After a couple of years of continual maintenance I fitted a system using standard 10mm plastic plumbing pipe and connectors with a hoselock fitting at front of trailer. The only modification I had to make was to use a standard pushfit to brass threaded adaptor fill the end up with epoxy resin and drill 2mm holes all around it to spray the water everywhere and it works great. total cost of project <£25.
the other modifiaction I made which is even better was to get rid of the bl***y bowden cables that kept binding causing bearing failure and replace them with a couple of pullys on the axle in the middlee and bare stainless steel wires out to each brake.
Now I only have to service the hubs & brakes once a year