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28/06/2016
COLD RETREADS FOR THE AFRIKA KORPS

History

 

True, Bandag introduced cold retreaded tires to the world and Marangoni invented the pre-prepared ring, but few know that the first large-scale users of this technology were the Afrika Korps soldiers during the Second World War

Paolo Ferrini

Spring 1942. The British war vessels sink an increasing number of ships carrying material from Italy to Libya and consequently Field Marshal Rommel’s Afrika Korps are short of supplies. Furthermore, usable tires are becoming increasingly scarce throughout North Africa, a commodity that, among other things, takes up a lot of space in the holds of the few ships able to pass the blockade in the Sicilian Channel.

To solve the problem the Wehrmacht decided to exploit the invention of Bernhard Anton Nowak who, some years earlier, proposed on the market a series of rubber strips with a pre-vulcanized tread to be applied to a worn tire, after being preheated, and give it a new life.

When the soldiers received these 8-12 - meter long pre-prepared tread strips (depending on the tire size to be rebuilt) all they had to do is scrape off the old worn tread, cut strips based on the size of the tire, apply first a special glue and then the tread strips. The “curing” process was easy enough, no need of high pressure moulds, just dig a hole in the hot desert sand and bury the tire inside. The African heat would do the rest. Thus, cold retreads found their first major application.

 

 

The birth of Bandag 

Years pass, in 1955 the war is a thing of the past and Roy J. Carver, an American inventor and salesman of industrial pumps, is on a promotional business trip in Europe, when he happens to hear from a taxi driver how in Germany tires are retreaded using pre-vulcanized tread strips.

Carver decides to pursue the matter further and manages to meet Novak to acquire the licensing rights to use his retreading process through a new company that Novak expressly asks to be called Bernhard Anton Nowak Darmstadt AG (AG in German is the acronym for limited company).

Thus Bandag (nothing more than the acronym of the name desired by Nowak) was born, and on December 20, 1955 the new company began its activities in Muscatine, Iowa. Since then this town of 23,000 inhabitants, mainly known because Mark Twain "remembered it for its sunsets", achieved world fame for being the headquarters of Bandag. Carver starts the new business in a former sauerkraut factory and simplifies the production process, taking advantage of the experience he gained producing industrial pumps.

The beginning of what could be called a great industrial adventure. Following a takeover in 2006, Bandag, now part of the Bridgestone Group, can now boast a turnover of 800 million dollars a year, making up 45% of the cold retreads market (followed by Marangoni and Vipal) catered for by 1,000 dealers around the world. About a third of these are in the United States alone while the Eastern Hemisphere Retreading Division (EHRD) coordinates Bandag operations in Europe, Africa and the Middle East from Belgium.

 

 

Marangoni, from strips to rings                         

Another success story in the technological evolution of the modern cold retreading process sees Mario Marangoni, the founder of the homonym industrial group, as the main protagonist. In 1973, while visiting a trade fair in the United States, Mario Marangoni had an idea destined to change the cold retreading system forever: a pre-cured tread ring to be applied on truck tires. A real breakthrough and, as it often happens with Marangoni, not long after the initial intuition the first physical model of the project made its debut.

Back in Italy, he immediately commissions Marangoni Meccanica to design and build a prototype circular press capable of producing the pre-cured tread rings. The advantages of this new technology are immediately evident. First, the ring-tread is pre-printed in a concave shape for a perfect fit on the tire, but most especially tires retreaded with this system are free from the joint  that has always been the most obvious limitation of flat pre-cured tread strips. The result is a retread that for appearance, performance and durability is absolutely comparable to a new tire.

The following year, in 1974, after the experimental phase, the company shifts to mass production assembling, again at Marangoni Meccanica, four Ring-Tread presses that earn the firm a positive response from the market. As a result, in 1976 a new plant, the Marangoni RTS (Ring Tread System) is inaugurated in Ferentino, 80 km south of Rome, where the pre-cured tread rings are manufactured soon to be joined by a second plant for flat pre-cured tread strips.

As the name suggests, RingTread is a highly automated retreading process during which a tire is received, checked through a sherography  inspection machine that automatically assesses the internal quality of the casing, buffed and sent to the Ringbuilder, a single fully automated machine that in its latest version extrudes the cushion gum directly onto the casing, fills the cratering, applies the ring and adequately rolls it, thus obtaining a tire ready for the curing process.

What more can we expect from cold retreading?

 

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