Scissor-mechanism closing rams of blow out preventors

A blowout preventor, comprising:

• a blowout preventor body having a main central bore and a radial bore normal to the main central bore;
• a ram body located in the radial bore, the ram body having a rotational pin at a radially inner end;
• a pair of ram arm assemblies with one ram arm assembly located on one side of the ram body and a second ram arm assembly located on opposite side of the ram body, each of the ram arm assemblies having a second end at a radially inner end and a first end opposite the second end, wherein the first end of each ram arm assembly has a curved outer surface on a side facing the opposite ram arm assembly;
• a pair of rotating rams, each rotating ram pivotally connected to the rotational pin and to an elbow pin of the second end of one of the ram arm assemblies;
• a ram actuator engaging the first end of the pair of ram arm assemblies and movable along the radial bore to pivot the rotating rams about the rotational pin between an open position and a closed position;
• a bearing located between the curved outer surface of the first end of one of the ram arm assemblies and the ram actuator, the bearing engaging and moveable along the curved outer surface;
• and
• a piston rod secured to the ram actuator, the piston rod extending radially through an opening and into a piston chamber at a radial outer end of the radial bore, the piston rod moveable linearly relative to the ram body and linearly fixed to the ram actuator;
• wherein
• the engagement of the ram actuator with the first end of the pair of ram arm assemblies converts linear movement of the piston rod to rotational movement of the rotating rams.

A method for moving a ram of a blowout preventor between an open position and a closed position, the method comprising:

• positioning a ram closing assembly in a radial bore of the blowout preventor, the ram closing assembly having a ram body with a rotational pin at an inner end, a pair of ram arm assemblies with one ram arm assembly located on one side of the ram body and a second ram arm assembly located on opposite side of the ram body, a pair of rotating rams, and a ram actuator, the ram arm assemblies having a second end at a radially inner end and a first end opposite the second end, the first end of each ram arm assembly having a curved outer surface on a side facing the opposite ram arm assembly, and a bearing located between the curved outer surface of the first end of one of the ram arm assemblies and the ram actuator and engaging the curved outer surface;
• injecting a pressure media into an outward side of a piston chamber located at a radially outer end of the radial bore, to move a piston rod that is linearly fixed to the ram actuator in a direction linearly relative to the ram body to cause the ram actuator to move radially inward, engaging the first end of the pair of ram arm assemblies with the bearing moving along the curved outer surface, and pivoting the rotating rams about the rotational pin towards the closed position;
• wherein
• engagement of the ram actuator with the first end of the pair of ram arm assemblies converts linear movement of the piston rod to rotational movement of the rotating rams.