRCs  containing  specific maintenance   instructions.   These   cards   are   used   at required  frequencies  to  maintain  JBD  equipment  in operating   condition   and   to   prevent   breakdown   and subsequent   shutdown   of   operations.   The   planned maintenance system and the maintenance data collection    system    are    described    in    OPNAVINST 4790.4. Current  MRCs  include  the  following  inspection and cleaning procedures: 1. Preoperational inspections 2. Postoperational inspections 3. Cleaning    and    inspecting    hydraulic    piping orifice plate(s) WARNING Before performing any maintenance procedures  behind  a  JBD  panel  in  the  raised position,  install  the  panel  supports  to  prevent the  panel  from  lowering.  Failure  to  do  this could result in serious injury to personnel. To    ensure    dependable    operation    of    the    JBD equipment,    proper    lubrication    of    the    mechanical linkage    is    essential.    Lubrication    is    part    of    the preoperational  checks  given  in  the  MRC.  Extension tubes are provided on trunnion bearings and hydraulic 5-13