I have been collecting and researching padlocks which have the oak leaf dust cover labelled “F. Sengpiel Patent” for the last 4-5 years. I managed to gather up 60+ specimens and draw a number of tentative conclusions. First, that there was a F. Sengpiel Company and it did patent a small number of divergent products, one being the Padlock Dust cover. The patent itself makes no reference to a lock - beyond stating that the dustcover will protect a padlock from the elements. So, it is reasonable to conclude that Sengpiel Company may have never manufactured padlocks, per se.
Second (and you can read a summary of my conclusions on the website MyViMu.pl , look under padlocks, go to the Sengpiel padlocks, and on the entry in which I show 5 different sizes of the padlock, I provide the overview or summary), the dustcover with said markings appeared on a reasonable number of padlocks - all with the same structure, in 5 sizes.
Another post mentions this lock was made by Damm & Ludwig Company. This may well be true but I have found no evidence of it. This assumption, I believe, arose from a comment made by a representative of D&L, when asked the question.
I would be interested in whether anyone has any concrete evidence of who manufactured F. Sengpiel padlocks, and when, and where.
