Each carriage is guided by {HEAD ~ a tongue and slot guiding arrangement}, whereby sealing pressure is applied between the valve member and {TAIL ~ the port plate} 
Each carriage is guided by { HEAD ~ a tongue and slot guiding arrangement } , whereby sealing pressure is applied between the valve member and { TAIL ~ the port plate }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL