Hans and Konrad were two Bavarian siblings, who worked at The Jones Salvage Yard, and lived somewhere near to the salvage yard. They frequently drove The Three Investigators when they did not have the Rolls-Roys sedan that they used, available. The siblings were physically very powerful, and, occasionally, acted as protectors of the boys.
They frequently drove Titus Jones to buy junk for the salvage yard, and also helped in loading things down, as they were capable of carrying heavy objects.
In the German translation they are Kenneth and Patrick from Ireland.