Several embodiments of a system for connecting brake shoes to brake beams in a railroad car retarder all provide enhanced connecting joint tightness that reduces premature connecting joint loosening, reduces maintenance, and reduces failure of connecting bolts or equivalent connecting pins. The device includes a cardiac contractility modulating unit capable of delivering cardiac contractility modulating signals to the heart for modulating the contractility of a portion of the heart. The drive mechanism is connected drive-wise to the movable knife. For example, in one set of embodiments, the particles may be at least partially coated with a protein, such as hemoglobin, that is able to interact with oxygen. Thus, the designers can select to use one output characteristics or the other for their designs.