All language subtitles for S17E04 - Corn Tortillas; Crankshafts & Camshafts; Bush Planes; Aluminum Bike Wheels (1080p AMZN WEB-DL x265 Garshasp)_track3_[eng]

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Narrator: the corn tortilla
Is the original flatbread

Invented, legend has it,

Thousands of years ago by a
Mayan peasant to feed his king.

A royal appetite
May have been the inspiration

For this unleavened creation,

But it soon gained mass appeal

And became a staple
Of the mexican diet.

The corn tortilla has been
Popular for thousands of years.

In the last century,
Demand has grown

As people in many countries

Acquire a taste
For tex-mex cuisine,

Like tacos, enchiladas,
And nachos.

Corn tortillas are now
Mass-produced in factories,

And the process starts
With grade-"A" corn --

Dehusked
And removed from the cob.

There are millions of kernels
In one truckload.

They unload onto an elevator

That takes them several stories
Up to deposit them in a silo.

They're stored here

Until the factory is ready
To start production.

They then spill out of the silo
And into big steel cooking vats.

A worker adds water,
Completely immersing the corn.

He activates a steam-injection
Heating system,

And as the temperature rises,

He tosses in numerous scoops
Of powdered limestone.

It acts as a preservative

And helps soften the kernels
During cooking.

As they soften, the outer skin,
Or pericarp, loosens,

Releasing starch
And creating a foamy effect.

After 45 minutes,
They turn off the heat,

And the corn steeps
For eight hours.

With the kernels softened
Even more by the long soak,

It's time to wash off
A lot of the loosened pericarp.

A little pericarp
Still clings to the cooked corn,

But that's part of the plan.

It will act as a bonding agent

When the corn
Is shaped into tortillas.

The corn now funnels
Into a spiraling blade

That delivers it to a grinder.

They add water
And a preservative.

The auger moves the ingredients
Between two volcanic stones

That grind everything
Into a corn mash.

The mash has a grainy texture
Similar to couscous.

That changes when they press it
Through an extruder.

The extruder kneads it
Into a dough called masa.

As the masa exits the machine,
It's collected by a worker.

He transfers the corn dough to
A machine called a pre-sheeter.

Here, automated paddles
Push the masa

Between two sets of rollers.

The rollers press it
Into a thick sheet.

The sheet of dough
Travels through another machine

Called the sheeter cutter.

In this machine, more rollers
Squeeze the dough paper-thin

As a die cuts out
Round tortilla shapes.

They roll and cut
84,000 tortillas an hour

On the sheet cutter.

Another big roller
Takes up the matrix

To be reused
In the next batch of dough,

As the cut tortillas
Head into the oven.

Once inside, the tortillas
Zigzag back and forth

On three tiers of conveyors.

The lowest tier
Has the lowest temperature,

And the top tier, the highest.

This three-tiered approach

Gradually bakes the tortillas
In just 21 seconds,

Producing corn tortillas
With just the right consistency.

A vacuum system suctions the
Tortillas to the next conveyor

To keep them from falling off,

As they now head
To a cooling station.

Here, the tortillas again move
To and fro --

This time on nine conveyor tiers
To cool.

From a handful of corn kernels

To a piece of round
Unleavened bread,

Once the corn has been cooked,

The transformation happens
In just minutes.

Whether the tortilla is made
From white corn, yellow corn,

Or dyed other colors,
The taste will be much the same.

Exiting the cooling zone,
The tortillas move into lanes.

These lanes orient the tortillas
In single file

So they land in slots
And stack up neatly.

A sensor keeps a running count,
And when there's a pile of 40,

A trapdoor opens and sends them
To the packaging line.

These tortillas are now ready
To add a little latin sizzle

To the menu.

Packaged in stacks of 80,

They're headed for restaurants
And cafeterias --

Fried, steamed,
Or just warmed in the oven.

When they start adding
The fillings,

Things could get spicy.

Narrator: in every vehicle,
There are rotating shafts.

The crankshaft converts
The pistons' vertical action

Into the circular motion
That drives the wheels.

At the same time,
The camshaft turns

To open and close
Airflow valves.

These precision parts are behind
Every successful start-up.

Life on the road can be tough,

And a good crankshaft
Has to keep on turning

When the engine is under stress.

The crankshaft starts
With a forged steel shape.

A computerized blade
Shaves off excess metal

From sections
Called counterweights.

They offset the load

Of the engine's pistons
And connecting rods,

And this process slims them down
To create a balance.

A computerized drill bores holes
Into one of the bearings

To reduce the overall weight.

Next a worker removes marks

The computerized tools
Have left on the metal.

He sands the entire crankshaft.

The surface
Must be completely flawless

For it to operate smoothly.

Fine glass beads blast the part

As it revolves
In a rotisserie-like device

To knock off sharp edges

And give the crankshaft
A consistent finish.

The crankshaft
Then spins in a lathe,

As a blade slices away
A precise amount of metal

From each of the counterweights.

This machining
Provides enough clearance

For the engine's pistons
And rods to function.

The crankshaft then takes
Another spin in a device

That has sensors
To detect any imbalance.

It calculates
That just over 29 grams of metal

Still needs to be removed.

Once the adjustment
Has been made,

He measures the degree
Of straightness.

If it's off even slightly,

He corrects it by applying
Pressure with a press

And tapping
A special radius chisel.

He then measures again to
Confirm he's done an even job.

On the left is a crankshaft

That hasn't been balanced
Or straightened.

On the right is one that has.

Production now moves to the
Engine's other rotating shaft --

The camshaft.

Machining transforms a steel
Billet into the basic shape.

Like the crankshaft,

This camshaft will need
A lot of fine-tuning.

An automated tool

First etches the part number
And date onto one end,

And then they get down
To the precision work.

The camshaft must also
Be completely straight,

So the technician measures it
From one end to the other

And makes adjustments
Where needed.

Next he selects a master
Template of a camshaft lobe

And places it
In a grinding machine.

This master is the pattern to be
Copied by a grinding wheel.

Once it's been locked in place,
He activates the grinder.

It carves into the camshaft

As it rotates and rocks
Back and forth in the machine.

The grinding wheel
Moves down the camshaft

To shape all 16 lobes to the
Exact contours of the template.

This is how the camshaft looked
Before the master grinding...

And after.

Next a computerized probe

Measures the profile
Of each lobe

And confirms that the dimensions
And lift are identical.

At the next station,
The camshaft spins

To allow a worker to completely
Coat the journal bearings

With a blue dye.

The dye masks the bearings
To keep them smooth

While the rest of the camshaft
Is being parkerized.

Parkerizing will give
The camshaft an etched finish,

Which protects against wear.

They start with a quick rinse.

Then they plunge the camshafts
Into hot phosphorus acid.

The acid
Microscopically etches the metal

While other chemicals
In the bath

Add a thin graphite coating.

They rinse the residue.

After the finish has dried,

A worker buffs the journal
Bearings as the camshaft spins.

This completely rubs off the
Blue dye and polishes the metal.

He then wipes down the entire
Camshaft with a dry rag.

He places the camshaft
On a perforated metal shelf

And floods it with oil.

Some oil drains away, but
A residue clings to the part,

And that residue
Will prevent rusting.

Once packaged,
This rotating shaft

Is on its way to a garage
Or car factory,

Where, ultimately,
It will do its part

To help set
The wheels in motion.

Narrator:
Bush planes are designed to fly
In and out of remote areas.

They're engineered
To be able to take off and land

On short runways.

They can also be outfitted
With floats

To be able to land on water

Or skis to land on snow.

Some are made of metal,

And others of tube
And fabric construction.

A bush plane starts out
As a design on paper.

This company handcrafts

Four-seater tube
And fabric models --

The tubes forming
The airplane's skeleton,

The fabric, its skin.

Welders construct a tubular
Frame for the fuselage,

The plane's main body.

The tubes are chromoly,
A type of steel

That contains chromium
And molybdenum,

Which makes it stronger
Than standard steel.

Machinists make the aluminum
Fuel-tank components...

And prepare the landing gear.

Here, they're threading
The axle for the tail wheel --

A small, rugged wheel
At the back,

Which helps steer the airplane
On the ground.

The landing gear consists
Of this tail wheel

And two bigger wheels
At the front.

They all have large
Low-pressure tires,

Which enable the plane to take
Off and land on rough terrain.

Workers spray aluminum pieces
Called ribs and spars

With anti-corrosion paint,
Then rivet them together

To build the internal structure
Of the wings.

Using a crimping tool, they make
Tiny indentations in the ribs

To perfect the alignment.

Then they rivet on a skin
Of aluminum panels,

About 1/50 of an inch thick
In most areas.

They construct the wing's
Hinged surface,

The flaps,
And ailerons the same way.

The factory's paint shop sprays
The wings, flaps, and ailerons

With highly durable
Urethane paint,

And the fuselage frame
With powder-coat paint,

Which is then baked on
For extra durability.

Now for the meticulous job
Of applying the fabric skin.

The material
Is heat-shrinkable polyester,

Commonly used
In the aircraft industry

Because it's thin, lightweight,
And exceptionally strong.

Workers brush an adhesive
Similar to contact cement

Onto the painted tubing,

Then adhere the fabric,

Working around the frame
Section by section.

Once the fuselage
Is completely covered,

They run a hot iron
Over the fabric.

This shrinks it taut
Around the framework.

After letting the adhesive dry
For a couple of hours,

They take strips of fabric,

Coat them with
A urethane-based adhesive,

And reinforce the seams.

It's the same construction
Process for the tail components.

At the front of the fuselage
Now, they install the pedals,

Which control both the brakes
And the rudder,

Which moves the tail
From right to left.

Then the cockpit
Instrument panel,

A thin sheet of aluminum
With laser-cut openings

For all
The flight instrumentation.

Next two linked control yokes.

They move a series of chains,

Which maneuver
Certain components

Such as the aileron
Control sprockets.

Mechanics ran the fuel lines

And most of the wiring
Within the fuselage frame

Prior to the fabric application.

Now they install
A stainless-steel fire wall

Between the cockpit
And the engine.

This seals the cockpit
From engine heat, noise,

And exhaust gases.

After installing the landing
Gear, brakes, and windshield,

Workers mount the engine
And exhaust system.

Next the plane's
Aluminum propeller.

Other workers are busy
Installing the fuel tanks

Inside the wings.

The fuselage now goes
To the paint shop.

When it comes back,
Workers bolt on the wings,

Supporting them from underneath
With steel wing struts.

The wings on a bush plane

Are positioned higher than those
On other types of aircraft

To give the pilot
Better ground visibility.

After rigging up
The flight controls

And installing the interior
Trim, workers install the doors,

Plexiglas windows,
And cockpit seating.

Each bush plane is inspected

At every stage
Of the production process.

When it's completed,

It undergoes a nose-to-tail
Final inspection.

And then a company pilot
Takes it out for a test flight.

Narrator: a serious cyclist
Won't pedal just any bike.

It's got to have wheels made of
Strong-yet-lightweight material

Such as carbon fiber
Or aluminum.

Advanced bicycle wheels
Have tubing and spokes,

Shaped as aerodynamically
As possible

To lower wind resistance.

These elite-level racing wheels
Are made of aluminum.

They're designed
To generate a smooth ride

With optimum responsiveness
To the rider's acceleration.

The starting material --

Long, straight tubes
Of extruded aluminum,

Preshaped
With a wheel-rim profile.

Workers load one extruded tube
At a time into a metal bender.

The machine coils the tube
Around and around,

Forming four connected rims.

After measuring
To ensure the diameter

Is exactly what it should be,

They mount the coil tube
Onto a cutter.

With a single downward slice,
It separates the four rims.

They fuse the cut ends later on.

First the rims need a bath
In a tank of acid.

The acid removes dust
And other contaminants

And etches the surface
Of the metal,

Both of which help ensure
Full adhesion

Of the anti-corrosion coating
They later apply.

Next a multiphase
Heat-treatment process.

This restructures
The aluminum molecules,

Making the metal harder
And stronger.

They join the two ends
Of the rim

By riveting on
An aluminum connector tab.

Then they weld the joint
To reinforce it.

Using a sharp,
Vibrating cutting tool,

A computer-guided machine
Smooths the weld line

Until it's nearly invisible.

This makes the rim
Appear seamless.

Now for that
Anti-corrosion coating.

The process
Is called anodization.

In a tank,
They plate the aluminum

With a protective chemical,

Using an electrical charge

To draw the coating particles
Onto the rim surface.

For this model,
The anodized coating is black.

However,
There are several color choices.

Next a computer-guided machine

Shaves off a minute amount
Of anodized metal

From nearly a third
Of the rim surface.

This creates a smooth,
Perfectly flat area

For the brake pads to grip.

The next computer-guided machine

Drills holes
For the tiny aluminum nipples,

Which hold the aluminum spokes
To the rim.

Now it's time
To assemble the wheel --

A manual task entrusted to
Specialized bicycle technicians,

As it requires
A level of craftsmanship

No machine can perform.

The first technician
Inserts a spoke into each slot

Of a carbon-fiber-and-aluminum
Flange --

Part of the hub
At the center of the wheel.

Once every spoke
Is in its respective spoke seat,

As it's called,

He sandwiches them
With a locking ring.

Now for the rim end
Of the spokes.

The next technician
Places a small steel plug

Inside a spoke nipple
To make it magnetic.

Then she puts the nipple
Into the rim,

And, using a magnet,
Draws it to a spoke hole,

Then through the hole
Toward the inside of the wheel.

Then she removes the steel plug

And inserts the free end
Of a spoke into the nipple.

She repeats the procedure
For each spoke hole.

This is known
As lacing the wheel.

The next technician
Holds each spoke steady

While tightening its nipple
With a spoke wrench.

Tightening the nipple
Straightens the spoke.

The process of perfectly
Aligning the wheel

By straightening every spoke
Is called trueing the wheel.

This gauge tells him
When the wheel is finally trued.

For quality-control assurance,

This robotic machine
Inspects each spoke

And makes any necessary
Tensioning adjustments.

Depending on the model,
A high-end bicycle wheel

Can have anywhere
From 10 to 46 spokes.

Different spokes
For different folks.

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