Sheet feeding apparatus and printing apparatus

A sheet feeding apparatus comprising:

• a feeding unit configured to feed a sheet by coming into contact with an uppermost sheet of a plurality of stacked sheets;
• a separation surface configured to be contacted by the sheet fed by the feeding unit to separate the sheet;
• a first separation part, provided separate from the separation surface, and configured to be switched between a first position in which the first separation part protrudes from the separation surface and the sheet is capable of contacting the first separation part and a second position in which the first separation part is retracted from the separation surface and the sheet is not capable of contacting the first separation part;
• a fixing unit configured to selectively fix the first separation part at the first position or the second position so that the first separation part is not moved between the first position and the second position as a result of a contact force which the first separation part receives from the sheet;
• and
• a second separation part, provided separate from the separation surface, and configured to be movable in a first direction from a condition in which the second separation part protrudes from the separation surface and the sheet is capable of contacting the second separation part to a condition in which the second separation part is retracted from the separation surface, the movement by a contact force which the second separation part receives from the sheet, and the second separation part configured to be biased in a second direction opposite to the first direction.