zetor12111 trailer hydrulic brake valve

im looking to fit a hydraulic trailer brake valve on a 12111, how do i go about this?

I fitted a unit to a 40k 12145 used to pull a silage wagon, this was done over ten years ago, so i could be leaving something out.
But the unit cost around E500, then pipes too. fitting is done by,a pipe comes from the hydraulic pump direct to the braking unit, then a pipe was taken from the brake line fed to the unit, and then a pipe brought to the back of the tractor.

thank you for your reply, where did you get yours? i asked a local agri parts supplier, he tried a few places, but no luck,

I got the unit in Tobin`s of Coalbrook Co,Tipperary. they are Case dealers now and carry Zetor spares but at the time I purchased mine they had several braking units but as I said this was in the 2000`s.