The second clamp 14 opens by removing {HEAD ~ a primary pin} and a safety pin in the nature of {TAIL ~ the first clamp} 
The second clamp 14 opens by removing { HEAD ~ a primary pin } and a safety pin in the nature of { TAIL ~ the first clamp }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL