Chains?

In the UK we have a brake cable which apparently puts the caravan brakes on when detached from the tow-ball, but no idea how helpful it is at a decent speed.

As with everything else in the US, of course we have Federal Regulations along with a variety of State regulations. There sometimes is some consistency between the two ... .

For lighter weight trailers, the "ball and socket" hitch connection is almost universally used in the US. The "Ball" is on the towing vehicle, and a "socket" on the tongue of the trailer latches onto the ball.

ALL TRAILERS using the ball and socket hitch are required to have two "safety chains," generally with one bolted (sometimes welded) to each side of the trailer tongue. Normal practice is to "cross" the chains under the ball/socket and hook them to attachment points on either side of the ball on the towing vehicle.

If the socket "comes loose" the theory is that the tongue will fall onto the "cradle" made by the crossed chains, keeping a somewhat "loose connection" that still provides some directional guidance to the trailer. This actually works better than might be expected ... ... ... sometimes.

Lightweight "utility trailers" may not be required to have brakes, but for most camper class (caravans) up to about 2,000 lb (900 kg) an "inertia brake" may be used. The trailer is equipped with hydraulic brakes, drum or disk, and a "master cyclinder" on the trailer tongue has sufficient "slip" that when the trailer pushes against the tow vehicle, as when the tow vehicle slows down, the piston is pushed in to apply hydraulic braking to the trailer.

An overlapping range of trailer sizes from around 1,500 lb up to around 8,000 lb generally will have electrically actuated brakes, with a controller in the tow vehicle that applies the trailer brakes whenever the tow vehicle brakes are applied.

Generally, any towed load with electric brakes is required to have a "breakaway switch." A pin in the switch (on the trailer tongue) is attached to the tow vehicle by a cable, so if the two separate the pin is pulled and the trailer brakes lock up. Most such setups require at least a battery in the trailer to apply the brakes, although sometimes power from the tow vehicle "unapplies" them and a spring applies them if the power goes away (railroad style?).

While theoretically the ball and socket hitch can be used up to around 12,000 lb gross towed load or higher, at about about 6,000 lb and up it's common to go to a "fifth wheel" arrangement that closely mimics the "tilt plate - pin and hole" arrangement used on tractor/trailer (a.k.a. semi/18-wheeler) transport rigs.

From the descriptions of the Al-Ko hitches here, I'd have to say that the common "anti-sway" devices commonly used in the US are signficiantly "more robust" than those, but that's sort of a separate subject. My impression (based on no real evidence) is that campers/caravans in the US tend to be bigger and heavier than in most elsewheres, but there aren't many places where you'd drive 1,850 miles each way to camp for a week at a festival - as we did the first 3 years we had our tiny little 1,800 lb (loaded) Jayco pop-up.

John