The plunger feeder, illus- trated in Fig. 330, is similar in operation to the swinging-plate feeder in pushing the material along the bottom plate. The plunger may be built either in one or two parts, moving ahead alternately and driven through a rocker shaft, as in the case of the one previously described. The capacity is fixed by the number and length of the strokes and the location of the adjusting gate. This type has the same disadvantages as the swinging-plate feeder, the most serious being that it is not self-cleaning.