Posted by Aether
don't know the difference between an americana and a kimura???
 Figure Four Arm-lock/Americana (Ude-garami)
The figure four arm-lock (also known in the USA as the americana) is a term used in Brazilian Jiu-Jitsu to specify the lateral keylock known in judo as ude-garami (arm entanglement). This lock is generally applied only from the mount or side control. The opponent's arm is pinned to the ground so that it is bent at the elbow, with the opponent's palm upwards. The wrist is grabbed with the opposite hand, and the arm on the same side is put under the opponents arm, gripping the attacker's wrist. This results in the necessary figure-four hold. While keeping the opponent's hand pinned to the ground, begin sliding their pinned arm down and parallel to your thigh while cranking their elbow upwards. This is referred to as *painting*. The opponent will feel pressure on their elbow and/or shoulder. From some positions, such as kesa-gatame, it is possible to apply this technique with a leg instead of using two arms.
The technique is one of the official 29 grappling techniques of Kodokan Judo. It is one of the nine joint techniques of the Kansetsu-waza list, one of the three grappling lists in Judo's Katame-waza enumerating 29 grappling techniques. All of Judo's competition legal joint techniques are arm locks.
 Kimura (Gyaku ude-garami)
Kimura (Brazilian Jiu-Jitsu), chicken wing/double wristlock (wrestling), or reverse keylock are terms used to specify a medial keylock known in judo as gyaku ude-garami (reverse arm entanglement) or simply as ude-garami. The application is similar to the americana, except that it is reversed. It needs some space behind the opponent to be effective, and can be applied from the side control or guard. Contrary to the americana, the opponent's wrist is grabbed with the hand on the same side, and the opposite arm is put on the back side the opponent's arm, and again grabbing the attacker's wrist and forming a figure-four. By controlling the opponent's body and cranking the arm away from the attacker, pressure is put on the shoulder joint, and depending on the angle, also the elbow joint (in some variations the opponent's arm is brought behind their back, resulting in a finishing position resembling that of the hammerlock outlined below). The kimura was named after the judoka Masahiko Kimura, who used it to defeat one of the founders of Brazilian Jiu-Jitsu, Hélio Gracie.