On newer trailers they have moved to parallel dual-race sealed bearings.
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There are a few things of note ... especially on Al-Ko brakes & drums. (Euro Hub)
To start you need a special tool to take off cover cap ... I made one in a lathe.
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To change the bearing you need a 5 Ton Hydraulic press .... I don't have one so I applied a bit of science.
You need first to remove the chunky circlip ... I managed to borrow a 10" circlip pliers.
I put the drum down on a hard surface, and put a socket that was a snug fit, and then drifted out the old bearing, they destroy on way out but that does not matter.
You then take the old outer shell and put a thin slot across it with a grinder & slitting disc.
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Then the science bit, without a 5 Ton press, just clobbering the bearing will damage it and probably not even get it all the way home.
So ... first step seal the bearing in a bag, and put it in your freezer overnight.
Then, having cleaned & degreased your drum heat it .... I used a MAPP gas torch, just keep applying heat in a circular pattern around the central boss.
I heated it to 120C
The my frozen bearing dropped 1/2 way in on its own, then using the old bearing outer as a drift, tap it home, you know when it is home as the note changes - and you can see the circlip groove.
The slit in the old casing means it will easily come out.
Job done on 2 drums.
The incredibly fiddly job of replacing shoes, springs and refitting them to backplate.
Anybody who has even changed the shoe spring retaining clip on the side of the trailer swing arm will know how much fun it is.
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To refit the drums, easy enough, you would think, but no they now use (single use) one-shot flange nuts,
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Not only are they not cheap ... you need a Torque Wrench that can apply 290Nm, and that is a LOT of torque, and in my case also a piece of tube to extend the torque wrench as you won't tighten without it.
Trailers are hard work.
