Trailer dampers

[Nigel Blandin]

I have a really nice PRG trailer with twin Al-Co axles. 2600 kg gross.

Now I am on the mainland and doing quite a few miles with it, I notice an oscillating motion in the tow car Disco 4) when loaded on long runs.

Al-Co do damper kits. Has anyone fitted similar and did they notice any improvement in ride?

[7 wonders of the world]

Is the trailer set level with correct nose weight and tyre pressures..?

[Nigel Blandin]

Yes, all set fine ( I have towed a lot for 30 years)

this is the first trailer with the rubber suspended swing axles I have had on mainland roads. All my others were Ifor Williams- solid axles and leaf springs which I found harsher, but with none of this oscillation.
I think the independent swing axles need damping. I assume this is what is fitted to caravans a lot, I wonder if they have dampers? 

[anthonym]

how about the weight per axle? i.e. hitch height

[7 wonders of the world]

Are the trailer wheels balanced...?

For some unknown reason people think its not required....

Followed many an empty trailer with the wheels parting company with the ground

[Nigel Blandin]

Thanks both, I take my trailering very seriously and do ensure my loads are balanced and trailer I'd serviced myself. I am pretty sure that it's just something different about independent suspension vs leaf springs that I have always used for work.

PRG, the manufacturer have agreed to look at it with me and we are looking down the shock absorber route. It has always surprised me they aren't on all trailers anyway.

[anthonym]

Interesting, I've never thought about having them balanced and they lock up very easily when empty. 

[anthonym]

On re reading, I don't have leaf springs.. does that mean independent suspension? 
How can I tell if I have rubber suspended swing axles? It's a Brian James Minno Shuttle having had several iterations of parts.

[Nigel Blandin]

By leaf springs, I mean a straight beam axle with the hum on the end. Ifor Williams work this way, maximum strength for heavy work.

Independants either have a beam axle bolted directly to the chassis for strength with small trailing arms off the end that the hubs are attached to, or separate trailing arms are bolted to the chassis. These units tend to have  a + shaped pivot arm, surrounded by rubber inside them to provide the springing rate and damping function.

The other reason for independent units is to lower the chassis height, especially for car trailers. They are great on road, but if you tow off road ( diggers, soil etc) when the going gets tough you tend to bend them a bit!