resitant to vapor locking the pump is a reciprocating sucker rod pump which has a top inlet valve which comprises one or more hinged flapper valves application_number US 66136591 A description fig1 shows a sucker rod pump of the present invention in which a plunger 101 is in the lowermost position in this position inlet valves 102 are open allowing the downstroke of the plunger to draw well fluids through inlet valve ports 103 as the plunger 101 is pulled upward by the rod 104 fluids within the working barrel 107 are forced out of the working barrel through an outlet valve 108 differential pressure between the working barrel and the well borehole forces the hinged inlet valve shut during this upward stroke the outlet valve shown slides freely over the rod 104 but seals against the rod the outlet valve rests on an outlet valve seat 109 when in the closed position preventing flow from backing down the well string 110 into the working barrel 107 when the plunger is moving upward fluids within the working barrel force the outlet valve upward and against a retaining cage 111 the inlet valves are hinged on hinge pins 105 and freely swing from a position sealing the inlet port to a position away from the inlet port by differential pressure between the well borehole and the working barrel 107 during the downward stroke the pressure outside of the inlet valve ports in the well borehole is less than the pressure in.