APPENDIX I GLOSSARY ABS—An     abbreviation     for     "anti-lock     braking system." ABS  SWITCH—Sensor    that    monitors    hydraulic system pressure and controls the pump motor in an ABS  application. AC —Alternating current. AC  GENERATOR—A device that produces alternating current; an alternator. ACTUATOR —A  device  that  performs  an  action  or outputs  a  signal  in  response  to  a  signal  from  a computer. AIR BRAKES—Vehicle    brakes    actuated    by    air pressure. AIR COMPRESSOR —A  pump  that  forces  air,  under pressure, into a storage tank. ALTERNATOR—An   ac   generator. ALTERNATOR BEARING—Needle-     or     ball-type bearings used to provide a low friction surface for a rotor. AMMETER—An     electric     meter     that     measures current, in amperes, in an electric circuit. AMPERE—A     unit     of     electric     current     flow measurement. ANTI-LOCK  BRAKE  COMPUTER—ECM that accepts wheels sensor inputs and controls braking of the vehicle. ANTI-LOCK  BRAKES—Computer controlled brakes that will not "lock" and permit the wheels to skid. ANTI-RATTLE   CLIPS—Metal components designed  to  keep  brake  pads  from  vibrating  and rattling. ANTI-SKID  SYSTEM—Another   name   for   anti-lock braking system. ARMATURE —Rotating support for multiple windings in a motor. ASPECT RATIO—The  relationship  of  tire  height  to width or profile. AUTOMATIC  TRANSMISSION—A transmission that does not have to be shifted manually. AUTOMATIC   TRANSMISSION   FLUID—Oil with special additives to make it compatible with friction clutches and bands. AUTOMOTIVE CLUTCH—A     mechanical     device used  to  connect  and  disconnect  a  manual transmission  from  engine  power. AXLE —A   cross   support   on   a   vehicle   on   which supporting wheel, or wheels, turn(s). AXLE  END  PLAY—In-and-out   movement   of   the axle, adjusted to specification by using shims. AXLE SHAFT RETAINER—Devices   that   attach   to the outside of an axle housing to prevent the axles from sliding out. AXLE SHIMS—Used  between  the  axle  housing  and retainer to limit end play of the axle. BACKLASH —The   backward   rotation   of   a   driven gear  that  is  permitted  by  clearance  between meshing teeth of two gears. BACKING  PLATE—A    component    that    holds    the shoes,  wheel  cylinder,  and  other  parts  inside  a brake drum. BACKUP  LIGHT  SWITCH—An    electrical    switch that  completes  a  circuit  to  the  backup  lights whenever the reverse gear is engaged. BALL JOINT—Swivel    joint    that    provides    free movement  for  the  steering  knuckle  and  control arm. BALL  SOCKETS—Component   that   allows   motion in up-and-down and side-to-side directions. BAND—Metal   strap   with   frictional   material   lining that  can  clamp  a  clutch  drum  in  an  automatic transmission to stop its rotation. BAND   ADJUSTMENT—Checking and altering tightness   of   automatic   transmission   bands   as necessary for proper operation. BATTERY —A device consisting of two or more cells for  converting  chemical  energy  into  electrical energy. AI-l