Jockey wheel falling down

On my old Dandy 4 the jockey wheel twice fell down whilst travelling last weekend despite I thought being tightened up. It is a Bradley CU 20 cast hitch with a hole 36mm dia and jockey tube 34mm dia. I took it apart and there is a small bent steel pad which I suppose clamps on the tube.
[You must be registered and logged in to see this link.]

Does anyone have any experience of this? So far no damage done - but..... Any practical advice will be gratefully received

The upper (fatter) tube fell through the clamp or the inner (thinner) centre unwound itself down?
Can't quite see how the first would happen unless the clamp bolt had a stripped thread or it was very course and unwound.
An unwinding lower leg. I've worn that T-shirt though. Lost a lower leg on my first folding camper. Since then the brackets that run from the leg centre to the jockey wheel have been passed through the V notches in the upper leg to stop the lower leg vibrating and unwinding. If no notches or the notches were shallow then the lower leg has been jammed against the A frame to stop the lower leg winding down. Even so had a leg partially unwind. The top handle must have revolved. Tightening the winding handle seems to work. If it had not bungying the handle or similar would have been tried.

Hi Tow itch - no it didn't unwind. The fatter tube fell through the clamp (twice, once going and once returning). The clampbolt didn't vibrate free, the threads seem ok and I even tapped it tight with a hammer. Doesn't make sense does it!? Unless there is something amiss with the pad which does look a bit quickly manufactured. I wondered if anybody had the same problem

Incidentally I put wd40 on my I thought knackered window stay as you recommend and all is fine now. Thank you.

We haven't had a problem with ours dropping down as yet touch wood.  
In ours there is a curved pad that sits in a recess inside the main hitch, when you tighten the pinch bolt it pushes on it to clamp the outer main shaft. What you may have is that there is some dirt or paint in the threads of the pinch bolt that is stopping it being able to go in far enough and tighten it up. To stop the inner leg unwinding the best thing to do would be to wind it right up till it goes tight, we then lift the whole jockey leg up so the wheel is against the A frame. It then should be able to unwind itself.

Thanks Phoenix - I suspect the pinch bolt may have been painted while its not been tightened and the threads aren't winding in enough. I've taken the jockey and plate out and will clean the threads and make sure the bolt winds in far enough before reassembling. I will also check that the curve on the plate fits the shaft. I too lift it into the frame to prevent unwinding. I will also put a rope preventer on the wheel just in case the jockey tries to fall again. I don't know why they don't have a hole right through and clevis pin for when you're driving - it would give peace of mind . If I'm near a man with a big enough drill I may fit one! I'll report back!

A hole right through and a clevis pin sounds like a good idea, but we could see a couple of problems with that.
1. If the hole is too big it will weaken the jockey leg.
2. You might have a job lining the holes up as you would have to get them in the exact place every time and you won't be able to see the hole in the inner shaft easily.

A rope or bungee to stop the wheel and handle turning and unwinding is probably the best idea.

Feeling a bit thick but you're right I forgot about the centre tube as I don't often wind it up or down! So how about a pin through the A frame and jockey wheel itself + pin. It should be easy to line up and it couldn't fall?

That sounds like it could work.  

To avoid any drilling though just putting a rope through the u shape bracket that the jockey wheel is fitted in and tying that to the A frame should suffice and give peace of mind.

[You must be registered and logged in to see this link.]

When you wind the jockey wheel down with it unhitched from the car, does it support the weight of the front of the dandy. if so, the clamp should be working.

Its a bit temperamental and inclined to slip - I'll have a go at the threads over the weekend.

Just to report - I've cleaned the threads with a wire brush in a drill. They were solid and the hammerite was stuck so fast I'm pretty sure it was preventing it fully tightening although it felt as if it was. Without the jockey wheel it went tight the moment the hammerite was reached.So if you hammerite your frame it would be a good idea to protect the threads first. Thank you for your suggestions - I will be adding a rope "preventer" next few trips just in case!