The throttle valve has {HEAD ~ at least two variable orifices} and {TAIL ~ a compensation chamber} between the variable orifices 
The throttle valve has { HEAD ~ at least two variable orifices } and { TAIL ~ a compensation chamber } between the variable orifices
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH