end 84 there is keyed lever handle 86 which may be pivoted in an arc on the underside of valve body 12 and is capable of rotating shaft 78 slightly more than one hundred eighty degrees within operator housing 66 there is mounted on shaft 78 for rotation therewith an eccentric link 88 having a circular portion 90 with its center offset form the axis of rotation of shaft 78 mounted on circular portion 90 of link 88 is a follower link 92 having a circular hole 94 sized to surround circular portion 90 and rotate thereon with respect thereto at the opposite end of link 92 there is provided a circular hole or eye 96 with a diameter greater than that of pin 52 on valve stem 46 to loosely surround pin 52 and provide a lost motion linkage therebetween as will be further explained hereinbelow link 92 is held in registry with circular portion 90 of eccentric 88 by a flange 98 on eccentric 88 and by a generally horseshoe shaped key member 100 which slips into a groove 102 on shaft 78 and is there keyed to shaft 78 key member 100 is then bolted to eccentric 88 by means of bolt 104 it can be seen that the assembly comprised of link 88 and key member 100 in groove 102 will prevent shaft 78 from being extruded through journal assembly 82 even under great liquid pressure which may exist in housing 66 during unloading of the liquid lading in.