Abstract: In oil and gas well pumping apparatus, a polish rod reciprocates through a stuffing box and connects to a submersible pump through a tubing string or the like. When servicing, it is desirable to close off the gas or oil pressure from below and hydraulic fluid is routed from a remote location to the blow out preventer. The blow out preventer consists of a cylindrical casing with a cap screw threadably engaged to the upper end thereof and containing a cylindrical spool or the like formed from elastomeric material having an annular channel around the outer perimeter which is operatively connected to the source of hydraulic fluid. When it is desired to close off the blow out preventer, hydraulic fluid is pumped under pressure to the channel thus forcing the center of the spool inwardly and clamping same around the polish rod thereby closing off the passageway around the polish rod. O rings surround the spool above and below the channel and assist in sealing.

Abstract: A cylindrical tube with a screw threaded packing gland in the upper end carries an upper guide rubber with a plurality of packing rubbers stacked thereabove and engaged by the gland which applies the necessary pressure to seal the polish rod reciprocating within the stuffing box. A blow-out preventor assembly is situated below the upper guide rubber and comprises a cylindrical rubber portion surrounding the polish rod and having O rings sealed adjacent the upper and lower ends of the cylindrical rubber. An annular chamber is formed on the outer surface of the cylindrical rubber between the O rings and communicates with a source of fluid under pressure which can firstly apply pressure to the rubber surrounding the polish rod and shut off the well so that the stuffing box can be serviced and secondly, can act as an automatic blow-out preventor if the polish rod breaks.