A forage harvester comprising: a feeder operable to move crop material in a direction of crop processing; a shear bar located downstream of the feeder relative to the direction of crop processing of the crop material; a panel (52A, 52B) configured for directing the crop material downstream of the shear bar relative to the direction of crop processing of the crop material; a processing component (58A, 58B, 58C, 58D) disposed downstream of the panel (52A, 52B) relative to the direction of crop processing of the crop material; and an impact sensor; wherein the panel (52A, 52B) is configured to be moveable from a first position to a second position in response to the impact sensor detecting an impact, wherein the first position of the panel (52A, 52B) forms a channel for directing the crop material in the direction of crop processing along a first path toward the processing component (58A, 58B, 58C, 58D), and wherein the second position of the panel (52A, 52B) alters the channel to direct the crop material along an alternative path not including the processing component (58A, 58B, 58C, 58D); characterized in that the impact sensor is coupled to the shear bar and operable to detect data related to a magnitude of a force applied to the shear bar, and in that the harvester is further configured such that the panel (52A, 52B) is moved from the first position to the second position in response to the impact sensor detecting an impact force having a magnitude greater than a defined limit which is larger than a normal operating force that the shear bar is subjected to during normal operation of chopping the crop material. a feeder operable to move crop material in a direction of crop processing; a shear bar located downstream of the feeder relative to the direction of crop processing of the crop material; a panel (52A, 52B) configured for directing the crop material downstream of the shear bar relative to the direction of crop processing of the crop material; a processing component (58A, 58B, 58C, 58D) disposed downstream of the panel (52A, 52B) relative to the direction of crop processing of the crop material; and an impact sensor; wherein the panel (52A, 52B) is configured to be moveable from a first position to a second position in response to the impact sensor detecting an impact, wherein the first position of the panel (52A, 52B) forms a channel for directing the crop material in the direction of crop processing along a first path toward the processing component (58A, 58B, 58C, 58D), and wherein the second position of the panel (52A, 52B) alters the channel to direct the crop material along an alternative path not including the processing component (58A, 58B, 58C, 58D); characterized in that the impact sensor is coupled to the shear bar and operable to detect data related to a magnitude of a force applied to the shear bar, and in that the harvester is further configured such that the panel (52A, 52B) is moved from the first position to the second position in response to the impact sensor detecting an impact force having a magnitude greater than a defined limit which is larger than a normal operating force that the shear bar is subjected to during normal operation of chopping the crop material.