All language subtitles for S23E04 - Railway Bridge Ties; Membrane Filters; Hydraulic Post Drivers; Bi-planes (1080p AMZN WEB-DL x265 Garshasp)_track4_[eng]1
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--captions by vitac--
Www.Vitac.Com
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00:00:04,620 --> 00:00:07,620
Captions paid for by
Discovery communications
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Narrator:
The deck of a railway bridge
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Is typically built of
Wood-timbers called bridge ties.
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They're bolted
To steel support beams
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00:01:02,000 --> 00:01:05,620
Located on concrete piers
Over the water or gully below.
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00:01:05,724 --> 00:01:07,517
The rails
On which the train travels
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Are bolted to the wooden ties.
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00:01:09,482 --> 00:01:11,448
Wood absorbs the noise
And vibration
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Of the passing train.
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00:01:16,068 --> 00:01:17,965
The load
The railway bridge will carry
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Determines the size of its ties.
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00:01:20,275 --> 00:01:21,896
To calculate the load,
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Engineers factor in
The number of tracks,
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Volume of traffic,
Weight of the transported cargo,
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00:01:28,379 --> 00:01:32,103
And whether the bridge
Is straight or curved.
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00:01:32,206 --> 00:01:36,034
A curve will put additional
Stress on the structure.
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The wood of choice is oak
Because it's hard and strong.
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When the logs
Arrive at the sawmill,
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They come face-to-face
With a menacing-looking device
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Called a debarker.
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A conveyor moves the shipment
Toward the debarker,
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00:01:52,482 --> 00:01:56,965
Then drops a single log in front
Of it onto spinning rollers.
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00:01:58,758 --> 00:02:01,758
The rollers rotate the log,
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00:02:01,862 --> 00:02:05,137
While the debarker makes its way
From one end to the other.
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00:02:05,241 --> 00:02:09,206
It chews off the bark
With its sharp-toothed blades.
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00:02:11,689 --> 00:02:14,931
What the debarker shaves
Off is put to good use.
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The bark gets processed
Into gardening mulch
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00:02:18,068 --> 00:02:20,758
And they burn the sawdust
In the wood-fired boiler
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00:02:20,862 --> 00:02:22,896
That runs another part
Of the plant.
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00:02:25,620 --> 00:02:28,931
Next, one log at a time
Drops into a mobile carriage
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00:02:29,034 --> 00:02:31,931
That runs it
Through a circular saw.
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00:02:32,034 --> 00:02:33,275
The carriage has sensors
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00:02:33,379 --> 00:02:35,620
Which detect
The log's extremities
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00:02:35,724 --> 00:02:36,931
And report its dimensions
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00:02:37,034 --> 00:02:40,586
To a console located
In the operator's cab.
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The operator
Interprets the data.
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00:02:43,103 --> 00:02:44,758
Using a joystick controller,
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00:02:44,862 --> 00:02:47,034
He flips the log
Into whichever position
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00:02:47,137 --> 00:02:49,000
Maximizes the yield.
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00:02:51,482 --> 00:02:52,724
The first few runs
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Trim off the rough surface
And square the shape.
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00:02:56,586 --> 00:02:58,448
The next runs cut boards,
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00:02:58,551 --> 00:03:01,344
Which the sawmill
Sells to flooring plants.
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This continues until the log
Is the exact dimensions
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Of the bridge tie.
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Again, nothing is wasted.
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00:03:09,724 --> 00:03:12,896
The sawmill processes
The cutoffs into wood chips,
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00:03:13,000 --> 00:03:15,896
Which it then sells to companies
That make particle board,
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00:03:16,000 --> 00:03:19,758
Strand board, and similar
Construction materials.
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00:03:21,827 --> 00:03:23,517
The sawmill stacks the ties
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For transfer
To the bridge mill next door.
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00:03:26,103 --> 00:03:29,482
The role of the bridge mill
Is to frame the bridge,
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00:03:29,586 --> 00:03:31,793
Also known as dapping.
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00:03:31,896 --> 00:03:34,827
That's the process
Of making the specific holes
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And notches in each tie
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For attaching it to the steel
Beam on which it will sit.
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00:03:42,655 --> 00:03:44,068
At the bridge mill,
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00:03:44,172 --> 00:03:48,275
The bridge layout supervisor
Processes one tie at a time.
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00:03:48,379 --> 00:03:51,000
He carefully reviews
The engineer's blueprints,
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00:03:51,103 --> 00:03:53,793
Which assign a number
To each and every tie.
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00:03:53,896 --> 00:03:58,413
These numbers specify precisely
Where the saw has to cut notches
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00:03:58,517 --> 00:04:01,344
And where the drill
Has to bore holes.
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00:04:01,448 --> 00:04:03,517
The locations of these notches
And holes vary,
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Depending on the tie's position
On the bridge.
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00:04:06,172 --> 00:04:09,482
So, he must follow
The blueprints meticulously.
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00:04:11,689 --> 00:04:13,896
After measuring
And marking it all out,
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00:04:14,000 --> 00:04:17,551
He sends the tie to the dap saw.
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00:04:17,655 --> 00:04:19,379
The operator sets up each cut,
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00:04:19,482 --> 00:04:21,206
Lining up the mark
With laser-lights,
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00:04:21,310 --> 00:04:23,413
Which indicate the location
And the cutting depth
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00:04:23,517 --> 00:04:24,965
Of the blade.
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00:04:38,827 --> 00:04:42,068
The notches are just the right
Size to fit over the steel beam
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00:04:42,172 --> 00:04:44,206
On which the tie will lie.
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00:04:45,827 --> 00:04:48,448
Next,
A worker using a drill press
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00:04:48,551 --> 00:04:51,172
Bores holes for hook bolts,
Which go through the tie
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To secure it
Onto the steel beams.
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Each tie receives a metal
Identification tag,
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Which includes the bridge
And tie numbers.
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00:05:03,655 --> 00:05:06,586
On each end,
Workers nail on a mesh plate,
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Made of rust-proof
Galvanized steel.
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The plate has teeth designed
To grasp and hold together
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The wood fiber to prevent
The end from splitting.
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00:05:16,551 --> 00:05:19,655
After nailing the id tag
To one of the end plates,
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00:05:19,758 --> 00:05:23,068
Workers force in both plates
With a press.
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00:05:27,827 --> 00:05:31,689
The tie's last stop
Is the adjacent treatment plant.
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They spend 24 hours
Inside a high-temperature,
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High-pressure chamber
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00:05:36,206 --> 00:05:40,000
Which penetrates them
With a creosote-borate solution.
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00:05:40,103 --> 00:05:43,103
This protects the wood
From rot and insect damage
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00:05:43,206 --> 00:05:44,965
And extends the tie's life-span
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00:05:45,068 --> 00:05:49,551
From about a decade
To at least 25 years.
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Narrator:
When filtering liquids,
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It's all about thinking small.
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Membrane filters can separate
The tiniest solids from fluids,
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00:06:09,413 --> 00:06:12,827
Which purifies the liquids
And recovers the solids.
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00:06:12,931 --> 00:06:15,137
Once separated,
The two substances
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00:06:15,241 --> 00:06:19,448
May then be reused
So that nothing goes to waste.
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00:06:23,724 --> 00:06:28,724
Membrane filters can turn murky
Water clear, almost magically.
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To demonstrate, a technician
Installs a spiral-wound membrane
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00:06:34,344 --> 00:06:36,517
In the housing
Of a pumping system,
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Which is a small-scale version
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00:06:38,068 --> 00:06:41,551
Of what you would see
In a factory.
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She turns on the tap,
And water flows into a tank.
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00:06:45,517 --> 00:06:49,172
She adds latex paint
To purposely sully the water.
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00:06:51,586 --> 00:06:53,655
The system pumps
The contaminated water
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00:06:53,758 --> 00:06:55,172
Through a strainer
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00:06:55,275 --> 00:07:00,379
And then the membrane filter
While meters measure the flow.
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00:07:00,482 --> 00:07:03,034
Within minutes, the paint
Has been filtered out,
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00:07:03,137 --> 00:07:05,275
And the water is clear.
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00:07:06,655 --> 00:07:11,241
The making of a membrane filter
Begins with polypropylene mesh.
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00:07:14,724 --> 00:07:18,965
An automated system unwinds
The mesh and cuts it to length.
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These mesh sheets
Will be used as spacers.
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They'll create gaps
For the liquid
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00:07:26,034 --> 00:07:29,000
To flow through the filter
And over the membrane.
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00:07:30,034 --> 00:07:33,275
Next, the system
Cuts sheets of polyester fabric.
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00:07:33,379 --> 00:07:34,827
These will form channels
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00:07:34,931 --> 00:07:37,793
Through which the filtered
Material will travel.
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00:07:37,896 --> 00:07:41,586
These sheets are known
As permeate spacers.
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00:07:41,689 --> 00:07:45,655
An employee stacks
The polyester fabric sheets.
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00:07:45,758 --> 00:07:47,896
Using high-frequency
Sound waves,
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00:07:48,000 --> 00:07:51,655
She welds one sheet to the next
At just one end.
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00:07:54,620 --> 00:07:58,103
She layers and welds
A total of 15 sheets,
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00:07:58,206 --> 00:08:00,137
And then applies
Double-sided tape.
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00:08:00,241 --> 00:08:03,413
The tape is for attaching
The packet to a central tube,
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00:08:03,517 --> 00:08:07,379
And it will also serve as
A guide to correctly align it.
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00:08:10,758 --> 00:08:14,482
Next, the membrane soup
Flows into a long trough.
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00:08:14,586 --> 00:08:18,827
It's a mix
Of melted plastics and solvents.
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00:08:18,931 --> 00:08:21,862
Paper backing unwinds
Into the trough
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00:08:21,965 --> 00:08:25,620
And is coated with the soup
On one side.
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00:08:25,724 --> 00:08:28,758
The coated paper then travels
Through two quench tanks,
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00:08:28,862 --> 00:08:31,344
And the plastic components
Solidify
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00:08:31,448 --> 00:08:33,689
As the solvents are drawn out.
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00:08:33,793 --> 00:08:36,689
The exiting solvents
Create a unique core structure
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00:08:36,793 --> 00:08:39,896
In the remaining
White plastic membrane.
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00:08:40,000 --> 00:08:42,620
The membrane now
Travels by a light box,
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00:08:42,724 --> 00:08:46,000
Which illuminates
Any visual defects.
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00:08:46,103 --> 00:08:50,551
An applicator also drips a
Preservative onto the membrane.
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00:08:50,655 --> 00:08:54,310
A team unrolls the membrane
Onto a work table.
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00:08:56,620 --> 00:08:58,965
They lay a sheet
Of the polypropylene mesh,
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00:08:59,068 --> 00:09:02,862
Which we saw cut to size
Earlier, on the membrane.
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00:09:05,551 --> 00:09:07,862
The employee
Then cuts the membrane
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00:09:07,965 --> 00:09:10,586
To twice the length of the mesh.
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00:09:10,689 --> 00:09:12,551
They fold the membrane
Over the mesh,
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00:09:12,655 --> 00:09:14,931
Creating a membrane envelope.
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00:09:15,034 --> 00:09:17,000
The mesh serves as a pathway
For fluid
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00:09:17,103 --> 00:09:19,655
To flow between the membranes.
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00:09:22,724 --> 00:09:24,206
Meanwhile, another worker
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00:09:24,310 --> 00:09:27,896
Applies epoxy
To perforated plastic tube.
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00:09:28,000 --> 00:09:30,206
He attaches
The permeate spacers to it
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00:09:30,310 --> 00:09:31,793
With the double-sided tape,
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00:09:31,896 --> 00:09:35,724
Giving the epoxy time to cure
For a permanent seal.
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00:09:37,586 --> 00:09:39,758
He and a colleague
Apply more epoxy
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00:09:39,862 --> 00:09:43,103
To the perimeter
Of the bottom sheet.
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00:09:43,206 --> 00:09:45,068
They transfer
The membrane envelope to it
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00:09:45,172 --> 00:09:46,896
And continue to layer,
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00:09:47,000 --> 00:09:50,034
Making a permeate fabric
And membrane sandwich.
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The worker then winds
The glued layers snuggly
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00:09:56,068 --> 00:09:58,103
To a perforated plastic core,
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00:09:58,206 --> 00:10:00,931
Forming
The spiral membrane filter.
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00:10:02,724 --> 00:10:06,344
He tapes the multi-layered wad
From one end to the other.
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00:10:06,448 --> 00:10:08,517
The tape holds everything
Tightly in place
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00:10:08,620 --> 00:10:11,241
As the epoxy cures overnight.
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00:10:12,758 --> 00:10:15,034
They leave the tape
On after the cure,
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00:10:15,137 --> 00:10:17,862
And a machine winds
Epoxy-drenched fiberglass rope
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00:10:17,965 --> 00:10:20,000
Around the entire filter.
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00:10:20,103 --> 00:10:23,068
As the epoxy cures,
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00:10:23,172 --> 00:10:27,724
The rope will form a hard shell
Around the membrane filter.
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00:10:27,827 --> 00:10:29,206
Partway through,
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They apply the label
With a company name.
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00:10:35,206 --> 00:10:40,551
The operator captures the glue
Runoff during the wind.
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00:10:40,655 --> 00:10:43,517
And it's a wrap,
So he cuts the rope.
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00:10:45,758 --> 00:10:47,655
From the side,
You can see the flow channels
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Between the layers.
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Concentrated contaminants will
Travel through them and out.
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The filtered liquid will seep
Into the core and exit,
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00:10:57,103 --> 00:10:59,275
Clearly improved.
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Narrator: the invention
Of the hydraulic post driver
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00:11:12,793 --> 00:11:14,310
In the 1960s
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00:11:14,413 --> 00:11:17,241
Allowed workers to drop
Their shovels and sledgehammers
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00:11:17,344 --> 00:11:20,344
And let a machine do the job
Of pounding fence and sign posts
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Into the ground.
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00:11:21,931 --> 00:11:24,413
When it comes
To labor-saving inventions,
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00:11:24,517 --> 00:11:27,827
This one is definitely
A striking example.
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00:11:31,413 --> 00:11:33,241
The post driver
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00:11:33,344 --> 00:11:36,965
Raises hefty fence
Or sign posts into position,
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00:11:37,068 --> 00:11:40,413
And then slams them
Into the ground.
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00:11:43,862 --> 00:11:47,448
Inside a vertical case,
A hydraulic system
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00:11:47,551 --> 00:11:50,172
Drops a 300-pound weight
To drive the post,
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00:11:50,275 --> 00:11:52,206
And then lifts it
For another hit.
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00:11:56,000 --> 00:11:59,241
This machine does the work
Of two or more brawny humans
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00:11:59,344 --> 00:12:03,379
With just one person
At the controls.
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00:12:03,482 --> 00:12:06,827
To make it, they start with
A vertical case for the weight.
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00:12:06,931 --> 00:12:08,862
A high-precision plasma torch
195
00:12:08,965 --> 00:12:11,206
Cuts steel
Into a rectangular shape
196
00:12:11,310 --> 00:12:13,724
And makes holes for components.
197
00:12:15,103 --> 00:12:19,034
They insert the rectangle
Into a break-press repeatedly
198
00:12:19,137 --> 00:12:21,379
To bend it
Into a three-sided part.
199
00:12:21,482 --> 00:12:23,517
The profile includes flanges
200
00:12:23,620 --> 00:12:27,103
For welding it
To the back wall of the case.
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00:12:29,068 --> 00:12:31,000
He fits the part
To the back wall
202
00:12:31,103 --> 00:12:34,965
And welds them together,
Completing the post driver case.
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00:12:38,896 --> 00:12:41,758
An employee builds
The post driver weight
204
00:12:41,862 --> 00:12:43,965
Working within a weld fixture.
205
00:12:45,758 --> 00:12:49,965
It's a box-shaped weight,
And he welds it at the seams.
206
00:12:51,896 --> 00:12:53,931
He taps the corners
Between the welds
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00:12:54,034 --> 00:12:56,827
To maintain
A tight configuration.
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00:12:58,034 --> 00:13:02,000
This 300-pound weight can later
Be filled with steel shot
209
00:13:02,103 --> 00:13:06,068
To make it even heavier
For greater impact.
210
00:13:06,172 --> 00:13:09,344
The next worker assembles
Yellow steel jaws to a hub
211
00:13:09,448 --> 00:13:11,448
To produce the grapple.
212
00:13:11,551 --> 00:13:14,379
This is the part
That grips the fence post
213
00:13:14,482 --> 00:13:16,413
And raises it into position.
214
00:13:19,068 --> 00:13:21,448
He sticks a danger label
Onto the hub
215
00:13:21,551 --> 00:13:25,275
To warn people to stay clear
Of these powerful jaws.
216
00:13:27,000 --> 00:13:29,241
He attaches
A hydraulic cylinder,
217
00:13:29,344 --> 00:13:32,551
Which will make
The jaws open and close.
218
00:13:34,068 --> 00:13:37,344
He connects the cylinder
To the grapple jaw.
219
00:13:40,034 --> 00:13:41,793
Next,
They move on to the metal plate
220
00:13:41,896 --> 00:13:44,724
That will be used to mount
The post driver to a vehicle,
221
00:13:44,827 --> 00:13:47,551
Like a skid-steer loader.
222
00:13:47,655 --> 00:13:49,586
It includes
A hydraulic mechanism
223
00:13:49,689 --> 00:13:52,413
For tilting the fence post
Left or right.
224
00:13:56,103 --> 00:13:59,068
The employee installs a control
Valve next to the cylinder
225
00:13:59,172 --> 00:14:02,620
And links the two with hoses.
226
00:14:02,724 --> 00:14:04,034
He'll also connect the grapple
227
00:14:04,137 --> 00:14:06,689
And weight hydraulics
To this valve.
228
00:14:14,413 --> 00:14:17,586
Back to the post driver case
Now -- it's been painted,
229
00:14:17,689 --> 00:14:20,206
And they're ready to install
The hydraulic motor.
230
00:14:20,310 --> 00:14:22,793
The worker connects it
To the sprockets and chains
231
00:14:22,896 --> 00:14:25,034
That will lift the weight.
232
00:14:25,137 --> 00:14:26,862
He pins the sprockets into place
233
00:14:26,965 --> 00:14:30,827
And installs tensioning rods
On either side.
234
00:14:33,482 --> 00:14:36,896
Next, a cover plate
Protects the sprockets.
235
00:14:37,000 --> 00:14:39,965
The tensioning rods
Protrude through it.
236
00:14:41,103 --> 00:14:44,793
He slides springs
Onto those tensioning rods
237
00:14:44,896 --> 00:14:48,000
And compresses the springs
To maintain the tension.
238
00:14:51,068 --> 00:14:54,896
He now attaches the grapple
To the post driver case.
239
00:14:57,241 --> 00:14:59,896
He locks it into place
With a long pin.
240
00:15:04,965 --> 00:15:08,068
He links the grapple hydraulics
To the control valve.
241
00:15:08,172 --> 00:15:10,344
And it's ready to grab
Big fence posts
242
00:15:10,448 --> 00:15:12,758
And hold on tight.
243
00:15:16,172 --> 00:15:21,068
They attach the metal mounting
Plate to the post driver case.
244
00:15:21,172 --> 00:15:23,724
The work table tilts back
To move the post driver
245
00:15:23,827 --> 00:15:26,068
Into an upright position.
246
00:15:28,137 --> 00:15:29,482
With the help of a crane,
247
00:15:29,586 --> 00:15:32,275
The next worker
Moves the weight into position
248
00:15:32,379 --> 00:15:34,758
And lowers it into the case.
249
00:15:42,379 --> 00:15:44,034
He slides a pin into the top end
250
00:15:44,137 --> 00:15:45,793
To keep the weight
From falling out
251
00:15:45,896 --> 00:15:48,413
When the post driver
Is on an angle.
252
00:15:53,655 --> 00:15:55,206
One day in the making,
253
00:15:55,310 --> 00:15:59,620
This hydraulic post driver is
Ready for years of heavy labor,
254
00:15:59,724 --> 00:16:05,000
Taking over for humans so they
Don't have to move a muscle.
255
00:16:17,827 --> 00:16:19,620
Narrator: a biplane
Is a vintage-style aircraft
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00:16:19,724 --> 00:16:22,758
With two pairs of wings
Sitting one above the other.
257
00:16:22,862 --> 00:16:26,034
The top wings are typically
Raised above the fuselage
258
00:16:26,137 --> 00:16:29,275
With vertical struts bracing
Them to the bottom wings.
259
00:16:29,379 --> 00:16:32,172
Dating back to the earliest days
Of aviation,
260
00:16:32,275 --> 00:16:35,931
They're still popular
For performing aerobatics.
261
00:16:36,034 --> 00:16:39,413
A biplane's lower wings
Have ailerons,
262
00:16:39,517 --> 00:16:42,793
Which bank the airplane
To the right or left.
263
00:16:42,896 --> 00:16:44,068
On the plane's tail,
264
00:16:44,172 --> 00:16:47,275
Elevators pitch the plane's nose
Up or down
265
00:16:47,379 --> 00:16:50,068
While a rudder steers it
Left or right.
266
00:16:50,172 --> 00:16:53,448
A propeller
Provides the propulsion.
267
00:16:53,551 --> 00:16:56,551
The plane has four wings.
268
00:16:56,655 --> 00:16:58,758
Each wing has two spars,
269
00:16:58,862 --> 00:17:00,965
Wooden beams
At the front and rear,
270
00:17:01,068 --> 00:17:03,034
Which form
The perimeter structure.
271
00:17:03,137 --> 00:17:07,862
A craftsman skillfully fashions
These spars out of sitka spruce.
272
00:17:07,965 --> 00:17:11,482
This wood is exceedingly light,
Yet exceptionally strong,
273
00:17:11,586 --> 00:17:13,344
Making it one
Of only a few woods
274
00:17:13,448 --> 00:17:17,551
Approved for structural use
In airplanes.
275
00:17:17,655 --> 00:17:19,965
After sawing the wood
To the spar's shape,
276
00:17:20,068 --> 00:17:22,931
He mounts attachment plates
Made of sitka spruce
277
00:17:23,034 --> 00:17:24,862
And mahogany plywood.
278
00:17:24,965 --> 00:17:26,448
These are the end struts,
279
00:17:26,551 --> 00:17:28,827
Steel vertical bars
Which will connect the upper
280
00:17:28,931 --> 00:17:31,068
And lower wings.
281
00:17:31,172 --> 00:17:34,379
He finishes the spar
By refining its contour,
282
00:17:34,482 --> 00:17:39,172
First with a hand plane,
Then an electric plane.
283
00:17:39,275 --> 00:17:41,379
Using strips of sitka spruce,
284
00:17:41,482 --> 00:17:45,344
He constructs 15 structural ribs
For each wing.
285
00:17:45,448 --> 00:17:47,344
He begins with long strips,
286
00:17:47,448 --> 00:17:51,275
Which have been soaking in water
For a week to make them pliable.
287
00:17:51,379 --> 00:17:54,034
He inserts one end
Into a curved fixture
288
00:17:54,137 --> 00:17:56,931
And leaves the strips to dry.
289
00:17:57,034 --> 00:17:59,448
When he removes them a couple
Of days later,
290
00:17:59,551 --> 00:18:02,068
They have a permanent
Aerodynamic curve.
291
00:18:02,172 --> 00:18:04,137
He glues
Two curved strips together
292
00:18:04,241 --> 00:18:06,103
To form the perimeter
Of one rib.
293
00:18:06,206 --> 00:18:11,413
In between, he glues short
Diagonal strips called trusses.
294
00:18:11,517 --> 00:18:14,344
He reinforces both sides
Of each intersection
295
00:18:14,448 --> 00:18:18,206
With a rectangular piece
Called a gusset.
296
00:18:18,310 --> 00:18:20,586
An assembler mounts the 15 ribs
Crosswise
297
00:18:20,689 --> 00:18:23,103
On the front and rear
Wing spars,
298
00:18:23,206 --> 00:18:27,931
Then installs three aluminum
Tubes called compression ribs.
299
00:18:28,034 --> 00:18:30,655
These absorb air load
Hitting the spars,
300
00:18:30,758 --> 00:18:34,034
Keeping the wooden ribs
From flexing under pressure.
301
00:18:34,137 --> 00:18:36,172
The craftsman
Connects the compression ribs
302
00:18:36,275 --> 00:18:38,655
With criss-crossing metal rods.
303
00:18:40,344 --> 00:18:45,241
After applying more glue
To critical areas,
304
00:18:45,344 --> 00:18:46,896
He nails an aluminum trim
305
00:18:47,000 --> 00:18:50,448
Over the front spar
And nose of the ribs.
306
00:18:50,551 --> 00:18:52,862
This is called the leading edge.
307
00:18:52,965 --> 00:18:56,241
It's the first part of the wing
To hit the wind,
308
00:18:56,344 --> 00:18:58,448
So it takes the brunt
Of the air load.
309
00:19:00,310 --> 00:19:04,379
Finally, he laces reinforcement
Tape through the ribs
310
00:19:04,482 --> 00:19:06,862
In an x pattern.
311
00:19:06,965 --> 00:19:10,482
The completed structure now
Moves to the covering department
312
00:19:10,586 --> 00:19:11,931
Where technicians drape it
313
00:19:12,034 --> 00:19:14,931
In heat shrinkable
Polyester fabric.
314
00:19:15,034 --> 00:19:18,551
They cut the fabric to size,
Glue it to the wing perimeter,
315
00:19:18,655 --> 00:19:20,137
And heat the surface
With an iron
316
00:19:20,241 --> 00:19:22,862
To shrink the fabric
Until it's taut.
317
00:19:22,965 --> 00:19:26,793
Then, they stitch over the glued
Areas with polyester cord.
318
00:19:26,896 --> 00:19:28,931
They brush on a chemical
Which seals the pores
319
00:19:29,034 --> 00:19:30,586
Of the fabric.
320
00:19:30,689 --> 00:19:33,448
This primes the surface
To receive a spray coat
321
00:19:33,551 --> 00:19:35,103
Of polyurethane paint,
322
00:19:35,206 --> 00:19:38,724
Which is a special formulation
Designed for aircraft bodies.
323
00:19:41,172 --> 00:19:43,620
Technicians construct
The fuselage frame
324
00:19:43,724 --> 00:19:47,206
Out of high-strength
Steel alloy tubes.
325
00:19:47,310 --> 00:19:50,758
They use an electric torch to
Slightly melt adjoining pieces
326
00:19:50,862 --> 00:19:53,517
So they fuse to each other.
327
00:19:53,620 --> 00:19:56,517
Because there's no filler metal
Bonding the pieces,
328
00:19:56,620 --> 00:19:59,379
The welds don't add any weight
To the structure.
329
00:20:02,172 --> 00:20:03,620
After painting the frame,
330
00:20:03,724 --> 00:20:07,586
Technicians install aluminum
Floor panels and bulkheads.
331
00:20:07,689 --> 00:20:09,931
In the tail, they add
Lighter weight bulkheads
332
00:20:10,034 --> 00:20:14,206
Made of mahogany plywood
And sitka spruce.
333
00:20:14,310 --> 00:20:15,862
Then it's time
To bolt the engine
334
00:20:15,965 --> 00:20:18,586
To the front
Of the fuselage frame.
335
00:20:24,413 --> 00:20:26,275
The engine drives a propeller
336
00:20:26,379 --> 00:20:30,068
Made of either wood, aluminum,
Or a composite material.
337
00:20:30,172 --> 00:20:33,793
Painted aluminum body panels
Cover the frame.
338
00:20:33,896 --> 00:20:35,517
Technicians
Install the fuel tank
339
00:20:35,620 --> 00:20:38,793
Between the front cockpit
And the engine.
340
00:20:38,896 --> 00:20:42,448
Then they bolt the wings
To the fuselage.
341
00:20:42,551 --> 00:20:44,931
Vertical steel struts
Connect and reinforce
342
00:20:45,034 --> 00:20:46,793
The two levels of wings
343
00:20:46,896 --> 00:20:49,793
Bolting to those attachment
Plates on the wing spars.
344
00:20:51,793 --> 00:20:55,241
Next, technicians mount
The painted aluminum ailerons,
345
00:20:55,344 --> 00:20:57,482
The tail,
With its elevators and rudder
346
00:20:57,586 --> 00:21:00,000
Made of painted fabric
Over welded steel,
347
00:21:00,103 --> 00:21:02,034
And then the engine cover.
348
00:21:02,137 --> 00:21:04,379
They install a windscreen
349
00:21:04,482 --> 00:21:06,793
And instrument panel
For each cockpit.
350
00:21:06,896 --> 00:21:10,482
The front screen can be replaced
With a cockpit cover
351
00:21:10,586 --> 00:21:14,448
To keep the pilots warm
When flying in cold weather.
28445
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