Girard Perregaux

A very short history of time - GP Gyromatic movements 1950-1962

 

G'day,

here?s some very short overview, because i received a number of questions regarding the early and later Gyromatic movements by GP. It?s far from being complete and some more comprehensive and detailed coverage will follow at some later point.

Nonetheless, this may help to put some things in a context and timeline:

GP 47 - GP?s first full-rotor movement

GP 47 is a full-rotor automatic movement based on an ETA ebauche (ETA 1256); a 11 1/12 ligne movement with 18.000 A/h. The archives note a use between 1950 and 1955.
And it?s a very nice piece, with a perlage decoration base plate.
Although it is inscribed "Gyromatic", it does not come with the famous free-drive using Gyrotrones.

GP 71 - GP?s other first full-rotor automatic





GP 71 is a full-rotor automatic movement based on an ebauche by A. Schild (AS 1320). With only 9 1/4 lignes i is significantly smaller than GP 47 and mostly found in rectangular watches of swiss production in a very typical style for the 1950?s; personally i?m not sure it was in use for round watches as well, because it?s a bit higher than a GP 47.
GP 71 had a short life, from 1950 to 1952.
Apart from the size, one may notice the different approach which leads to a visual appearance much like bumper automatics ("Hammerautomaten" in german). Interestingly these movements are not inscribed "Gyromatic", but some few dials are.

GP?s first own automatic - the second generation




GP 19 (rare, with sub-second at 6)



GP 21

This is probably the most unusual approach; a 11 1/2 ligne and relatively thick movement based on an ebauche by Peseux (P310 for the sub-second and P310A for the center second variant). These movements were in use between 1955 and around 1961/1962.
At this point, the general confidence in full-rotor was not too high; GP did some serious research in how the winding could be improved, which resulted in the famous "Gyrotrone" free-drive using ruby rolls and later steel rolls. Click here for some more in-depth explanation of the function.
The stunning aspect is that GP used a manual-wind base movement and placed the automatic winding unit and rotor on top of it; this becomes more clear when the automatic unit is removed:



GP 21 automatic (automatic bridge and rotor removed)



GP 20 manual wind movement




automatic unit, bottom view, Gyrotrone wheels are visible

The downside of the movement is the height; GP 21 and variants didn?t match the need for thin movements which came up in the 1960?s.

GP 31/32 - GP?s most successfull Gyromatic



GP 31/32 (no date/date versions) are based on ebauches by AS, which apparently were exclusively in use by GP for some years.
Like the predessor GP21, it is an 11 1/2 ligne movement and had a rather long life from 1962 to around 1975.
The main difference is the height





GP 22 (the date variant of GP 21, left) and GP 31 (right)

It is much thinner, due to a completely different automatic bridge (which bears the jewels and settings for the gear train) and a different rotor.
There are quite some variants with different beat rates; GP 31/32 come with 21.600 to 36.000 A/h and several jewel counts from 17 over 25 to 39 jewels.

Now how to spot the difference?
Just look for the calibre inscription:
- GP 47 and GP 71 are inscribed on the rotor and come with the typical nomenclature for GP?s movements in the 1950?s (like "47 BF 123" or "71 AE 456")
- GP 21/22 are inscribed on the automatic bridge, but no longer on the rotor. And the calibre is indicated by the first 4 digits of the number
- GP 31/32 are inscribed on the plate which holds the rotor.

Personally, i think it?s an interesting development!

Greetings from germany,

Peter

Site Info.

Privacy Policy Cookie Policy