{HEAD ~ a casing} having a pump port, a tank port, and {TAIL ~ an output port}, 
{ HEAD ~ a casing } having a pump port , a tank port , and { TAIL ~ an output port } ,
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH