Back-up Ring

FIG. 1 is a front, top, right perspective view of a first embodiment of a back-up ring; FIG. 2 is a rear, top, left perspective view thereof; FIG. 3 is a front elevation view thereof; FIG. 4 is a rear elevation view thereof; FIG. 5 is a left-side elevation view thereof; FIG. 6 is a right-side elevation view thereof; FIG. 7 is a top plan view thereof; FIG. 8 is a bottom plan view thereof; FIG. 9 is an enlarged partial front elevation view thereof; FIG. 10 is an enlarged partial rear elevation view thereof; FIG. 11 is an enlarged partial right-side elevation view thereof; FIG. 12 is another enlarged partial right-side elevation view thereof; FIG. 13 is an enlarged partial top plan view thereof; FIG. 14 is a partial cross-sectional front, top, left perspective view thereof in an environment of use, which may include a hydraulic cylinder; FIG. 15 is an enlarged partial cross-sectional front, top, left perspective view thereof in an environment of use, which may include a hydraulic cylinder; and, FIG. 16 is another partial cross-sectional front, top, left perspective view thereof in an environment of use, which may include a hydraulic cylinder. The broken lines of even length shown in the drawings illustrate portions that form no part of the claimed design.