Help identifying braking system component/function

[Kountry87Air]

I hope someone can help identify a braking system component for me. I can only guess at its purpose..not enough or accurate to repair/replace. I've attached a picture to help identify.
This is on a 1987 Ford F-350 chassis/460/hydralic brakes/with tag axle.
On the drive axle pig a bracket holds a scissoring linkage. Linkage has two equal length arms of ~8", connected together to pivot. Linkage rotates on pig anchored end. Linkage attaches overhead to a roundish component apprx. 3" in diameter/2"wide with a knurled rotating shaft on one side. Linkage is supposed to attach to the knurled shaft, shaft appears to be broken or abused outboard of knurling. The linkage is not attached currently to the component..and there does not appear to be a method of affixing it..no hole thru shaft for a cotter pin etc.
Brakes hoses go into and out of the compnent. I have a guess on its function to somehow help regulate brake fluid between the drive axle/tag axle...but I consider it a weak guess.
CAn anyone help identify the function of this part?
Thank you.

[ChrisNiemann]

don't mean to burn up your "unanswered thread" but the last time i saw anything like that was on a conversion from "drum" to "disc" brakes... on the left picture, there is that nub sticking out to the right, that was used to regulate the pressure between the left and right calipers after the disc brakes were installed from the drum... that is all i know of that part, hopefully someone else can help but I thought i would throw out my .02.... good luck, will follow thread to see what comes of this.

[Kountry87Air]

Quote:

Originally Posted by ChrisNiemann don't mean to burn up your "unanswered thread" but the last time i saw anything like that was on a conversion from "drum" to "disc" brakes... on the left picture, there is that nub sticking out to the right, that was used to regulate the pressure between the left and right calipers after the disc brakes were installed from the drum... that is all i know of that part, hopefully someone else can help but I thought i would throw out my .02.... good luck, will follow thread to see what comes of this.

Thanks for your input Chris! Our rig still has drum brakes..but the function could be as you say for those or the tag axle brakes. I have noted the drive axle may not be original...on each end underside there are what appears to me to be leaf spring guides welds.
When I first saw this "mystery component" I twirled the knurled shaft before I could think not to. We haven't used it since I did that so no telling what that did to whatever setting it was at..and brakes worked effectively.
Part of the fun, eh?

[speed racer]

This is the early rear wheel antilock brakeing controler. The idea was that when the pickup was empty and you aplyed the brakes hard the back of the truck would rise up and this valve would limit the braking power to the rear wheels so they wouldn't skid.

[ChrisNiemann]

nice job speed!! thanks a ton on that one!

[Kountry87Air]

Quote:

Originally Posted by speed racer This is the early rear wheel antilock brakeing controler. The idea was that when the pickup was empty and you aplyed the brakes hard the back of the truck would rise up and this valve would limit the braking power to the rear wheels so they wouldn't skid.

Ahhh..that makes some sense Speed.
I sure wish I had not twirled the shaft. There does not seem to be a "neutral" position. I guess I will have to trial and error kind of thing to find a shaft position that works.

Thanks all!