Hamilton 992B Railroad Pocket Watch, Hamilton Railway SpecialThe Hamilton 992B Railroad Pocket Watch, Hamilton Railway SpecialThe Hamilton grade 992B is a high quality antique mechanical pocket watch. A well maintained and adjusted watch kept ina fixed location at room temperature can reach accuraciesnormally only seen with quartz watches. If you use it and the watchis exposed to different temperatures and shaken or turnedthen you will achieve about +/- 15sec accuracyper week. A lot of other mechanical watches are off that much in just one day.The need for Railroad Watches to be 'railroad approved' stemmed from a number of train accidents in the late 1800's where two trains collided head on due to poor time keeping. Regular watch inspection and consistent time keeping was the only thing that kept trains from running into each other on Americas single track railways. These railways had a single track for both directions and two trains running in opposite direction could pass each other at railway stations and other places which had two tracks, one for each direction, for a short distance only.A notable watch inspector was Webb C. His first job as a time inspector was when he was brought in by the Lake Shore and Michigan Southern Railways in 1891 after a crash and was tasked with bringing their time inspection system up to industry standards.
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Ball's career eventually led to him being the time inspector on more than half the United States' railways, leading to a far more uniform set of standards across the US. He gave a very interessting interview in the New-York Tribune January 16, 1910.An interesting question from a historic point of view is of course: why did nobody in North America come up with any solution other than time keeping?
Many other countries solved the root cause of the problem with station to station communication, signaling, tokens or dual track. In this article we focus however on watches and it is this focus on timing only that lead to those beautiful and precise American railroad watches.The Hamilton 992B pocket watch is a beautiful watch not only on the outside.
Position adjustment refers to the mechanical design of the balance wheel and the hairspring. The little weights on the balance wheel are an important part of that adjustment. It is done to maintain approximately the same rate of balance wheel oscillation, regardless of which of the specified positions the watch is in. Melamine resin (melamine formaldehyde) was one of the first widely used plastics. It's the stuff you findon old light switches or old electrical sockets.
It's a very hard and brittleplastic. It does not easily burn and is very resistant to chemicals. The melamine resin dials do usually have cracks and hairlines after a few decades. The enamel dials may get hairlines too but generally not as big ones as the melamine dials. I have seen some cases where people have removed the original melamine and completely re-painted the dial. It looks nice but it is not original and Hamilton did not use such 'paint on brass' dials for the 992b.Hamilton 992B cases and dials992b is the movement and you could have it withdifferent dials and cases.The term 'Railway Special', as found on most Hamilton 992B watches, is a registered trademark of Hamilton.I am not sure why most Hamilton 992B watches had the words 'Hamilton Railway Special' on the dial while a few had just the word 'Hamilton' on the dial.Hamilton pocket watch movement partsThe following picture shows an exploded view of a Hamilton size 16 pocket watch.
Thispicture can be useful during service and maintenance and when you needto know the names of the watch parts.Exploded view of a Hamilton pocket watch movement (click for a printable PDF version)Regulating the Hamilton 992B (adjusting the speed or rate)The Hamilton 992B regulator is adjusted not with a simple 'F - S' lever, but with a spring loaded micrometer screw that adjusts the regulator far more precisely. One full turn of the precision regulator screw changes the rate of the 992B by about 18 to 22 seconds per day.You need a very small watch maker screw driver to adjust the regulator. Use the watch for at least a week before you change anything. Talk to a watchmaker if you are not comfortable doing this.
You don't want to ruin your watch.The Hamilton 992B has far less temperature dependencies than many other mechanical pocket watches from the railroad area but there isstill a little temperature dependency and of course a positional dependency.The Hamilton 992b is adjusted to 6 positions but there is still a noticeabledifference between running in horizontal position and running in upright position. Hamilton tried to minimize the positional dependency but it can't reallydo anything about the basic laws of physics.
Hamilton was very goodat marketing and advertising their watches. The 992b was however in realitynot much better than any other high end pocket watch made around the sametime.A mechanical watch runsa little faster when it is steady in horizontal position on the desk anda little slower in vertical position. This is becausethe rate at which the balance oscillates depends on the amplitude (howfar it swings around) and the balance wheel (and all the other wheels) are experiencing frictionon both ends of the pivots in vertical position. This reduces the amplitude a bitand lowers the rate at which the watch is running in vertical position comparedto horizontal position (all wheels are experiencing only frictionon one pivot in horizontal position).In other words the rate depends on how you carry the watch.Hamilton published in 1951 a technicalnote that explains regulation nicely.
Click on the picture for a PDF version ofthe document:Hamilton tech. Note on regulation (PDF, 1031997 bytes)The Hamilton 992b precision regulator screwA modern timegrapher can be helpful when you regulate a 992b but it isnot absolutely required since the 992b has a regulator screw and onefull turn on the screw changes the rate by about 20sec a day. If you wantto change the rate by a given daily rate then you can simply calculateby how many degrees you have to turn the regulator screw.A timegrapher (or timing machine) is a machinethat listens to the various 'click events' that a mechanical watch producesand it times those events. It can be used to check instantly if the watch movementis running well.I don't know what the lift angle of the Hamilton 992b really is butif you set it on the timegrapher to 52° then you can expect an amplitude of just over 250°in horizontal position.
I have never seen a 992b that had amplitude higher than 300°. Thismay seem like a low amplitude to those familiar with timegraphersand swiss movements. I don't know why the 992b has a relatively low amplitude but it is normal.Hamilton 992 watches (without the b) and old steel springs can have amplitudes above 300°.A Hamilton 992b mounted with a movement holder on a timegrapherTimegrapher readings from an average Hamilton 992b.
It's normal for a 992b to have only an aplitude in the 250° range. A beat error of 2ms is at the upper limit of what is acceptable.Timegrapher readings from a very good Hamilton 992b. The amplitude is still only 263°The distance between the lines drawn by the timegrapher corresponds to the beat error. That is: the beat error is difference between a balance swing to the left and one to the right.
It would be zero if the roller jewel was in idle position exactly in the middle between the banking pins. A 2ms beat error is not great and shows that such a watch had a balance staff replaced without adjusting it afterwards. In some modern watches you can adjust both the rate and the beat error on the running watch. To adjust the beat error on a Hamilton 992b one has to take out the balance, carefully turn the balance collet and put it back. This is not easy.
It requires a very steady hand and you might need to repeat this process a few times until you have the beat error below 1ms. A watchmaker might be tempted to take shortcuts thinking that and old watch will anyhow only sit in the drawer of a collector.Top view of a typical 992B balance wheel with hairspring. The green dot marksthe normal position of the hairspring stud (where it will be connected to the balance cock) and the red dot corresponds to the position of the impulse jewel (or roller jewel). The impulse jewel is normally not visible from the top since it is sitting on the other side.
There is roughly a 90' angle between balance arm and the direction the impulse jewel is pointing to. Observe as well the distribution of the timing screws on the outer ring of the balance.
It does not have to be exactly as in this drawing but my observation is that there is 'one screw missing' in the direction towards which the impulse jewel is pointing (at 9 o'clock in the drawing). That pattern of screws is always mirrored to the other side of the balance ring.To adjust the beat error you take the balance out and you remove it from thebalance cock. I place it on a little wooden board that has a hole in the middle.This is to ensure that the balance is well supported. Make sure the boardis clean and does not have any saw dust in the hole. The hole has to bejust big enough for the roller table to fit in comfortably (about 3mm wide).Top view of a typical 992B balance wheel with hairspring. The arrow points towards a slot in the hairspring collet. This balance has a few scratches on the balance arm just below the hairspring stud.
Some watchmakers do that to mark positions. A more gentle method would be to use a sharpie permanent marker. Sharpie marks can be removed with alcohol. The other scratches might be from a balance staff replacement procedure that was a bit rough.To adjust the beat error of the watch you put the smallest watchmaker screwdriver that you have into the slot on the hairspring collet and you turn it just a little bit.
Be gentle and don't slip. You would ruin the hairspring if the screw driver slips. Turning it by an angle of maybe 2° makes all the difference between a beat error of 2ms and 1ms. So be careful.
Put everything back together and check the beat error again with the timegrapher. If it increased then you have been turning in the wrong direction and you need to take it out again and turn in the other direction. There is no easy way to know up-front in which direction to turn since the needed change is so small and it is hard to see to which side it is off. You can stop when the beat error is below 1ms.
A beat error of 2ms is not the end of the world either. Anything above 2ms should be corrected.Timegrapher readings after beat error adjustment.
This watch used to be at a beat error of 2.8ms. It took me 4 attempts to get it to 0.2ms.Scribbling inside the case?watch inspector repair markings on the inside of the caseLocomotive engineers, conductors, and switch yard controllers had to have their watches inspected and certified by the railroad's designated watch inspector.
This was typically twice a year but some railroads required quarterly inspection. The inspector would check to see that the kind of watch was allowed by that particular railroad's rules and that it was in good running order (the requirement was typically +/- 30 seconds per week).
Finding everything satisfactory, the inspector would certify the watch. Otherwise the watch would need to be repaired. The inspector was typicallyas well the watchmaker who would carry out those repairs. The railroad watch inspectors scribbled their number orsome number letter combination into the back of the case if some sort of repair or cleaning was required. This way the inspector would easily know if they had worked on thiswatch before. They would as well keep paper records but these inspector repair marks where more convenient thansearching through paper records.In other words you know that a given watch was actually used on the railroad if it has those watch inspector repair markson the inside back cover.
These tiny scribbles proof that this is a real railroad watch.watch inspection cardwatch inspection certificate for a hamilton 992, 1974-Oct-05,another watch inspection certificateThe Canadian National Railways followed the same principles as the railroad companies in the US. The watch inspectors filled out an 'Employees watch rating card' which the employee had to carry with him while on duty.
The the offset ofthe watch against standard time was recorded about every 30 days on the back of the card.A CNR 'Employees watch rating card' for a Hamilton 992B pocket watchHamilton 992B historyThe Hamilton Pocket Watch Co started as the Adams & Perry Watch Manufacturing Co in 1874. It changed its name to the Hamilton Watch Co in 1892. The company had many failures until it became finally very successful. Click here for a.The Hamilton watch factory around 1900The Hamilton watch factory in 1912, employs about 750 peopleThe Hamilton 992B is a successor of the 992E (992 Elinvar, made from 1931-1941) which is asuccessor of the Hamilton 992 (made from 1903-1930). One of the main improvements in the 992Bover the previous watches was the use of the 'Elinvar Extra' hairsprings.A Hamilton 992 from 1913, notice the cut bi-metallic compensation balance (the outer ring does not go all the way round, there is a cut)The special alloy Elinvar, was invented in 1890.
Is a specialtemperature compensated steel alloy (Fe 52%, Ni 36%, Cr 12%).The word 'Elinvar' is an acronym made of the words 'elasticity invariable'.Because Elinvar does not expand asmuch with temperature as normal steel it simplifies the watch productionprocess since it did not require the labor-intensive adjustments and didnot need a bi-metallic balance to compensate the temperature coefficientof the hairspring. It is as well resistant to magnetism and does not easily rust. Hamilton had an interessting one page add in the Popular Science magazine issue in 1931 explaining Elinvar and advertising the Hamilton 992E pocket watch:A Hamilton add for the 992 Elinvar in the Popular Science magazine, Nov 1931.The Hamilton booklet: Elinvar in your watch, 1931, Click for the full PDF version.source: nawcc.org.This sounds fantastic but there were a few problems. Swiss watch companiesused by 1930 already the Elinvar. Hamilton decided therefore to buy theElinvar hairsprings from Swiss manufactures for its new 992E watches. TheSwiss watches where however smaller and it seems they did thereforenot see the same problems as Hamilton. Elinvar was softer than thesteel hairsprings that it replaced.
That meant that it was more easilydamaged by watchmakers who worked on it during the frequent servicingthat railroad watches had to endure. There were reports of the softerhairsprings sagging and coming in contact with the balance arms.Hamilton's watchmakers noticed that the railroad watches with Elinvarhairsprings did not run as strong as watches with steelhairsprings and bi-metallic compensation balances. The heat-treatingprocess used in making the Elinvar hairsprings yielded a product thatwas unevenly striped in color and had to be dyed blue to look good.Hamilton realized that it could not continue with the Swiss Elinvar andset out to develop a better hairspring alloy that would offer the theadvantages of Elinvar without its disadvantages. They foundthe answer at International Nickel in the form of a product calledNi-Span-C. Hamilton obtained the rights to manufacture the alloy for usein hairsprings and it was first used in the new 'B' seriesof watches that Hamilton introduced in 1940 (992B, 950B).Ni-Span-C has a constant modulus of elasticity at temperatures from-45°C to 65°C.The newalloy was called 'Elinvar Extra' (Fe 48%, Ni 43%, Cr 5%, Ti 2.75%, Si 0.5%, Co 0.35%, Al 0.3%, C 0.04%). The name 'Elinvar Extra' was probably chosen because Hamilton had investedso heavily in promoting the Swiss Elinvar that they wanted the word Elinvar in the new metal. This Elinvar Extra was indeed superior and the 992B (and other B-series watches) where the most accurate watches at the time.The Hamilton 992B was introduced in November 1940 and produced until 1969when the market had moved away from pocket watches to wrist watches.Wrist watches were able to achieve by 1969 similar accuracies as pocketwatches.
The other big competition to the Hamilton 992B where pocket watcheswith Swiss Unitas movements such as e.g the following Elco pocket watch from 1960.It had a Unitas 429 movement with Incabloc shock protection. Those movementswhere more reliable in rough environments than the Hamilton 992B movement.Elco pocket watch with a Swiss Unitas 429 movement.This watch was made (assembly of dial, case and movement) by Levy Brothers Co. Hamilton, Ontario for the Canadian railroad. The Levy Brothers were Jewish immigrants from Alsace Lorraine who settled in the 19th century in Canada. They had a jewelery business.
This watch is in functionality, appearance, size, weight and accuracy very similar to the 992B but it is more reliable in harsh working environments due to its Incabloc shock protection.Here is the official announcement letter for the Hamilton 992B from November 1940:Hamilton 992b announcement, 5 Nov. 1940source: nawcc.orgA letter explaining the technical innovation that went into the Hamilton 992b was sent to selected jewelers, 6 Nov.