Grease and quality.
I run the Baldor/Dodge bearings on every piece of equipment I can. A few things about high quality pillow block bearings you may want to know.
1. Don't over-grease them!!! this is very important. What happens when you over-grease a bearing is that you literally push the seals out of them. The Baldor/Dodge bearins are sealed. When the seal is "broken" or pushed out then the bearing will let dirt and moisture into the bearing surface, causing them to fail prematurely. I only grease my bearings when then start to make a slight amount of noise when rotating the cutter wheel by hand with the machine off, and then only give them enough to quiet them down. Using this simple technique, I made the main load pillow block bearings on my drilling rig last for approx 20,000 hours and still counting. (yes you read that right, 20,000 hours)
2. The ammount of preasure against them is nearly irrelevent. The bearings on the rig have a tremendous ammount of pressure against them. They are holding ALL of the power that a 6 cylinder Perkins diesel can put out! There is no good reason why these bearings should fail in 500 hours on a stump grinder if taken care of properly. They take a serious beating on the rig and keep right on spinning smoothly. Also, just as a point of refference, the rig has 4 belts that drive a 3-stack hydraulic pump that runs the whole rig. Those 4 belts have roughy 6-8 times the holding power of the belts on the vermeer sc252. And they are cranked down tight enough that you could almost play a tune on them. These bearings are on a 1 1/4" shaft. Also, another place we have pillow block bearings on the rig is the winch. The winch has a 1" diameter shaft and is subjected to well over 2,000 lbs on a fairly regular basis. Those bearings are still the original bearings put on in 1975!!!
3. The angle of the shaft is also nearly irrelevent as the purpose for pillow block bearings is to make up the difference of not being able to get things perfectly aligned. The shaft hole through the center of the bearing allows for a lot of angular movement. In my experience, it really doesn't matter if the shaft is a few degrees off. The bearing surface on the inside of the pillow block is meant to handle a load in a lot of different angles, just so the main load is not side to side.
4. The quality of the grease is a huge key factor to making the bearings last! I personally use and very highly recommend the Amsoil E.P. Moly grease. It works great in this application. The moly in the grease helps make it extremely slick and also coats the bearing surfaces. The moly also protects the bearings in a "run dry" situation, meaning that the bearings are still slick even if the grease has dried up or worked it's way out of the bearing. Though I do not recommend running them dry for any length of time.
I appologize for the lengthy post, but feel it is important to get the information out to my fellow equipment owners/operators. I hope this helps all of you in your quest for less maintenance and better proffit.
I am currently working on retrofitting a Lombardini diesel engine in place of my old 20 hp Honda on my vermeer sc252. I replaced the bearings on the grinder shortly after I bought it and put the Baldor/Dodge bearings on. The bearings on the jack shaft were a simple direct replacement. The bearings on the grinding wheel took a small amount of grinding to make them fit. I will get the part numbers for these bearings later this week and will get back to you with them.
Have a great day and happy grinding