This bolt-and-nut assembly secures a wear part or structural bracket to the chassis of a tillage implement. It passes through the mounting hole and is torqued against the mating surface to maintain clamp force under the vibration and shock loads typical of soil-engaging equipment. The hardness rating indicates the tensile strength of the fastener, which determines the maximum tightening torque the assembly can withstand before yielding. A fastener that has been over-torqued or fatigued will lose preload, allowing the attached component to loosen during operation. On reinstallation, clean the threads and the contact faces, then tighten the nut to the torque value specified for this hardness class.