Komatsu AX20 Operation & Maintenance Manual page 57

For the lift truck to be stable, the position of the combined center of
gravity must be inside the triangle (stable range of center of gravity)
formed by the ground contact points of the left and right front tires and
the center of the rear axle.
If the position of the overall center of gravity is in front of the front axle,
the front tires will form the fulcrum and the lift truck will tip to the front. If
the position of the combined center of gravity moves outside the triangle
forming the stable area for the center of gravity, the lift truck will tip in the
direction where the combined center of gravity moves outside of the
triangle.
The horizontal distance between the center of gravity of the load on the
forks and the load backrest of the forks, or the front face of the forks
(whichever is shorter), is called the load center. The maximum load is
the maximum weight of the load that can be loaded at the standard load
center. The relationship between the maximum load and the load
center is given in the load capacity charts on the nameplate on the lift
truck. If the load center moves to the front of the forks, the overall
center of gravity also moves to the front, so this means that the load
must be reduced.
The allowable load is stamped on the nameplate to show the
relationship regarding the position of the load center, the
height of the fork and the maximum load. Before loading the
forks, check that the load and load center are within the
permitted range on the stamped allowable load.
If the shape of the load is complex, set it so that the heaviest
part of the load is at the center of the forks and set the load
close to the load backrest.
If the forks are loaded more than the allowable value, the drive
wheels will float during travel and the steering system will not
work. This is very dangerous. Furthermore, the lift truck will tip
over easily under this condition. Therefore, be sure to keep
the load below the allowable value and properly balanced.
15. STRUCTURE AND STABILITY OF THE LIFT TRUCK
STABLE RANGE OF CENTER OF GRAVITY
MAXIMUM LOAD (weight and center of gravity of load)
ALLOWABLE LOAD
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