How to preload this type of double ball nut?

Does anyone know how to adjust the preload on this type of double ball nut?

 

There are pins that hold the middle section to the front half of the nut, and 2 thicker bars with set screws connected to the back half.
Do I just apply some force by hand and use the set screws to lock them off?
Or do I use shims?  Do I put the shims on before I put the nut on the screw?

Thanks in advance,
Frank

Looks like set screws on the middle ring are used for preload.

I haven't seen that exact design before.
Generally the two halves are only really held together by the ballscrew. Then the bars hold everything in a fixed phase relationship and the thickness of the central spacer is adjusted to set the preload. (pushing the halves apart to preload the balls).

This one looks like it _might_ have tapered screws to push the halves apart via the bars, but it's not so easy to tell from the photo.

Thank you all for your comments.  It made me look a bit closer at the nut.

The flanged end that has pins, also has multiple holes so that 2nd nut can be turned to provide a coarse adjustment.

 

The back section has 2 regular set screws to position the 2nd nut, but the slot in the middle section, in which the bar sits, is wide allowing for fine adjustment.