HOW IT WORKS: Mechanical Watch

to understand what goes on inside a watch let's make a simple device that will keep time now let's see what these four elements are like our watch first we'll take our watch apart like this we'll begin with this part the mainspring and barrel assembly and so we can see everything that goes on inside let's use giant parts to make a watch model this is the main screen and it lives inside the mainspring barrel the mainspring is the powerplant of the watch the source of power like the faucet in our water clock by winding the spring we can store up energy here is a winding stem with gears and a click to keep the spring from unwinding and here is the unit that controls the flow of power like the nozzle on our hose it is called the balance wheel and hair spring assembly it consists of the balance wheel hair spring balance staff or axle fastened to the balance staff is a part called a roller to the roller is attached an upright dual pin let's see how these work together a push on the dual pin will start the balance wheel moving and more pushes will keep it moving to do this job of pushing we need this odd anchor shaped lever called a pallet it can be mounted so that when we move the pallet back and forth we can apply a series of impulses to the dual pin to keep the balance wheel in motion now to the pallet cross-arm we add a pallet jewel shaped like this here is a wheel called an escape wheel with teeth on it so shaped that they will push the pallet jewel and jog the balance wheel into motion now we'll use the energy stored up in our mainspring to drive the escape wheel as the mean spring on coils it causes the barrel to rotate with it that didn't last long did it let's try it again once things get started there is nothing to stop them what we need now is a way of holding the power in check releasing it a little at a time just when it's needed another power joule at the other end of the power cross arm will do the trick just as the first pellet jewel gets a push from the escape wheel the second power jewel locks against another tooth of the escape wheel to hold the power of the mainspring in check but the balance wheel keeps swinging and the jewel pin moves the fork end of the pallet until the escape wheel is again unlocked but when we connect the mainspring directly to the escape wheel the power is soon exhausted in an actual watch it would last only a few seconds what we need is a way to stretch the power so it will last for more than a day in our water clock we used a hose to transmit power from the faucet to the nozzle we also need a way to transmit power here so let's add a system of gears and wheels we'll stretch them out in a line instead of in their usual closely confined location in a watch look at the gears a moment and see what they do first a small partial turning of the mainspring barrel drives the center wheel a complete revolution a partial revolution of the center wheel drives the third wheel a complete revolution and this in turn drives the fourth wheel much further as a result a few turns of the mainspring barrel driven by the mainspring will drive the escape wheel many many revolutions enough to last a full day and longer what we have now is a complete model watch train through the gears the mainspring drives the escape wheel the escape wheel teeth push first on one power jewel and then the other the power fork nudges the jewel pin on the balance wheel to keep it moving the swinging balance wheel on its return trip moves the power fork this unlocks the escape wheel to release a little more energy from the mainspring back and forth the balance wheel swings controlled by a small coiled spring the hair spring in perfect rhythm each swing unlocks the escape wheel so it can give an extra push to a pallet jewel and this is passed on to the balance wheel assembly to keep the watch ticking far more steadily than any beating heart all we have to do now to measure time is count the ticks but this would be a tedious job and not very practical just as we needed a dial on our water clock here too we need a method for recording the flow of power so to the shaft of this gear or wheel we add an indicating hand to measure seconds as the gear train of a watch moves far enough to make five ticks of the escapement the second hand moves one graduation on its dial to count the minutes we can attach a dial and fasten a pointer to this gear wheel which is just the right size so that it turns one complete revolution while the second hand makes 60 revolutions and to count the hours we can have another pointer geared just so to move one complete revolution every 12 hours the second hand makes a complete revolution and the minute hand moves one graduation and from the minute hand makes a complete revolution than hour has passed now we can tell what time it is but a gear train all strung out like this is a long way from an actual launch let's let our model do a bit of rearranging all by itself now we know what time it is and how and why we know a fine watch itself is of course a compact precision mechanism with parts miraculously small and fashioned by craftsmen with incredible accuracy but the basic principles are those we have just seen frequently applied on a scale almost microscopic to produce the world's most accurate portable measuring instrument in a truly fine wash there are many things which make possible the accurate control and release of power jewels for example many people correctly believe jewels increase the value of a watch they increase the value alright but not by being ornamental jewels are in a watch strictly for business they add to the value only when correctly placed and used they are the bearings which lessen friction increase the regularity of the running and greatly extend or watch's life of dependable service harder than the finest steel these tiny services are finished so smoothly they reflect images like a camera lens and working with oil it takes a drop no larger than a pinhead for the entire watch there is almost no friction if any single part of a watch can be called more important it's the hair spring it absorbs and gives out an equal amount of force with each beat or swing as regular intervals in a fine watch the hair spring has uniform thickness throughout its whole length is polished to a mirror-like finish and made of metal relatively unaffected by magnetism or changes in temperature it can be apparently distorted but it always returns to perfect shape hair Springs are over coiled like we see here to allow the spring to breathe evenly were this not done the spring would coil and uncoil unevenly fluff out on one side and interfere with the accuracy of the watch because of watch is required to run in any position to be accurate the balance wheel must be perfectly balanced in any position this is done by poising the wheel is poised when there is no effect of the pull of gravity reflected in its action on the knife like edges of the instrument which checks it with perfect poising and with the hairspring centered on the balance wheel it runs accurately in any position all the time and it's the same with all the parts the tiny screws scarcely larger than a speck of dust the exceedingly small shafts the precisely made gears and pinions the sturdy nickel silver plates and bridges every part is made with utmost precision precision which approaches perfection when we look at the almost invisible parts understand what they are required to do realize the uncanny skill needed to make a fine watch we can easily understand why it is a masterpiece of precision and accuracy here is a truly wonderful mechanism with it you can accurately measure the passing of time and record that passing or your use and convenience but this mighty little servant is a creation of beauty - a precious possession to be worn with pride and competence every day every week every month year after year listen what do you hear is the ticking of a fine one wherever you go whatever you do America's fine watch tick steadily accurately on five ticks every second

Channel: DOCUMENTARY TUBE

Views: 1,855,486

Keywords: clock, engineering, physics, device, things, mechanics

Id: G1XBb7kJJWg

Length: 13min 59sec (839 seconds)

Published: Wed Dec 24 2014