Hello Arnold,
I did some research on "Saalfrank and Tange". The company was probably an armature winding factory that mainly produced electric motors.The company was located at Schmiedestraße 31, in Kappeln an der Schlei, Schleswig-Holstein, Germany.
Under the link you will find a reference to the company.
https://www.schulzeitreisen.de/?p=28516However, you may already be familiar with it.