Hi Folks,
Being quite new at this hobby, what is the difference between a 4992B or a 3992B movement wise, they look very much the same from photos I have observed, of course that is by the untrained eye.
Thanks for clarification,
Bill

I am by far no expert but I think the only difference is in the dial & the serial number prefix. If I understand correctly they were made for the Canadian Military & only about 2400 made. I have been keeping my eye out for one to own someday.

Tom

Hi Bill, a Good question, The common points for the 3992 and 4992 were;
1. Hacking sweep second hand.
2. Used and marked as Air Navigation watches.

The differences are;
1. The 4992 was a 24 Hour (GCT) movement, while the 3992 was a 12 hour movement.
2. The 4992 had "seconds" counts marked on the outer chapter while the 3992 was .01 minutes rather than seconds.
3. For reasons 1 & 2, the dials are VERY different and the 3992 was a front mounted dial.
4. The 3992 Dial Hands are color coded to the Hour Minute 0.01 Minute Chapters (to reduce confusion?).

But both movement are quite similar

And Then there was the Longines A9 nav watch which ceased production in 1939! It is a Hacking, Sweep Second 24 Hour Dial "GCT" wind indicator, size 21 Chronograph sold to the US Army Air Corps. Pictured 1938 vintage s/n 5939452 that I adjust every month whether it needs it or not! sigh . .

David,
Thanks for the info regarding these 2 mdls, the main difference is in the dials,hands, etc, and the hack mechanism.Do I understand that the movements are very similar except for the sweep second and hack assmbly.
Wow, what a great looking Longines.
Thanks again,
Bill

I believe both the 4992B & 3992B have the hack action & both have the sweep second hand. The difference is the dial & one is 12 hour & the other 24 so some of the wheels have different count to them so one runs one revolution in 24 hours & the other makes two in 24.

The only other difference is that the serial numbers start with different prefixes & the model number stamped on the plate.

Tom

Noew here's another "rub" a 12 Hr Hamilton 4992 B and a 1941 Elgin both sweepers and both 12 Hour.

We are all aware that some Hamilton 4992B's got into civvies with a 12 hour dial, but I have no explanation for a 12 hr sweep Sec Elgin that is engraved "US ARMY AC" on the movement and has a 1941 s/n Except the sweep sec cock looks like it was made with \a file and a hacksaw, so Elgin must have been in a real hurry to get some of these delivered in early 1942.

David,

I have an Elgin BW Raymond, Grade 581, s/n 40470155, that has a 24 hr dial with a center hack seconds hand and is marked "US Army AC". Mine has a gold flashed movement with ordnance markings on the back. Sorry no pic as this one is in the safety deposit box.

Perhaps your Elgin was also converted to 12 hr after the war.

Getting back to the original question Bill raised regarding differences between 4992B and 3992B.

The one big difference to me is the relative scarcity of these 3 star 3992B watches. I only see them come up for auction rarely and they alway go for higher than high book value.

Imagine my surprise when one of the guys brought one in for show and tell in the local Ch 121 meeting this week (Hamilton for "H" month). It was in a silver case with ordnance markings, but it didn't have the interesting dial that is on David's example.

I asked if the watch was for sale, but it was not. The owner was interested in Canadian military history so it had special meaning for him which I completely understand.

I'll have to keep looking...

Aloha all

I intended to put this watch up for auction on eBay
but with the interest expressed here within our 185 family for a 3992B I will instead put this up for auction on our members only site.
I like the idea of it staying in the Family

NAVIGATION
MASTER WATCH
MFR’S PART NO.3992B 0552/520-8049
BROAD ARROW SERIAL NO. 1914-1942
HAMILTON WATCH CO.
H.S.3 LINED OUT
MOVEMENT NO. 3C2062
STANDARD HAMILTON WATCH CO. U.S.A. 3992B 22 JEWELS
ADJ. TEMP. AND 6 POSITIONS U.S.GOVT. BLOCK FONT.
CASE, KEYSTONE BASE METAL 570672
DIAL, 12 HOUR HAMILTON WHITE FACE BLACK NUMBERS AND BROAD ARROW THE OUTER MINUTE ORBIT IS GRADUATED IN 60 EVEN DIVISIONS NUMBERED AT EACH 5TH DIVISION, BLACK HOUR MINUTE AND SECOND HANDS

I will send it to our own Mr Chris Abell for a COA
and maybe some photos

Mahalo and Aloha Scott