About 20 years back I started thinking about what I considered to be a completely new class of vehicle.
It seemed obvious to me that the ubiquitous pickup truck, so much a part of the American culture, was, and still is, one of the most useless vehicles ever conceived. Apparently I was not alone with these thoughts as you can read here
I really started thinking seriously about this after studying, and pricing, a flatbed truck as used by tow companies to move cars around. The idea of lifting the car more than a meter in the air so that it could be carried over the top of the differential and suspension of the flat bed seemed to be ridiculous. I figured that a much better solution would be to use a front wheel drive vehicle and carry the load on a deck between the rear wheels. At the time 1982 -5 the Chrysler Minivan was a new concept but it only sported a 4 cylinder engine which just didn’t have the power that a vehicle of the type I was envisioning would require.
I had, on a trip to the Carolinas, seen a similar type of vehicle built from of a Cadillac Eldorado but this was a pretty rough sort of rig using the original Eldorado chassis with a tray big enough to carry a car fitted where the rear seats and trunk used to be.
Other projects and working for a living got in the way for many intervening years but in the late ’80s and ’90s the minivan really came of age and they were now fitted with powerful V6 engines which would be more than adequate for my purposes and I started giving the idea deeper consideration. I felt strongly that if the rear suspension were designed properly the vehicle could be made to kneel down, like a camel, for simple loading eliminating the need for loading ramps. Over the years the concept started to take shape and, after I learned how to use a good 3D CAD program I started to sketch things up.
I looked at many possibilities for the rear suspension from swing arms to lever actuated systems and everything in between. I finally hit on the idea of using air springs. These things have been around for years and are very reliable. I managed to design a suspension system which used a trailing and a leading arm on each side. I could find no information on a leading arm suspension system and had to spend quite a bit of time studying the dynamics of such a system to ensure that it would behave in the manner I required.
A couple of years ago I decided that it was time to either build the vehicle of forget about it, so build it I did. I started off with a perfectly good 1994 Dodge Caravan and had Dwight Auer cut about 1 1/2 meters out of the middle.
Because the minivan is a unibody type of construction we had to build a fairly substantial subframe inside to attach the deck to. What we did was probably overkill but I figured better safe than bent. Fortunately the fuel tank on a Caravan is easily moved forward but re-routing the fuel filler took a little time.
The deck was constructed of rectangular tubing with heavy expanded metal as the load surface.
The suspension arms pivot on the steel shafts that you can see poking out the side of the deck. Once the deck was completed the entire thing was sent off for hot dip galvanizing. This turned out to be a bit of a disaster because, despite my sending detailed instructions that the frame was to be used as an air reservoir, the galvanizers decided that they had to cut holes in every closed member for venting, which they proceeded to do with a gas torch. I managed to convince them that they had screwed up royally and they agreed to weld all the holes closed and make things good, which they did.
To get the air springs to inflate I installed the air suspension compressor from an Oldsmobile under the van floor and using a series of solenoid valves and relays managed to set things up such that I can inflate the air springs in sequence to ensure that the leading axle gets up to full pressure before the loaded ride height is trimmed using those of the rear axle.
The deck brakes are straight off the Caravan and I built an air cylinder operated compensator which adjusts the pressure to the rear brakes in proportion to the load that that axle is carrying to prevent premature lock up when unloaded.
We have been using the transporter for some time now and all the engineering is working very well. No major issues have arisen and on a trip of over 3000 km to Newfoundland hauling a Mini rally car, all its support equipment and two people with all their gear we averaged over 23 MPG (imperial).
Loading is really easy with the onboard winch and the expanded metal deck prevents the slipping and sliding issues i had with my previous trailer.
The rig remarkably easy to manouver although the turning circle is somewhat increased as a result of the extended wheelbase. Vision through the huge rear window, particularly when unloaded is fantastic and I can back up to within a few inches of a car to be loaded.