A cycling valve , {HEAD ~ reversing valve} and actuator mechanism provide {TAIL ~ operator control} of the devices contained in housing  
provide
A cycling valve , { HEAD ~ reversing valve } and actuator mechanism provide { TAIL ~ operator control } of the devices contained in housing
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH