I have a 1992 Puck, and there seems to be no way to stop the brakes fighting my car when I reverse. The clutch on my Volvo gets very hot every time I reverse, even for short distances on the flat, but when reversing on wet grass or up any kind of incline becomes very alarming as front wheels start to smoke.

Shouldn't there be a lever of some kind to engage when reversing, to prevent this happening? I can't find anything like this on my Puck's hitch, and wondering if the 2 red buttons might be something to do with this?

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No, the two red buttons simply pull off and underneath you'll find greasing points. In the old days there used to be a lever that had to be released on the caravan when reversing although I'm not sure whether or not the Eriba's had this system or not - I doubt it.
Anyway, I had a similar problem first time out with our earlier Triton and a trip to the dealer was called for in order to adjust the overrun brake. I would suggest a call to your dealer is also in order or alternatively contact a mobile service engineer.

Roger, your post is suggesting that the concertina rubber gaiter plays some part in the braking action when in fact it can be looked at as simply a dust/dirt cover. On both our Triton and Troll this gaiter wasn't/isn't attached to anything merely slipped over the exposed end once the hitch has been removed. When replacing the AL-KO hitch, which I did recently, the rearmost bolt pushes through the end piece of the draw bar thereby holding it in place resulting in a fixed point.

The picture below shows the major components of an AL-KO over-run braking system:

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The tow ball (in white) exerts all the mechanical force from the towing vehicle onto the draw bar. When pulling the trailer or caravan forward, the force is opposite to the arrows shown. However when you apply your brakes, the trailer or caravan tries to continue at the same speed (inertia) and travels forward in relation to the towing vehicle and compresses the drawbar and spring. This compression causes the lever to rotate pulling on the brake rod and operating the brakes. (Red arrows)



The operation of the over-run system is simple and effective, the harder you brake, the more force that is transferred to the drawbar and the further the drawbar compresses transferring more force to the brake rod, therefore applying more braking effort. As you ease up on the brake pedal, the force being transferred eases, so releasing some of the braking effort. This cycle continues through out the braking phase… any increase in the braking force by the tow vehicle causes the trailer or caravan to try to “over run” the towing vehicle and reduction in braking force causes a reduction in braking effort by the trailer or caravan.

The system is self-regulating to a certain extent, but there are problems with this system:

The cycle of braking and releasing above is reliant on a sprung damper system. If it was just an un-dampened spring, what would happen is when you braked, the trailer would push into the back of the towing vehicle compressing the spring, activating the brakes, then as the brakes took effect, the trailer would slow quicker than the towing vehicle, releasing the brakes…. and then catch the towing vehicle up and apply the brakes… the cycle would go on and all you would feel is a series of thumps to the back of the towing vehicle.

So how can we stop this? Well the easiest way it to put a damper, or shock absorber (exactly the same way your vehicles suspension has springs and shock absorbers) to absorb and reduce the “bouncing” of the spring. Getting the spring and damper rate right for a given trailer or caravan weight is important. If the spring is too strong and the damper too stiff for the weight of the trailer, then the brakes will not operate with enough force or worse case, not operate at all. However, if we go to the other extreme and the spring is too weak and the damper too free for the weight being towed, the brakes will operate too easily and could start being applied even when you just lifted off the throttle slightly or at simple bumps in the road.

Having the spring and damper rate too low for the weight being towed will result in vibration when braking and compromising the effectiveness of the trailer brake efficiency. Having the spring and damper rate too high, will cause the towing vehicle to have to do more braking for the trailer, the tow vehicle then is not braking efficiently. In either case, the stability of the vehicle and trailer are compromised.

With our Triton the braking system hadn't been adjusted correctly by the factory resulting in the feeling of trying to reverse the caravan against an immovable object and with a smell coming from the clutch as though something that was once alive under the bonnet had long since died LOL. Now when the caravan goes in for it's annual service I am at pains to point out that the over-run brake system is correctly service It’s a hassle, it’s a cost…. it’s potentially a life saver and not something to be overlooked.

Credit to Caravan Chronicles for the diagram and a good percentage of the accompanying text.

Thanks for the explanations, which I'm trying to get my head around, as not mechanically inclined. So, am I correct that what you're saying is there should be an automatic brake over-ride rather than a lever to be put in place? .... and if so, that I'll need to get a caravan mechanic to sort this out for me? I had her serviced and safety checked last year and assumed any issues discovered would have been dealt with, or at least flagged up to me, by the caravan mechanic. I was unaware of the over ride issue on my Puck, and thought the hot clutch was something experienced by all caravanners when reversing. This happened a lot last summer, but the fact this is not normal
was only pointed out to me last weekend.

Yes I would definitely get it sorted before you burn out the cars clutch. My wife's cousin used own a caravan for which one had to mechanically disengage the overrun break although this wasn't pointed out to him upon purchase with the result that he burned out the cars clutch. Most caravans don't use this system any longer with everything now being automatic. The system works well but does require periodic maintenance.