The circuit requires {HEAD ~ reduction} of the engine speed to {TAIL ~ a speed} below the lower response speed in order to restore the response speed of the speed responsive control to the predetermined speed 
The circuit requires { HEAD ~ reduction } of the engine speed to { TAIL ~ a speed } below the lower response speed in order to restore the response speed of the speed responsive control to the predetermined speed
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH