Lubricants and tribology

One verb in this list sets a trap for English readers: walken. It looks like « to walk », and German has in fact borrowed that meaning as well — ich gehe walken, said the English way, is brisk walking in a park. The technical verb is older and native. Walken means to knead, flex or work something over and over: a fuller once did it to cloth, a tyre does it to its own rubber, and a grease tester does it with a perforated plunger. Die Walkpenetration is therefore not a test of anything moving on foot but the depth a cone sinks into grease that has just been worked through sixty double strokes. The two words are distant relatives — English once used « walk » for fulling cloth, and the surname Walker still remembers it — but nobody in a German workshop hears a stroll in it.