preventor manufactured by cameron oil tools but could also have been a heavy duty hydraulic blowout preventor manufactured by bowen oil tools inc or similar models from other manufacturers this type of blowout preventor is actuated by pumping hydraulic fluid into a cylinder to cause a piston to push a ram into the central opening if hydraulic pressure is not available a manually actuated pusher may be used to push the ram into the opening dual cylinders and rams are provided one on each side of the central opening with each ram closing one half of the opening the ram actuators 58 and 58a are identical in construction and operation and a discussion of only one will be provided hydraulic fluid that is pumped into the ram actuator 58a through supply line 54a forces piston 60a to move towards the central opening 68 this movement causes ram 62a which is attached to the end of piston 60a to begin closing off one half of the chamber of opening 68 a rubber insert 64a is mounted on the opposite end of ram 62a from where piston 60a is attached rubber insert 64a is compressed against a like insert from opposite side ram 62 not shown to form a pressure seal and close off the entire central opening 68 ram 64a is opened by removing the pressure in fluid supply line 54a and pumping hydraulic fluid into supply line 56a.