Original subtitles

As a boy, I loved playing with these -

but today I'm more interested in these.

They are diggers!

They're the backbone of the construction industry.

Building houses, bridges, schools and roads!

So, I've got special access to a factory that builds

the ultimate big kid's toy.

It's a mind-blowing feat of engineering.

Every week in this massive factory,

specialist teams get through 650 tonnes of steel,

170,000 bolts,

5,000 litres of paint,

and 236 miles of wiring

to make these iconic diggers.

I'm Gregg Wallace...

He's like a spaceman on Bonfire Night!

..and I'll be digging deep...

HEAVY CRASH

Sorry.

..to find out how advanced engineering...

Oh, mate, that's brilliant!

..and the skill of specialist teams come together

to construct one of these 8.5 ton beauties.

That's a flying digger!

I'm Cherry Healey...

Looks like something out of Star Wars.

..and I'm learning how machines like this are helping to build

hundreds of miles of road every year.

And, historian Ruth Goodman...

Now, this is massive engineering, isn't it?

..is uplifted by the history of hydraulics.

So, this is absolutely perfect when you need a LOT of power.

This place makes up to 100 of these huge machines every day.

That is some super-sized production line!

Welcome to Inside The Factory XL.

This is the JCB factory in Rocester, Staffordshire.

They've been making diggers here since 1950.

This giant factory, covering 60,000 square metres,

is a cathedral to construction,

where cutting edge technology...

..and a super skilled workforce...

..keep this astonishing production line rolling -

taking just 45 hours to make one of these amazing machines from scratch.

Today, we are following the production of their most

well-known model, the backhoe loader.

So-called because it's got a loader shovel at the front

and a hoe arm for digging at the back.

Production begins with a delivery of some very heavy metal...

..at one of the factory's vast intake bays.

This 12-metre long lorry is carrying steel sheets

ready to be transformed into a digger.

I'm meeting manager Lee Elliot.

Lee. Gregg.

Delivery? Delivery, yes.

This is the start of the process for our excavator.

What's on there, then?

There is 8mm steel.

The steel sheets measure 4m x 2m

and weigh half a ton each.

This is just one of the five steel deliveries arriving here every day,

bringing in 30,000 tonnes of metal a year.

Is it all right to touch it? Yes.

That, to me, just says industry.

That is heavy-duty, isn't it?

Are there different types of steel?

Yes, this is mild steel, Gregg.

Why do you use mild steel?

It's easier to cut, it's easier to bend, it's easier to weld.

Steel is made from iron, mixed with carbon for strength.

The more carbon in the steel, the harder and brittler it is.

Mild steel, like this, contains less than 0.25% carbon,

making it the perfect metal for shaping into parts for the digger.

Is this steel for the whole of your digger?

This steel is for making the back end boom.

What, the arm? It's the rear digging application of the machine.

Shall we get this off? Yes.

Come on!

The most important part of any digger...

..is the arm at the back that actually does the digging.

It's called the excavator end,

and requires 626kg of steel sheets.

There are three main parts -

the bucket,

the dipper,

and the boom -

which use state-of-the-art hydraulics

to raise and lower their loads.

We're kicking off this monster build by constructing the boom.

It starts life in this cavernous hall,

known as fabrication.

Oh, Lee, I like this.

This is proper old school.

This is the heart of the factory, Gregg.

There's a little spark of welding going up.

I love this.

But there's nothing old school about the first stage,

as our steel is loaded into a 12-metre long laser cutter.

Can I go and have a look? Yes, certainly.

Whoa. What's it doing, is it cutting the steel?

This is a 12-kilowatt laser cutting through the 8mm steel

we've just seen outside being unloaded, Gregg.

It's like James Bond.

Why do you use a laser?

Precise cutting, Gregg, and it gives us no sharp edges.

Inside the safety chamber, a 12-kilowatt laser beam is focused

to a precise point on the steel plate,

heating it to 900 degrees Celsius...

..cutting clean through.

How many of those bits are going to end up on our boom, or our arm?

There will be two, a left hand and a right hand.

To minimise wastage, a computer controls the laser's movements,

so it can cut the side plates for four and a half diggers

from one half-ton sheet of steel.

How long does that take to cut out the shape we want? Nine minutes.

How long would it take a human to do? Hours.

Shouldn't Dr No be on the other side with Oddjob?

Fascinating. It is.

Absolutely fascinating.

A three-ton forklift carries the boom's steel side pieces

to the next stage of production...

..where they pass through a super-sized hydraulic press

that crashes down with the weight of 40 African elephants.

It forms a recessed lip on the plates to help slot them together,

along with holes to secure powerful hydraulic rams

which will act as the machine's muscles.

We're well on our way to making our rear digging arm.

It will eventually be controlled by hydraulics,

which will enable the driver to dig accurate holes with ease.

Ruth is delving into the surprising history of hydraulics.

Hydraulics are everywhere.

They power the brakes on our vehicles,

enable aeroplanes to fly,

and operate enormous cranes, like this...

..in ports across the globe.

And the architect of these marvels?

A lawyer from Newcastle upon Tyne.

So I'm heading up the River Tyne

and meeting historian Henrietta Heald to learn more

about this game-changing invention.

Hello, Henrietta. Hello, Ruth.

So, I mean, everybody's heard of hydraulics,

but where exactly does it begin?

It begins here on the Newcastle quayside.

William Armstrong built the first hydraulic machine.

He was born about a mile away from here,

and his father was a corn merchant with a business on the quayside,

so young William would have grown up seeing all the ships

coming in and out.

The now peaceful quayside was once a hive of activity,

with merchant ships exporting coal and importing products,

like cotton and tobacco, from across the Empire -

all of which needed moving around the docks.

The loading and unloading was a hugely laborious process,

and, in fact, most of it was done by hand.

Really physical work.

Yes, and very slow, of course.

Witnessing this arduous process first-hand,

a young Armstrong set about devising a mechanical alternative.

And, in 1845, he built the world's first hydraulic crane,

powered by pressurised water drawn from reservoirs high above the city.

I've got a copy of his original patent.

Well, this is very obviously a crane. Yes.

The water comes in, a piston is driven up,

and it's attached to the chain. Right.

So, by simply turning that stopcock,

you've lifted your load. Exactly.

No muscle power needed.

That's almost like magic. It is, it is.

The beauty of this ground-breaking invention was its simplicity.

This is a great model! Yes, isn't it fun?

So, the water comes in through the pipe at very high pressure,

transfers the force, and lifts... Straight up.

Whatever force you put in one end gets transferred to the other end.

Yes.

And because there's a lot of pressure going in,

there's a lot of force coming out,

so you can lift really big weights.

And letting the water out lowers the load.

Armstrong's hydraulic cranes revolutionised the movement

of cargo around the quayside.

Here is an illustration from the 1870s,

and you can see what a difference the cranes have made.

Here we have this great industrial image -

cranes all the way along.

Overnight, everything changed.

The cranes arrived at the perfect time.

The Industrial Revolution was raging, and in a push

to improve productivity, ports across the country

were desperate for hydraulics.

But there was a problem.

Armstrong's hydraulic machines required a constant supply

of pressurised water, something not available in most locations,

so he came up with yet another engineering masterstroke -

the accumulator.

Rather than rely on huge quantities of water,

this is replaced by a very heavy weight.

So, instead of a huge volume of water, we're talking about,

like, a little bit of water that's been really, really squished. Yes.

This was the key to hydraulic systems being used

all over the world.

Without the need for pressurised water, hydraulics were quickly

set to work in cities everywhere -

running power stations, and even railway turntables.

One of the best preserved examples of Armstrong's accumulator

can be found just a few hundred metres up the Tyne.

Opened in 1876, when fully operational

the Newcastle Swing Bridge uses this advanced innovation

to allow ships to pass up the river.

Look at this!

It's overseen by engineer Steven Porter.

Now, this is massive engineering, isn't it?

It certainly is.

So, can we get it running?

We certainly can.

OK, Ruth, I'm going to put the pump on. Right.

PUMP POWERS UP

And this really is the original accumulator?

Yes. Wow!

That has around about 60 tonnes on it. 60 tonnes?!

The accumulator weight is forced up above a cylinder

containing a thousand litres of water...

That's it.

..and when the weight is released, it pushes down,

powering the bridge's hydraulic engine.

So, I'm lifting the valve, which is allowing the water

to come from the accumulator.

And that's moving our engine.

Listen to that!

When in working order, it relies on the power of hydraulics

to sweep effortlessly open.

Due to the success of this extraordinary technology,

William Armstrong was asked to provide the hydraulic equipment

for the most famous bridge in the world - London's Tower Bridge.

And his designs form the basis of hydraulically-operated

engineering all over the world.

Today, little remains of Armstrong's 19th century quayside -

but his legacy can still be seen.

Just 500 metres away from Armstrong's Swing Bridge

is the Gateshead Millennium Bridge, an icon of the 21st century.

And how is it powered to let all those important ships through?

Well, hydraulically, of course.

Back at the digger factory, in Staffordshire...

..the first section under construction

is the hydraulically-powered boom.

It's one part of the one-ton digging arm known as the excavator end.

The two steel side sections of the boom have been cut

and shaped in a hydraulic press.

The next stop across this vast hall

is the 6,000-square metre welding department.

In charge is operations director Dave Parry.

OK, Gregg, so, what we have here is our boom tacking jig.

Are these are my bits?

So, these bits here are the two side plates.

This is where we take all the components that we've made,

we put all these clamps, hold the parts in the absolute

correct position, and then they're tack welded.

What's tack weld?

So, if you look inside here, you'll see lots of little blobs of weld,

and that is tack weld that are holding the pieces together.

So, you're just using a little bit of glue to stick it together?

Correct.

Tack welds are holding 19 of the 20 boom parts in place,

and the final piece of this 3D steel jigsaw is the top plate.

Why is he banging it with a hammer?

All of these components are very tight fit

to make sure that they go together correctly,

and then he's tack welding it to hold it there.

He's like a spaceman on Bonfire Night!

Blue line below, and then just loads of orange sparks.

The welding torch contains 1.2mm thick steel

and copper wire called weld wire.

There's heat and electricity going into that weld wire,

and that creates a pool of weld

which fuses those two parts together.

I'm loving this, because this digger is coming together before my eyes.

Once all 20 pieces are tack welded in position,

a robot welder takes over to put full length welds over the tacks.

It takes just an hour to fuse the boom together.

Holes are then bored for the thick steel pins,

which will eventually join it to the digger.

They measure 6cm in diameter,

almost as thick as a can of fizzy pop.

OK, Gregg, so what we've got here is our fully welded boom.

Now, that looks like a bit of a digger.

I can see now, very clearly, every single join is now sealed,

welded, right? Yeah, fully welded.

So, what we've got, these two ends here attach

to the back of the chassis.

The way we hold it on is by using these big pivot pins

through these bores here.

And then, that end, there'll be a dipper,

and at the end of the dipper, there'll be a bucket -

and that's your excavator end.

I think there's something quite lovely about this.

Strong, industrial - but lovely.

The half-ton boom is ready to become part

of the ultimate earth-moving machine.

Diggers are a common sight on many a construction site

and play a big role in building Britain's infrastructure,

be it roads, bridges or flyovers.

Cherry's learning how they help to keep us moving.

There are nearly 250,000 miles of roads in Great Britain,

driven on by more than 38 million vehicles.

Many are unable to cope with the sheer volume of traffic

and need to be replaced.

Like this one - the A602 in Hertfordshire,

which struggles with 25,000 vehicles a day.

Like so many roads in Britain, this one is narrow and slow

with loads of blind bends.

Clearly in need of replacement.

But how do you go about building a brand-new road?

I'm visiting the site where they're 16 months into

a two-year project - constructing a brand-new 1.75-mile long

straighter road alongside the existing windy one.

In charge is chartered engineer Robin Clark.

Robin, lovely to meet you. You, too.

Look at this amazing hive of activity.

I don't think I've ever seen so many diggers in one place at one time.

Yeah, we are working hard.

We've got five, six diggers there.

We've got bulldozers.

We're trying to get the new A602 open

for the residents of Hertfordshire.

Where on earth do you start a project

this complicated and this huge?

So, we start cutting through the hills and filling up the valleys.

The first stage of any road build is something that relies almost

exclusively on enormous hydraulically-powered diggers -

the earthworks phase.

To increase driving safety, new roads are designed to be

as straight and level as possible.

Excavators capable of shifting 1.5 tonnes at a time begin

by carving out huge amounts of rock and soil to create cuttings.

What is going on over there?

So, you can see we're stood in a cutting here,

which is below the topsoil, we're about three metres down.

So, the diggers there are digging down into the clay here.

Cuttings like these reduce the number of hills on a road

to provide better sightlines.

The diggers are loading the clay onto one of our lorries.

It'll get taken to another part of the site and get used

in another area to build up the level of the road.

There's around 20 tonnes of soil on that lorry,

and it's probably been loaded in about three minutes.

Those excavators are working hard.

So, that lorry's off again with a whole lorry load of clay -

and it just arrived.

The soil and clay are unloaded to form embankments,

which also reduce dips in the new road to provide

a smoother, safer surface.

So, in this bit of the site, we're needing to lift

the level of the ground up to give us a nice, smooth platform

to build the road on.

What is this machine doing?

So, this roller here is compacting the clay.

Just the weight of the roller and the vibration from it

forces the clay down to give it a nice, stable platform for our road.

Why do you need to compact it?

If we built all the clay up without compaction,

what would happen is, over time it would settle.

So, our nice, smooth road is going to be up and down in no time.

The second stage of road building is the foundations.

The largest digger on site, a 38-tonne monster,

spreads out a layer of recycled stone and concrete called aggregate.

This creates a solid foundation,

preventing the finished road from buckling over time.

Smaller stones are used to form the top layer of the foundations.

What is this amazing looking robot doing?

It looks like something out of Star Wars.

This is a compactor, and it's compacting the stone.

If the foundations aren't properly compacted,

the road surface could become unstable.

On this project, 150,000 tonnes of earth will be excavated

and compacted over 12 months.

That's half of the total construction timeline.

Preparing the way for the third and final stage

of any road build, asphalting.

Robin has one small section that's very nearly finished.

Robin, I think this is the first and last time I get to sit on a road.

We don't want to get to do that, no.

But it's an excellent way to see how they're built.

This is made out of a mixture of stone and bitumen

that we call asphalt.

What is asphalt?

Well, asphalt is a mix of stone and a binder that we call bitumen.

So, it's a sticky, gloopy, black tar material.

Bitumen is a by-product of the crude oil refining process.

Specialised machines called pavers spread the asphalt

32 centimetres deep in four different layers

to build up the road strength -

the third of which is the binder layer.

That uses a smaller stone in the mix with the bitumen

to give us a nice, smooth surface to keep the road nice and even.

But you don't want it too smooth,

otherwise, everything is just going to be flying about.

And that's where the final level comes in, the surface course.

That has stone embedded in it which is particularly grippy and strong,

and doesn't get worn down by the car tyres,

and that stops everybody sliding off the road.

So, you save the best till last.

A bit like icing on a cake.

Just like that.

The final surface course of black asphalt may be what we all see -

but it's only thanks to the diggers of all shapes and sizes

that a road like this can be constructed at all.

By the time the new road opens, a total of 40 different excavators

will have been used in its construction -

helping to shave precious minutes off rush hour journey times.

I never appreciated how much planning, engineering,

digging and filling was involved in highway construction,

and I hereby solemnly swear that I will never

whinge about roadworks ever again.

At the digger factory,

the steel boom has been welded solid...

..and the digger's other key weight lifting components

have been assembled.

The 300-kilo dipper,

which is the central part of the excavator end,

and the 600-kilo front loader arms,

which will lift the enormous shovel up and down.

These huge steel sections come together at the paint plant,

where I'm meeting assembly manager Richard Williams.

Richard. Hi, Gregg. You OK? Good to be here.

I recognise this, Richard. This is my boom, right?

Yes, ready for the paint shop.

You can see now that the guys there are applying the first coat

of primer paint to the product.

Why is primer important?

Primer is important on our product because it's got anti-corrosive

chemicals within the paint, and preps ready to put the top coat on.

An astonishing 4,000 separate digger parts pass through

the paint plant every week...

..and each one gets the personal touch.

You've got high-tech machines throughout this massive factory,

and you spray this by hand.

We've been doing it for over 30 odd years now.

And though there's robots about and we're looking at technology

all the time, that's the best coverage we get -

by the guys themselves doing it.

And it's such a size that you have to go up a ladder

up onto a platform to spray the top.

Yeah, the guys haven't cracked the art of jumping that high yet

to spray, so, yeah...

Trampolines, mate, is the answer.

Hang on a minute.

That's a kind of sandy, beigey colour,

but it's definitely going to be bright yellow, isn't it?

Of course it's going to be bright yellow.

Let me show you.

It takes seven and a half minutes to apply the primer,

and while the steel parts are still wet, they are hoisted

to the final painting chamber.

There you go, Gregg.

I never doubted you.

I never doubted you, and I like it.

I'll tell you why I like it.

Because I pass these all the time, we all do.

But before that, it just looked like metal bits.

Now it's recognisable. Yeah.

Now that's starting to make it look like a machine.

Why is it yellow?

It's yellow because building sites are dangerous places.

Yellow's a bright colour, you can see it coming,

so, yeah, that's why the yellow.

What sort of paint is it you're putting on there?

This topcoat is made of polyurethane.

So, it's all about helping the product form together

and give a good, tough exterior coating.

Right, not just looking pretty.

Not just looking pretty. It serves a purpose, so it's long lasting.

It takes another seven and a half minutes for the boom to get

its coat of polyurethane paint.

It's a liquid plastic to create a shiny, strong finish

which bonds perfectly with the primer underneath.

There is a lot of heat coming from here.

What is going on here?

Once the guys have put the yellow gloss topcoat on,

it now enters into the oven.

Very similar to a hairdryer process, dries the product.

But what it's doing is, it's fusing the primer you saw earlier

and the topcoat together. So, that makes a durable bond

and gives a lasting coverage on the machine.

The painted pieces bake in the oven for a scorching 25 minutes,

heated to 100 degrees Celsius,

before passing through a cooling chamber.

Should we get out?

It's a bit hot and I don't really care for hair dryers.

Come on, let's go.

While the boom is cooking and cooling,

Richard and I are heading...

..here...

..to this enormous hall,

housing the heart of the factory - the assembly line.

It's a massive 180 metres long.

That's even longer than Westminster Abbey.

This is a serious hub of activity, isn't it?

Yeah.

And unlike many car factories,

this digger production line isn't populated by robots.

There's a huge team of 260 people here

busily putting the diggers together by hand.

This is a proper, proper assembly line.

So, look, the floor is moving. It is moving, yeah.

And do you set the speed of the floor? We do, yeah,

based on the volume that we need to build on the day.

The line is capable of moving fast enough to turn out

up to 100 finished diggers a day.

I don't think many people have actually ever seen

anything like this. I certainly haven't.

I honestly haven't.

If you look right down, hundreds of yards away,

you can actually see a fully blown digger.

The assembly line starts with the base - the axles.

It really is just like building a giant toy digger.

Come on, talk me through this.

So, what we've got here is the rear axle,

and then to the front of you there, the front axle.

So, this is the base of what the wheels are going to attach to,

so the guys can drive around the building site.

Axle comes to the line side,

gets fitted to the moving track.

Every 12 and a half minutes, starting this end,

a full machine rolls off at the other end.

Really? Every 12 and a half minutes.

Really? Yeah.

The two axles can support more than 12 tonnes,

the weight of the digger and its load.

The digger has four-wheel drive, so its engine powers all four wheels

at once to give it better traction on muddy building sites.

But it's going to need a heavyweight component

to get those wheels moving.

Our digger will be powered by a diesel engine -

and there are an estimated two billion internal combustion

engines in use around the world.

Cherry is taking a peek under the bonnet

to master these complex motors.

Ah, the good old internal combustion engine.

Most of us rely on them almost every single day,

but not many of us know how they work -

myself included.

These mysterious contraptions are in all diesel powered vehicles.

So, to find out how they function...

..I've travelled 12 miles from the main digger factory

to the 14,500-square metre engine plant.

Here, 300 people work around the clock,

producing more than 200 engines every day

for all manner of machines.

Chief engineer Chris Ward is showing me how they make the engine

for our backhoe loader.

Chris, lovely to meet you. Good to meet you.

I'm ready for a masterclass in engines.

Well, let's start at the beginning.

These are cylinder blocks. Right.

These are the very first thing to come into our factory.

It's a four-cylinder engine, so it's got four holes.

OK, I can see that. These are the cylinders.

The cylinders are probably the most important part

of an internal combustion engine, because it's inside each of these

four holes that the diesel fuel will combust to power the digger.

When our engine is complete, air will be sucked into

the cylinders through inlet valves.

Pistons moving inside each of the cylinders will push up

against the air, compressing it, causing the temperature

to reach above 600 degrees Celsius.

Then, a fuel injection nozzle will spray a fine mist of diesel,

which will instantly combust due to the extreme heat,

forcing the pistons down, rotating a crankshaft to drive the wheels.

The spent air will then be forced out through exhaust valves

as the pistons rise, and the cycle happens all over again.

To ensure the cylinder block can withstand the huge

combustion forces, it's made from solid cast iron.

So, this is the heart of our digger.

We've got to make it beat.

Correct. Cos at the moment it's just a block of cast iron.

It's not doing its beating.

Right, well, let's get cracking.

Before it can beat, our 200kg cast iron heart passes through

a honing machine to make sure the inside of each cylinder is smooth.

To cope with the demands of the building site, our digger has

a large 4.8 litre engine.

That's the same size as a powerful sports car,

around three times bigger than an average family car.

With the cylinders honed, it's sent to the start of the assembly line,

where a vital part is fitted.

So, the first thing that needs to happen is, this crankshaft

needs to go into that cylinder block.

I know that the crankshaft is important.

That is the bit that spins in the bottom of the engine,

and that is the bit that powers the machine.

So, without that there to spin, we don't have a working engine.

So, you've got the fuel combusting... Yep.

..and that's making the pistons move up and down like this. Yep.

And then you connect them to the crankshaft,

and that movement makes the crankshaft go round and round.

Exactly. And that's what will make the wheels rotate

on the machine itself.

So, this is so key to the whole operation?

Yes. Without this, the piston moves down, and that's the end of it.

With the crankshaft in position, a gear plate is bolted to the side,

onto which the gears, known as transmission,

will ultimately be connected.

And we're ready to add what will create the beat

of our digger's heart.

Something I think I recognise.

Are these the pistons? So, these are the pistons.

The piston will sit inside the cylinders.

This thing is moving up and down 40 times a second.

That's going to pass the power into the crankshaft.

And this part, because it's got that amazing joint,

can move around and around with the crankshaft -

and that's why the wheels on the digger go round and round.

Absolutely.

Every aluminium piston is the same size

and must be fed into each of the four cylinders.

The lightweight metal allows them to move freely inside the engine.

Can I give you a hand?

Yes, you can.

A little lubricant...

Right.

..and each one slides effortlessly in.

Right, one push? Yeah.

That's it.

Did it, yes!

When the engines are finished and powering our diggers...

Yeah!

..the two inner pistons will move together in tandem,

and the two outer together.

The next important part is the cylinder head,

which sits above the pistons.

What are these smart looking things?

I can see that there's a number of springs.

Those are valves. Yeah.

They're acting to let the gas into the engine,

and then to be exhausted.

So, these will press down at one point,

and these will press down at another point.

Before our cylinder head which contains these valves can be added,

a thin sheet of steel, called a head gasket, is sealed in place.

It becomes the meat in the cylinder block and cylinder head sandwich.

This thin piece of metal's job is to keep the combustion gas pressure

separated from the water pressure, separated from the engine oil.

What happens if a gasket breaks?

That cylinder head has got to come off that cylinder block.

And if that's in an engine in a passenger car,

that's an awful lot of work to get to.

Normally, it's expensive.

Next along the assembly line, fuel injectors are bolted on,

which sends the mist of fuel into the cylinders to be combusted.

And the starter motor is added,

which fires the engine into life when the ignition key is turned.

After just three and a half hours, the finished engines are tested

and roll off the end of the production line.

These precious hearts are wrapped and loaded onto lorries,

ready to be brought to life inside our digger.

It's amazing to see how quickly the team put together

such a complex engine, and I'm just really glad that now

I know my camshaft from my crankshaft.

One thing's for sure - I'll know where to look

for leaks from that pesky cylinder head gasket.

Back at the 175-acre digger plant...

..the 500kg engine has arrived,

and is attached to a hoist.

Then the engine team steps in to crane it carefully

over the top of the axle assembly.

We've seen the axles, now the engine goes in the middle.

But also with the engine, we have the gearbox

that's bolted onto the back of it.

Which bit's the gearbox? The big black bit behind the engine there

that you can see, the big lump.

So, inside there, there's all the gears, the cogs.

Just like a car, diggers can be manual or automatic,

with up to six gears.

We then attach the prop shafts.

The prop shafts then link up to the front and rear axle.

So, that's what drives the machine.

That's what moves the wheels through all the mud on the building site.

In the future, these diesel engines may be replaced

by greener options, like hydrogen power.

But today the engine team has done its work,

and the assembly line rolls on.

Next, the chassis team moves into position

to add the bright yellow frame.

It's the heaviest part of the entire machine

and is the framework that supports all the other parts of the digger.

It's also been laser cut and welded here at the factory.

Fabulous.

What's the weight of that?

That is 1.5 tonnes.

Look at that!

Tat's one serious lump of custard, that is.

The chassis is moved into place by a four-tonne, 4.5m tall crane

that towers over the assembly line.

Once you lower this chassis, what are you connecting to it?

We are connecting the rear axle, engine and gearbox into the chassis,

and we do that with zinc-plated bolts.

Why zinc-plated? Well, zinc-plated helps out in the field,

all kinds of weather, so it helps with the corrosion

and the longevity of everything.

Just eight of these huge bolts fix the chassis to the axles.

All together, 660 bolts of all sizes are used to put the digger together.

Step by step, we are getting more -

I'm going to coin a phrase here - diggerish.

Diggerish? Yeah, that's what we're...

We are more diggerish than a box of liquorice.

Along this incredible assembly line, specialist teams work in unison,

stepping into position to fit the 4,700 separate components

needed to produce a single digger.

It's all quite overwhelming.

The diesel tanks have now gone on.

The steps to get up into the cab.

We can see things like the cooler packs are cooling

the heating system down.

All that's been fitted on the front.

Brackets ready for the bonnets to go on.

So, it's really starting to turn into that machine.

From here, it looks like a racing car.

Yeah, it's not built for racing. It's built for digging.

I really am beginning to understand it.

I really am.

At the halfway point of the assembly line,

the moment has come...

..to fit the 600-kilo front loader arms that hold the shovel.

Loader arm picks up 3.5 tonnes of soil or rocks, or whatever

the operator needs to use, raises it up,

and it's set at a height ready to load into the back of vehicles.

If you pick up 3.5 tonnes at the front and lift it up in the air,

what stops the back coming up?

So, the excavator ends, once that's fitted, all counterbalances.

So, it's all been worked out to be able to operate at that level

and that weight in the front shovel.

It takes two of the front loader team just 12 and a half minutes

to fit the loading arms,

using six pivot pins to attach them to the chassis.

And now these magnificent machines are starting

to look less like racing cars...

..and even more diggerish.

But they're clearly missing one very important ingredient -

a nice warm cab for the driver to sit in.

Cherry is six miles down the road finding out how they're made.

This is the firm's very own specialist cab factory.

Like everything to do with our digger,

everything here is on a super-sized scale!

This place is vast!

Inside this huge space, 600 people produce 260 driver's cockpits

of all shapes and sizes each day.

To learn how the cab for our backhoe loader comes together,

I've tracked down production leader Ben Beeby.

Ben.

I am here to help make a cab for a digger.

Where do you even start?

So, we start here with the steel sheets.

Little individual parts are then created to make the cab.

It's like a big jigsaw puzzle.

Just like at the main digger factory, the individual

steel sections are welded together on site.

And, hey, presto, here it is!

Here it is.

And this is all about the strength, as well.

The robot welder reinforces all the steel and just makes sure

that every single part of it is crucially safe.

Four robot arms spray the cab with a coat of durable powder paint...

..before it's dried in an oven at 180 degrees Celsius

and sent along to the cab factory's very own moving assembly line.

So, we've got 21 stages.

Each operator's got eight minutes to do their stages.

What happens if they don't do it?

It starts backing up. It's like a traffic jam, then, essentially.

First, I help to fit 68 rivets by hand to the frame.

They're essential, as every component will be secured

with a bolt into a rivet.

And that's where the heat will be on you, Cherry.

Do I need to be on my toes? Yes, you do.

OK, I'm on it, I'm on it! Yeah, let's go.

I can see the cab is moving very slowly, so I'm aware

that time is not on our side.

My first-ever rivet. Yes.

That's it. Perfect.

The rivet gun fires each one into a pre-drilled hole.

I've never riveted before. No?

It's absolutely riveting! It is riveting, yeah.

Just 66 more to go.

It takes eight minutes to fit all 68 rivets -

that's just seven seconds each -

before the fibreglass floor can be bolted on.

Made from plastic resin and fine sheets of woven glass fibre,

it provides our cab with an incredibly lightweight

and durable base.

Next, something called a wiring harness.

Looks like you're wrestling with a big snake.

All these wires talk to the individual parts of the cab.

So, if you'd like to have a go, carry on.

I love to help, but I think riveting is probably my limit.

I think I'll leave this to the professionals.

So, this deals with the lights, the electric windows, the radio,

all the control panel, everything?

Yes, that's correct, yeah.

So, each individual component talks to its relevant part.

Every harness contains 650 metres of wiring -

enough to reach the top of the Eiffel Tower and back.

It's like someone's nervous system.

Yeah, it really is like the nervous system, yeah.

A very big one.

Next, the doors are bolted on,

and the parts just keep coming.

So, this is the steering column assembly.

So, you can see here with the shaft, it goes down through

the steering column, rotates the wheels whatever way you want to go.

Like a car, but super-sized. Yeah.

With the production line constantly moving,

next on is the front windscreen.

Polyurethane sealant is piped around the edge of the 6.7mm thick

toughened glass, which is up to five times stronger than regular glass.

This is lifted manually here, and we're about to take it

over to the cab - and you're going to do it with us.

I'm going to do it with you? Yes, you're going to do it with us.

You sure that's safe?

Got it? Yeah.

That way.

I can't believe you're letting me do this.

The windscreen measures 1.4m x 1.1m...

So, we lower it down just here.

..and, thankfully, vacuum handles hold it in position.

Is that right? That way.

Is that on? Push on, yeah.

Oh, my God.

That's how it's fitted.

Are you kidding me?

How is that still holding on?

So, the adhesive was cured,

and it's secured it on all the way around.

It doesn't need any screws or anything?

No screws, and that's the best part about it.

It keeps it waterproof.

That's amazing stuff. Yeah.

To make the cab fully watertight, the roof is bolted into place.

Then electrical components - including the driver's switches,

the speakers and interior lighting - are connected to the wiring harness.

The seat's installed.

And we're ready for testing.

Look at this.

Oh, it's so new and shiny!

OK, so how do I test?

So, if you just turn the ignition key there. OK.

BEEPING TONE

That's our testing noise.

You can turn the wipers.

There they go. Look at that!

Then you've got the lights at the front, so click them.

And the rear.

I feel like she is ready to dig.

She is ready to dig.

Three hours and 30 minutes after joining the start

of the assembly line, the cabs roll into the light of day.

Each one weighs 600kg and contains 68 metal sections,

130 bolts and 160kg of glass.

Oh, there she is.

There she is. Stunning.

Did I hold it up today?

You've done very well. OK.

We haven't stopped at all, we've been OK.

No way. Yeah.

These perfectly finished cabs will be sent 12 minutes down the road

to Gregg at the main factory.

Our cab is now ready for its new life on a construction site -

a safe and waterproof haven for many a builder's bum.

Back at the main factory, we're 140 metres along

the 180-metre assembly line.

And the digger is all ready for Cherry's cab to be winched in place.

I think that's maybe the crowning moment.

That's the bridge, innit?

Yeah, starts to look like a proper digger now, yeah.

Now we're going to start and connect all the cables,

so yeah, this is about the bits all coming together as one.

Let me ask you something, how long have you worked here, mate?

Well, I'm coming up for 35 years now.

35 years, yeah. You're kidding me. Yeah, no, long time.

Why did you come here? Well, my father was here before me.

How long was he here?

He was here for close on 35 years too, before he retired, yeah.

Have you got any other family here?

Yeah, my wife works here, so she's up in group purchasing.

I've got two children here as well.

Oh, yeah. One's a sprayer. Seriously? Family job, yeah.

Your dad, you, your wife and your kids! Yeah. Definitely.

16 metres further down the line, the plastic bonnet is attached.

But our digger's going nowhere without these.

The wheels. The wheels, right? Yeah, this is where the wheels go on.

Look at the size of those blighters! Look at that!

Tell me, seriously, why are the back ones massive

and the front ones aren't the size? Those dirty great big ones at the

back, they're all about driving the machine forward,

so that's about traction when they're out in the field,

working and digging the holes.

The front ones, small wheels, they help with manoeuvrability,

better turning circles.

The back wheels weigh a massive 185 kilograms each!

Even the smaller front wheels weigh a huge 130 kilograms

and the tyre tread is four and a half times deeper than a car's.

The wheels are lifted into place with a clamp called a manipulator,

before the wheel nuts are attached with a torque-control pulse gun.

It IS like building a model at home.

Honestly, the last thing you'd put on is the wheels.

But hang on a minute, Richard. We're still missing my excavator end.

It's all about timing in the production process,

so if you can see in front of the machine, there's not too much

room to be able to fit the excavator end on this current process.

So, very shortly, you'll see the excavator end being fitted.

It's because my arm is too big.

And the factory's devised an amazing solution...

..to make room to add the arm at the back.

He's not going to lift it over the other side, surely?

Yeah, he's going to do exactly that.

How much does that weigh? Just over seven tonnes, Gregg.

That's a flying digger!

As it's hoisted off the line, it's rotated 90 degrees.

Is that turning on its own, or is he turning that?

No, the operator's controlling that on the crate controller box,

so he's turning the machine.

He's the strongest man in the factory!

With the digger down on terra firma,

it's finally time to fit the excavator end.

The freshly painted boom and dipper sections are now dry,

but before we can join them together,

they need their hydraulics.

I've heard about the history, now we're putting science into practice.

The hydraulic system, comprising hoses and rams, is attached.

These are the machine's muscles,

allowing the digger's excavator end to move up and down, forwards

and back. I'm meeting Dave again, who's promised me

a simple explanation of how they work.

All right, Dave? Go on, tell me about this.

OK, if I show you how all this goes together, so this piece here is this

boom and what we've got is we've got the ram inside and then we've got

the ram on the top. That ram there moves that up and down.

And this cylinder here moves the dipper up and down.

I getcha. It took a toy to explain to me properly!

If we have a look behind you there,

I've got an example of some hydraulic rams.

So what we've got here, Gregg, are the two boom rams,

one where the hydraulic ram is closed

and one where it's extended and the rod is out.

Opening and closing the ram makes the digger arm go up

and down and instead of water, like William Armstrong's 19th century

cranes, this system is powered by pressurised hydraulic oil.

So what we have is we're putting oil in through these two ports.

If we put oil in through this port, it is forcing this rod that way.

If we put oil into this port,

it's filling this end of the reservoir and pushing the rod out.

Mate, that is a genius invention!

Now the boom and the dipper have got their powerful muscles,

they're joined together by pivot pins to form the excavator end.

At long last, the digger's about to be united with,

in my humble opinion, its most important part.

It's all coming together now.

So if you see there,

he's putting the bottom main pivot pin in and then he'll put the

top pivot pin through our boom ram that'll power the boom up and down.

He's giving that some serious welly, isn't he?

I mean, he's seriously whacking that in!

They're a very tight fit,

to make sure that they're very strong and robust.

There are just two very important things still

missing from my supersized toy.

First, the shovel is bolted on to the front loader.

And the excavator end gets its finishing touch, the bucket.

It weighs in at 150 kilograms

and you could fit more than 35 pints in there.

Is that it? Is that our finished article? Yes, it is, Gregg.

Our digger, complete.

And there's one final thing before that machine goes to the customer.

We've arranged for you to go and join our testers

and have a play on it. What, get in it? Yes, get in it. Yeah! Ha-ha!

Really? Yes. Mate, thank you very much indeed!

I just wish I could tell the six-year-old me

what I'm about to do!

But I don't think he'd believe me.

Steve! Gregg. The boss said that I could have a go at this. He's right.

Climb in. We'll show you how to do it. Right.

Right, what have I got to do?

Spin round and face the back. All right.

And push that red lever away from you.

Wow! Now you're in position. Ha-ha-ho-ho!

You ready to start the engine? Just turn the key.

BEEPING AND ENGINE STARTS Hold on, hold on, let go. There you go.

So now, you're live. If you move any of those joysticks, the arm will move, OK?

CLUNK

It's all right. It's all right. Sorry.

Oh...

Now I've "mastered" the controls... HORN BEEPS LOUDLY

..I can finally see... Yes! ..what this machine can do.

Scoop it up. Look at that! Now, I've got a bucket of earth. That's it.

Bring it up. Move it left.

That's the way. Oh! Goes faster than you think. Whoa! Whoa!

GREGG LAUGHS

Oh! Ho-ho!

Down a bit, down a bit, splash everywhere and then empty the bucket...

Dumped it! You've done it. Dumped it!

Wow! Mate, this is a mega, mega machine!

I've never done anything like that in my life. There you go.

I had cranes, I had diggers when I was a kid

and they worked with little winches.

Brings the kid out in you as well, doesn't it? That was absolutely extraordinary!

The finished diggers are loaded onto the back of 12-metre long triple

axel trailers and driven to customers across the country

and beyond. From this factory in Staffordshire,

backhoe loaders are put to work all over the world.

Their biggest markets are the UK, Central Europe, Russia...

..and North America.

Once it leaves the factory, if our digger's properly maintained,

it could have a lifespan of 60 years and in that time,

could shift a phenomenal two million tonnes of soil.

I've really, really enjoyed watching this big earth movers being

put together. For me, it's just like a giant toy being made.

Now, let's be honest, we see these machines absolutely everywhere,

but now I've operated one, and I realise just what it can do,

it's really easy to understand why.