Most do have a pto powered hydraulic pump, some with a remote tank, others with the loader frame also holding the oil. I built my frame to also serve as the oil reservoir.
Found a used Haldex with a disp. of .258 cu.in./rev. 2 gal./min.at 1800 rpm.and 4 gal./min. at 3600 rpm. It will develop 2300 psi cont. I have relief valve set at 1200 psi. so it puts out plenty for my use.I got it on ebay for about 1/3 cost of new.
Prev. pict. shows hoses cleaned up and idler stiffened. Next one shows belt on. Other pict.shows it guarded. If you would like a certain area let me know.
Here are pict.of frame components I made. Michael has posted many pictures of Simp. loaders in past,ask him for link. Make a mirror image of long member for other side.