Herr Raby, My German is limited and I am still learning. The plural form of a word in German will use an umlaut to show that it is plural, usually adding an -er to the end. "Wheels" in German is "Räder". However, in my haste I pluralized (<- is that an English word?) "Wheel". The second part of the word is the plural part so "Schloss" becomes "Schlösser".
Wheellocks should be Radschlösser.
I had to ask my German wife... German wife's are always correct...
William