Technical Model A Bendix Drive

Does anybody know what the Head Sleeve in the above diagram do?
The Head Sleeve is hidden inside the big spring and normally not seen. It engages with the Driving Head but just spins on the Bendix Shaft, it doesn't drive anything.

 

does it centre the spring around the shaft?

 

Maybe @e1956v has seen a few come through the shop?

 

It helps prevent drive flex in the spring, stiffening up the drive in the middle of the spring. They commonly break which puts more pressure on the spring itself under engagement.

 

Thanks for the reply but, no sorry, that doesn't seem right. The head Sleeve has an OD of 1" while the big spring has an ID of 1.3". So there is a large gap between the two. The spring couldn't flex that much in the middle to contact thd Head Sleeve for it to help support the spring.
I had a theory that when the big spring got wound up it would shorten in length and maybe this Head Sleeve limits the shortening. Or maybe it acts as a clutch and locks the ***embly so the big spring cannot keep winding up.
I don't know, still open to ideas. But I do know I just spent hours making 2 new ones. It is hard to get Bendix units for the early 1/2" starter shafts.

 

My bad I don’t know what I’m talking about

 

Ha! Well Bazza, if you already knew more than the experts, why did you ask? Too bad there's nobody here with decades of experience rebuilding auto generators and starters.....

 

I apologize for the smart *** response.

 

I'm still mystified what it does. Mine were just ideas I came up with.
Still open for suggestions. It must be there to do something but what?

 

I'm mystified that @e1956v gave you the answer and you rejected it.
You do know he has been a speedometer and auto electric rebuilder for 40 plus years, right ???

 

Definitely keeps the spring from breaking, test it by not using it and you will see.

 

Thanks for your replies, you've convinced me. Sorry to come across ungrateful for your various replies.