STEAMING WATCH–Watches stood when the main engines are in use and the ship is underway. STEAM  LANCE–A  device  that  uses  low-pressure steam to remove soot from inside boilers and to remove  carbon  from  boiler  tubes. STEERING ENGINE–The machinery that turns the rudder. STERN   TUBE–A   watertight   enclosure   for   the propeller  shaft. STRAIN–The deformation, or change in shape, of a material that results from the weight of an applied load. STRENGTH–The ability of a material to resist strain. STRESS–A force that produces or tends to produce deformation  in  a  metal. STUFFING  BOX–A  cavity  in  which  packing  is  placed to prevent leakage between a moving shaft and a fixed part of a valve or pump. STUFFING   TUBE–A   packed   tube   that   makes   a watertight fitting for a cable or small pipe passing through a bulkhead. SUMP–A container, compartment, or reservoir used as a drain or receptacle for fluids. SUPERHEATER–A unit in the boiler that dries the steam and raises its temperature. SWASHPLATES–Metal plates in the lower part of the steam drum that prevent the surging of boiler water with the motion of the ship. SWITCHBOARD–A  panel  or  group  of  panels  that distribute  electrical  power  throughout  the  ship, normally  with  automatic  protective  devices. TAKE  LEADS–A  method  of  determining  bearing clearance. TANK  TOP–The  top  side  of  tank  section  or  double bottom of a ship. TOP   DEAD   CENTER   (TDC)–The   position   of   a reciprocating piston at its uppermost point of travel. TEMPERING–The heating and controlled cooling of a  metal  to  produce  the  desired  hardness. THIEF SAMPLE–A sample of oil or water taken for analysis. THROTTLEMAN–The  person  in  the  engine  room who  operates  the  throttles  to  control  the  main engines. THRUST  BEARING–A  bearing  that  limits  the  end play and absorbs the axial thrust of a shaft. TOP OFF–To fill up a tankA ship tops off its tanks with fuel oil before leaving port. TORQUE–The force that produces or tends to produce rotation. TOUGHNESS–The property of a material that enables it to withstand shock as well as to be deformed without  breaking. TRANSFORMER–An  electrical  device  used  to  step  up or step down an ac voltage. TRICK  WHEEL–A  steering  wheel  in  the  steering engine room or emergency steering station of a ship. TUBE  EXPANDER–A  tool  that  expands  replacement tubes into their seats in boiler drums and headers. TURBINE–A multibladed rotor driven by steam, gas, or water. TURBINE   STAGE–One   set   of   nozzles   and succeeding  row  or  rows  of  moving  blades. hot the TURBINE  TURNING  GEAR–A  motor-driven  gear arrangement that Slowly rotates idle propulsion shafts,  reduction  gears,  and  turbines. UPTAKES   (EXHAUST   TRUNKS)–Large   enclosed passages that direct the flow of exhaust gases to the stacks. VACUUM–A  space  that  has  less  than  atmospheric pressure in it. VENT–A valve in a tank or compartment that primarily permits  air  to  escape. VISCOSITY–A liquids resistance to flow. VOID–An  empty,  watertight  compartment  separating other  compartments. VOLATILE–The  term  that  describes  a  liquid  that vaporizes  quickly. VOLTAGE–Electric   potential   (emf). VOLTAGE   TESTER–A   portable   instrument   that detects  electricity. WATER TUBE BOILER–Boilers in which the water flows through the tubes and is heated by the gases of  combustion. WATER WASHING–A method of cleaning to remove contaminants. AI-7