Shock protection

Introduction

One of the most valuable innovations in watch design is shock protection for the balance staff. This key part is the one most likely to break upon impact, which until the 1930's or so was a real problem. The basic idea is to house the jewel in a circumferential spring mount, so that it can flex and absorb the energy.

Here's a side view from Europa Star:

and another example from the Elgin site:

And from 'The Universal Escapement Ltd':

Various companies have differently shaped springs, with different trade names, I've gathered a list of the most commonly seen ones below.

Incabloc

Used in ETA, Seagull and others, depending on grade:

(Image credit: Christoph Lorenz)

Diashock

Used in Seikos:

(Image credit: Christoph Lorenz)

Etachocs/Novodiac

Used in ETA, Seagull and others, depending on grade:

(Image credit: TZ Toolshop)

Kif

Most famously seen in Rolexes:

(Image credit: Rolexforums.com)

Paraflex

(Image credit: Rolex via Horozima)
The followon to Kif, introduced in 2005.

Parashock

Miyota's system, as seen on the Miyota 8215. There's an excellent pictorial analysis here.

Links

• Europa Star article on shock protection
• Discussion thread on SCWF
• Nice Elgin page