Tractor Repair: CIH 5140 service brakes, service brakes, supply hose

Question
Thanks for the help on the injector pump yesterday.  Got her running like a top.  But now I have another question.  I have no brakes.  The pedals go to the floor.  There is no fluid in the reservoir above the master cylinders.  I filled the tractor with hy-tran.  The hydraulics work fine.  Is there a separate pump or something that feeds the brake reservoir?  If not, what do you think the problem is?

Answer
  There is a hose that feeds the reservoir above the master cylinders that is connected to one of the oil cooler lines.  There is also a drain hose from the reservoir to the transmission housing.  Oil pressure from the oil cooler line feeds a small amount of oil through the supply hose to keep the brake reservoir full.  There may be an orifice inside the hose to limit the amount of oil it gets.  Check if the orifice is plugged.  When bleeding the brakes, you have to do it slowly or the reservoir will run out of oil because the supply hose can't keep up if you bleed too fast.