Forklift Capacities with Attachments

Many loads which are lifted and transported with forklifts are better

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handled by using a forklift attachment mounted to the forklift’s carriage. There are many types of forklift attachments. Attachments have been designed to handle paper rolls, clamp boxes, move loads without pallets, handle concrete blocks, and handle or manipulate many other loads. Generally, adding an attachment to your new or existing forklift will reduce the maximum load weight your lift truck will safely lift and transport. Many lift trucks are capacity rated based on a 48” tall by 48” wide by 48” deep load which has the weight uniformly distributed within the cube. The reality is that most loads do not fit this narrow definition. Every load which deviates from this set of criteria changes your trucks carrying capacity. In many cases decreasing the load center (i.e. having the load center closer to the truck) does not increase the carrying capacity because of other limiting factor such as the design and load bearing abilities of lift cylinders, tilt

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cylinders, tires etc. Most attachments will decrease the forklifts rated capacity for two reasons. First, the weight of the attachment will reduce the capacity of the forklift. Second, most attachments will move the load center of the load further away from the face of the carriage and thereby have the effect of lowering the capacity.


First, let’s look at some quick calculators which can help you quickly determine if you have a big enough forklift to handle the attachment and load weight you want to handle. Here is a guide to determine the effect of increasing load center:


Truck Capacity x Load Center / New Load Center = New Reduced Capacity




TC = 5,000-lbs

LC = 24” Manufacturer Rated Load Center

NLC = 30”


5000 x 24 / 30 = 4,000-lbs.


If this increase in load center is due to adding attachment don’t forget to account for the weight of the attachment itself. For example, in the above case if the attachment weighed 200-lbs. our new load capacity would be 4000 – 200 = 3,800-lbs. Keep in mind this calculation is just a quick calculation to see if your forklift may be capable of safely handling your forklift with the attachment and load. Also, keep in mind that capacity is further reduced the higher you lift the load. A rule of thumb is that above 150” of lift your capacity will begin to decrease the higher you lift.


Now let’s look at a more precise calculator. You will need to contact your local dealer for exact measurements for both your forklift and attachment.


You will need to know:

A = Truck’s Rated Capacity Cascade Dimensions 1

B = Distance from front wheel center line to fork face

C = Distance from fork face to rated load center

D = Weight of attachment

Cascade Dimensions 2

E = Distance from front wheel center line to carriage face

F = Distance from carriage face to attachment’s center of gravity (HCG)

G = Distance from carriage face to rear face of the load (ET)

H = Distance from rear face of load to center of load


Let’s assume you determined your application included the following measurements:

A = 6,000-lbs.

B = 14-inches

C = 24-inches

D = 900-lbs.

E = 12-inches

F = 9-inches

G = 10-inches

H = 27-inches


Quick Capacity Calculator:

Net Capacity


A (B+C) – D (E+F)




E + G + H








Net Capacity


6000 (14+24) – 900 (12+9)




12 + 10 + 27








Net Capacity


228,000 – 18,900












Lost Capacity


6,000-lbs. – 4,267.35-lbs.





Now you can clearly see that by adding a 900-lb. attachment you will reduce your net capacity by much more than the weight of the attachment due to the increase in load center. Remember these quick calculators are intended to give you a quick idea of the net capacity reduction an attachment will have on a forklift. You should contact your local dealer to determine the exact effect the forklift attachment will have on your forklift. The forklift manufacturer’s engineers have used additional test methods such as tilt-table tests to confirm what the arithmetic shows us.


If an attachment is added to a lift truck and alternate data-plate must be attached to the forklift to remain in compliance with OSHA regulations. This plate will clearly show the forklift operator the capacity with the attachment factored in.

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