So tomorrow I need to return that Polaris Ranger XD press loaner I had (story coming soon!) and that means I need to hook up a trailer to my old F-150 to return it. I’m not really looking forward to this errand because trailers are an ass-pain. I’ve pulled plenty of trailers over my driving life, in a variety of vehicles, but I’ve always hated backing them up, the geometry of which tends to make my brain hurt, and they always just seem sort of, I don’t know, janky.
It’s the pivot point between the towing vehicle and the trailer, of course, that gives these feelings. You’re adding a hinge to the middle of your combined vehicle, and we’re just not generally used to driving vehicles that bend in the middle there.
Sure, you can get good at it – real big-rig truckers tend to be incredible at it, having re-wired their brains over time with lots and lots of practice. I once tried it myself, and discovered that I have a surprising amount of hidden complete lack of talent at doing it! Look, you can watch me try!
Yeah, I was terrible at it. It’s not easy!
I think all of this is why I’m so taken by this peculiar little trailer from the 1960s, this one designed specifically for Volkswagen Beetles, and known as an Efes Auto-Porter:
The Auto-Porter would certainly have significantly increased the cargo capacity of your Beetle, sort of turning it into a little pick-up truck. But what I think is most interesting about this trailer is the way it mounts to the car. Oh, and the fact that it has just one wheel, on a caster, like a colossal shopping cart wheel.
First, let’s talk about the mounting; it’s not connected via a conventional trailer hitch, instead it mounts to the Beetle’s rear bumper brackets, which are in turn mounted to the bod, behind the fenders. The Beetle is a sort of semi-unibody design, where the body is self-supporting, but it’s still mounted to a separate chassis. I mention this because those bumper brackets aren’t just screwed into a bit of sheet metal, they can take at least a bit of load.
So, the result here is that the trailer acts as an extension of the car, with no pivot, which means that reversing should be easier, provided you remember that your Beetle is now about, what three feet longer? So that should be easier to drive and deal with. Of course, you’re also increasing the weight at the rear of an already rear-biased car prone to oversteer, so have fun with that.
You know what also may make for, um, interesting handling? That one caster wheel. Being a swiveling caster means that maneuvering is likely quite good, but I am a bit concerned about something I just learned is called “caster flutter.”
You know how sometimes you’ll be pushing a shopping cart in a nice straight path but one wheel decides it wants to go all crazy and wobbles all around? That’s what caster flutter is.
So what causes this? Happily, caster experts exist, and not just exist, they make videos! Like this one:
So, according to that video, caster flutter is caused by the caster hitting some resonant frequency of vibration, which makes it go nuts. One of the factors there is something called “swivel lead,” which seems to be the distance between the pivot of the caster and the axle of the wheel:
It seems a longer swivel lead can reduce flutter. The Auto-Porter wheel seems to have a bit of swivel lead there, but is it enough? Maybe!
I’d love to find one to test! Which seems pretty difficult, as these appear to be quite rare. Still, I’ve learned more about casters just now than I have in decades, so I’ll just enjoy that little victory.
According to one source, the Autoporter Amphibien, a sleek body style that can float, was made from 1955 to 1970.
Available with a ski for snow too.
First, motorcycle trailers are a totally different animal.
Best ones now camber.
I have one of the production single wheel trailers.
It has an aluminum frame and a fibreglas body.
Attaches at two points and moves up and down and is fixed laterally which is the huge advantage of these trailers.
It takes a fifth wheel or gooseneck hitch to match the control, or some even more complex and costly designs.
There is usually an aerodynamic advantage having the fit so close to the rear body also.
My suspension is a swingarm supported by a coil spring.
I think the better designs are modeled on aircraft tail wheels.
Looking at Aircraft Spruce some designs look exactly like the VW caster but conceal springs and dampers.
I have seen single wheel trailers homebuilt for larger vehicles as large as 6′ or 7 feet wide and 10 feet long.
They only require enough clearance to move up and down, so little wasted length.
It’s best to use them for lighter, bulky items and keep weight in the main vehicle.
I can highly recommend going with torsion suspension on a conventional trailer.
The improvement over crude suspensions is huge.
Even with a light sports car, I could move most things in a trailer I first built on a Subaru suspension, light enough I can move it by myself.
Single wheel trailers are quite special though.
Looking closely at the undercarriage of the Autoporter trailer I think there is a suspension above the caster assembly.
I found a large number of single wheel caster suspensions on Pinterest.
Here is a new single-wheel motorcycle trailer: Pasq Moto Trailers
Or as reported here on Autopian: https://www.theautopian.com/a-man-created-a-single-wheel-overlanding-trailer-for-motorcycles-and-its-wild/
Mono=one Mono=one
Rail=Rail Wheel=Wheel
Monorail! Monowheel! Monorail!
https://youtu.be/rLck4DQipuQ?si=X4Y_66XeQn3TiRGC
you’re also increasing the weight at the rear of an already rear-biased car prone to oversteer.
Are you though? As it is supported by the wheel only a small amount of the weight is added to the car. More concerning is the lack of springs, which could actually cause it to unload the rear or even front. Imagine taking this over a speed bump and the rear wheels leaving the ground.
Looking closely at the drawings I don’t think this is an issue. It appears to me that the reason why it attaches at two points instead of just using a receiver in the middle is to allow it to pivot up and down freely in the vertical plane while remaining rigid in the horizontal plane. This way nearly all the weight rests on the caster wheel because any added weight would simply cause it to want to pivot downward. Then if the caster were to hit something like a speed bump it would simply pivot upwards without lifting the back of the car because it’s free to pivot up and down.
Exactly correct.
Ahh, I see where that looks possible now.
This is the only one i could find:
https://www.amazon.co.uk/Schuco-450269200-Porter-Pretzel-Trailer/dp/B086F5HH83
Edit:
Oh, and this one:
https://www.super-hobby.com/products/Volkswagen-Beetle-Ovali-with-Trailer-and-Luggage-Auto-Porter.html?srsltid=AfmBOoriHNpjmf2y_LHbk6KwmYN5yjcY97Pkk0V43cg-trBunF7OiPiF
I think it would work OK for light weights and low speeds, like European back roads in the 1960s. At higher speeds both caster flutter and wheel bearing issues with the small wheel come up.
Single wheel trailers are more common in bicycle and motorcycle applications. These usually have a rigid trailer wheel and a flexible coupler.
Backing up trailers mostly requires understanding the geometry and having a sense of where the trailer is. I was surprised how well I did with a rented camper after almost 30 years of not towing. Counterintuitively longer is easier, my long wheelbase pickup and a 25′ 2 axle camper are pretty easy to back up and track well on the road. A Jeep with a teardrop trailer would actually be harder to drive.
How applicable would the study of bicycle/motorcycle geometry be to improving the design of casters on such trailers? https://en.m.wikipedia.org/wiki/Bicycle_and_motorcycle_geometry
It’s lunchtime and I’ve already had plenty of coffee but I’m still having a hard time wrapping my head around steering axis angle, fork rake, trail, etc, etc.
And I’m reminded of what looks like a slightly backwards fork on the bicycle seen here being ridden by Harry Grant behind a rather sinister-looking motorcyclist to achieve a paced record of 52 miles and 215 yards in one hour: https://bikeville.net/wp-content/uploads/2011/04/98076-harry-grant-motor-paced-hour-record-curved-cranks-1933.jpg
old post, but I found at least one person you could ask
https://opposite-lock.com/topic/100888/seent/1?_=1737739239427
A very useful link!
And relation to the beer? I wouldn’t be surprised, as this seems like the product of a few late nights at the brewery. Efes Pilsener | Anadolu Efes Brewery | BeerAdvocate
Caster flutter is the Jeep Death Wobble of shopping carts.
I am going to chuckle at this all day.
My friend says the length of semi trailers makes them easier to back up.
Of course, he learned backing up articulated farm trailers never intended to be reversed at all.
A design like this could be the solution to EV range anxiety. Have standardized mounting points and socket to connect the electrical, and then just go rent a generator trailer when you need to take your EV cross country.
This would eliminate the “I can’t back up a trailer” problem a lot of people have with a standard trailer while providing a simple means of adding a range extender when needed.
It will never happen, of course, but it seems like a neat engineering solution to the fear of an EV running out of juice in the middle of nowhere.
Something like that exists. There was an RV generator made by Onan called the Juice Box that mounted to the rear bumper of a trailer. It didn’t have caster wheels but could act as a range extender for an EV
That would be a fair amount of weight to hang off the back end of a unibody. The caster wheel (or perhaps computer controlled mono wheel that shifted into caster mode in the event of a controller failure) that supports the weight of the generator and fuel is what would make this viable. Otherwise you’re looking at way too much additional structure in the vehicle, and the economics likely won’t work.
I’ve had a similar idea to yours in the back of my head for a while now. There would be a similar universal port you describe, but on the inside of the trunk. One could either buy or rent an auxiliary battery, maybe the size of a milk crate which would extend the range either for a long trip or emergency use. My vision for latter being that if I “ran out of gas,” a service truck could deliver a battery pack which would get me to a proper charging station, and then I’d return the rescue pack afterwards.
Your idea of the generator also works and makes sense, but every single time one was used, it would end up photographed and captioned on social media with “haha i’m so stupid bought an electric car and now I’m burning gas to power it har har har,” and why fuel that fire?
CASTER FLUTTER!
Thanks for giving it a name, Torch. FWIW, I still use “Heimholtz Resonance” on a regular basis ever since I learned it from the Jello a few years ago.
I was coming here to call it “That annoying thing that happens when you don’t lock the front wheel on a jogging stroller”
Similarly, I don’t see why a single wheel couldn’t be locked, but then I realize that the turning radius of the car vs the trailer would be slightly different and put some unusual strain on the trailer wheel if it wasn’t a caster (like driving around in 4 low, it’s gonna have a little hop to it, or just rip itself off the bumper).
Caster Fluffer is Torch’s OnlyFans name 😉
A lawyer I know has a 50’s or 60’s 1 wheel motorcycle trailer he uses behind his old harley and he loves the thing. He told me that he used to use a normal trailer behind it, but the single wheel lets him have much better maneuvering.
I’ve seen variations used behind motorcycles. Not sure how the bikes dynamics would be impacted. Pretty sure negatively. OTOH, you could fit a small shower/toilet unit inside one for a full camping experience.
Check out Pasq Moto Trailers, or as reported here on Autopian:
https://www.theautopian.com/a-man-created-a-single-wheel-overlanding-trailer-for-motorcycles-and-its-wild/
One would think that it’d be fine when consistently going forward. The problem with this design is that the caster has to rotate 180 degrees because of…forces when you decide to go backwards. So, while it is “swiveling” it’d get all sorts of wonky since it is the leading edge.
I suppose you could lock the caster, but then it’d probably just snap off.
This seems like a horrible idea, lol.
This is pretty nifty, but [in the Efes brochure] what are the two things attached to the Beetle’s vent above the decklid?
We can see one of them a little better in pic #3 of the montage. It looks like a grab handle but it’s not bolted to a particularly strong piece of the car, so that would be a little odd. Ditto for them being tie-down points.
The thing on the vents are ski holders!
I should have guessed that 😀 Thank you!
There is a small but weird thing about the pictured Beetle here, that apparently (to my surprise) Jason didn’t notice. At first glance this seems a circa 1960 Euro Beetle. But strangely, it has double turn signal arrangements, both of earlier and of later Beetles. It has the later rear lights with their orange (washed out here) blinkers. And at the same time, this one also has the pre-1960 flap-out semaphore turn signals: it’s clearly visible in the B-pillar, right where it alwas was in early Beetles. No real Beetle ever had both these two kinds of turn signals combined!
Perhaps it’s to give the impression that this trailer will fit every vintage of Beetle.
Efes Mono Flutter!
Seems like two attachment points to the vehicle would make it more stable for cruising, and a blown trailer tire would have less potential for catastrophe. I wonder if you could design it with independently telescoping arms between the vehicle and trailer to lend a little articulation when turning or backing.*
On the other hand, load balancing from side to side would be critical.
*Not an engineer.
Does it have any suspension? Doesn’t look like it.
First bump, and the suitcases go flying, then the trailer bounces and flutters until the attachment points break or rattle loose.
Can’t see using this above 20 mph
This rig will turn you into a regular Trailer Swift.
You.
Out.
COTD right here. Close the polls, we’re done.
This would be like driving a small school bus in the sense that you now have to be aware of a large amount of tail swing.
So you’re trading your pivot point for several feet of vehicle that swings in the opposite direction of your turn. Considering how often new bus drivers tag stuff with the ass-end, I’m concerned this may be an issue for Torch.
The other solution for the caster, assuming one has difficulty getting the caster lead correct, would be to have a viscous bearing for the swivel. One that dampens the action.
It would slow down the reaction time of the caster to turns, so I don’t recommend running the slalom with it, but if you have this thing hooked up, you’re probably not taking it to Autocross that day anyways.
Remind me to write an article on the pivot point of articulated buses and send it to Mercedes. Their system for damping is SUPER cool in the sense that it’s very simple.
I am having a moment where I never knew just how badly I need to know about the inner workings of articulated buses.
The inner workings of transit buses, in general, are pretty cool. It’s been my main squeeze for 9 years. 6 years working on em, and now 3 years teaching others about em.
I really need to try my hand at writing some guest articles instead of just writing curriculum.
And this is why hitch carriers are so common, and these trailers are virtually extinct. Obviously not direct substitutes, but same idea.
Even those little “car backpacks” that hang from the roof rack or tailgate seam are a better idea, but definitely not for a Beetle unless you want to overheat immediately…
The hitch carriers are more common because they’re cheaper and simpler.
However, if your rear suspension can’t take the weight, you’re better off with a solution like this. I’d rather just a small utility trailer, but the Torches among us are deathly afraid of pivot points.
As a kid, the family would travel across the country ever summer (Parents were school teachers) We had a Pontiac station wagon pulling a mono wheel trailer. We stayed at camp grounds (giant canvas tent) across the US. By time I was 12, I think we hit every state except Alaska. What fun times.
It doesn’t appear to have suspension, I wonder if you could see it bouncing in your rear view.
I imagine it probably has a tire pressure that helps smooth out the ride. You could always modify it to add a torsion or shock mount.
All empty trailers bounce like a toddler on a trampoline when they’re empty anyways, so the only concern is what it’s behaviour loaded is.
There was a two-wheeled version of this for sale on FM for weeks in my area. It also came with an attachment so you could hook it into a standard 2″ hitch reciever. I believe it was a Montgomery Ward.
I gave it some modest consideration, but ultimately decided not simply because I was unfamiliar with it.
I’ve wondered why a design like this hasn’t been popular for something like a motorcycle carrier. Those are the motorcycle carriers that put the full weight of the motorcycle on the hitch, and thus squat most vehicles they are mounted to; but a swivel wheel would help a lot. I did manage to find that CruiserLifts makes modern types of these trailers; they seem aimed at RV’ers who want to bring a trike or golf cart with them.
I use one of those hitch-receiver-mounted motorcycle carriers, so I’ll chime in here.
In general, if you’re carrying/hauling something on a hitch carrier and it is completely off the surface of the road, you don’t really need to do anything else. However, once you put a wheel on the road you will almost certainly need to have proper lighting (e.g. a 4-pin connection to the vehicle’s wiring harness) and a license plate for whatever you’re towing, even if it’s very small.
tl;dr hitch carriers are much simpler, especially for small bikes
Laws vary state to state on the plate/registration for registration. I know growing up in Utah, a single axle trailer under a certain weight that I don’t recall did not need anything. Lights yes, but no plate.
Yep, that’s why I included the “almost”: I’m not familiar with the requirements everywhere, esp in wild and crazy places like Utah and Michigan. 🙂
Pretty sure Texas doesn’t require anything, or at least they don’t enforce anything. Man the shady crap out on the roads there is crazy.
Makes sense. The thing that doesn’t make sense is that a hitch carrier just seems bonkers for most bikes that aren’t dual sports or dirt bikes. Even something modest (and known for being light weight) like a Street Triple weighs in at ~420lbs. Add in, what 25lbs (50lbs?) for the rack itself, and you’ve just effectively maxed out a class III hitch.
This past summer I saw a R1250GS on a hitch rack of a F250. It made me wince.
That BMW weighs over 500lb – dang 😮
The receiver (a Draw-Tite) on my vehicle is structural, in that it replaces something called an “impact bar” behind the bumper skin; IIRC it has a max tongue weight of 900lb.
The carrier I use has a max weight capacity of either 500lb or 600lb.
The bike I carry weighs under 300lb, and I still worry about it – especially when going over bumps. I do know that one or more catastrophic things would need to happen for the bike to fall off but I still cringe.
I guess the F250 driver wasn’t worried about safety margins…
He may have added support to the rear suspension.