I've got next doors ifor williams cattle trailer here with three wheels on ATM, long story short, i borrowed it for shifting a big batch of cattle from one block of land to another so we could run two and the wheel fel off on the first load. my friend had only just fitted a new hub and the bearings had collapsed in the new hub, so he goes for another one, seller swaps it for a replacement, fitted that, one load and it went again. sp i've pulled it apart, i haven't got any photos as the camera is playing up so i'll try and describe it as best i can. the new hub is a modified part, the old on has tapered wheel bearings that go straight onto the hub shaft on the trailer and are loaded to the correct tightness by the end nut, as you do. the new type has some sort of sealed unit bearing in it which has a larger center than the hub shaft and requires a spacer with a collar on to fit on the shaft, the spacer fits over the shaft on the axle, and inside the wheel bearings on the hub and has a collar on it that gos on the outside 9wheel side0 of the bearings and the nut tightens up against that. Now i've been told that these type of bearings aren't set like a taper roller, you bang up the hub nut ans tight as it will go and that's it, job done, but the spacer is about 1/4 of an inch shorter than the width of the bearing, so when you tighten the hub nut, you're trying to push the sleeve through the bearings rather than tighten it against the flange on the axle shaft, if that makes sense. It was thinking that surely the spacer should surely be the same length as the combined width of the bearings, anyone have any experience of this type of bearing?