Forklift Attachment Capacity: Fact vs. Fiction

Your Forklift is measured for a definite maximum load capacity. If you don’t
know what it is, you can find the maximum load capacity for your particular
vehicle as it will be recorded on a plate installed in a highly visible area usually at eye level to the driver.
It also determines what is workable when attempting to build and
implement longer, high-capacity attachments.

Hence, forklifts are measured at a load center, the more you want to lift, the
lower the capacity becomes. A 5,000-lb, capacity forklift will lift that much
weight upto 48-inch forks (with a 24-inch load center) but going out to
60-inches (with a 30-inch load center), for example, drops the capacity to
4,000 pounds.

Load Moment:
The weight capacity of a forklift attachment is known as the Maximum Load
Moment, when the load center distance increases, changing the weight
distribution, and as a result, the amount of weight a truck can carry under
those circumstances. Increasing the load center’s gap too far can cause a
forklift to tip.

Whenever the load center distance is increased, it is actually increasing,
which is called “Load Moment”. The object’s weight capacity is multiplied by
the object’s distance from the fulcrum point equals load moment. On a
sit-down counterbalanced forklift, the fulcrum point is the axle of the front
wheels. The Load moment determines how much overturning force is being
applied to the forklift (Load moment= weight X Distance).

For example, a forklift rated to carry 6,000 lbs at a 24’’ would have a
maximum load moment of 144,000 pounds.

This equation is useful for determining if an unusual load (e.g., one longer
than 48’’ or with uneven weight distribution) can handle safely. In the above
example, the weight has a maximum load moment of 144,000 lbs.
In order to locate the maximum load, when the load center distance is
greater than the distance stated on the data plate, one must divide the
maximum Load Moment by the actual load center distance.

Calculate Weight Capacity:
To determine what your forklift’s capacity be when we use an attachment,
use the following formula:
Truck Capacity X Load Center (for its Load moment) / New load center of
desired attachment.

You can express this formula with an equation: (TC x LC)/NLC

For example, Truck’s capacity is 5,000 lb and load center is 24, then we
multiply 5,000 by 24, and the result will be 120,000 inch-pounds as its
maximum load moment. Then, we divide 120,000 by 30, which is the load
center for the desired 60-inch attachment. The final result is 4,000 pounds
of maximum weight using that specific attachment.

Positioning Concerns:
The way a load is displayed on a forklift will also factor load capacity. Most
loads do not have their center of gravity exactly in the middle, so to
whatever extent that load is different from its theoretical centered load- for
example, when the load is irregularly shaped , has unbalanced weight
distribution, or is not centered on the forks- capacity may be reduced. This
can cause tipping, collision, and loss of steering control if not factored into
the calculated capacity.

Reducing the distance from the front wheels to the load center can be the
way to address the positioning concerns.

For example, load a large rectangular box widthwise instead of lengthwise across the forks of the
truck, which causes the load center to shift forward and away from the front
wheels, lifting the rear wheels off the ground. It also helps to load as close
to the front wheels as much as possible, limiting the load center distance,
and can load the massive parts towards the mast.

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