A lower retaining member is linked to {TAIL ~ the lower ramp} and movable into and out of the sheet feed plane in alternating relation to {HEAD ~ the upper ramp} 
A lower retaining member is linked to { TAIL ~ the lower ramp } and movable into and out of the sheet feed plane in alternating relation to { HEAD ~ the upper ramp }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD