The DKW 3=6 family - the first production car to use Polyurethane suspension components?
Some time ago, I re-read an article published in New Zealand Classic Driver magazine in 2011, about the Auto Union 1000S, that contained the line - " You could never say that this was a landmark car in any way".
Well! I protest! I think it's very important to understand the design lineage of these cars properly, in order to put them into perspective properly in the era that they were designed in - the 1000S should be seen as a member of its family, not on its own, in my opinion. We need to draw the line all the way back to 1939 and consider what this car was at that time - and again, in my humble opinion the DKW F9 was remarkable for its day. Yes. I've said it. It was a landmark car in many ways.
Many people forget or do not know, for example, that Duroplast
was first used in an automotive application by Auto Union in 1938, and not, as commonly thought, devised in post war communist Eastern Europe (Wikipedia, I am looking you!)! Photographs of Auto Union's pre-war Duroplast body panels may be seen here on Paul Markham's excellent blog: http://heinkelscooter.blogspot.co.nz/2012/12/1939-dkw-f9-prototype.html
Postwar, the F9's offspring (as it were), the F89 and later F91, 93,94,95, 1000 etc.. were less remarkable in some ways (the body was steel for example). However they did contain something new and very revolutionary, which, although not headline news at the time, changed the world in few years. This thing was called Vulkollan
. Vulkollan was/is a polyurethane product - known today as "The King of Urethanes".
Polyurethane was invented in 1937 by Otto Bayer (unrelated to the Bayers of Bayer AG)- or more correctly, Otto Bayer was head of the research group that, in 1937, discovered the polyaddition for the synthesis of polyurethanes out of polyisocyanate and polyol. This was under the umbrella of the German company IG Farben. A major breakthrough in the commercial application of polyurethane did not occur until 1941, when a trace of moisture reacted with isocyanate to produce carbon dioxide. The production of this gas resulted in many small empty areas, or cells, in the product (which was subsequently called “imitation Swiss cheese”). As early as 1943, some military uses were made of the product - but it wasn't until the early 1950's that the product was refined into a new solid medium called "Vulkollan". IG Farben had been liquidated in 1952 and on Bayer AG regaining its independence as a company, they immediately pressed ahead with "Vulkollan". Bayer themselves have never manufactured Vulkollan, and in the early 1950's granted several licences for its production, finally trademarking it in July 1955.
The solid polyurethane elastomer that is "Vulkollan" is very popular, still – due to its substantial mechanic and dynamic material characteristics. The main components of Vulkollan consist of a polyesterpolyol and a diisocyanate. Special cross-linking agents are individually added to obtain the required material characteristics.
Vulkollan is especially popular in the manufacture of wheels. Sectors of major use of Vulkollan wheels include:general industrial wheels (forklift wheels as one example), bottling, mechanical industry, automatic and packaging machines, labelling systems, wire-guided conveyor systems, AGV systems, airports, paper, ceramics, cement mixing, heavy-load wheels for refuse compacters, foundries, glass working machinery, etc..
OK - so where did DKW start with Vulkollan? Well, the answer lies in another Auto Union invention - the so-called "Schwebeachse" or floating axle, used on DKW's from 1932 (invented by J Rasmussen himself). This design consisted of a rigid axle with two trailing arms, an overhead transverse leaf spring, the transverse leaf spring is connected to the arms of the axle body at the level of the center of gravity of the vehicle; One end of the spring uses an "eye" as a fixed bearing , the other end rests in a sliding block ( as a floating bearing). The center of the spring is attached to the chassis. Here's what it looks like;
This is the sliding end on the right hand side of the car:
In 1955 the traditional DKW Schwebeachse
was adapted to use a Vulkollan shoe on its floating or sliding end - on the right hand side of the spring. This is the first documented production automotive use of Vulkollan. From 1955 DKW even made kits available to retrofit earlier cars with Vulkollan shoes, so successful was the innovation. The combination of the Schwebeachse and the Vulkollan shoe, of course, were a very large contributor to the DKW 3=6 family of car's legendary handling.
Here is the early incarnation:
Here is the version incorporating the Vulkollan shoe, released in 1955:The Schwebeachse at work;
For the sake of completeness - I should add that Auto Union also used Vulkollan in the steering box bushes of its cars, and as with the suspension components, with excellent effect. As for the Schwebeachse, it continued in use on cars such as Wartburg 311 (ending production in 1965)