Description of my Hamilton 992:

This auction is for a beautiful Mens 16size American pocket watch made by Hamilton Watch Co. in good running condition! Watch has 21 jewels & is a model 992, 16size. sn# 2515239. This dates it to 1934. The gold filled Case is marked Keystone 10k gold filled, and is in good condition with some wear. Circle diameter at 2". No brassing! Glass crystal is good. Porcelain dial is in good condition with no hairlines, but has a chip repair above 2pm. It is a stemwind, leverset watch. Set time by pulling out small lever at 2pm. Runs and keeping time. Great watch to wear, or for your investment.

The 992 in its various forms

Another model that is very popular is the 992B. I am told that the movement is quite different from the older 992. They aimed to leverage the existing reputation of the 992 by adding a letter rather than using a new number. I like the more elegant 992 dial better than the usual bold 992B dial, but some 992B watches have an elegant dial just like the 992. I see 992B watches selling for $315, $275 - and I saw one go for $459. I saw one go for $320, then lost the bid on a very nice one (it went for $538, just above my $528 bid). I followed another that was going for $377, but jumped to $534 in the last seconds of the auction.

Then there are the "Elinvar" versions of the 992 and 992B. The creator of elinvar, Charles Guillaume, was awarded a Nobel Prize in 1920 for its invention, and that of its counterpart, Invar. Above all it has an extremely low coefficient of thermal expansion, allowing hairsprings to be monometallic - it is non-magnetic by accident. It is also, like stainless still, rust resistant. Hamilton acquired the rights to use elinvar in 1931. I see both 992 and 992B with Elinvar markings. The hairspring in these watches is made of "elinvar" and the balance wheel is made of non-magnetic material.

Hamilton made a lot of marketing noise about the non-magnetic properties. The first Elinvar came from europe, but Hamilton was not satisfied with the quality and began making their own, which they called "Elinvar Extra". This was introduced with the 992B and 950B. They used it in all their watches after they introduced it, until they went out of business.

It is not clear to me what the 992E is. This may be a 992 with Elinvar, or a 992B with Elinvar. The markings on the watch movement will indicate whether it is a 992 or 992B.

I recently followed an auction for a 992B Elinvar that sold for $602.01. Another went for $449.44 - these watches are very popular when in superb condition. The description of the more pricey of the two stated "This is the more desirable second model with solid gold center wheel and one screw in the crown wheel. The movement has a fine patented micrometric regulator, 21 jewels adjusted to 5 positions. Elinvar is signed under the balance cock - double roller elinvar. It also has solid gold jewel settings and solid gold balance screws." Next, I bid on a running movement (no dial or hands) of a 992B Elinvar. My high bid was $271 and it went for $305.

Hamilton 4992B

There are a couple of special things about the 4992. One is that it has a sweep second hand (this requires an additional wheel inside that complicates disassembling the watch for service). Also the watch will "hack" when being set, i.e. unlike most other watches, the movement will stop when setting time.

Note that there is also a 3992B model, which is essentially the same thing, but in a 12 hour version (but having the sweep second hand, and the "hack" when setting time). Some of these were supplied to the british during WW-II.

Removing the exposed wheel mounted on the extended third wheel is a trick for these watches. It can be pried off with a couple of levers if you are brave, confident, or foolish. The word is that it tends to come off all at once and fly into the air. The word also is that replacement third wheels are hard to come by, and expensive, so be sure not to bend the pivot. The really sensible thing to do is to acquire a proper third wheel puller. The puller looks like a Presto hands puller except that the one you need has a split "jaw" on one side and a thin one on the other. These are for the five armed wheels, six armed wheels require the other type. Fit over the wheel after removing the hold-down and spring for the center seconds pivot and press the sides -- this pull the wheel straight off the extended pivot. Prying with screwdrivers very often breaks off the pivot. A good choice would be the Bergeon presto 3 tool. (The presto 3 is for 5 spoke wheels, the 3A is for 6 spoke wheels). The "3" is what you want, this is a $55 Bergeon tool. See the hand removers and pullers at this link.

Here is some additional information from a post by peter (psfred) on the nawcc message board (see this thread). The 4992B has a sweep center second hand. This is implemented by pressing an extra wheel onto the third wheel pinion which extends above the bridge. This wheel drives a very small gear on a shaft which extends through the hollow center wheel, driving the seconds hand. The seconds hand pinion is supported by a small bridge (with jewel). This setup is known as "indirect seconds". (Other designs moved the fourth wheel - the one that normally drives the second hand on pocket watches - to the center of the watch). The extended pinion on the third gear of the 4992B is problematic, the seconds drive wheel must be tight, which mandates the use of the special puller. And you must pull the wheel if you want to properly clean and oil the third wheel pivot and upper jewel.

The mainspring inside the 4992B is (near as I can find out) identical to the one in the 992, 992B and 950. The part number is 534B, but this part was available in three strengths. One fellow says that the mainspring for a 4992B is a 534B. It is 23.5" long. Width is 3.00mm (dennison 21) strength 0.155 (dennison 6.75). MB end. Another fellow says that the mainspring is a 21 X 6 1/2 X 23.5 for 992B and 4992B.

The old blue steel springs are undesirable. Some are old enough to be brittle and to have taken a set - making them useless. What you want is a white metal spring of more modern vintage. I have seen these labeled "SA204" 21 width, 6.5 strength, 23.5 inches long. You will probably also be glad to have a spring winder to install the spring in the barrel.

Just for the record, the pivot is a pivot 11 staff, old part numbers are 659 and 607048, new is 22BB58BB for the size 16 models 992B, 950B and 4992B.

I have never tried him, but I am told that Larry Crutsinger has a big stock of parts for the 4992 and other military watches. He is at 767-650-9470 detent21@aol.com (if you are lucky).