Shock Protection.By Avalon.

[padi56]

By Avalon.
JJ's thread on Rolex v ETA had some comments in it by Padi on shock protection. I have become familiar with some of the different styles out there, so thought I would present some pictures of a few for your reference. I am certainly no expert on this, so just some observations I've made on the various types I've seen personally.......

Shock protection is designed to allow the shaft (pivot) of the balance to move under a shock, reducing the chance of damage, but to also bring it back in it's proper place. I found this diagram that shows some section views of what this looks like.



The two main players in this area are Incabloc and Kif. I have found some information from the 50's to show what their respective "signature" style of shock absorber design looks like.

First, the "traditional" Incabloc design.



And this is the original Kif design.




The first photo is from a vintage Bulova watch movement that I have taken apart to clean, lubricate, and hopefully get back running again. It's a Caliber 10BT.....note the lack of any shock protection.......at least that I can see......



In my view this is not good at all, as there is a chance that a hard shock could break the balance pivot.

The next is from my Seiko 5 - I cracked the case to take this photo of the 7S26 movement. It has shock protection, but it looks quite crude in it's construction - certainly a good movement, but you can see why it's not expensive. I don't recognize this design, so it is likely Seiko's own.



The next is from my project watch. It shows the Incabloc system used on this particular 2801 hand wound movement. Some may mistake this for an older style Kif shock protection, with the "clover" shaped spring. I can tell you that this one is a challenge to work with, as you have to bend the outside diameter of the spring down over the jewel, and then hold it there as you rotate it into the grooves to keep it in place. This design is the Incabloc Novadiac system.



Here's a different photo of the same unit.......



The Incabloc that most are used to seeing is like the one shown in this ETA2836 that just arrived this week for my next project watch. This is an automatic movement from ETA, complete with day and date complications. It shows the lyre shaped spring that holds the jewel in place.



Note the difference between the style used in the 2801 and 2836 - the 2801's spring has 3 points of contact with the jewel, where the 2836's style has only two points (one on either side of the jewel). Theoretically, the style with 3 points of contact should center the jewel better after a shock. Of course with these kinds of things, I'm sure there are many trade-offs in the designs. Only the manufacturer's know the real details, so I'm just speculating on some obvious points here. One thing that has crossed my mind is the effective spring length between these two designs - it may be the the spring with 2 points of contact can travel further out of position than the other can......

Here is a shot of the shock protection in my Glashutte Original, Caliber 65.....



It appears to be the standard Incabloc style.

This last photo of mine shows my JLC Master Moon Caliber 891's shock protection, which is the same style that you will find in a modern Rolex movement. This is the current Kif design, which looks a lot like the Incabloc at first glance, but then you can see a difference. It has 3 points of contact on the jewel rather than 2. However, it is clipped in place like the Incabloc standard design is, so I'm sure this is easier to work with than the Novadiac (old Kif) style would be.




Now I have this image of a Rolex 3135 movement, where you can see that the shock protection is the same as in my JLC - the "newer" Kif style.



So, I hope this will help you all recognize what the different types of shock protection look like, as they can easily be confused if you don't look at them closely.