It doesn’t have to be a watch, it could be an old phonograph. I am having a hard time figuring out how they release energy at a controlled speed using a coiled spring that gradually unwinds? I would also be interested in the various applications this has been applied to.
The spring wants to uncoil. That’s the energy. It is not a lot but not a lot is needed.
As the spring unwinds it loses energy. Winding the watch puts energy back in the spring by tightening it up again so it can unwind and power the watch.
The other gears in the watch help regulate how fast the spring can unwind.
Yes, I understand this. What I don’t understand is how a spring that has more tension in the beginning than it has in the end can run at a steady speed, precisely steady speed.
The spring itself has no control. A phonograph or similar system has a governor that controls the speed, and a watch or clock relies upon the escapement to control the rate.
A governor mechanism can be seen in simple clockwork motors as well. Often a simple mechanism is a friction device with a pair of weights that rotate, the faster the mechanism runs the more the weights press on an outer race, slowing the rate down, so it reaches a steady pace.
The mechanism that makes a watch spring unwind at a constant rate is called an escapement. There are a large number of types of escapements, and the development of better escapements played a large part in the improvement of watch design over the centuries.
That’s exactly what I was hoping to hear, are the weights on the governor also spring loaded? The escapement is a fascinating invention. I would like to read more about the inventor.
This is the best explanation of how a watch works that I have ever seen. In fact, this document is so good, it may be the best explanation of anything that I have ever seen. The interactive 3d demos are just astonishing to me. I go through this top to bottom every time I see this site mentioned.
One thing that helps to know upfront - a watch mainspring is not a uniform thing. Totally unwound, you can see that the its curvature varies along its length, with the goal or making the torque delivery from fully wound to almost depleted much more consistent.
The spring needs a small amount of the energy to advance a pendulum catch mechanism or other time interval mechanism like in clocks. As the spring unwinds at some point there’s not enough energy available to keep accurate time. If it’s a catch mechanism the catch won’t release and it stops. With other mechanisms it just slows down and it’s no longer a precisely steady speed.
Without a time interval mechanism a centrifugal governor will use up the spring’s energy rapidly and slow down. I recall something where a governor rotating slow enough would activate a catch to stop until the spring was rewound. Not actually a spring I think, but a weighted line on a pulley.
They might be. Maybe to provide some preload, maybe to do the opposite. Tune to need. It is a pretty basic idea. Rather like clockwork motors in general.
FWIW here is a real simple demo of an escapement doing its thing:
Thank you that makes perfect sense I was having a hard time grasping it until I actually saw the picture
Here’s a video of a mechanical governor in an old record player:
Great video. For those confused, the spring you see there is not the mainspring that powers the watch, but the hairspring or balance spring. The balance spring oscillates at a fixed rate and locks and unlocks the escapement to release the power from the mainspring on a precise schedule.
Yes the balance spring is what I was failing to put into the equation
You may also be interested in researching the fusee, a conic pulley or drum that performs a similar function.
The Ignatz Flying Pendulum Clock uses no catch mechanism or governor on a spring driven clock. The ‘Flying Pendulum’ is not functioning like a common clock pendulum which needs a catch mechanism (escapement) to keep regular time. The weighted string wrapping and unwrapping around a pair or posts produces a regular time interval as the spring unwinds. That terminal is not that precise though, the length of the string needs to be adjusted for changing conditions and the clocks can lose as much as a minute per hour. A sort of teetering wheel would produce a similar time interval in early pre-pendulum clocks.
Yes I have been looking at those lately but they weren’t being used for timing something it would be interesting
Wow. That is an amazing site.
He’s got an incredible talent for explaining complex things by breaking everything down into knowable steps.
Unfortunately, the balance spring is also a spring that unwinds (and rewinds). The period is almost constant, but not exactly constant if it is hit a little harder.
The shape of the mainspring is designed to flatten-out the force of the mainspring, but chronometers (including some expensive watches) may also use “constant force” mechanisms between the mainspring and the escapement, so that the escapement isn’t overdriven. The “fusee” mentioned above is one such mechanism. Another way is to use a secondary spring and escapement, with the primary spring keeping the secondary spring wound as it unwinds. The secondary spring may be just a leaf spring.