Monday, June 23, 2014

Load Composition

As the center of gravity for the load moves forward, the lifting capacity for the forklift decreases.
Figure 1. As the center of gravity for the load moves forward, the lifting capacity for the forklift decreases.
The stated capacity of a forklift only applies to the load center indicated on the data plate. If the load is not centered at the specified position, the forklift's capacity will be reduced. Loads come in all shapes and sizes, not just symmetrical boxes. The load size, position, and weight distribution critically affect the forklift's capacity and the stability of the truck. Consider the following factors before engaging a load:
  • Weight, Size, and Position
  • Safe Load Capacity
  • Maximum Load Moment
  • Balance
  • Stability
Weight, Size, and Position
The same 4500 pounds weight loaded properly (top) will exceed the rated capacity of 4500 pounds if the rectangular box is positioned lengthwise (bottom).
Figure 2. The same 4500 pounds weight loaded properly (top) will exceed the rated capacity of 4500 pounds if the rectangular box is positioned lengthwise (bottom).
Load weight, weight distribution, size, shape, and position are key factors affecting the stability of the forklift. Forklifts are designed to carry a capacity load at a standard load center, commonly 24 inches. This means that the forklift’s capacity was determined as if the load were a cube whose weight is evenly distributed (i.e., whose center of gravity is exactly in the center of the cube) and which is resting on a standard pallet having dimensions of 48 inches by 48 inches. With such a load, the horizontal distance from the center of the load to the vertical part of the forks would be 24 inches. Of course, most loads are not perfectly shaped cubes having their center of gravity exactly in the middle of the cube. To the extent that the load differs from this theoretical load — such as if it is irregularly shaped, has unbalanced weight distribution, or is not centered on the forks — the capacity may be reduced.

Potential Hazards:

While arranging a load, be aware of the following:
  • tipover
  • Loss of steering control (Shifting too much weight forward raises the rear wheels.)
  • Falling load
  • Collision
Requirements and Recommended Practices:
  • Do not exceed the capacity of the forklift that appears on the forklift's data plate (sometimes called the "nameplate"). If the load is oversized, irregularly shaped, or loaded incorrectly, the actual load center distance could exceed the stated load center distance, causing the truck's capacity to be exceeded. (Figure 2).

  • Always minimize the distance from the front wheels to the load center. Load a large rectangular box widthwise across the forks of the truck as in Figure 2. Placing a large rectangular load lengthwise causes the load center to shift forward further away from the front wheels, exceeding the truck's capacity and lifting the rear wheels off the ground.

    The heaviest weight should be loaded as close to the masts as possible.
    Figure 3. The heaviest weight should be loaded as close to the masts as possible.
  • Load as close to the front wheels as possible to minimize the load center distance. Load the heaviest part toward the mast. (Figure 3)

  • Position the load in a way that will shorten the load center distance.




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