When the switching means disconnect the motor from the electrical power source, {HEAD ~ the disks} coast to {TAIL ~ a stop} 
coast to
When the switching means disconnect the motor from the electrical power source , { HEAD ~ the disks } coast to { TAIL ~ a stop }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL