chamber 30 as shown passage 32 extends through housing section 28 into chamber 30 to deliver fluid under pressure to the lower side of piston 14 causing it to move upward and to exhaust fluids as piston 14 moves downward passage 34 extends through housing section 28 into chamber 30 to deliver fluid under pressure to the upper side of piston 14 causing it to move downward and to exhaust fluids as piston 14 moves upward packer 20 is annular in shape as hereinafter described is positioned within the recess under shoulder 36 of retainer ring 16 and is engaged on its lower end by annular arm 38 of piston 14 thus as piston 14 moves upward its arm 38 exerts an axial force on packer 20 shoulder 36 prevents upward movement of packer 20 and inner surface 40 of retainer ring 16 prevents radial outward movement of packer 20 whereby the packer is moved to its closed or sealed position as shown in fig2 packer 20 is illustrated in greater detail in fig3 5 and 6 and includes resilient annulus 42 an upper circular series of rigid inserts 44 arranged on bonded to and embedded in the upper surface of annulus 42 and a lower circular series of rigid inserts 46 bonded to the lower surface of and embedded in annulus 42 rigid inserts 44.