How a Mechanical Watch Works

I'm Jake O'Neill creator of anima graphs

and this is how a mechanical watch works

watches have no battery microchip or

circuitry watch parts are machined to

near perfection at microscopic sizes and

tolerances and can produce accuracy

within two to three seconds per day

let's take a high-level view before

diving into specific parts power is

stored in the mainspring and released in

reliable increments by the escapement

assembly the gears that connect the

mainspring and escapement turn at

various speeds allowing the watch to

tell time now let's look at each section

in depth the crown the crown is pulled

out to set the time and pushed in to

wind the watch the setting jumper has

indents to keep the crown mechanism

locked in place

each mode engages different gear sets

when the crown is pushed in for winding

the sliding pinion meshes with a set of

gears connected to the mainspring the

crown is pulled out to set the time when

the crown is pulled outwards the setting

lever clicks into the second indent in

the rigid setting jumper at the same

time this setting lever presses against

the spring-loaded yoke the yoke moves

the sliding pinion into connection with

time setting gears let's see that

transition a few more times

the mainspring the mainspring is a thin

nearly foot long strip of hardened metal

coiled into a spring and contained by

the mainspring barrel it's connected to

the winding pinion at one end and the

mainspring barrel at the other the

winding pinion moves independently of

the barrel a connected ratchet wheel and

click assembly allows the pinions who

rotate in only one direction

keeping the spring from unwinding and

ensuring that spring power can only exit

through the barrel the wheel train the

wheel train drives time keeping hands

and associated wheels the center wheel

is driven by the mainspring barrel and

rotates once per hour

it holds the minute hand and it's 60

minute journey is often divided up into

minute marks on the watch face the third

wheel flows power through to the fourth

wheel the fourth wheel rotates once per

minute in incremental ticks and holds

the seconds hand again marks on the

watch face can make it easier to see how

many seconds have passed within one full

minute long revolution the axle of each

wheel rests in a synthetic jewel bearing

the near frictionless jewels can keep

internal watch mechanics running

smoothly for decades the motion works

the motion works allows watch hands to

be freely rotated for time setting and

also performs a twelve to one speed

reduction for the hour hand since the

center wheel and minute hand rotates

once per hour the hour hand needs to

make a much slower journey completing a

full rotation once every 12 hours as it

passes by our marks on the watch face

this speed reduction is achieved as

power flows from the cannon pinion

through the minute wheel to the hour

wheel the cannon pinion and our wheel

are press fit to the pinions that

support them this means that with enough

force that can be moved for time setting

without disturbing the rigid underlying

wheel train that otherwise drives them


the escapement and balance wheel the

balance wheel swings in a precise rhythm

knocking the pallet fork back and forth

allowing the escape wheel to move which

releases mainspring power in small

metered increments the balance wheel the

balance wheel is the most fragile part

of the watch it's supported by a shock

absorbent mounting system complete with

a jewel bearing and capstone which

protects sensitive parts from impact for

example if the watch is dropped the

balance wheel is partly driven by the

hair spring the escapement the pallet

fork and escape wheel formed the

escapement a clever exchange of power

happens here that forms the heart of

mechanical watch operation

driven by the hair spring the balance

wheel impulse pin bumps into one side of

the pallet fork releasing the opposing

pallet jewel from its locked position

against an escape wheel tooth just as

the pallet jewel slips free the

specially shaped escape wheel tooth

delivers a little impulsive power from

the mainspring through the pallet fork

which in turn pushes the impulse pin

launching the balance wheel into another

swing and so the process repeats as long

as the watch has mainspring power the

hair spring has regulator pins to adjust

the active length of the spring this

alters the balance wheel swing rate and

as such the speed of the entire watch

this is what is meant by regulating a

watch that keeps time too fast or too

slow the characteristic watch ticking

sound is made by pallet jewels as they

catch escape wheel teeth each

incremental escape wheel rotation is

called a beat a common watch beat rate

is 20 1600 beats per hour

which is six beats per second supporting

structure various specially shaped metal

plates support watch internals the main

plate serves as the base


the barrel bridge holds the mainspring

barrel and associated parts the train

wheel bridge supports the wheel train

the pallet bridge holds the pallet fork

and the balance bridge supports the

balance wheel and regulator assembly