Why a pig and not a dog?

Actually, there are plenty of "dog Trailers" on the road, usually a smaller "SUV" towed behind a motorhome.
Have also seen vehicles as large as a Patrol or Landcruiser tabletop behind a motorhome providing quite a decent payload capacity.
How the trailer braking arrangements in these situations are handled may be a challenge.
mike

Peter, that's an interesting rig. But no mention of it, on the Bimobil website.

They specialise in "custom constructions", and I'd suspect that rig above is a custom build, to a clients request.

Bimobil - All models

Cheers, Ron.

I would suggest that any dog trailer that 'swishes about' is in need of a wheel alignment or other attention. Cars towed behind other vehicles on A frames tend to be quite stable.

In 1969, I towed a Cooper S on an home made A frame behind a Mini Deluxe from Adelaide to Canberra at 100kph. The bumper bars were about 350mm apart. The combination was quite stable. The only difficulty was the lack of brakes going down through the mountains :).
I made no attempts at reversing the combination :)

A dog trailer is inherently stable (if set up correctly) whereas a pig trailer is inherently unstable. Chalk and cheese really.
Cheers,
Peter
OKA196 motorhome

There are many factors that makes dog trailers tailwag excessively. Here are some.

1. The amount of overhang between the trucks drive wheels and the drawbar pivot point. A longer overhang between the drive wheels and the drawbar pivot point increases the amount the front of the trailer drawbar moves when steering corrections are made. This is exacerbated if a short trailer drawbar is used as well.

2. The height of the C of G of the load being carried. Some of the tall, dry freight vans, suffer from a high C of G when fully loaded, and thus suffer from more upper side-to-side sway, with steering corrections. This side-to-side sway then translates to trailer tailwag.

3. The style of suspension. Air bag suspensions are notorious for increased side-to-side sway, because they lack the roll resistance of mechanical (spring) suspensions. Anti-sway bars and heavier shock absorbers are often fitted to try and improve this suspensions performance.

4. The amount of bump steer suffered by the truck (the prime mover). Some trucks have poorer front suspension geometry than others, and suffer more from bump steer (unwanted steering movement created by bumps in the road).
Wear in the trucks steering mechanism also reduces the steerings resistance to road input, as it does when the vehicle is new.

5. The width of the spring packs. Some spring packs aren't sufficiently wide enough to prevent excessive side-to-side axle movement. This problem is not confined to trucks, it affects many vehicles.
I can recall Holden fitting wider rear spring leaves to the HR Holden to reduce the side-to-side rear axle sway, that was a problem with the HD Holdens handling.

6 Wear in suspensions overall, can contribute to tailwag and sway. Worn suspension pin bushings are common with high km vehicles.

Trailer tailwag is a multi-faceted problem and many technical studies have been undertaken to try and pin down the major factors affecting the handling performance of combinations.
Many road train combinations today still suffer from poor handling and excessive tailwag, not helped by constantly varying load concentrations, in many cases.
In all cases, the load positioning in your trailer is crucial to good handling behaviour.

Cheers, Ron.

Ron's correct, but we can't compare truck dog trailers of 30 years ago with the one's of today.

The Australian design rules and modern trailer design have nearly eliminated that giggle headed movement, they include distances like overhang, length of drawbar and positioning of axles, many also have esc with manufacturers testing their trailers. Unlike caravans if a trailer doesn't perform word gets round very quickly in the transport industry.

Just follow any modern truck and dog combination and watch, of course if the road is bad they will wobble around a small amount but settle quickly.

From memory in the 80's Mossman mill carted sugar to Cairns with trucks and dogs. They were an absolute nightmare on the Captain Cook Highway.

Not to mention that a mini being towed isn’t a dog trailer at all. No centre pivot turntable. You cannot spin a towed mini in its own wheelbase backwards to tip the main body....... every design has its own pluses and minuses.

I think you will find that the caravan in the pic I posted has no turntable either.
Still a dog trailer in my book.
Cheers,
Peter
OKA196 motorhome

Peter, there's one of those Bimobil dog-trailer-style caravans for sale in the link below, and if you do a Google translate, the first sentence in the sales description says the van has a turntable.

Bimobil turntable caravan for sale

That particular van model is called the Bimobil AX 575, and there's quite a few European websites that have articles about that particular van.

Not especially cheap at around 70,000 to 75,000 Euros new, but nothing from Europe (and Germany in particular) comes cheap.
Cheers, Ron.

OK, thanks.

It also says "So there is no lurching, no weight on the trailer hitch and it is on the road like on rails."

Cheers,
Peter
OKA196 motorhome

One hell of a long range fuel tank!

What a pair of scumbags!! When they catch them, they should hand them over to the locals for a bit of "rough handling"!

Break and Enter - Mungindi

Theft from isolated farm sheds is a huge problem - but industrial/commercial theft is always ongoing, too.

The W.A. Police caught a bloke locally, who had rented a factory unit, and filled it with stolen goods, such as thousands of litres of fuel, power tools, hand tools and even two stolen Bobcats!!

They only caught him after he broke into a local toolstore, which had a monitored alarm system.
The Police arrived and promptly grabbed one of the thieves outside the toolstore, equipped with a 2-way - and his scummy mate was found hiding inside the toolstore, equipped with the other 2-way.

Cheers, Ron.