The use of {TAIL ~ hydraulic motors} allows {HEAD ~ a simple system} of electrically controlled valves 406 to be used to control these functions 
The use of { TAIL ~ hydraulic motors } allows { HEAD ~ a simple system } of electrically controlled valves 406 to be used to control these functions
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH