Thread: Understanding and repairing automatic movement.. Diagram in hand.. long read

Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. #1
    Member
    Join Date
    Dec 2011
    Posts
    32

    Understanding and repairing automatic movement.. Diagram in hand.. long read

    I have a Seiko 5 with a 7009 movement. when i initially received it, it had a pretty short reserve, definitely less than 24 hours. It kept time pretty well. For the past few days, it would run a little slow, losing about a minute an hour. Today I started wearing it at 7am, periodically looked checked the time and it was okay up until about 2pm. at 4pm, the watch was 5 minutes behind, at 4:45 the watch was alomst 20 minutes behind..

    So i got home, opened the case, and found a service manual online with an exploded diagram. This was a cheap watch so I have no problem tearing it apart with the use of this manual. I was able to learn a lot more about mechanical movements (knew almost nothing other than winding would power the watch). I have one question about the balance wheel and balance spring.

    My balance wheel has a little (what i believe is a) jewel located right around the center of the wheel, much like the black piece at the 9-10 oclock position in the picture below:


    To my understanding, the jewel on the balance spring, hits the little two pronged fork on the pallet which in turn, pushes the escapement. as the balance wheel oscilates back, it hits the fork on the other side. This little contact initiates the escapement to turn a bit more at a faster angular velocity than the first time, which pushes the pallet, which gives a little shove to the already spinning balance wheel. this shove maintains the oscillating motion of the balance wheel.

    Please correct me if I am wrong.

    said pallet:


    So now, I have my questions: what gives the balance wheel the initial "kick start"?
    Can anybody diagnose the symptoms in the first paragraph?


    Now for part 2: I opened the watch and began taking things off on the non-face side. This is how i came to my above conclusions of the operation of the watch. I used the following manual:
    http://service.seiko.com.au/i/seiko/...ides/7009A.pdf

    now on page 3, I turned the ratchet wheel screw (35) which is connected to the barrel with the main spring. I turned it clockwise and started to "manually" wind the watch. Of course, it did not unwind. thus my next question is what was holding the main spring from unwinding instantly? was it one of the jewels (entry/exit) pallets?

    Also, I took out the balance cock, wheel, and spring. when i tried to put it back, I was unsure of whether or not the spring needed to be slightly wound (therefore providing a bit of tension). what is the orientation of the wheel when it is placed back in the movement? Should I let the wheel sit in its equilibrium state then put the balance cock on?

    I know this was an incredibly long read but I am actually very excited to be learning about movements. If you're still reading, thank you for bearing with me and for your time.

  2. #2
    Member
    Join Date
    Sep 2012
    Location
    Maine, USA
    Posts
    153

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    ...let me see if I can offer some help (I'm sort of in your position). The first thing that comes to mind with your problem (and most of the experts will probably agree with this) is that the movement probably needs to be completely disassembled, cleaned, and re-oiled. That is probably best left to someone who has done it a few times at least.

    >>now on page 3, I turned the ratchet wheel screw (35) which is connected to the barrel with the main spring. I turned it clockwise and started to "manually" wind the watch. Of course, it did not unwind. thus my next question is what was holding the main spring from unwinding instantly? was it one of the jewels (entry/exit) pallets?>>

    ...the short answer to that would be part 42 on page 3. Every watch has such a 'click' in any of a variety of designs; its purpose is to allow part 36 (barrel wheel, here called a 'ratchet wheel') to turn in only one direction and lock it tightly from turning in the other. This allows for winding the mainspring from the center through the barrel wheel and arbor while preventing it from unwinding. In an automatic (aka 'self-winding') movement such as this one, there is also the rotor assembly (parts 25, 26, 27, 40 and 41) that also drives the barrel wheel from natural wrist motions. Because of this, the mainspring inside the barrel is a special type. The outer end of the mainspring has a 'bridle' that normally grips the inside of the barrel, but as the mainspring winds up, eventually the bridle will slip and allow the mainspring to unwind slightly. It is designed that way to prevent overwinding, as there is the potential for that to happen from that 'self-winding' action.

    ...The whole purpose is to have the mainspring unwind slowly and in a controlled manner. This is accomplished through the 'time train' which consists of the barrel (44, which could also be thought of as the 'first wheel'), the center wheel (49, which could also be thought of as the 'second wheel'), the third wheel (45), the fourth wheel (43), the pallet ('escape') wheel (46), the pallet fork (34) and the balance wheel (31). The mainspring inside the barrel provides the power to drive the train as it tries to unwind itself; since the center of the mainspring is prevented from unwinding by the barrel wheel and click, the only way it can do this is through the train. The pent-up power of the mainspring (aka potential energy) is transferred through the train, but it is blocked by the pallet fork, which locks the pallet wheel and prevents any further release of energy. The speed and 'amplitude' (distance of rotational travel) of the balance wheel controls the rate of release of energy and thus sets the timing. Each time the jewel on the balance wheel engages and moves the pallet fork, the pallet wheel momentarily unlocks and moves a small amount until the pallet fork moves to its other side and locks the pallet wheel again. Each time the pallet wheel momentarily unlocks, a portion of the released energy is transferred back through the pallet fork to the balance wheel (called an 'impulse') as the tooth of the pallet wheel runs up the angled surface of the entry or exit pallet jewel. This 'impulse' is the 'nudge' that keeps the balance wheel moving back and forth. Now, if you know anything about mechanics, you would recognize that each wheel in the time train is driving a smaller wheel (pinion) on the next wheel. This multiplies the rotating speed of the driven wheel, but reduces the power being transferred (known as a 'negative mechanical advantage'). As this happens four times, the power that actually gets to the pallet wheel is much less than that of the mainspring. And any friction in the train, such as dirty or gummed-up pivot jewels, will interfere with that power transfer, which could be showing up as your loss of reserve...

    ...you want to be very careful of that spring (hairspring) on the balance wheel; you don't want to do anything to it that will bend or kink it, as that will throw off its timing and adversely affect accuracy...so I don't think 'pre-winding' it when trying to put the balance back in is a good idea...

    ...now, that's my somewhat basic understanding of the workings. I will defer to the real experts for better answers...

    ...I only wish I could find a manual like that for my AS 5008 movement ...
    Last edited by ZedU54; December 8th, 2012 at 06:23.
    '...we've got the 17 Jewels that dictate the rules...'

  3. #3
    Member radger's Avatar
    Join Date
    Nov 2007
    Location
    N.E England
    Posts
    2,936

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Zed, that is a great, in-depth answer and explains in some detail the workings of
    an automatic mechanical watch.

    You obviously know your stuff and I'm curious as to your use of the term 'Pallet Wheel' in
    place of escape wheel.
    Is this a term used by U.S enthusiasts?
    I swear that is the first time I've saw that alternative name for the escape wheel used ever.

  4. #4
    Member lysanderxiii's Avatar
    Join Date
    Oct 2006
    Location
    N 32 deg, 47' 27.9168"; W 79 deg, 54' 30.3372"
    Posts
    8,142

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Quote Originally Posted by Jonpwn View Post
    ...it had a pretty short reserve, definitely less than 24 hours.
    Weak mainspring...old age.

    Quote Originally Posted by Jonpwn View Post
    My balance wheel has a little (what i believe is a) jewel located right around the center of the wheel, much like the black piece at the 9-10 oclock position in the picture below:


    To my understanding, the jewel on the balance spring, hits the little two pronged fork on the pallet which in turn, pushes the escapement. as the balance wheel oscilates back, it hits the fork on the other side. This little contact initiates the escapement to turn a bit more at a faster angular velocity than the first time, which pushes the pallet, which gives a little shove to the already spinning balance wheel. this shove maintains the oscillating motion of the balance wheel.

    Please correct me if I am wrong.

    said pallet:


    So now, I have my questions: what gives the balance wheel the initial "kick start"?
    When the balance is in the neutral position, and the pallet fork centered, the two pallet stones will be held in a position where neither is locked by the escapement wheel teeth. As long as there is no load on the escapement wheel, this will be the static position. As soon as there is a load on the escapement wheel (you wind the watch) one of the two pallet stones will be forced into locking position. This will move the fork against one of the banking pins and push the balance into motion.

    If, however, the movement is badly out of beat, the neutral position of the balance may allow one of the pallet stones to be locked and the movement will not self start. Because of this fact, you can get an out-of-beat movement into beat without a timer.

    Quote Originally Posted by Jonpwn View Post
    Can anybody diagnose the symptoms in the first paragraph?
    see above
    Quote Originally Posted by Jonpwn View Post
    Now for part 2: I opened the watch and began taking things off on the non-face side. This is how i came to my above conclusions of the operation of the watch. I used the following manual:
    http://service.seiko.com.au/i/seiko/...ides/7009A.pdf

    now on page 3, I turned the ratchet wheel screw (35) which is connected to the barrel with the main spring. I turned it clockwise and started to "manually" wind the watch. Of course, it did not unwind. thus my next question is what was holding the main spring from unwinding instantly? was it one of the jewels (entry/exit) pallets?
    yes

    Quote Originally Posted by Jonpwn View Post
    Also, I took out the balance cock, wheel, and spring. when i tried to put it back, I was unsure of whether or not the spring needed to be slightly wound (therefore providing a bit of tension). what is the orientation of the wheel when it is placed back in the movement? Should I let the wheel sit in its equilibrium state then put the balance cock on?.
    Normally, I have slight tension on the mainspring, so when the impulse jewel gets in the pallet fork and the pivots in there places, the movement takes off. This lets me know everything is in its place correctly. But, if you don't have tension on the mainspring, it won't matter.
    Parit enim conversatio contemptum; raritas conciliat admirationem.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

  5. #5
    Member
    Join Date
    Sep 2012
    Location
    Maine, USA
    Posts
    153

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Quote Originally Posted by radger View Post
    Zed, that is a great, in-depth answer and explains in some detail the workings of
    an automatic mechanical watch.

    You obviously know your stuff and I'm curious as to your use of the term 'Pallet Wheel' in
    place of escape wheel.
    Is this a term used by U.S enthusiasts?
    I swear that is the first time I've saw that alternative name for the escape wheel used ever.
    ... *turning ten shades of red*...no, that was a simple screw-up on my part. 'Escape wheel' it is; I got it and the 'pallet fork' sort of mixed up. I still have a few problems getting the terminology specific to watchmaking straight. I mean, let's see...inside a watch, you can have a 'movement', a 'caliber' or an 'ebauche'...which is it? ...and the moving parts are not 'gears', they're 'wheels' (even though they look and act for all the world like gears!)...I guess in the world of watchmaking, it can walk like a duck and quack like a duck...but you're supposed to call it a goose...
    ...now, realize that I am not a watchmaker, but I do understand basic mechanical principles and have worked with all sorts of small mechanisms (tape decks, VCRs, and such, for example) and I have successfully torn down and reassembled some mechanical clock movements (same principles as mechanical watches, just the parts are a lot larger and easier to work with). These things have always interested me to some degree since I was quite young (almost as much as electronics, which I gleefully worked in for years), and that includes watches, too. Since I myself picked up an automatic watch with a few issues (mostly the day/date mechanism) a few months ago, I have done some reading (as well as joined this forum) to get some ideas on how to resolve the issues...and learned things in the process. I also have little difficulty reading and following diagrams such as the one the OP included in his post, which helped me greatly in formulating my answer...it's a lot like reading an electronic schematic and I've done that for years...

    ...edit: now, while I was writing this, one of the experts responded to the OP, and I can see where there are flaws in my explanation. So as I said, it may be better to defer to them for better or more specific answers...
    Last edited by ZedU54; December 8th, 2012 at 16:44.
    '...we've got the 17 Jewels that dictate the rules...'

  6. #6
    Member lysanderxiii's Avatar
    Join Date
    Oct 2006
    Location
    N 32 deg, 47' 27.9168"; W 79 deg, 54' 30.3372"
    Posts
    8,142

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Quote Originally Posted by ZedU54 View Post
    ...you can have a 'movement', a 'caliber' or an 'ebauche'...which is it? .....
    Ébauche (from French) meaning blank, outline or sketch, is an incomplete and unfinished movement missing the regulating parts, balance assembly, pallet etc...

    Movement - that part of the watch that actually measures time through the movement of the mainspring. (technically not to be confused with "module" which is the quartz equivalent. Many, myself included, use the word movement as well when referring to a quartz "module")

    Caliber (from French, calibre)- the diameter of a round or cylindrical body, since most movements are round, this term has come to mean not only the size but type and particular design of movement.

    Chablon (from French) - an ebauche sold with the regulating parts, ie a complete movement kit. (chablonnage, the act of selling chablons, frowned upon by the Swiss during the 1930s)
    Last edited by lysanderxiii; December 8th, 2012 at 18:27.
    Parit enim conversatio contemptum; raritas conciliat admirationem.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

  7. #7
    Member radger's Avatar
    Join Date
    Nov 2007
    Location
    N.E England
    Posts
    2,936

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Quote Originally Posted by ZedU54 View Post
    ... *turning ten shades of red*...no, that was a simple screw-up on my part. 'Escape wheel' it is; I got it and the 'pallet fork' sort of mixed up. I still have a few problems getting the terminology specific to watchmaking straight. I mean, let's see...inside a watch, you can have a 'movement', a 'caliber' or an 'ebauche'...which is it? ...and the moving parts are not 'gears', they're 'wheels' (even though they look and act for all the world like gears!)...I guess in the world of watchmaking, it can walk like a duck and quack like a duck...but you're supposed to call it a goose...
    ...now, realize that I am not a watchmaker, but I do understand basic mechanical principles and have worked with all sorts of small mechanisms (tape decks, VCRs, and such, for example) and I have successfully torn down and reassembled some mechanical clock movements (same principles as mechanical watches, just the parts are a lot larger and easier to work with). These things have always interested me to some degree since I was quite young (almost as much as electronics, which I gleefully worked in for years), and that includes watches, too. Since I myself picked up an automatic watch with a few issues (mostly the day/date mechanism) a few months ago, I have done some reading (as well as joined this forum) to get some ideas on how to resolve the issues...and learned things in the process. I also have little difficulty reading and following diagrams such as the one the OP included in his post, which helped me greatly in formulating my answer...it's a lot like reading an electronic schematic and I've done that for years...

    ...edit: now, while I was writing this, one of the experts responded to the OP, and I can see where there are flaws in my explanation. So as I said, it may be better to defer to them for better or more specific answers...

    No probs Zed, we all get confused with terminology when learning any new discipline and your term 'Pallet Wheel' was
    new to me s'all, I though an 'Americanism' had crept in and had passed me by.

    Your post was good, you packed a lot in there, you show a good understanding and I'm sure you helped the OP.

  8. #8
    Member
    Join Date
    Sep 2012
    Location
    Maine, USA
    Posts
    153

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Quote Originally Posted by lysanderxiii View Post
    Ébauche (from French) meaning blank, outline or sketch, is an incomplete and unfinished movement missing the regulating parts, balance assembly, pallet etc...

    Movement - that part of the watch that actually measures time through the movement of the mainspring. (technically not to be confused with "module" which is the quartz equivalent. Many, myself included, use the word movement as well when referring to a quartz "module")

    Caliber (from French, calibre)- the diameter of a round or cylindrical body, since most movements are round, this term has come to mean not only the size but type and particular design of movement.

    Chablon (from French) - an ebauche sold with the regulating parts, ie a complete movement kit. (chablonnage, the act of selling chablons, frowned upon by the Swiss during the 1930s)
    ...ah. That does help clear things up some. The terms 'movement' and 'caliber/calibre' are used almost interchangeably...

    ...BTW, I also tend to think of quartz 'modules' as 'movements' if they are quartz/mechanical 'hybrids' (because there is still some sort of 'time train' in there, even if it is being driven by a quartz-referenced stepper motor; you could say that the typical 32.786 kHz quartz crystal that it runs off is analogous to a 118-million-beats-per-hour mechanical balance wheel--which would be physically impossible to make)...I think of a 'module' as a strictly digital assembly, with the digital display and no moving parts...
    '...we've got the 17 Jewels that dictate the rules...'

  9. #9
    Member
    Join Date
    Sep 2012
    Location
    Maine, USA
    Posts
    153

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    Quote Originally Posted by radger View Post
    No probs Zed, we all get confused with terminology when learning any new discipline and your term 'Pallet Wheel' was
    new to me s'all, I though an 'Americanism' had crept in and had passed me by.

    Your post was good, you packed a lot in there, you show a good understanding and I'm sure you helped the OP.
    ...well...I thank you very much for your vote of confidence ...
    '...we've got the 17 Jewels that dictate the rules...'

  10. #10
    Member dacattoo's Avatar
    Join Date
    Jan 2011
    Location
    Stevensville, Montana
    Posts
    1,079

    Re: Understanding and repairing automatic movement.. Diagram in hand.. long read

    what gives the balance wheel the initial "kick start"?



    When the escapement is at rest, in other words the balance wheel is not in motion, and there is no power applied to the train meaning the mainspring is totally unwound, the pallet lever will be, if properly adjusted, will be centered between the banking pins. In addition, the teeth of the escape wheel will not be in contact with the pallets. On the other end of the lever the impulse jewel will be centered in the fork. When power is applied, the mainspring is wound, the escape wheel advances and engages the pallets. This causes the lever to move to one side. On the fork end the fork hits the impulse jewel and the balance wheel moves. When it has gone as far as it can it returns and the process starts all over again. Now if the lever is out of beat or in other words not centered between the pins, the engagement of the escape wheel teeth and pallets will not result in the impulse jewel receiving sufficient force in which to get the balance wheel to begin oscillating. Often moving the watch gently to get the balance to move can be enough to start the watch in this case but this is not an acceptable substitute for being "in beat". There is a great more description that I have left out and can be discovered studying the lever escapement. I encourage newbies to do so. It is probably the least understood aspect of watchmaking and one of the most important.

Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •