But on all 4 wheels at same time points to a common fault not on a hub
issue (at least I think)

On 07/05/2018 08:51, Chris J Dixon wrote:
rick wrote:

Have a twin axle trailer.

The brakes are AlKo auto reverse type.
Going fwd brakes work fine, stationary handbrakes applies and holds.

In reverse after a short distance (presume until hitch damper completes
travel) the brakes lock on.
If I unhook trailer and manoeuvre by hand it will reverse with no issue
.... so only a problem when push rod activates.

AIUI, in reverse when the shoes touch the drum they move and are
then retracted from the drum, it would seem that this mechanism
is for some reason not working.

Chris