Forklift on Truck
Potential Hazards: While arranging a load, be aware of the following:


Field Calculation of Safe Load Capacity
Assume a situation where a forklift truck that has a 5, 000 pound capacity at a 24 inch load center needs to handle a load whose center is 28 inches from the front face of the forks in the horizontal direction. The first thing to recognize is that the actual load center distance of 28 inches exceeds the standard load center distance of 24 inches on which the 5000 pound capacity is based, so the safe load capacity is actually less than 5000 pounds. To estimate the truck's safe load capacity at a 28inch load center, take the rated load center and divide it by the actual load center. Then multiply this number by the stated capacity to get the new approximate safe load capacity: 24 in/28 in x 5, 000 lb = 4, 285 lb (approximate safe load capacity) Using the example in Figure 4, take the stated standard load center of 24 inches and divide it by the actual load center of 36 inches. Multiply this number by the stated capacity of 4, 000 lb to get the new approximate safe load capacity: 24 in/36 in x 4, 000 lb = 2, 666 (approximate safe load capacity) 
Lift a 5 pound box. As you extend your arms, the center of the boxs weight moves a greater distance from your body, so the box feels heavier and you will tend to fall forward. The same idea of increasing the load center distance applies to a playground seesaw: the farther you sit from the middle, the more you increase the load center distance and the more force you put on that end. The same principleincreasing the load center distancecan cause a forklift to tipover. When the load center distance increases, it is actually increasing something called the "Load Moment": Load Moment is the product of the object's weight multiplied by the objects distance from the fulcrum, which is a fixed point that acts as the pivot point. On a sitdown counterbalanced forklift, the fulcrum or pivot point is the axle of the front wheels. It is this product, or Load Moment, which determines how much overturning force is being applied to the forklift. Load Moment = Weight X DistanceBecause the overturning force depends on both the weight of the load and the loads distance from the pivot point, a forklifts capacity is always stated in terms of both: the loads weight and its load center distance. For example, if a forklifts capacity as stated on its data plate is 3, 000 pounds at a 24 inch load center, this means that the Load Moment cannot safely exceed 72, 000 inchpounds (24in. x 3, 000 lb = 72, 000 inchpounds.) If the load center distance for the actual load is greater than the standard 24 inches, the only way to keep the Load Moment from exceeding 72, 000 inchpounds is to reduce the load. The easiest way to determine the maximum load when the load center distance is greater than the distance stated on the data plate is to divide the maximum Load Moment by the actual load center distance. For example: If a load is 60 inches long (30inch load center) then the maximum that this load can weigh is: 72, 000 inchpounds / 30 inload center = 2, 400 pounds
While carrying a load near the maximum allowable capacity, be aware of the following:


Center of Gravity
While operating a forklift, be aware of the following:

Shifting Center of Gravity
Figure 11. A 4, 000 pound truck is balanced by a 4, 000 pound load. Figure 12. Notice the center of gravity of the load and truck system shift forward toward the front wheels as the load is engaged.
