Hydraulically balanced marine loading arm

An articulated loading arm structure for transferring fluid, comprising:

• a supporting base, a column rotatably supported on the base for rotation about a vertical axis, a boom, means hingedly securing the boom at one end to the column for rotation of the boom about a first horizontal axis, an outer arm, means hingedly connecting one end of the arm to the outer end of the boom for rotation about a second horizontal axis parallel to the first axis of rotation of the boom, first means connected between the column and the boom means exerting a couple tending to rotate the boom about the first horizontal axis in the opposite direction from the couple produced by the weight of the boom and arm, said first means including at least one hydraulic cylinder having one end pivotally connected to the column and the other pivotally connected to the boom at a point offset from the first horizontal axis, and means including a volume of compressed gas for pressurizing hydraulic fluid in the cylinder, the volume of gas being large compared to the displacement volume of the hydraulic cylinder, second means connected between the column and the arm exerting a couple tending to rotate the arm about the second horizontal axis in the opposite direction from the couple produced by the weight of the arm, said second means including a lever arm rotatable about said first horizontal axis, and linkage means coupling the lever arm to the outer arm, the linkage means maintaining the lever arm and outer arm in fixed angular relationship relative to each other as they rotate about said first and second horizontal axes, the second means further including at least one hydraulic cylinder having one end pivotally connected to the column and the other end connected to the lever arm;
• and means including a volume of compressed gas for pressurizing hydraulic fluid in the hydraulic cylinder, the volume of gas being large compared to the displacement volume of the hydraulic cylinder, and means for adjusting the pressure of the gas for pressurizing the hydraulic fluid respectively in the first and second hydraulic cylinders, the means for pressurizing hydraulic fluid in the respective cylinders including a pair of accumulator tanks mounted directly on the column hydraulically connected respectively to the two cylinders, each accumulator being pressured by a gas from said volumes of compressed gas. pg,22