This subject does not really fit anywhere, but here it is. I have used the sure lube system in my trailers for 16 years and never had a bearing failure. I only take them apart to service the brakes every few years. Here is a schematic of how it works: It is not like the rest in that the grease fitting is in the cap and not the end of the spindle. The cap is recessed to help protect the fitting. The grease goes in through the cap, then through the outer bearing and then through the inner bearing. It then travels through a hole into the center of the spindle and out through a passage leading to the inner end of the spindle. On a straight axle, it winds up inside the axle tube and there is a vent hole in the axle tube for it to escape. On a drop axle it just dumps on the top of the axle and needs to be wiped off. Since the bearing cavity is never pressurized it does not force the seals or the cap. It can't pull water in because the passage is too long for that. I have submerged mine many times when the bearing were still warm from interstate pulling with no ill effects. Pumping 5-7 ounces of grease into it will change the grease completely so the bearing assembly does not need to come apart to do that. The end play does need to be checked occasionally. They use special double lipped seals and they seem to last forever. http://www.reliabletool.com jim
