If I remember correctly either Krupp adopted or applied for a trademark in 1875: http://en.wikipedia.org/wiki/Krupp . I don't know about the Thalmann suit. Sauer never had the 3 interlocking rail wheels, but it was Krupp and in 1893 Krupp and Sauer entered into an agreement for Sauer only to peddle "Weapons Grade Steel" which bore the 3 interlocking rings. The Krupp trademark was a symbol of a certain composition of steel. Others followed such as Nirosta, http://www.nirosta.de/fileadmin/media/PDF/4565_en.pdf . In 1959 you should have a quality stamp on the left side of the rear lug.

Kind Regards,

Raimey
rse