Enter values for the following parameters based on the graphs below.
A = truck’s basic capacity
B = distance from front wheel center line to fork face
C = Distance from fork face to rated load center
D = Weight of attachment
E = Distance from front wheel center line to carriage face
F = Distance from carriage face to attachment’s center of gravity (CGH)
G = Distance from carriage face to rear face of load (ET)
H = Distance from rear face of load to center of load
CAUTION: Formulas can give you a good ballpark estimate of how capacity will be affected.
But you should work closely with your truck manufacturer before making a decision.
Their data reflects, in most cases, testing with specific trucks and attachments.
Maximum Lateral Offset while in the fully sideshifted position may dramatically affect residual capacity. Check with your OEM lift truck manufacturer for actual capacity.
How to calculate the effect of an attachment on truck capacity
1. Determine measurements
2. Assume, for example, that:
3. Apply this formula:
The capacity factor is important in your selection regardless of whether you are buying the truck with the attachment or are adding the attachment to a truck yourself. In addition to the safety aspect — stability and avoidance of damage to the truck — you should assure yourself that the truck can do the work you need done.
Normally, an attachment tends to move the center of gravity of the combined truck and load forward. It does this by adding its own weight to the load side of the fulcrum, and by moving the truck’s load center forward. The farther forward the center of gravity moves, the smaller the load weight must be and the more likely the truck is to tip forward.
Truck manufacturers generally calculate the net capacity of a truck, with an attachment, using simple formulas. The formula used in the illustration is typical. Many truck manufacturers prefer not to rely on arithmetic alone, but use test methods, such as the tilt-table test.
The formula used here helps you find the net capacity which is, in effect, your load-weight limit, and can be substantially lower than the truck’s original rated capacity.
If the load-weight limit is too restricting for your job, you will probably need a truck with a higher original capacity rating. Thus selection of an attachment can also involve selection of a truck. It may be wise not to regard arithmetic formulas as anything more than rules of thumb. They provide a good basis for discussion with your supplier, and give you an idea of your ballpark limits.
For exact determination of the attachment/truck capacity, you should contact your truck manufacturer.
Cascade Customer Service will supply you weight, lost load and center of gravity figures for the truck manufacturer’s calculations.