What is flanged washer spring？

What is flanged washer spring？
Accordingly, a flanged washer spring is provided, comprising a disk having a central opening, outer periphery, a first side and a second side, the disk further having an annular inner flange extending axially from the first side, and an annular outer flange extending axially from the second side, wherein a radial distance from the outer flange to the central opening is greater than a radial distance from the inner flange to the central opening. The disks are normally used in pairs with the outer flanges of the disks positioned axially adjacent to and abutting each other. The springs may be used in combination with a tool, such as a drilling accelerator or jar, having an elongated tubular body having a body stop for axially retaining a spring, and an elongated mandrel smilingly mounted within the tubular body, the mandrel having a mandrel stop for axially retaining a spring, the spring comprising a plurality of stacked flanged washer springs.