School Me Please: Sliding Mainspring Bridles

[RickTock]

I'm working on a Schild AS 1250 (a 'bumper' automatic) and it's the first time I've seen a mainspring like this. It has what looks like a regular manual-wind mainspring with a 'hook' at its outer extremity. On a manual-wind watch that 'hook' would engage with a 'hook' in the barrel wall to prevent it from rotating. However, the AS 1250's mainspring does not engage directly with the barrel but rather with a 'sliding bridle' that sits between the mainspring and the barrel wall, and evidently facilitates the slip necessary in an automatic. I'm not sure what advantage this two-piece configuration provides, but it highlights a gap (one of many) in my horological knowledge.

I'm not sure if 'hook' is the correct term as used above, but please see photo below to see what I mean.

Therefore, two questions please.
1. What is the proper way to lubricate a barrel from an automatic watch with a sliding bridle? My guess is the same as any automatic ms/barrel (e.g, a few dabs of braking grease on the interior barrel wall). What do the experts say?

2. I purchased a Generale Ressorts GR3472X mainspring, made for the AS 1250. It looks like the bridle is included and I don't need to salvage and re-use the old one. Is this a safe assumption?

Thanks for the advice. If you have any other wisdom you'd like to share about separate sliding mainspring bridles, I would be very interested.

Cheers!

[caseback]

This is the old/first(?) way for making a mainspring for an automatic. "Evolution-wise" it is an logical first step forward from a standard spring. Usually these are indeed replaced with a new spring with an integrated/fixed bridle. Lubrication as you would do with any automatic.

Added: I can also imagine this construction was originally made to achieve some safeguard against "brute force" handwinding...?

Edited 58 minutes ago by caseback