The HP B3Q10-40081 ADF pick extension shaft is a replacement part for the automatic document feeder’s paper-pick mechanism. It is identified specifically as a shaft for the feeder, making its role clear within the printer’s document handling assembly.
The part is listed for the HP Color LaserJet Pro MFP M377dw, M477fdn, M477fdw and M477fnw, as well as the HP LaserJet Pro MFP M426fdn and M426fdw. Its exact part number is B3Q10-40081, which distinguishes it from other parts in the ADF assembly.