Do I really need a 3rd function valve to angle a hydraulic snow plow on a SSQA? I know I'll need to raise and lower the plow (using one set of valves on the loader), but I don't think I'll actually need to tilt it, as I do with my loader bucket. If I don't need to tilt the snow plow, that leaves the tilt valves on the FEL to angle it. Can I lock the tilt function into one fixed position, and use the snow plow this way, and without causing damage to the hydraulics?
The loader is a LA525 on an L3800.
I use the curl and dump functions when backdragging away from the garage or when wanting a more aggressive cut. The blade normally floats via chains. To backdrag I dump the plow and usually the weight of the blade is sufficient. The frame is made to enable two more levels of downward force. Occasionally if more down pressure is needed I can float the loader arms and let them bear down on the blade frame. If there's something really stuck on, I can add the weight of the front of the tractor. The curl/dump is needed to get the geometry right for the different modes.
You will want to have the plow frame parallel with the surface that's being plowed. Otherwise when you angle the blade, one end will dig and the other may not even be on the ground. I have markings for the level indicator to return to that setting following backdragging, etc.
The way I built my SSQA plow followed the designs of Paul Short and Gordon Gould. If you search for "Setback Underslung Snow Plow" there's a lot of info to peruse.
I've had manual angle plows on a Jeep and a Power Wagon as well as several rear scraper blades on tractors that were manual. I've had power angle plows on a K5 Blazer and the Kubota. As Jay said, the manual plows work but take planning (and getting out of the warm to adjust them). I'd pick power angle if at all possible. I find myself swinging the blade when coming to the end of a push sometimes. It's easier to stack the snow with the blade straight.
Can't recall the whole conversation, but recently there was a post in which the guy complained about only being able to angle in one direction or some such situation when trying to use just the regular loader hydraulics.