Thus, there can be an acceptable degree of {TAIL ~ lapse} in the rotational relationship between {HEAD ~ the valve disc} and the stem 
Thus , there can be an acceptable degree of { TAIL ~ lapse } in the rotational relationship between { HEAD ~ the valve disc } and the stem
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH