Elgin Grade 7, Counting the Train

This watch has an interesting repair in the unjeweled lower pivot hole for the 3rd wheel.

There is a divot right next to the hole. A punch has been used to displace a little brass and close the hole some.

When a watch is run without getting it cleaned, the grit that is dust and old oil grinds away at pivots, making them egg-shaped. Eventually, the wheel will no longer sit straight, and the watch will stop. That must have happened here. Some repairer of old has punched the brass to close the hole, then reshaped it to be more round.

This is the dial side. This watch is key-wind, from the back. The ratchet is on the other side, here.

Here we can see the secondary serial number on the underside of the hour wheel.

These are three freshly made pins for the dial feet. Older American watches have posts on the dials (feet) that stuck through the base plate. These pins get pushed into holes in the feet on the other side of the plate, and thus hold the dial on.

The balance for this watch had *a lot* of extra weight on it. The reason soon became clear.

The hairspring needed a little work. This tool holds the spring by the stud. It's ideal for certain manipulations of the spring.

This watch timed perfectly on the timing machine after removing all that extra balance weight, and fixing the hairspring. But the hands traveled much too fast, which is why all that weight had been added to the balance.

Why?

The rate the watch beats is one thing. How far the hands move with each beat is a function of normal gear ratios. The calculation is called "counting the train". We count the teeth on each wheel, and the leaves on each pinion, and plug the numbers into a formula that tell us how the watch will work.

Skipping the algebra, the formula we're interested in here takes this form...

(el * bph) / (ft * et * 2) = [4th wheel revolutions per hour]

Where...
the 4th wheel carries the second hand. So 4th wheel revolutions per hour should be 60, we hope.
el is escape wheel pinion leaves
bph is the beats per hour
ft is 4th wheel teeth
et is escape wheel teeth
and 2 is....  well 2. This is actually the "teeth" on the next thing in the train, which is the 2 pallet stones.

The watch we have is running at 18000 bph.
el is 7
et is 15
ft is 13

(7 * 18000) / (13 * 15 * 2) is 66.67
That's pretty fast, it works out to 160 minutes per 24 hours fast! But this is a grade 7 Elgin. The records say this design runs at 16200 bph, here:
http://home.elgintime.com/elgintime/GnumLookup/7.html

And...
(7 * 16200) / (13 * 15 * 2) is 60!

Conclusion: This watch has an incorrect hairspring, which acts as a simple pendulum, causing the escapement to cycle at 18000 beats per hour rather than 16200, which the train is geared for. This simply runs the hands too fast and the watch reads incorrectly, even though it is not actually running fast.

Replacing the hairspring is difficult. These parts are rare and very often not identified, or incorrectly labeled (even in factory packages).

In this instance we opted to replace the selected train wheels with Elgin parts for 18,000 bph. The hands then tracked correct time.

This watch is an Elgin grade 7, 18 size, 7 jewels, made about 1883

Information Please!

From The American Horologist magazine, May 1946

Information Please!
Directed by 
W. H. Samelius, Chairman
Science of Horology and Technical Board

ERS: What is elapsed time and what is a dead beat escapement?

Answer. Webster defines "elapse" slip or glide away. Special instruments were made for. the armed forces to show elapsed time. The timepiece has the conventional 24 hour dial with hour minute and second hand. A small dial showing hours and minutes is placed midway from the center of the large dial and the outer diameter of dial.

The hour and minute hand for this smaller dial, or elapsed time dial are controlled by a start, stop and flyback mechanism, similar to the mechanism as we find in the timer watch. When the elapsed time is to be read, the hour and minute hand are on the zero point.

Pressing a button connects the elapsed time train with the regular train, thus setting the hands in motion. Pressing the button again disconnects the elapsed train from the regular train and locks the hands from further motion. Thus, the hours and minutes read from the elapsed time dial is the time accumulated from the starting of the mechanism to the stopping, or the time accumulated from any given point to destination. After reading "elapsed time" the button is pressed once more when the hour and minute hand return to zero position. All this takes place without interfering with the mean time train, or the mean time as shown on the large dial.

The deadbeat escapement was invented by George Graham at the beginning of the 18th Century. It has proved to be very satisfactory for seconds beat clocks such as regulators or clocks employing long pendulums. The deadbeat escapement is designed to give the pendulum a very short arc, around two or three degrees. A short arc of two or three degrees is advantageous in eliminating the circular error that occurs in pendulums taking greater arcs. The escape wheel has pointed teeth, the points leaning forward about 10 degrees. The locking faces of the pallet are ground concentric to pallet the arbor, so when the tooth comes to rest on the locking face of the pallet, the tooth will remain as the pallet or locking face swings into the wheel. The only resistance we have is the pressure of the tooth against the pallet which is constant regardless of the amount of slide or run. There is very little oil adhesion. Usually the dead beat escapement has 30 teeth where the seconds beat pendulum is employed and the pallet embraces 8 teeth. The object of leaning the teeth forward 10 degrees is so the very tip of the tooth rides the face of the pallet, eliminating oil adhesion and I friction.

AK: I hear about hairspring collets poised and also that roller tables are poised. Is someone spoofing me?

Answer: No, no one is "spoofing" you. The practice of poising hairspring collet and rollers has been carried on for many years, especially in the high grade watches. Ordinarily, the roller and roller jewel are attached to the balance wheel when the poising operation is being performed. This is putting the balance in static poise. After placing the hairspring on the balance and putting the balance into motion, we then enter into dynamic poise and even though the balance and roller may appear to be statically poised, it can still be dynamically out of poise for that reason you will find the hairspring collet having been poised by cutting away one side and drilling holes into it so the mass of weight when put into motion will be in dynamic poise. Perhaps you have heard· or know that an automobile engine or some of the running wheels will start vibrating at certain speeds. That is because the weight is not equally distributed dynamically.

HSW: Please explain the difference or meaning of undersprung spring and the oversprung hairspring.

Answer: In the earliest watches, the hairspring was attached to the balance staff under the balance wheel so it vibrated between the balance and the lower plate. This method was more or less conventional in our earliest verge watches and continued with many of the English watches and even some of our early American watches were Undersprung in this manner.

The oversprung spring is the conventional spring as we have it today, the hairspring being attached over the balance and between the balance bridge, which is a great deal more convenient when adjusting.

OP: I lost a cannon pinion for an antique watch and am at a loss to know how many leaves the cannon pinion should hawe so the hands will register properly. There are 40 teeth in the hour wheel, 30 minute wheel teeth and ten leaves in the minute pinion.

Answer. Assuming you have a 12 hour dial, the formula for finding the number of leaves in the cannon pinion will be: Multiply the number of teeth in the hour wheel by number of teeth in the minute wheel. Then multiply the number of leaves in the minute pinion by 12. Dividing the results of teeth x teeth.

(30 x 30) / (10 x 12) = 10

number of leaves for missing pinion.
Proof:

(10 x 10) / (30 x 40) = 12

or 12 revolutions for cannon pinion to one. revolution of hour wheel.

TBT: I have a French clock with cylinder escapement. I removed the escape wheel from the pinion in order to polish the pivots, somehow I lost the escape wheel. What I want to know is how many teeth it had, and how can I select the proper size 1

Answer: Generally speaking all cylinder escapements have 15 teeth. When selecting the size of escape wheel, place the escape wheel directly over the escape pivot hole so the hole in the wheel and jewel hole coincide. Then select a wheel large enough so when the tooth is passing by the balance pivot hole, the pivot hole in the' jewel will be half way up the incline of the tooth. In other words, half the impulse angle of the escape tooth should be inside the hole and the other half outside. You will find on all cylinder escapements, means for adjusting. The balance bridge is attached to a lower bridge or chariot. This chariot is attached to the lower side of the plate, having a lower balance hole jewel. By loosening this chariot, both the chariot and balance bridge can be moved forward or backward from the escape wheel so proper impulses and a safe drop lock can be acquired. The escape wheel tooth must drop on the outside of the cylinder safely close to the impulse edge. In other words, the cylinder escapement has drop, lock and slide similar to the lever escapement.

DL: I would like to know how to true a mainspring barrel.

Answer: The writer assumes the barrel is out of flat causing it to rub the center wheel or bind between the plates. It is possible that you did not replace the barrel cover to its fixed position, as in many hand made watches the parts are marked for location, that is, the cover and the barrel are marked with dots so when the cover is replaced these dots must n be opposite each other. Sometimes they are called locating marks. If this is not your trouble, more than likely the cover has been damaged and needs repairing. To repair the cover and get the barrel to run true in the flat, the following procedure will be helpful.

First see that the cover snaps safely into place. If not, you may have to undercut the snap edge of the barrel and possibly stretch the cover by lightly hammering the cover along its edge on the underside. This operation must be carefully and slowly done so as not to overdo it. When the cover has been prepared, then open the hole in the center a liberal amount and fit in a blind bushing or solid plug. Next, cement the barrel to a cement chuck that runs perfectly true in the flat and center the barrel hole so it runs perfectly true in the round. Snap the cover to its proper position, drill and bore a hole through the bushing to fit the barrel arbor. If this is carefully carried out, the barrel will run perfectly true in the flat once more. If you have a slide rest, you may use that with a boring tool which is more convenient and safer to use than trying to bore the hole in the cover by hand. 

A Charles Stark Mystery Train

This unusual pocketwatch had an unusual problem.  This watch is an 18 size, 7 jewel movement labeled "Charles Stark".  More about that here...

At first this project seemed straight forward.  All the parts are here, nothing is broken.

The movement cleaned up well and ran.  Good end-shake and side-shake through-out, good pallet, everything was fine.  It timed well on the timing machine also, reading at less than +/- 30 seconds per day at 18,000 BPH (beats per hour).

My last step in watch testing is to run each watch for several days in various orientations; dial up, dial down, hanging, etc.  I didn't expect any issues with this watch.  But it turned out to be one of my more difficult and puzzling projects.

While the movement tested fine on the machine, it ran consistently fast, very fast, or so it seemed.

My first reaction was of course to recheck everything, especially the hairspring.  It was all fine.  I ultimately disassembled and reassembled this watch several times finding no problems.

Finally in desperation, I counted the teeth on the wheels, and the leaves on the pinions.

For a bit of background here, it may be helpful to refer back to this post on counting the train.  Watches operate by regulating, slowly releasing at a certain beat rate, a power source through a set of gears.  These gears, or wheels, have ratios such that hands attached to the right gears rotate at a rate we recognize in seconds, minutes and hours per day.  It isn't magic, it's mechanics.

These are the count values for this movement.

Great Pinion: 10
Great Wheel: 65
3rd Pinion: 8
3rd Wheel: 60
4th Pinion: 8
4th Wheel: 70
Esc Pinion: 8
Esc Wheel: 15

The 4th wheel's revolutions per hour is therefore:
( 18,000 * 8 ) / ( 70 * 14 + 2 ) = 68.57

The 4th wheel is the seconds hand.  This should be 60 revolutions per hour, one per minute!

But is gets worse.  If we calculate the rate of the center wheel:
(8 * 8 * 68.57 ) / ( 65 * 60 ) = 1.57

At 18,000 BPH, this leaves an erroneous rate of the center wheel, which is to say the minute hand, of 1.57 revolutions per hour.  That's +180.4 minutes per 24 hours on the hour and minute hands!  But that's only the beginning.  The error on the second hand is not relatively the same as that of the minute and hour hands.  In other words even if we did awful things to the balance wheel to shift the rate away from 18,000 BPH to the point where the main hands read OK, the seconds hand would go around a bit more than one time per minute.

This watch's train contains incorrect parts.

In fact, it contains more than one incorrect part.  The strange thing though is that this watch "ticks" fine - quite well in fact.  Because of the geometry of the way gears work, all possible combinations of tooth and pinion counts will not all run smoothly in practice.  They have to mesh well.  This is why any 18,000 BPH movement, with a seconds hand, will tend to have the same counts.  This movement's combination also runs fine at 18,000 BPH, but it is physically impossible for the hands to read correctly.

For comparison, here are the values of the train counts for a typical 18 size Elgin pocketwatch, non-slow beat.

Great Pinion: 12
Great Wheel: 80
3rd Pinion: 10
3rd Wheel: 75
4th Pinion: 10
4th Wheel: 80
Esc Pinion: 8
Esc Wheel: 15

Fortunately, this watch's train layout is very similar to other American watches or this size and era.  The height, the distance between the plates, is a bit atypical in places, but the layout is common.  It was a bit of work but I was able to swap to wheels with replacements having different counts.  The wheels only had to be altered a small amount for a good pivot size and for the height of the movement.

I replaced three wheels for an atypical count, but one that worked out to give the correct time readings at 18,000 beats per hour.

There's more about this mysterious watch here.

These additional images show the lever-setting mechanism.

Train Counting

First, some terminology...

The train of a watch is made up of wheels and pinions, each on an axis, or staff. The pinion the the small part on the inside, and the wheel generally is the large part. Wheels have teeth. Pinions have leaves.  The train starts with the mainspring barrel, then the center wheel (or great wheel), then the third wheel, the fourth wheel, and finally the escape wheel.  In this image, the center wheel is the large wheel at the left.  The train goes clockwise up and to the right from there, in the picture.

Looking at this next view, we see the mainspring barrel at the left, the center wheel in the center, and so on, pinion to wheel, to pinion, to wheel, etc.  

The third wheel is a bit tucked away and hard to see in this photo.

As an aside, this watch has a "motor barrel."

Next, this is a different movement, with a different layout.  The design is the same.

This watch has a "going barrel."

Counting the Train

Here's a commonly used equation to get started.

n1 is the number of revolutions of the center wheel per hour. This is almost always one, this is the minute hand.

n4 is the number of revolutions of the 4th wheel per hour. This is almost always 60, this is the seconds hand.

z1 is the number of teeth on the center wheel.

z2 is the number of leaves on the third wheel pinion.

z3 is the number of teeth on the third wheel.

z4 is the number of leaves on the fourth wheel pinion.

n4    z1 * z3

-- = ---------

n1    z2 * z4

This equation gets to a watch that reads correctly, that is the minute and hour hands are in sync with the seconds hand.  For this we don't care about the number of teeth on the barrel, nor the number of leaves on the center pinion.  This is because time reading begins at the center wheel; it is the minute hand.  

Considering the rate take a little more work.  

"Fast-beat" vintage American watches beat at 18,000 beats per hour, or 2.5 Hz. One way to observe this is the fact that for each second, the second hand jumps five times.

 z6 * 18000

------------- = 1

 z5 * ze * 2

z5 is the number of teeth on the forth wheel.

z6 is the number of leaves on the escape wheel pinion.

xe if the number of "teeth" on the escape wheel.

This equals one because one is the number of revolutions per hour of the center wheel (n1 above). Because of the action of the pallet stones the number of foot-shaped teeth on the escape is multiplied by two.

There's another way to look at this, by fixing the number of revolutions per hour of the 4th wheel (the seconds hand) to 60.

 60 * z2 * z4

-------------- = 1

   z1 * z3

And there you have it.  Pinion leaves are on the top, wheel teeth are on the bottom.

Why worry about this?  Simple, every now and then an obscure watch will be missing a part.  Using the above, and some algebra, it is possible to figure out what the part should be like.  Sometimes, if the balance is missing, we won't know what the beat rate should be.  If the train is there it can be calculated.

Analyzing the Watch Train

From The American Horologist magazine, February 1939

Analyzing the Watch Train
By W. H. Samelius

QUITE often we find a watch that stops at regular intervals and by understanding the watch train as to relationship of gear ratios to one another, we can readily tell where to locate the cause of the trouble. Let us take the accompanying diagram of an ordinary watch train where the balance wheel vibrates 18,000 per hour.

The barrel has 72 teeth and the center pinion 12 leaves, so for each revolution of the barrel the center pinion makes 6 revolutions, or, for each turn of the mainspring the watch would run 6 hours and in order to have the watch run for 36 hours it would be necessary to have as many turns of the mainspring as 6 is contained in 36 or 6 turns of spring driving the mainspring barrel 6 revolutions.

The mainspring must not be too long or too short, for in either case it cannot drive the barrel the full number of turns required. Since we find the barrel revolves one turn each 6 hours, it is obvious where a watch gives trouble or falls off motion each 6 hours, the barrel may be the cause. It may be out of flat, out of round or may have a damaged tooth.  

Following up we find the center pinion makes one revolution per hour and naturally, a watch that stops or shows poor motion hourly tells us to look for our trouble at the center wheel. This wheel may be out of flat, rubbing a plate, or, it may be out of round, or, like the barrel, have a damaged tooth.  We also might look to the cannon pinion which is attached to the center arbor, making one revolution per hour. It is possible the cannon pinion may be out of round, binding on the plate or have a broken tooth. A cracked center pinion, or center pinion out of round may also cause trouble. If the center pinion has 12 leaves, one leaf passes through the barrel each 5 minutes so we can look to the center pinion should the watch stop each 5 minutes or the motion of the balance fall off.

Sometimes we find the center arbor out of upright causing the hands to rub on the dial on one side and directly opposite the minute hand will rub on the glass, in both cases create friction enough to slow up the motion of the balance, or possibly stop the watch entirely.

Continuing further through the train we find the center wheel has 64 teeth and the 3rd pinion 8 leaves. If the center wheel makes one revolution per hour, the 3rd pinion will make 8 revolutions per hour or one revolution every 70 minutes so a watch stopping or falling off motion each 7 1/2 minutes tells us to look for our trouble at the 3rd wheel, which like the other wheel, can be out of round, out of flat ·or have a damaged 3rd pinion.

The third wheel has 75 teeth and the 4th pinion 10 leaves and while the 3rd wheel is making one revolution, the 4th pinion is making 7 1/2 revolutions and while the 3rd wheel is making 8 revolutions per hour the 4th pinion will make 8x7 1/2 or 60 revolutions per hour or one revolution per minute, so a watch falling off motion each minute or stopping each minute shows our trouble lies in the 4th wheel or pinion.

The 4th wheel has 60 teeth and the escape pinion 6 leaves, so when the 4th wheel is making one revolution, the escape pinion is making 10 revolutions per minute, the escape wheel having 15 teeth and as each tooth of the escape wheel delivers two impulses, each revolution of the wheel then will give 30 impulses and as the escape wheel makes 10 revolutions per minute there will be 10x30 or 300 vibrations per minute the balance makes and multiplying this by 60, the number of minutes in the hour we will have 60x300 or 18,000 vibrations per hour, a watch that is commonly known as a quick train.

As was stated above, the cannon pinion has 10 leaves and we find the minute wheel has 30 teeth so as our cannon pinion makes one revolution per hour, the minute wheel would make 30 divided by 10 or one revolution in three hours.  Continuing we find the minute wheel pinion has 8 leaves, and the hour wheel has 32 teeth which is a gear ratio of 4 to 1 so while the cannon pinion is making one revolution, the minute wheel is making 1/2 revolution, and the hour wheel is making one-fourth less or 1-12th revolution, so it is possible to find trouble in the hour wheel and minute pinion when the watch stops each hour, or, should it stop each 12 hours it would indicate the hour wheel is out of round, out of flat, or may be binding between the plates. It might also indicate the dial being off center, the hour hand binding on one side of the opening each 12 hours.

I trust these suggestions will be helpful to our readers.