Portex Chronograph (Landeron Cal. 248)…

Not a brand I’m familiar with, but time has certainly been kind to this Portex chronograph which dates to the late sixties or early seventies…

(Click pictures to enlarge)

I looked for information on the Portex company, but aside from one mention of a ladies watch, and an LED manufacturer called “Pierre Portex”  (which may or may not be related), there was nothing else to uncover. The calibre inside however is not quite so enigmatic, a Landeron cal. 248.

Landeron is a well known name in the chronograph world, their calibres appearing in many different watch brands over the years. Bought by  Ebauches SA. (the company we know today as ETA) in 1921, Landeron went on to produce a variety of chronograph calibres, many featuring one of their most significant developments, the “cam-lever” mechanism, which they patented in 1940.

The cam-lever mechanism controls the start/stop and reset functions the chronograph, and its introduction provided a cheaper alternative to the column wheel mechanism which was more labour intensive and expensive to produce. (I explained the difference between the two systems in a previous post, here if you missed it). The development of the cam lever system was the breakthrough which led to more affordable chronographs appearing on the market.

The ’48 Series’ of calibres were some of the most popular that Landeron produced. The series started in 1937 with the cal. 48 and was revised twice to produce the cal. 148 and cal. 248 respectively. Production of the 48 series stopped in 1970 after making around 3.5 million units, and the Landeron name itself disappeared shortly afterwards.  While researching this post I came across a site suggesting that the Landeron name could be making a comeback… let’s hope so.

It’s also worth mentioning that the operation of Landeron’s cam-lever chronograph is also slightly different. In most chronograph calibres, regardless of type, the mechanism is started and stopped using the upper button, and reset using the lower button. With a Landeron chronograph, the top button starts the mechanism, and the lower button is used for both stop and reset.

The Portex arrived in non-running condition, and the sweep second hand for the chronograph wouldn’t reset. With the caseback removed, the problem was easy to see, one leg of the reset hammer had broken off and was jamming the escapement…

Luckily, a replacement hammer wasn’t too hard to find this time…

… so after a service for the movement and fitting and adjusting the new hammer, the watch was fully operational again. It’s a shame that all watches can’t age this well!

Rich.

** Many thanks to Peter Rosier for letting me feature his watch on the blog. **