Originally Posted by TeJay
I do have my opinion regarding this issue but I am always open to accept new technology. When that happens I will change my opinion. Here's my concern Is there something about the AL-KO Ultrulube design set up that will prevent the rear seal from blowing out if to much grease is pumped into the axle hub??? When the grease is pumped into the hub it usually passes through a narrow passage way to get to the inner bearing. When that grease is replaced with the new then the grease travels outward and eventually replaces the hub grease and the outer wheel bearing grease. Maybe the AL-KO set up prevents the seals from blowing out. I'll look them up on the net to see.
What you describe is exactly what happens, you could pump gallons of grease in and gallons will come out the front, however (as Herk mentioned) there is a possibility pressure type grease guns could pump in faster than it can make its way so it could exert too much force on the rear seal and blow grease out there too. AL-KO do not mention this possibility at all, not even as a get out clause so maybe this is not an issue to be too concerned about.
Here's another thing, the AL-KO system, unlike conventional type hand packed bearings, displaces all the air, this is a good thing. Air expands when hot and can help force grease past a rear seal, and worse, on a boat trailer when a drum rapidly cools when reversed into the ocean the contracting air pocket can create a partial vacuum and suck sea water past the seal into the bearings
for this reason I have fitted Bearing Buddies to my boat trailer bearings, these mimic the AL-KO system by allowing me to pump grease until it flows out the front thus eliminating air pockets.