3pt hitches coming in different categories, 0,1,2,3 if you are having to ask, i am going to assume you have a small tractor which will most likely be cat 1,
a riding lawn mower might have cat 0
if you were a farmer or like, you might have a bigger tractor that may have cat 2 (category 2) 3 pt hitch
3pt hitches on all tractors exception riding lawn mowers, are all spec'ed out to same size and like. the only difference might come up is HP at the PTO
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you might want a "slip clutch" that goes between tractor PTO and PHD gear box. so if you do snag something that stops the PHD dead in its track, the slip clutch will let the tractor PTO shaft keep spinning, but let the PHD auger stop spinning. other words the slip clutch protects the tractors PTO shaft.
NOTE TO ABOVE! most PHD i see normally have a "shear bolt" were the auger bit (drill bit) attaches to the gear box. this removing need for a slip clutch. if you hit something that causes auger bit to stop dead in its tracks, the shear bolt will be cut in half. the shear bolt protects the "gear box" and the tractor PTO shaft. Shear bolts are not run of the mill bolt you can pickup at some hardware store. and pending on PHD you get may require a specific grade of metal the bolt is made out of, to be a shear bolt. ((to strong of metal and shear bolt does not get cut)), ((too week of metal, and you end up going through sheer bolts left and right))
a generic cheap 3pt PHD with no down force kit. does have some problem with small tree roots. and rocks. and keep them from digging any further down. and you may need to pickup the PHD and then drop it down. to get the auger bit to grab ahold and keep on digging down.
you do not need "super fast RPMS" slow and easy works good for me.
the "down force kit" for myself on farm, would be awesome to have, dealing with so many different types of dirt, from muddy dirt, to hard compacted dirt, to dirt that has rocks and tree roots in it. to other. though i have gotten away for now without needing down force kit, buy taking some 8x8x16 concrete blocks and wiring them firmly onto the PHD. so the blocks never get in way of PTO shaft or auger bit.
warning to above, be carefull of a PHD, you can get into some pretty deadly situations with a PHD, due to the PTO shaft and auger bit are so much out in the open and no type of real good shield to protect someone from getting wrapped around the PTO shaft or auger bit.