Sentence:  My invention relates to pianofortes of the general character embodied in my United States Letters Patent No. 2,377,582, issued June 5, 1945, and wherein is disclosed and claimed a horizontal, <WSD>downstrike</WSD> hammer action particularly adapted, although not necessarily, for use in a lightweight, portable piano. 
Meaning of the word marked with <WSD> tags:  A variety of various devices that operates primarily by a downward striking action.