This bolt secures the flail assembly to the rotor drum on a self-propelled forage harvester. It is installed at the pivot point where the flail swings, and it must withstand repeated impact loads during operation. The bolt is manufactured to the original hardness specification so it resists deformation under the shear forces generated by the rotor. A loose or stretched bolt causes the flail to shift, leading to uneven cutting and increased vibration in the drum. On reinstallation, torque the nut to the specified value and replace any worn locking element.