Original subtitles

--Captions by VITAC-- www.vitac.com

CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS

A COMBINATION SQUARE IS A MEASURING TOOL YOU USE

WHEN BUILDING WITH WOOD,

MASONRY OR METAL

TO MAKE SURE SOMETHING'S STRAIGHT,

EVEN AND LEVEL.

IT'S ESSENTIALLY A RULER

WITH INTERCHANGEABLE SLIDING HEADS.

THE MOST BASIC HEAD, CALLED A SQUARE,

MEASURES 90 AND 45 DEGREE ANGLES.

THIS COMBINATION SQUARE COMES WITH THREE HEADS.

THEY LOCK INTO A GROOVE ON ONE SIDE OF THE BLADE.

THE BLADE STARTS OUT GROOVED BUT BLANK.

SO TO ETCH THE GRADUATIONS INTO IT,

THEY FIRST COAT THE SURFACES WITH PHOTORESIST,

A CHEMICAL THAT HARDENS

WHEN EXPOSED TO ULTRAVIOLET LIGHT.

THEN THEY FLASH UV

LIGHT ON BOTH SIDES OF THE BLADE

THROUGH POLYESTER FILM NEGATIVES OF THE GRADUATIONS.

THE LIGHT HARDENS ONLY THE PHOTO

RESISTANT HITS THROUGH THE CLEAR PARTS.

THE REST REMAIN SOFT.

AFTER MANUALLY MASKING THE GROOVE,

WORKERS PUT THE BLADE THROUGH A PHOTOCHEMICAL ETCHING MACHINE.

IT WASHES OFF THE SOFT PHOTORESIST

THAT'S IN THE PATTERN OF THE GRADUATIONS,

THEN HITS THAT BARED STEEL

WITH A METAL-EATING SALT SOLUTION,

ETCHING THE GRADUATIONS INTO THE BLADE.

EVERYTHING ELSE IS MASKED BY HARDENED PHOTO RESIST,

WHICH THEY WASH OFF AFTERWARD.

THE BLADE MEASURES IN IMPERIAL UNITS.

THEY SET IT IN THIS MACHINE,

WHICH REGISTERS THE LOCATION OF THE 1-INCH MARK,

THEN GRINDS DOWN THE END OF THE BLADE

UNTIL IT'S PRECISELY 1 INCH FROM THAT LINE.

THEY RUN THE BLADE THROUGH A SANDBLASTER.

IT SHOOTS GLASS BEADS ONTO THE STEEL SURFACE

TO MAKE IT MICROSCOPICALLY ROUGH.

THIS WILL GIVE THE CHROME PLATING A MATTE,

RATHER THAN GLOSSY FINISH,

MAKING THE GRADUATIONS EASIER TO READ.

BEFORE PLATING,

THEY CLEAN THE BLADE BY DIPPING IT IN ACID.

THEN THEY SUBMERGE IT IN THE ELECTROPLATING TANK

FOR ABOUT 15 SECONDS.

NOW, THE STEEL BLADE,

WITH ITS GRADUATIONS ON BOTH SIDES,

IS PLATED IN CHROME.

THE NEXT STEP IS CALLED BLACK FILLING.

THEY APPLY BLACK ENAMEL PAINT

TO BOTH SIDES OF THE BLADE,

THEN WIPE THE SURFACE CLEAN.

THE BLACK REMAINS IN THE RECESSED GRADUATIONS,

MAKING THE NUMBERS AND LINES EASIER TO READ.

FIFTEEN MINUTES IN AN OVEN TO BAKE ON THE BLACKFILL,

THEN A QUALITY CONTROL INSPECTION

AND THE BLADE IS FINISHED.

MEANWHILE, IN ANOTHER PART OF THE FACTORY,

THIS COMPUTER GUIDED MACHINE USES BOTH MILLING

AND DRILLING TOOLS TO MACHINE

FORGED PIECES OF STEEL INTO HEADS.

THIS IS THE FORGED SQUARE HEAD,

BEFORE AND AFTER MACHINING TO ITS FINISHED SHAPE.

THE NEXT STEP IS TO HARDEN THE STEEL.

THEY PLACE THE HEAD INTO THE FURNACE FOR 3 MINUTES

AT MORE THAN 1,472 DEGREES FAHRENHEIT.

THE HEAD COMES OUT COVERED IN BLACK SOOT.

SO THEY SANDBLAST IT CLEAN.

THE SURFACE IS NOW PREPPED FOR PAINTING.

THE APPLY POWDERED PAINT ELECTROSTATICALLY,

RUNNING A POSITIVE ELECTRICAL CHARGE TO THE HEAD

AND A NEGATIVE ONE TO THE PAINT.

THIS DRAWS THE PAINT TO THE PART LIKE A MAGNET,

COATING THE ENTIRE SERVICE IN AN EVEN LAYER.

A 45 MINUTE TRIP THROUGH AN OVEN BAKES ON THE PAINT.

THEN, THEY MOUNT THE HEAD ON A COMPUTER-GUIDED MACHINE

THAT GRINDS THAT PAINT OFF

THE HEAD'S ANGLE-MEASURING SURFACES.

THEY INSTALL THE HEAD'S BUBBLE LEVEL.

FIRST, THEY INSERT A WHITE PAPER BACKGROUND,

WHICH MAKES IT EASIER TO SEE THE AIR BUBBLE.

THEN THEY INSERT THE GLASS VIAL CONTAINING THE BUBBLE

FLOATING IN A GLUCOSE SOLUTION.

A DAB OF PLASTER AT BOTH ENDS HOLDS THE VIAL

IN ITS DESIGNATED SLOT.

THEY ASSEMBLE THE LOCK BOLT

THAT HOLDS THE HEAD IN THE BLADE'S GROOVE.

THEY MOUNT IT WITH A SPRING

AND A WASHER TO PREVENT THE LOCK

FROM ROTATING AND SECURE IT WITH A NUT.

THEN THEY CLOSE UP THE BUBBLE LEVEL SLOT WITH AN ENDCAP.

THEY RUN THE UNPAINTED ANGLE MEASURING SURFACES

AGAINST THE BUFFING WHEEL TO POLISH THE STEEL TO A SHINE.

THE LAST STEP,

INSERTING A SCRIBING AWL INTO ITS SLOT.

YOU USE THE AWL TO MAKE A SCRATCH MARK

WHEN YOU TAKE A MEASUREMENT.

NOW, THE FINAL ASSEMBLY, THE SQUARE HEAD,

THE PROTRACTOR HEAD

AND THE CENTER HEAD.

ALL THREE COME ON THE COMBINATION SQUARE.

BUT WHEN USING THE TOOL, YOU INSTALL ONLY ONE AT A TIME.

NARRATOR: BY THE LATE 1960s,

FISHERMEN JUST COULDN'T KEEP UP

WITH A GROWING GLOBAL DEMAND FOR SHRIMP.

THIS GAVE BIRTH TO COMMERCIAL SHRIMP FARMING.

MOST SHRIMP FARMS ARE LOCATED

NEAR THE SEA FOR ACCESS TO SALT WATER.

THE GREATEST PRODUCER OF FARMED SHRIMP IS ASIA,

WITH THAILAND BEING THE LARGEST EXPORTER.

SHRIMP HATCHERIES RAISE THE OFFSPRING

OF THEIR BREEDING STOCK THROUGH THREE LARVAL STAGES,

THEN SELL THEM TO SHRIMP FARMS,

WHICH GROW THEM TO MARKET SIZE.

AS THIS MODEL DEMONSTRATES,

THE SHRIMP FARM FIRST PURIFIES THE SEAWATER IT USES,

THROUGH A SYSTEM OF TREATMENT PONDS

CONTAINING FISH THAT FEED ON MICROORGANISMS.

THEN THE FARM PUMPS THE TREATED WATER

TO A CULTURE POND,

IN WHICH THE JUVENILE SHRIMP GROW TO MATURITY.

THIS IS WHAT THE SHRIMP LOOK LIKE AT ABOUT 2 MONTHS OLD.

SHRIMP FARMS ARE TYPICALLY LOCATED

ON A COAST FOR SEAWATER ACCESS.

WORKERS SPREAD ORGANIC FERTILIZER

BEFORE FILLING THE CULTURE POND

TO RESTORE THE SOIL BOTTOM

TO OPTIMUM CONDITIONS BETWEEN HARVESTS.

THEY PUMP SEAWATER INTO THE FIRST TREATMENT POND,

WHERE TILAPIA FISH NATURALLY PURIFY THE WATER BY CONSUMING

FLOATING MICROSCOPIC ORGANISMS CALLED PLANKTON.

PLANT MATTER IN FISH FECES SETTLE

AT THE BOTTOM OF THE POND.

A PUMP MOVES WATER FROM THIS

FIRST TREATMENT POND TO A SECOND ONE.

FOR ANOTHER ROUND OF THIS NATURAL CLEANING PROCESS.

THEN A PUMP TRANSFERS THE WATER

FROM THE SECOND TREATMENT POND TO THE CULTURAL POND.

ONCE THE POND IS FULL,

THEY RELEASE THE JUVENILE SHRIMP PURCHASED FROM THE HATCHERY.

WORKERS REGULARLY MONITOR THE WATER'S OXYGEN LEVEL

AND RUN AERATION PROPELLERS

WHEN IT DROPS TOO LOW.

THE AGITATION ALSO HELPS

DEBRIS SETTLE AT THE BOTTOM OF THE POND.

WORKERS RUN A WEEKLY WATER QUALITY TEST ON SAMPLES

DRAWN FROM THE TREATMENT AND CULTURE PONDS.

REGULARLY MONITORING THE CULTURAL POND

IS PARTICULARLY CRITICAL

BECAUSE SHRIMP FECES AND URINE BREAK DOWN INTO AMMONIA,

WHICH IS TOXIC AT HIGH LEVEL.

THE TEST SOLUTION REACTS TO THE CONCENTRATION OF AMMONIA

IN THE WATER SAMPLE,

TURNING A SHADE OF YELLOW OR GREEN.

THEY CONSULT A COLOR CHART TO TRANSLATE THIS

INTO A MILLIGRAMS OF AMMONIA PER METER READING.

THEN THEY CONSULT A TABLE SHOWING SAFE,

DANGEROUS AND TOXIC LEVELS.

IF THE READING IS ABOVE THE SAFE RANGE,

THEY DILUTE THE AMMONIA

BY PUMPING MORE TREATED WATER

INTO THE CULTURE POND.

ONCE A WEEK, THEY ALSO PULL A FEW SHRIMP

FROM THE CULTURE POND TO EXTRACT THEIR LIVERS.

FIRST, THEY EXAMINE THE SHAPE OF THE ORGAN.

THEY EXAMINE IT UNDER A MICROSCOPE

TO SEE HOW FATTY IT IS.

A WELL-SHAPED LIVER WITH SUFFICIENT FAT INDICATES

THE SHRIMP WAS IN GOOD HEALTH,

AND, THEREFORE, THE OTHERS BACK IN THE POND ARE TOO.

THE GROWING SHRIMP ARE FED AN ALL-NATURAL DIET,

WHICH INCLUDES PROBIOTICS,

TAMARIND,

WHICH IS SOAKED IN WATER...

AND GARLIC.

WORKERS ADD THESE THREE INGREDIENTS TO THE SHRIMP FEED,

WHICH IS A MIXTURE OF FISH MEAL, FISH OIL,

SOY BEAN PULP AND RICE FLOUR.

TAMARIND MAINTAINS THE RIGHT LEVEL OF ACIDITY

IN THE SHRIMP'S GUT.

GARLIC PREVENTS BACTERIA BUILDUP IN THE COLON.

AND THE PROBIOTIC SOLUTION PROVIDES BENEFICIAL BACTERIA,

WHICH PREVENTS INFECTIONS AND IMPROVES

HOW THE SHRIMP DIGESTS NUTRIENTS.

AFTER BLENDING AND LIQUEFYING THE THREE INGREDIENTS,

THEY MIX IN 6 FLUID OUNCES PER

2 POUNDS OF SHRIMP FEED.

FOUR TIMES A DAY, AT 8 AM, NOON,

4 PM AND 8 PM, WORKERS POUR FOOD

ONTO AN AUTOMATIC FEEDING MACHINE,

WHICH DISTRIBUTES IT EVENLY THROUGHOUT THE CULTURE POND.

THE SHRIMP FEED OVER THE ENTIRE 12 HOUR PERIOD,

EATING THE EQUIVALENT OF ABOUT 4%

TO 5% OF THEIR BODY WEIGHT.

AFTER 4 TO 5 MONTHS IN THE CULTURAL POND,

THE SHRIMP MATURE TO MARKET SIZE,

WHICH IS 20 TO 30 GRAMS.

ONCE THEY'RE HARVESTED,

THE FARM DRAINS THE CULTURE POND

AND STARTS THE PROCESS ALL OVER AGAIN.

THE BALL VALVE CAME INTO LARGE SCALE INDUSTRIAL USE

DURING THE 20th CENTURY.

WITH A HOLLOW AND PIVOTING BALL

TO CONTROL THE FLOW OF FLUIDS,

THIS VALVE IS DURABLE AND RESISTANT TO CONTAMINATION.

IT'S WHY MANY INDUSTRIES RELY ON BALL VALVES

TO KEEP PRODUCTION FLOWING.

BALL VALVES CONTROL THE FLOW OF GASES.

IN MACHINERY USED TO PRODUCE HIGH-TECH PRODUCTS

LIKE LED LIGHTS.

IT'S JUST ONE WAY THEY CONTRIBUTE

TO THE MODERN WORLD.

MAKING BALL VALVES FOR LED

MANUFACTURING STARTS

WITH AN 11-FOOT LONG STEEL BAR STOCK.

AS COOLANT, A SAW CARVES IT UP LIKE SALAMI,

PRODUCING 50 OR 60 STEEL PUCKS.

COMPUTERIZED TOOLING THEN DRILLS HOLES IN THE PUCKS,

AS IT BEGINS TO TRANSFORM THEM INTO THE VALVE CENTER PARTS.

THE SYSTEM CHANGES TOOL BITS AUTOMATICALLY.

CUTTERS SQUARE UP THE PUCKS,

SO THAT THEY'LL FIT IN THE LED CHIP MAKING MACHINERY.

A GRINDING TOOL MILLS THE TOPS OF THE PARTS

TO A PRECISE TOLERANCE.

ONCE THE FINAL SHAPE HAS BEEN ACHIEVED,

A WORKER GIVES THE PART A SANDING.

HE REMOVES ROUGH BITS, KNOWN AS BURRS,

AND SMOOTHES THE ENTIRE SURFACE.

WITH A NARROW BLADE,

HE THEN SCRAPES OFF ANY BURRS IN THE HOLES

THAT COULD IMPEDE THE VALVE'S FUNCTION.

WITH THE DEBURRING COMPLETE,

HE MEASURES EACH VALVE BODY.

CERAMIC BITS THAT LOOK LIKE AQUARIUM GRAVEL

WILL NOW BE USED TO POLISH THE STEEL VALVE PARTS.

THE OPERATOR PLACES THE VALVE BODIES

IN THE CELLS OF A DRUM TUMBLER.

HE PUTS THE LID ON THE TUMBLER AND SETS IT IN MOTION.

THE FRICTION POLISHES THE STEEL,

CREATING A SMOOTH SURFACE

THAT WON'T BLOCK THE MOVEMENT OF GAS MOLECULES.

NEXT, THEY ASSEMBLE FLANGES TO THE ENDCAPS.

AFTER TACK WELDING THE TWO PARTS TOGETHER,

AN OPERATOR PLACES THEM IN A REVOLVING FIXTURE.

HE WELDS THEM TOGETHER,

CREATING A SUBSTANTIAL INSIDE SEAM

THAT WILL HOLD UP TO VACUUM CONDITIONS.

HE SCRUBS OFF THE HEAT STAIN INSIDE THE PART,

USING A WIRE BRUSH.

THE STAIN HAS ALSO SPREAD AROUND THE SEAMS

ON THE OUTSIDE OF THE PARTS.

SO A WORKER RINSES THE OUTSIDE OF THE SEAM WITH WATER.

HE WASHES OFF THE STAIN

USING AN ELECTRIFIED CARBON BRUSH

AND AN ACID CLEANING SOLUTION.

THEN IT'S IN TO AN ULTRASONIC CLEANER,

WHERE SOUNDWAVES RIPPLE THROUGH WATER

TO REMOVE DUST AND CLEANING SOLUTION RESIDUE.

TO ASSEMBLE THE BALL VALVE,

THE TECHNICIAN PLACES

TWO RUBBER O-RINGS ON TOP OF AN ENDCAP.

NEXT IS A THICK SYNTHETIC RING,

WHICH WILL SECURE THE BALL IN THE VALVE.

HE SEATS THE VALVE BODY OVER IT.

HE CLEANSES THE HOLLOW STEEL BALL

AND INSERTS IT IN THE VALVE BODY.

HE STACKS MORE RUBBER SEALERS,

ANOTHER SYNTHETIC SEALER AND ANOTHER ENDCAP ON TOP.

HE INSERTS LONG BOLTS INTO THE FOUR CORNERS

OF THE VALVE

AND SECURES THEM TIGHTLY WITH NUTS TO KEEP AIR

FROM SEEPING INTO THE VALVE.

HE ATTACHES A HANDLE TO THE STEM,

PROTRUDING FROM THE VALVE BODY.

HE INSTALLS A STOP PIN TO PREVENT THE HANDLE

FROM OPENING BEYOND A QUARTER TURN.

FINALLY, HE TIGHTENS THE NUT THAT LOCKS THE HANDLE

TO THE VALVE STEM.

HE NOW SECURES THE BALL VALVE IN A VISE

TO HOLD IT STEADY WHILE HE TESTS ITS FUNCTION.

WHEN THE WHOLE OF THE BALL IS ALIGNED WITH FLANGES

OF THE ENDCAPS, THE VALVE IS OPEN.

AND WHEN IT'S PERPENDICULAR TO IT, IT'S SHUT.

SATISFIED WITH ITS FUNCTION,

HE TRANSFERS THE BALL VALVE TO THE LASER ENGRAVER.

THE LASER ETCHES THE SERIAL NUMBER

AND OTHER INFORMATION ONTO THE VALVE BODY.

AND NOW, ONE FINAL TEST,

THE TECHNICIAN CONNECTS THE VALVE

TO A VACUUM PUMPING SYSTEM

AND ACTIVATES A LEAK-DETECTING DEVICE.

WHILE THE PUMP DRAWS A VACUUM,

HE SPRAYS HELIUM GAS ONTO THE VALVE

TO DETECT ANY LEAKS.

THIS ENSURES THE VALVE WILL OPERATE PROPERLY

IN A HIGH VACUUM ENVIRONMENT.

SOME OF THESE BALL VALVES ARE MANUALLY OPERATED.

AND OTHERS ARE COMPUTERIZED.

BOTH VERSIONS ARE DESIGNED TO HOLD UP

TO HIGH VACUUM CONDITIONS AND HANDLE THE FLOW.

Narrator: IF YOU HAVE GRASS OR WEEDS TO CUT,

BUT CAN'T ACCESS THE SPOT WITH YOUR LAWN MOWER,

YOU NEED A STRING TRIMMER FOR THE JOB.

IT'S COMPACT, LETTING YOU CUT AROUND

AND IN BETWEEN OBJECTS,

AND DOESN'T RIDE ON THE GROUND.

SO YOU CAN EASILY USE IT ON A STEEP TERRAIN.

A STRING TRIMMER SLICES THE VEGETATION IN ITS PATH

WITH A ROTATING NYLON LINE.

THE MOTOR THAT TURNS THE SPOOL OF LINE

IS PROTECTED BY A TWO-PART HOUSING MADE OF POLYMER.

THE POLYMER PELLETS ARE PUMPED THROUGH PIPES TO THE HOPPER,

THAT FEEDS AN INJECTION MOLDING MACHINE.

THE MACHINE MELTS THEM,

THEN SHOOTS THE LIQUID PLASTIC INTO HOUSING-SHAPED MOLDS.

THE MACHINE THEN COOLS THE MOLDS TO SOLIDIFY THE PLASTIC

AND EJECTS THE MOLDED PARTS,

WHICH A ROBOT GRABS AND PLACES IN A COLLECTION BOX.

TO MAKE OTHER PLASTIC PARTS OF THE STRING TRIMMER,

THEY INSTALL DIFFERENT MOLDS ON THE INJECTION MOLDING MACHINE

AND HOOK UP THE FEED LINE

FOR WHICHEVER COLOR PELLETS THEY'RE USING.

TO MAKE THE CUTTING LINE,

AN EXTRUSION MACHINE MELTS DOWN PLASTIC PELLETS,

THEN FORCES THE LIQUID PLASTIC THROUGH

A ROUND DIE TO FORM LINE.

A COLD WATER BATH COOLS AND SOLIDIFIES THE SHAPE.

THEN, HEATED ROLLERS STRETCH THE LINE

UNTIL ITS REDUCED TO 3 MILLIMETERS IN DIAMETER.

THE LINE IS WOUND ONTO LARGE SPOOLS,

WHICH FEED THE MACHINES

THAT WIND THE FINISHED TRIMMER SPOOLS.

ON THE ENGINE ASSEMBLY LINE,

AN AUTOMATED MACHINE APPLIES SEALANT

TO THE MAGNESIUM ENGINE PAN.

THEY PLACE THE CYLINDER

ON AN ASSEMBLY FIXTURE,

APPLY A GASKET, THEN INSERT THE PISTON.

ALREADY ASSEMBLED TO THE CRANKCASE,

ITS UP AND DOWN MOTION TURNS.

THEN THEY MATE THE ENGINE PAN TO THE CRANKCASE.

THE SEALANT IN BETWEEN MAKING THAT CONNECTION AIRTIGHT.

AN AUTOMATED MACHINE SCREWS THE COMPONENTS TOGETHER,

THEN CLOSES OFF THE EXHAUST PORTS

AND PULLS A VACUUM TO TEST THE SEAL.

IF THE ENGINE ASSEMBLY PASSES THE TEST,

IT CONTINUES DOWN THE ASSEMBLY LINE.

THEY INSTALL A GASKET...

THE CARBURETOR...

ANOTHER GASKET

AND THE HOUSING FOR THE AIR FILTER.

THEN THEY INSTALL A BAFFLE,

WHICH DISTRIBUTES AIR

SO THAT IT ENTERS THE AIR FILTER EVENLY.

THEY ATTACH A GASKET UNDER THE MUFFLER

AND SCREW THE MUFFLER ONTO THE CYLINDER.

THE GASKET AND SEALANT ON THE SCREWS ENSURE

THE ONLY EXHAUST GASES CAN ESCAPE THROUGH THE MUFFLER.

NEXT, THE FLYWHEEL.

WHEN IT ROTATES, MAGNETS INSIDE PRODUCE

AN ELECTROMAGNETIC FIELD THE IGNITION USES

TO SET OFF THE SPARK PLUG

THAT STARTS THE ENGINE COMBUSTION CYCLE.

AFTER MOUNTING THE CLUTCH ON THE FLYWHEEL,

THEY INSTALL THE SPARK PLUG ON THE CYLINDER.

THIS AUTOMATED MACHINE

SIMULTANEOUSLY TIGHTENS THE SPARK PLUG,

THE CLUTCH AND THE FLYWHEEL TO SPECIFIED TORQUES.

BY THIS POINT, WORKERS HAVE WELDED

A FUEL TANK TO THE MOTOR HOUSING.

THEY'VE ALSO INSTALLED A TRIGGER,

A TRIGGER RELEASE, AND A STOP SWITCH.

THEY PLACE THE ASSEMBLED ENGINE INTO THE HOUSING.

THEY ALSO PLACE THE AIR FILTER INTO THE FILTER HOUSING.

AT THE NEXT STATION,

THEY ATTACH THE OTHER HALF OF THE MOTOR HOUSING.

A ROBOT TIGHTENS THE SCREWS TO A SPECIFIC TORQUE.

NEXT, THEY SCREW A COVER ON TO THE FILTER HOUSING.

THEN THEY CREATE THE TRIMMER'S POWERHEAD

BY INSTALLING THE STARTER COVER.

IT CONTAINS THE CORD YOU PULL TO START THE ENGINE.

ELSEWHERE IN THE FACTORY,

THEY BUILD THE SHAFT ASSEMBLY,

TO WHICH THEY'LL LATER ATTACH THE POWERHEAD.

FIRST, THEY PUT TOGETHER THE HANDLE IN THE GEARHEAD

THAT TURNS THE SPOOL OF LINE.

THEN THEY INSTALL THE SPOOL.

WHEN THE CUTTING LINE WEARS DOWN FROM USE,

YOU TAP THE SPOOL AGAINST THE GROUND

TO AUTOMATICALLY ADVANCE MORE LINE.

THEY INSERT THE SHAFT ASSEMBLY INTO THE POWERHEAD.

THE OTHER END OF THE DRIVE SHAFT CONNECTS TO THE GEARHEAD.

THE LAST STEP IS TO ATTACH THE GEARHEAD'S DEFLECTOR,

WHICH IS DESIGNED TO HELP PREVENT

WHAT YOU'RE TRIMMING FROM FLYING UP AT YOU.

TO USE THE STRING TRIMMER,

YOU FILL THE FUEL TANK WITH A GAS AND OIL MIXTURE.

THEN, JUST PULL THE CORD TO START HER UP.