What does the balance wheel do for accuracy? How do I set the hands on my watch and how do I wind it? What does "railroad-grade" mean?
Learn the basics of jeweling, configuration styles, movement sizes, winding and setting, dial construction, types of adjustments, watch mechanics, railroad standards, and more. There isn't nearly enough room on this page to cover everything, but it'll get you started.
All watches from the railroad era used a balance wheel as a means of achieving accuracy. The earliest wheels were solid metal, while later models were bi-metallic with expansion cuts to adapt for changes in temperature and carried many weights that added mass to the wheel.
Its steady rate was controlled by an oscillating hairspring, and nearly all American models had some kind of regulator for fine adjustments.
Most American brands used at least one pair of these special screws to easily make bulk timing changes. They are usually found near the ends of the balance wheels arms and were made with a special interference thread to prevent them from turning without force. Any company that failed to install them on their watches (Elgin was one) invited a century of jewelers to molest the other weights to make timing changes.
When a watch inevitably slowed from thickening oils and carried no mean-time screws to make adjustments, the lazy choice was to simply grind off part of the balance weights to gain time. At some later point the watch was cleaned properly, which then ran way too fast because of the missing weight, so washers had to be installed to add mass - all of which thoroughly ruined the factory poise, or positional accuracy.
The hairspring is the rebound mechanism for the balance wheel, "breathing" in and out five times every second. The coils of a flat spring all lay on the same plane, anchored at either end. At the center is the collet, a brass split-ring that grips the balance staff, and at the tail is the stud, produced in many different styles, depending on the brand.
Prussian watchmaker Abraham Breguet is credited for the invention of the overcoil hairspring, which raises the final turn of the hairspring above the other coils. Whereas a flat hairspring applies lateral stress (and friction) to the balance staff when expanding or contracting, the overcoil minimizes this effect by moving a much smaller distance.
Any watch using an anchor or lever escapement requires a roller jewel, which is mounted in the roller table using shellac. On every cycle of the balance wheel this jewel gives an impulse to the pallet fork via the cup located at the end of the pallet arm. A vertical guide pin behind the cup prevented the pallet fork from drifting too early by meshing with a crescent-shaped cutout milled in the edge of the roller table.
Overbanking occurs when the roller jewel becomes misaligned with the pallet cup, which was possible with the earlier single roller design.
The double roller was developed to address this, using a smaller lower table with the cutout to mesh with the now-horizontal guard pin. This allowed the pallet to swing only when the roller jewel was in the cup, eliminating overbanking. The jewel is still mounted in the upper table.
Jewels were used as bearings for polished steel pivots that generated very little friction when properly oiled and maintained.
They were made from industrial-grade precious stones, such as rubies, garnets, sapphires, and even diamonds.
Hole jewels by themselves relied on the flat jewel face to control endshake. Balance wheels use hole and cap jewels, which trap the staffs by their pivot tips. Capped pairs generate less friction because smaller surface areas are in contact with each other.
Jewels were also used in lever escapements, which was the eventual design choice of most American watch companies. The roller jewel, mounted on the balance wheel, gives the impulse to the pallet fork, alternately locking and releasing the entry and exit pallet stones. This allows the escape wheel to rotate at a specific rate one tooth at a time, which gradually lets down the mainspring until it's completely spent.
The lowest jewel count offered by most American factories was seven. All of them were used in the balance and escapement, including two pairs of hole and cap jewels for the balance staff, two pallet stones for entry and exit, and one roller jewel to give the impulse to the pallet.
The purpose of hole and cap jewels was to reduce friction between the gear pivots and the plates in which they rotated. In a 7-jewel watch the entire gear train used bushings instead of jewels. Over time the pivots and the bushings can wear badly, especially with poor maintenance, and once the plate bushings become enlarged the watch is ruined.
A fully-jeweled railroad pocket watch contains seventeen jewels - a total of seven for the balance assembly and a pair for each wheel of the gear train. In 1891 Hampden introduced the first 23-jewel watch in America, and the jewel race was on. Companies added jewels anywhere they could put them, like the mainspring arbor and unnecessary caps on the pivots. There were many jeweling combinations that added up to different totals.
Who had the highest jewel count? The Illinois Watch Co, with 26.
Open face was the most common, with the winding stem at the 12:00 position, and was available in every size that American watch companies had to offer. This configuration eventually became a requirement as one of the primary railroad criteria.
Hunter (hunting) placed the stem at the 3:00 position, and was not railroad approved. The cases had a front lid to protect the dial and crystal, which opened by depressing the crown, along with several hinges, a dust cover, and springs for the front cover and the latch.
Sidewinders are hunter movements in open-face cases. Seldom purchased this way historically, this arrangement means the original hunting case has likely been melted down.
Most collectors believe this configuration to be incorrect.
Conversion dials allowed hunter movements to be used in an open-face case by moving the seconds bit to the 3:00 position, returning the winding stem to 12:00. These began showing up after WWI, were usually made of metal or melamine, and could be railroad acceptable.
Reversible cases had a center ring that rotated within the case frame, allowing the movement to be displayed as if it were either a hunter or an open-face style. However, this does not convert the movement, since the winding pinion doesn't change positions. For example, an open-face movement with the winding stem at 12:00 used as a hunter profile will simply be laying on its side when displayed that way.
No single part on an American pocket watch was as visible as the dial, and they came in an incredible array of colors, designs and fonts. See all the familiar variants in one place, learn what dials were made from, how they were mounted, discover who applied for patents, and don't forget the section on hand styles and colors at the bottom of the page.
Pendant (or stem-set) was the most common, even though the design required twice as many parts as a lever-set variant. The hands are set by popping up the crown, which did not meet the railroad standards of the day because the hands could accidentally be reset. The watch is wound by twisting the crown in a ratcheting motion.
Lever-set watches did meet railroad standards, as long as it was an open-face model. Setting the time meant removing the bezel and pulling out a small lever, which could be in several different locations around the dial rim. The watch still gets wound by twisting the crown.
Key-wind and key-set watches also didn't meet railroad requirements. The watch was wound with a small square key through the back and the hands were set by removing the bezel, although a few were able to also set the hands from the back, such as Waltham's Model 70.
Pin (or nail) setting was largely a Swiss innovation and was seldom used on American brands. It was an awkward arrangement, requiring the pin to be held in while turning the crown to set the hands.
The most common, found on most brands.
Used in hanging barrels with internal hooks.
Used on most Elgins with slotted barrels.
A watch barrel contains the mainspring and the cover for a going barrel snaps on tightly, so the spring must uncoil in that rigid space. Newer alloy mainsprings have sharp edges that will snag on anything inside this type of barrel, including any stamped numbers, making for an erratic letdown.
This is the most common design, using a slotted or T-end spring.
A hanging barrel consists of a barrel and cover that never touch each other, rotating on a common arbor and giving the spring more room. Waltham used this design on several of their models. The mainspring is allowed to unspool at a much smoother rate, producing more consistent torque.
Hanging barrels have an internal hook to anchor the mainspring.
A motor barrel has a pair of internal jewels between the winding arbor and the barrel and its cover. This increases accuracy by allowing the mainspring to unspool without friction, and when used with a hanging barrel makes for the smoothest possible letdown.
External jewels on the plate are for show and do not reduce friction or improve accuracy, though they make winding the watch easier.
Gilded plates were the most common prior to 1880, with a thin layer of gold on bronze.
Nickel-plated steel was an ideal choice to mill patterns into, called damaskeening.
Two-toning required the masking of parts of the nickel plates with wax and then gilding.
Similar to two-toning, except the pattern was milled first before the plates were gilded.
Waltham first pioneered this look, with the pattern milled after bead-blasting the plates.
US Watch of Waltham was the first to etch a pattern with acid on mirror-smooth plates.
American watches used the Lancashire gauge, which is based on the dial plate of a O-size watch measuring precisely a standard inch in diameter as a starting point, with each ascending size adding exactly 1/30th of an inch. The additional 5/30 inches was for the mounting shoulder up to a 16-size watch, when the diameter was increased to 6/30 inches.
Different countries had their own system, adding to the confusion.
The verge dates to the 1200s and used a pair of steel paddles mounted 90 degrees apart on the balance staff to alternately lock and release the crown wheel. It was bulky and the mating surfaces wore quickly.
Invented around 1700, the cylinder was part of the balance wheel and utilized half-cutouts to let down the escape wheel. It was much thinner than the verge but was found to have excessive friction.
Also dating from the 1700s, the duplex consisted of tandem escape wheels that required separate impulses to rotate. It could achieve high accuracy but was too sensitive to sudden jarring.
The lever was a form of the earlier anchor escapement used in clocks and was the eventual choice for the railroad era. Its self-starting design was capable of high accuracy with low friction.
The chain-driven fusee was a very simple yet effective method of equalizing drive torque as the mainspring unspooled and lost power. The design dates back to the 1400s, with the earliest versions using gut or wire instead of the delicate chain.
When the watch is fully wound the chain is coiled entirely around the fusee cone, and the mainspring is applying the largest force with the smallest amount of leverage. As the mainspring unspools the chain begins to wrap around the barrel, and its weakening pull is applied to the expanding spiral radius toward the bottom of the fusee cone.
Verge fusees inevitably speed up over time because of the design and the wear of the mating surfaces. The brass teeth of the crown wheel (see above) become flattened out against the steel paddles on the balance staff, reducing the travel of the balance wheel. This decreases the amount of time between impulses, causing the watch to run faster.
Accuracy was the most important aspect of any watch, so high-grade movements were adjusted to keep better time. These adjustments offset the effects of friction and gravity by fine-tuning the balance assembly, and getting a watch to run accurately took many hours of careful work by a skilled watchmaker. Some companies simply milled the word "Adjusted" on the plates, while other firms inscribed the total number of adjustments to which the watch was timed against.
A watch can be oriented pendant up or down, pendant left or right, or the dial up or down. There are nine adjustments - the six positional ones, plus isochronism, plus one each for heat and cold.
The word means "same time" in Greek, and is the accuracy of a watch whether the mainspring is fully wound or almost spent. Barrel stopworks, counter-balanced pallet forks, and longer hairsprings with overcoils all helped to equalize mainspring torque in pocket watches.
Changes in temperature affected both the hairspring and the organic oils in a watch, altering its accuracy. Thermal-expansion bi-metallic cut balance wheels, new synthetic oils, and the invention and use of alloy metals like Elinvar in hairsprings in the 1920s all helped to offset this.
The growing country moved nearly everything by rail in the 1880s, so an accurate timetable between freights became increasingly important. For decades the railroad companies had generally accepted any 18-size 15-jewel watch for service, but in 1891 the terrible Kipton, Ohio crash killed several people because an engineer's watch had stopped, and the rules changed.
Webster Clayton Ball, a successful jeweler and store owner, was given authority as Chief Time Inspector, overseeing thousands of miles of track. New standards were adopted, and by the turn of the century a Railroad Grade watch was American-made, open-face, lever-set, either 16 or 18-size, had a minimum of 17 jewels and was adjusted for temperature and positions. It had to be equipped with a steel escape wheel, a micro-regulator, and a bold-font Arabic dial. Railroad workers were required to submit their watches for regular servicing and inspection, and the most important criteria was that any watch had to be accurate to within 30 seconds a week.