Here are some construction photos of a hydraulic stone splitter that I made, as well as links to some youtube videos. I studied a number of commercial splitters but the one that finally made me try to build my own was this one built by Thomas in Kentucky. Thomas used his splitter to add stone cladding and a massive stone fireplace to his very nice timberframe house.
Since building mine Calder Stratford in Utah has also built a similar one, I have some photos of it here.
The basics of the construction (not that I would necessarily do it the same way again):
Video of the splitter which featurs it working in slow motion.
Splitting 8.25" high by 13" wide granite slabs.
Splitting 8.25" high by 19" wide granite slabs.