Today in 1951, US Patent 2536927 A was issued, an invention of Porter E. Griswold, for his “Hop-Picking Machine.” There’s no Abstract, although in the description it includes this summary:

My invention relates to a machine especially designed for use in the hop-picking industry for stemming hop clusters.

Hops are generally grown on trellises from sixteen to twenty feet high, the vines being trained over these trellises. In picking by machinery, the vine stalks are out about four feet from the ground and passed through the hop-picking machine, the hops being removed mechanically from the vines during the traverse of the latter through the machine. Some of the hops are removed from the vine -in the form of clusters or bouquets, such clusters having more or less of the stems or small branches, which are undesirable in the finished product, and it is necessary to pull these clusters apart to free the hops from this trash.

The object of the present invention is to design a simple, practical machine of large capacity for this work..

The invention consists of the parts and the construction and combination of parts as hereinafter more fully described and claimed, having reference to the accompanying drawings, in which Figure 1 is a plan view of the invention, one-half of the outer casing being broken away to show the inner stemming centrifugal cone. Fig. 2 is a side elevation in partial section of the invention. Fig. 3 is a detail of the cooperating series of outer and inner, or stationary and movable, pickers.