Referred to as sealed bearings, but not exactly sealed. More like dust covers to keep most of the junk out. And studies were conducted years ago, that when they used one color grease inside the bearing and another color grease in the grease zerk, they found that there was some mixing of the two inside the bearing.
Something people don't realize also this same concept applies to ATV and UTV bearings on axles and differentials. The seals are designed to keep the oil in, but when dunked in cold water will cause water and other debris to be sucked past the seal, quickly leading to bearing failures.
Sealed bearings (as shown) really are sealed. Shielded bearings are not.
The seal of a sealed bearing as shown in the spindle bearing video keeps grease in the bearing which would be thrown out in normal use. It is not a robust seal to protect against the elements. Disappointing that mower spindles do not have an external 2nd seal the way motorcycles and ATVs have. Even street motorcycles.
I have seen a few Country Clipper spindles. Sealed bearings. No zerk fittings. The zerk fittings in the video are useless but for “feel good” factor. Make someone feel good about doing the right thing servicing their machine without actually doing anything useful. Just like ethanol in gasoline makes people believe they are saving the environment or something.
The external seal on motorcycle and ATV wears and quits sealling. Otherwise it does a good job protecting against “cold water”. Even worn it provides a shield lessening the amount of crud reaching the bearing seal. The right thing to do installing new or prepping a new motorcycle is to pack the space between sealed bearing and external seal with waterproof/marine grease. This lubricates the seal and provides yet another barrier before crud can reach the bearing.
The wrong headed person in the video did not bend the spindle tapping on it with a soft hammer. Is not the preferable means to extract a bearing one wishes to reuse, a purist would use a press. The issue is hitting the inner race of bearing to extract the outer race. Ball bearings are held to millionths of an inch, little things matter. But I am far from convinced his hammer abused the bearing anywhere near what the bearing gets holding a blade hitting things we all hit with mowers no matter how much care. Motorcycle wheel bearings are usually much tighter in the hub and very likely to be destroyed using a drift to drive out from the inner race. If I remove, I replace with new. I can pull the outer seal to inspect, clean, and/or add grease without removing the bearing.
The primary reason to add grease to bearings is to push crud out of the bearing. No way is the pressure of grease going to push his bearings out when clamped on both ends by the spindle. Seals without supplementary retainers will come out, which is bad. Is desirable to push old grease out the seal. His stupid weep hole is exactly the thing which will vent pressure preventing new grease from reaching his bearings.
Many motorcyclists rant about how little grease they find in “cheap” sealed wheel bearings, even in premium brand new motorcycles and OE replacement bearings. It doesn’t take much grease to do the job and too much grease in a high speed bearing only pops the seals out. “Too much” is ok in a low speed bearing.
