Rubber cow

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BMW R 69 S, disrespectfully called "rubber cow"

In motorcyclist jargon, rubber cow refers to two-cylinder motorcycles of the BMW model series R from 1955 to approx. 1990 with a full swing chassis.

Concept emergence

The expression "rubber cow" was coined by the motorcycle journalist Ernst Leverkus . During a test drive on a new BMW, he was credited with clearly ascertaining the lifting of the rear wheel suspension by the cardan drive in conjunction with the rear wheel swing arm and making a comparison with domestic cattle: cows usually rise upside down first.

The word component "rubber" was partly lost in the course of time; Often the only thing left was the “cow” as a synonym for BMW boxer motorcycles . The letter "Q" is often used as an abbreviation.

Technical background

As a result of a design change in 1955 with the appearance of the full swing BMW , the ring gear of which is on the inside of the rear wheel, the rear wheel suspension lifts when starting. The opposite effect occurs when the accelerator is released: the long-stroke, comfortable suspension collapses at the front as well as at the rear, an effect that also gave rise to the expression "elevator motorcycle". With the introduction of the Paralever chassis in the late 2-valve models, the era of the rubber cows ended, technically speaking, because the new chassis prevents the “elevator effect” by eliminating the load change forces and erection moments.

Further use

However, the use of the term rubber cow is much older. Already at the beginning of the 20th century, airships from the manufacturer Parseval were mocked with this word.

literature

  • Verlag der Schillerbuchhandlung Hans Banger (Hrsg.): German-language magazines. Volume 40, 1996.
  • Machine design . Volume 68, issues 11–15, Penton / IPC, 1996.

Web links