The armature 23 and pole piece 24 are preferably fabricated from {HEAD ~ a magnetic material}, such as {TAIL ~ soft iron} 
The armature 23 and pole piece 24 are preferably fabricated from { HEAD ~ a magnetic material } , such as { TAIL ~ soft iron }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL