Lawnmower James May: The Reassembler

Hello and welcome to The Reassembler, with me, James May.

It's a new series in which we take everyday familiar objects

in their component form and put them back together very slowly.

This was a familiar bit.

'It is only when these objects are laid out in hundreds of bits

'and then slowly reassembled...'

Dun-dun-dun-dun-dun.

'..that you can truly understand and appreciate how they work...'

Ee!

'..and just how ingenious they are.'

Deep joy!

'And if pain-stakingly putting hundreds of pieces

'back together again...'

Electrics.

'..wasn't hard enough...'

Fantastic! We've used all the bits.

'..I then have to find out...'

Oh, yes!

'..if they'll work.'

No, it's all come apart.

Tonight, it's the turn of the humble lawnmower -

a British invention that's been annoying our neighbours

and keeping our grass short since 1830.

An estimated 20 million of us own them

but how many of us actually know how they work?

Let's find out by slowly reassembling this one.

Even when it is presented like this, ruthlessly stripped down to

its last nut and bolt, you will, of course, have recognised that this

is the seminal 1959 Suffolk Colt

12-inch four-stroke petrol lawnmower -

the people's lawnmower,

the lawnmower that revolutionised the idea of popular grass-cutting.

And it is fashionable, these days, to deconstruct history,

but that's not what we're going to do here.

We are going to put history back together again.

I have as long as it takes to reassemble

this beast from a pile of 331 lawnmowery-type bits.

And to help me, I have a 50-year-old owner's manual and some tea.

Right, we'll start with the engine

because that's what makes this a petrol lawnmower.

If it didn't have a petrol engine, it would merely be a lawnmower.

The first bits to go into the engine are the valves that control

the flow of fuel and exhaust gases in and out of the cylinder.

This might be a good time to tell you a little bit about the history

of the lawnmower,

which was invented by Edwin Beard Budding in 1830.

He was actually inspired by a machine that removed

the pilling, or whatever you call it, from fabric

at a factory that made uniforms for army officers, I think.

And he saw that and thought, if I make it a bit bigger, it would

cut the grass in a very neat, uniform way.

A lot of people thought Budding was a lunatic for wanting to make

a machine to cut grass.

Apparently, he had to test it at night so that people

wouldn't see him and throw stones at him and all the rest of it.

Here you go.

Over the next 57 minutes, I assembled the camshaft,

the tappets and the remaining valve.

Bliss was it in that dawn to be alive!

Right, next, I am going to need

the all-important crankshaft, which is that bit there,

and I'm going to need the four screws to retain it.

I should really clean my hands before doing this bit

because it's precision engineering.

Now, the crankshaft is obviously a critical part

of the internal combustion engine.

It's the most significant part, in a way, because it's what converts all

that furious combustion action and reciprocating motion into something

going round and round, which is what we want from the machine.

It's what we wanted from the water wheel-powered mills

of the Industrial Revolution. That's what you need.

So would everybody agree that that is top dead centre?

CLUNK

There. So the piston is at the top of its stroke.

Both the valves are closed, but if you rotate it either way,

either one is ready to open.

So that should make the timing correct.

There's no other real way of checking it

apart from assembling the whole thing and seeing if it works.

So let's do that.

It'll be a satisfying clunking noise any second as this goes home.

CLUNK

If this was a Japanese motorcycle engine,

there'd be an actual torque setting for all of these,

but you sort of do things up until they feel about right.

So let's call that "hm" tight...

..and that one is "mm" tight and then we'll go for...

"Heurgh"!

"Heurgh"! There you are. They're even.

Excellent! We now need - and this is a nerve-racking bit -

the piston, the connecting rod, the gudgeon pin,

the circlips and the piston rings.

That is the piston,

that is the connecting rod and these are the very delicate piston rings.

Yes, there you go.

Sorry about the slight cut but there was some blasphemy.

I have two of the piston rings on - the bottom one, the oil control ring

and the middle one, which is the oil scraper.

I didn't want you to share my trauma as I did that.

It's a very, very fiddly nerve-racking job

but I've saved the last one for you to watch.

This is the compression ring.

And now, it's a simple matter of finding your inner power animal.

Oh, man! You have to spread it. It could...

CLICK

Now, before we put that in, we have to put the conrod on.

It's worth remembering that the piston goes up

and down inside the cylinder in a straight line,

but because the crankshaft is going round and round

and has a throw on it, the connecting rod has to do that -

has to go from side to side -

so, obviously, it has to pivot at this end,

otherwise it would just shatter.

Oh, that's interesting.

That ought to just slide in

very smoothly but without any of this resistance.

Why doesn't it just go in?

Bloody British rubbish! Good God!

That looks like it was machined with a knife and fork by the council!

There are two possible solutions here.

There's the lawnmower solution,

which would be give it a gentle whack to take it past that problem,

or there is the aerospace solution, which is remove that little bit.

I'm inclined, by nature, to go for the aerospace solution

because it's more proper.

So what do we think, crew?

Take the clip out of the other side or hit it with a hammer?

-Don't know.

-Hammer.

-Hammer?

-Hammer.

You're all wrong.

If I hit that with a hammer, my reputation is ruined.

I told you we should have hitted it with a hammer.

Hitted it? Hit it.

It's not proper, though.

The conrod moves freely. That's a good sign.

And now, the defining component of the piston engine

is about to go in - the piston.

CLUNK

The interesting thing about...well, I say interesting,

it's mildly interesting if you're interested in that sort of thing,

is that the Suffolk Iron Foundry made the whole lawnmower,

a bit like Ford did with cars in its earlier days.

So it didn't just buy an engine in from, say,

a motorcycle manufacturer.

It made it itself, so all these castings

and all these machine bits all came out of the same factory that

was making the blades, the rollers, the pressed steel for the casing,

the grass box and all that sort of thing.

It all came from the same place.

And here is that place - the Suffolk Iron Foundry in Suffolk.

These lawn-trimming titans have been a producer of lawnmowers

since the late 1920s.

By the '50s, they were making 600 mowers a day,

going on to sell millions of affordable petrol lawnmowers -

a shining light to emerge from Britain's post-war industrial age.

Do you know, the very first petrol engine thing

I ever drove was a lawnmower?

It was a twin-clutch device,

a bit bigger than this one, that my parents owned,

and it lived in a shed in the garden.

And when I was about 12 years old, I worked out how you started it.

And I used to lie awake at night, excitedly thinking about how

I could get up in seven hours' time and mow the grass again,

even though I'd mown it at 6pm the previous day.

And to be a blade of grass in our garden in those days

was a very ephemeral existence.

And I loved this thing.

And then I lent it to a mate many years later

cos I didn't have a lawn in my house in London,

and while I wasn't looking, he sold it on eBay.

Are you ready?

Here's a legitimate use of the hammer.

That's why it's a nylon-headed hammer -

so that it doesn't damage these delicate aluminium parts.

I've attached the sump.

I'm now going to very carefully turn the engine over

the right way up, and finally, we can stand it on the bench safely.

There you are - engine going round. You want to see the piston go up and down.

Look at that. Fuel-air mixture goes in there, drives that down,

it comes up, exhaust - get some more in - bang, bang, bang!

And as a result of that...

CLUNK Argh!

..your lawn is mown. Good, isn't it?

We are now three hours and 21 minutes into our attempt to

reassemble a 1959 petrol lawnmower, and not a minute's been wasted.

So far, I've put in the valves, the crankshaft, the tricky piston rings,

the sump, the magneto, flywheel and cylinder head.

The engine is nearly complete as I tighten the last nut

on the valve chest.

Excellent! Let us think about the carburettor.

There are a lot of bits to this,

quite delicate bits, but they're also rather wonderful.

I will take those.

That'll do for starters.

What it does is it combines fuel from the tank,

i.e. petrol, in this case, with oxygen from the air

because the vast majority of what an internal combustion engine

burns is, in fact, oxygen, not the fuel that you put in the tank,

and it's called a carburettor because it adds carbon to the air,

i.e. it adds petrol to the air and then squirts it in the engine.

Let's get some more bits.

Gasket and a jet, some washers -

lovely - selection of screws. OK. Let's have a go at this.

So I did need to use both hands and my gob to get that in but it's in.

The butterfly regulates the amount of air that's allowed to

enter the carburettor, therefore the amount that gets sucked

through the venturi, therefore the amount of fuel that's picked up,

and therefore how fast or how strongly the engine runs.

I'm simplifying it massively.

It's very, very... There's a huge amount of physics

and all that stuff in it. So that can go in there.

What else do I need to put on the bottom half?

What the hell is that? "Strangler flap"?

Oh, I think they mean the choke.

Oh, this has a different choke cos... That's right. This is not

entirely right for this... Yes, it is.

No, it isn't. Yeah, that is the strangler flap.

They mean the choke butterfly. OK. That's already in.

Right, we are getting very, very close to completing the engine.

I'm going to put this governor on.

Now, this is something you do need on a lawnmower,

so that if you crack the throttle open in a moment of sort of

lawnmowing red mist, the thing doesn't run away with you.

It sort of partly shuts the throttle again to stop it going

completely mad. Um...

I'll show you how it works when we've got it together cos it's a little bit baffling

and you have to put it together in the right...

Ah, you see, I'm already

thinking the best thing to do would be to install this spring first.

This... Hang on. That way.

It's quite elegant when you see it all together.

When you insert that end of the rod...

There you go.

CLICK Ooh, that was nice. Did you hear that?

So this bit goes on that little threaded pin there.

And the throttle cable will go through here,

which is all part of the system.

That will go on later, but for now, we put on a washer and a nyloc nut.

This nut is an unusual size -

not the same size as any of the spanners I have here

or, indeed, any of the sockets, which would mean, normally,

you might resort to the adjustable spanner,

the screw adjustable spanner, like this.

And the interesting thing about the adjustable spanner -

it was invented by Edwin Budding, who also invented the lawnmower.

The only problem is I hate adjustable spanners

because I think they are the tool of the charlatan.

And, as luck would have it, Rebecca, who's our other camera person,

not Sean, the fat Australian one -

she's the nice one -

carries this bicycle spanner around with her in case her bicycle

goes wrong. And one end of it just happens to fit this nut perfectly.

Very clever. Pure mechanics.

See? Springs and rods. I love it.

There's no denying it - engines are fun, even on lawnmowers.

But if you're thinking of using one as your commute to work,

be warned - taking one on the road still requires a driving licence.

-ARCHIVE:

-It has to travel 50 yards along the main road.

So red tape wins and Mr Hester, the groundsman,

proves that he is fit to drive this dangerous machine.

We have now spent six hours and one minute reassembling

nearly 200 of the 331 pieces that make up our mower.

And with the attachment of the carburettor and the governor,

the engine is tantalisingly close to completion.

Right, I reckon we can put the cowl and the tank and so on

onto the engine, which is nice

because it will suddenly become a riot of colour.

All these bits are red. OK.

Doesn't that look brilliant?

If you're still watching. It's hard to imagine.

Do you think this has ever happened on television before?

I mean, I know there have been some catastrophically unpopular

programmes over the years -

anything made by Richard Hammond, obviously -

but has it ever got to the point where the only person still

interested in what's happening is the person who's on the telly

so there's nobody actually watching it?

It's a bit like a tree falling in the woods.

If a man is on the television talking about a lawnmower

but nobody sees it, does it actually happen?

Who knows?

Assuming this is actually happening, I carry on

and attach the recoil starter mechanism to the body of the engine.

I will go to bed tonight with a sense of deep peace,

and when I wake up in the morning,

I will suddenly think, I put a lawnmower engine together yesterday!

And that matters. It's a sort of muse.

The Greeks didn't have the lawnmower engine. They had Melpomene.

But I have that.

Now to build the rest of the lawnmower. Um...

Spark plug and spark plug cap.

Well, the point of the spark plug is to make a spark, which is what

ignites the mixture inside the cylinder.

It's like a...it's a miniature bolt of lightning.

That's a good way of thinking of it.

And that's how you stop it

because that shorts out the core of the spark plug to the earth,

i.e. the engine case.

I remember the one we had, when I was a kid, stopping it, like this.

I used to do it with my foot, normally,

and eventually, the little rubber bit wore away cos it was so old

and I put my finger down and did that but, of course, I got

an immediate high-tension shock from the spark plug straight up my arm,

and at the age of 12, or whatever I was, it was the end of the world,

whereas these days, at the age of 53, it would actually kill me.

Let's just take a moment...

..quietly, to contemplate that.

It's taken me seven hours and 39 minutes but I've reassembled

an entire lawnmower engine and now there's no holding me back.

Right, that's that finished. That's an internal combustion engine -

one of two things that, to my mind, defined the 20th century.

That and the microprocessor.

So, right, let's put together the...

What shall we call it? The chassis?

Is that a good word for lawnmower? We need this cast iron.

Lovely. We need these four.

You might think I'm doing this,

thinking, oh, will he get it right? But this is genuine.

I don't know and it's not clear.

I'll just... So that you know, and I'm not sure you've seen this

properly yet, this is all I have to work from -

1950s exploded diagram.

It's not like in the modern world,

where they very helpfully do it in stages so that a numpty can do it.

Here is the whole lawnmower,

one one-hundredth of a second after a bomb went off in the middle of it.

So I will need that bearing block, bearing itself.

Spring - lovely.

This I need.

This is a defining moment.

At the moment, that is some green-painted cast iron and steel,

but as soon as I do that, you know, do you not?

Aha! It's a lawnmower!

Oh, I need to put the roller in, don't I?

Oh!

I thought that would be really heavy.

This one's made of tin.

Now, the roller actually has two purposes here.

One is it's effectively like wheels, so that the lawnmower rolls along

cos if you didn't have it, it would just churn your garden up,

but the other is it does roll the grass in one direction or the other,

which is why a lawnmower like this gives you stripes, and everybody's

absolutely obsessed with the idea that gardens must be stripy.

Grass was lovely, it was stripy.

I actually... I'm not a massive fan of stripes

outside of things like football pitches and so on.

I think if you have stripes on a small lawn on your urban house,

you look a bit of a plonker because what are you trying to say?

"Yes, here's my garden.

"Later on, we'll be having the Super Bowl."

Well, you're not going to, are you, because it's only ten feet long?

So... But anyway, people love stripes.

That will give you stripes. A proper lawnmower,

as this would be called by the lawnmower enthusiasts,

actually slices your grass.

It doesn't chop it, like a rotary mower would.

In some ways, a rotary mower is a bit like an upside down helicopter.

You have the same problem of the advancing blade

and the retreating blade in any one time.

And helicopters, as we know, are like women,

as far as men are concerned because, as a friend of mine said, you know

they work and you trust them but if you make any effort to understand

them whatsoever, you'd be too terrified to go near them.

And if you thought that was sexist,

just look how the new Flymo was advertised in 1965.

-ARCHIVE:

-The rotor blade can be adjusted for height of cut

and the mower is so light, women can use it easily -

something that men gardeners have waited for for a long time.

My lawnmower felt reassuringly heavy

as the second cast iron side plate was fitted.

Piece by piece, bit by bit, it was all coming together.

BEEP

Do you know what? I've got to be brutally honest.

I would say I've got that in back to front

and the long thread should be at that end.

Look how much spare thread I've got on that end

and look how little I have on that end.

It's not right, is it?

Why the bloody hell didn't you say so while I was doing it, then?

Can I just split those enough to get that out without having to

take the whole thing apart again?

See, the problem gets worse now cos there's more threads together.

I'm just wrong, aren't I? Let's face it. I'm wrong.

No, it's all come apart.

CLUNK

What do you think? And if I turn it to there...

..we're ready to contemplate this bit.

And it has to screw on here, which all sounds simple enough,

and is...

You can see slots for doing up the screws.

That's about as tight as I can go before it slips out.

Oh, look at that. Can you see?

Look at the blade skimming along there.

You can see now how it works like a pair of scissors.

According to some 19th century advice, the keenness of the cut

in this was such that it would trim a gentleman's business card.

So, if the makers of this thing are to be believed, this

being my 19th century gentleman's business card, that will cut that.

How brilliant is that?

I love the smell of freshly-cut paper.

Makes me think of spring.

It was now nine hours and 50 minutes since I began reassembling.

I've built the engine, added the cowl and fuel tank,

attached the blades and rear roller and assembled the chassis.

Once the chains and sprockets are on, the transmission is complete.

We are getting close to mounting the engine on the lawnmower.

Let's set it back down on its roller...

..so that we can see it properly.

It is... Ee!

It is quite heavy cos it was made of cast iron, obviously, in the 1950s.

But you have to remember that this was actually

the acceptably convenient size and weight of the lawnmower

cos the very first lawnmowers were so massive, they needed two men

from the working classes to haul them along

and another man just to steer it.

And then later, they were hauled by ponies or horses,

and horses were given special shoes so that they didn't damage

the ground that they were going across -

the cricket pitch or whatever.

And sometimes, they used camels cos camels' hooves have evolved

not to sink into the ground because, obviously,

they normally walk on sand, not on people's expensive lawns.

So you could have two classes of shoe.

I think you could have a first and second-class shoe for your horse to spread the load.

It was all part of the class war.

If you were poor, you could only afford the second-class shoe

and your lawn looked a little bit cack as a result.

If you were posh, you had the first-class shoe,

then your lawn looked wonderful

to remind the neighbours that you were just a better person.

Now, look at that.

The parts of the centrifugal clutch/brackets engine side.

Look how this pile of bits has diminished.

This is fantastic.

This half of the clutch - this is mounted to the engine.

As the engine spins, the centrifugal, or centripetal, if

you want to be pedantic, force will force those out against the springs,

and then the friction surface there will lock onto the inside of that

and start it spinning, but as the engine slows down as you throttle

back, the springs will take over, move the shoes in again, and then

it will be disengaged cos it fits in there loosely, you see?

When the shoes are retracted, that's free to spin.

It's been used on all sorts of things.

It's used on very basic mopeds.

It's used on lots of things, like lawnmowers.

What else uses centrifugal clutches?

Let me think.

Loads of things. Right - engine.

HE GASPS

Look at that! How lawnmowery does that look?

This is suddenly... This is...

After being what seems like half my life as a collection of vaguely

lawnmowery bits, this has now suddenly become a lawnmower.

This is deeply, deeply exciting because once this bit is on...

..we can fit the handle.

The handle!

Putting the handle on is a very exciting moment

but I haven't actually contemplated it yet cos I need to stand back

and see what it looks like with the handle on.

So, hang on, let...let me just tighten it up.

Then I can enjoy that moment.

Oh, yeah!

The lawnmower is almost complete.

As I attach the throttle lever,

it's become apparent how ten hours can fly by

when all you have to do is slowly reassemble a Suffolk Colt 1959

12-inch four-stroke petrol lawnmower from its 331 component parts.

But all of this will have been for nothing

if it doesn't actually start.

There is just one component left.

This one is the grass box.

When this is on, it becomes a complete and utter lawnmower.

There. That's perfect. That's fabulous!

Let's see if it works.

You join us at a very exciting moment outside the workshop,

where we're about to find out

if the freshly reassembled 1959 lawnmower will start.

And this is for real. We haven't tested it in secret.

There hasn't actually been any petrol in it until now.

Let's find out. OK.

Petrol - on.

Choke - on.

Carburettor - tickled.

Throttle - set.

Are you ready?

ENGINE SPLUTTERS Oh!

ENGINE FIRES UP

Of course it works!

It's a lawnmower!

Has anybody got a lawn?