Box2D Forums

public static function makeRevoluteJoint(world:b2World,ref_angle:Number,body_1:b2Body,body_2:b2Body,anchor_1:b2Vec2,anchor_2:b2Vec2,motor:Boolean=false,limits:Array=null):b2RevoluteJoint{
   var jd:b2RevoluteJointDef = new b2RevoluteJointDef();

    jd.Initialize(body_1, body_2,new b2Vec2(0,0));
   jd.referenceAngle=ref_angle

    jd.localAnchorA=anchor_1
    jd.localAnchorB=anchor_2
   jd.enableMotor=motor;

   var revolute_joint:b2RevoluteJoint=world.CreateJoint(jd) as b2RevoluteJoint;
   if(limits!=null){
      revolute_joint.EnableLimit(true)
      revolute_joint.SetLimits(limits[0],limits[1]);
   }
    return revolute_joint
};

_joint=makeRevoluteJoint(_world,0,_firstbody,_secondbody,new b2Vec2(0,0),new b2Vec2(0,0))