- [Jared] Elizabeth Tower, also known as Big Ben,
is the famous clock tower that's located in London, England.
In this video, I want to show you inside of the tower.
We'll look at the different levels, the five bells inside,
and, of course, the mechanism that runs it all.
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When the tower was first built,
it was known as the Clock Tower.
But in 2012, it was officially renamed
to the Elizabeth tower.
The name Big Ben actually refers
to the largest bell inside of it.
However, even to this day,
many people still refer to the entire tower as Big Ben.
Let's come over to Europe.
This is England.
Big Ben is right here in the city of London.
The tower is actually part of a larger structure.
This is called the Palace of Westminster.
This is where the British parliament
assembles to help run the government.
The palace is right along the banks of the River Thames.
This is Westminster Bridge,
and across the river is the famous
London Eye observation wheel.
We're actually not too far away from Buckingham Palace.
This way, the Queen can actually see
the Clock Tower from her residence.
The tower was built in the 1840s and '50s,
and it took more than 10 years to complete.
It was finally completed in 1859.
However, there were some problems with the bells
and it wasn't until 1862 that the clock
was fully functional and the bells
could be heard throughout the surrounding area.
The clock was built to be accurate within two seconds,
which is difficult considering that these hands
are more than four meters long
and completely exposed to the outside weather.
A tower clock like this had never been built before.
It was the first of its kind.
For over 150 years, Big Ben has been ticking almost nonstop.
It has survived two world wars
and has come to be very well known worldwide.
When you see this Clock Tower,
you immediately know that you are in London, England.
Look at the tower from only one side and it's easy to forget
that it actually has four clock faces,
making it visible in any direction.
The tower is 12 meters wide
and 96 meters tall.
At the time the tower was built,
it was one of the largest clock towers in the world,
but that has been surpassed many times over.
By comparison, the largest clock tower now
is the Abraj Al Bait in Saudi Arabia.
The clock dials are also much different in size.
For the last 150 years,
the only way to climb up the Clock Tower
is to use the spiral stairs.
There are 334 steps to get to the top.
However, they are currently installing
an elevator into one of the open shafts.
It'll be used for maintenance and security purposes.
Just a little too small for regular use,
but at least there's another option,
but right now, let's focus on the stairs.
There is a door here towards the outside wall.
This leads to an enclosed walkway
that goes behind each of the four clock faces.
There's not a lot of space in here.
This is the size of a person,
so you can get an idea for the scale.
There are light bulbs that turn on at night
to illuminate each clock face.
They used to be lit by gas instead of electricity.
Go up the stairs a little farther
and you'll get to another door.
This is the Clock Room.
It holds the mechanism that runs the clock.
We'll take a closer look at this later in the video.
Go up the spiral stairs even more
and you'll get to the Belfry,
which is the room with all of the bells.
There are five of them.
A large one in the center is officially named Big Ben.
The four outside bells are called Quarter Bells.
You'll notice that all of the bells are different sizes.
When the hammer hits the side bell,
it produces a music note,
(bells dings)
and the size of the bell determines
what note the bell will play.
Every 15 minutes, the Quarter Bells
play part of what's known as the Westminster Chimes.
(bells dinging)
Then, once every hour, these Quarter Bells
are followed by the hammer strike
on the largest bell, Big Ben.
(bell dings)
The number of strikes indicates what hour it is.
For example, at three o'clock,
it will strike the bell three times.
(bell dings)
And, of course, there's even more stairs here.
You can go above the Belfry
and see the bells from above.
The Belfry, however, is not the highest place.
You can take these spiral stairs all the way to the top.
This is called the Ayrton Light.
This light will be on when members of parliament
are meeting down below in the palace.
Let's take a closer look at the mechanism
down below in the Clock Room.
This is known as the Clock Movement,
which means the mechanical piece that makes the clock work.
It runs off of gravity,
and I'll show you what I mean by that in just a minute.
This type of clock is sometimes called a turret clock.
On a smaller scale, it's called a pendulum clock.
You might find versions of these
in an antique store or even in your own house.
If it has a pendulum that swings back and forth,
then it works very similar to this clock tower.
On the mechanism, there are three sections called trains.
When I say the word train,
I'm referring to gear trains,
or groups of gears that are linked together.
So on the mechanism, we have the Striking Train,
the Going Train and the Chiming Train.
These all have very specific responsibilities.
The Going Train is in the center.
This is responsible for turning the hands
of each of the four dials.
The Chiming Train is on the right.
This is responsible for the ringing
of the four Quarter Bells every 15 minutes.
The Striking Train is on the left side.
Every hour, this is responsible for ringing Big Ben,
the large bell in the very center.
Each of the three trains are driven by weight.
There are three of them in the shaft directly below.
Let's focus on the Going Train in the center.
This is the one that turns the hands on the clock.
The gears are only allowed to spin at a precise speed.
This speed is controlled by the pendulum,
the piece that slowly swings back and forth.
It takes a full two seconds to swing across.
Then you have what's called the Escapement.
There's three parts here.
You've already seen the pendulum.
Then there's the two Gravity Arms and the Escape Wheel.
Let's focus in on just the Escape Wheel.
With nothing to stop it, it will spin uncontrollably
due to the weight down below.
The two Gravity Arms will block
the Escape Wheel from spinning.
But if you push one of the arms,
it frees the wheel to spin just a little
before getting caught again on the other side.
Now push the other arm,
and the same thing happens on this side.
If we switch back and forth,
the wheel will spin at a controlled rate.
This is where the pendulum comes into play.
Each time it goes back and forth,
it spins the Escape Wheel a precise amount.
The Escape Wheel is what makes
that familiar ticking sound of the clock.
(clock ticking)
Right in front is three-legged fly fan
which catches air to help slow the rotation.
This rotation travels through the gears,
up this rotating slanted shaft,
and then these gears on top, which are called bevel gears.
They split the motion into four separate directions,
out to each dial to move the clock hands.
So this is the Going Train,
which is basically responsible for keeping the time.
Now let's go to the Chiming Train.
Every 15 minutes, the Chiming Train is set into motion.
You'll notice there are several cables attached here.
These control the hammers on the four Quarter Bells.
The cables run all the way through the ceiling.
There's a smaller room up above called the Link Room.
These cables go up and connect directly to the hammers
above the Quarter Bells.
Watch what happens when you pull on one of these cables.
It moves the levers, which pulls another cable,
which then lifts the hammer up.
When you release the cable, it strikes the bell.
(bell dings)
Each cable is attached to a lever down below,
and these levers go right up next to the gear,
and you'll notice that these gear teeth
are arranged in an interesting pattern.
Once the gear is spinning,
these levers are pulled in just the right order
and timing to create the Westminster Chimes.
(bell dinging)
The chiming of these bells happens once every 15 minutes.
There are five cables here, but only four Quarter Bells.
This is because one of the bells
actually has two hammers on it.
This note needs to be played twice
without a lot of time in between.
And finally, let's look at the Striking Train.
Once every hour, the Striking Train is set into motion.
This has only one cable that runs straight up,
goes through the Link Room,
and then connects to the hammer above Big Ben.
It works very similar to the Chiming Train,
but this time, we're only ringing one bell.
(bell dinging)
It must be timed precisely
so the first strike happens exactly on the hour.
This bell initially cracked
when it was first put into use in 1859.
It is said that the hammer they used was too heavy.
But instead of replacing the bell,
they drilled holes in the top
and bottom of the crack to stop it from spreading.
Then they turned the bell 90 degrees
and used a slightly smaller hammer.
This same bell is still in use today.
The small crack is what gives it the unique sound you hear.
Above here, you'll see the two fly fans.
They work similar to the three-legged fly fan
we saw earlier.
They act as air brakes to control
how fast the ringing of the bells happen.
Now, as the clock ticks,
the center weight will get lower and lower.
Then as the bells ring,
the outer weights will get lower and lower.
Three times a week, the clock must be wound up.
This was all initially done by hand,
but nowadays, we have an electric motor.
This winds up the two outside weights
which are the heaviest.
But the weight in the center for the Going Train,
this is still wound up by hand.
Once the weights are wound up,
the clock is once again run completely by gravity.
There's no electricity needed
to keep the clock hands moving.
The clock movement is very reliable at keeping the time,
but occasionally, it will drift off.
Changes in the temperature or weather
can cause the pendulum on the clock
to swing too fast or too slow.
To speed it up just a little bit,
they will add one or more pennies
to the top of the pendulum.
To slow it down, they will remove pennies.
Each penny affects the speed of the clock
by two-fifths of a second in a 24-hour period.
In 2017, the Elizabeth Tower started major renovations.
They built scaffolding up the entire tower
to gain better access.
They are repairing and replacing the stone
and metalwork to ensure the future of the tower.
They are also restoring the original colors.
The clock face will once again be a vibrant blue.
The renovation work on the tower
is set to complete in the summer of 2022.
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My name's Jared.
I create 3D animations to show and explain how things work.
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