Carrying the Load: Basic Concepts
How much lift capacity do I need in a forklift? Join us for a discussion where we consider a load’s shape, size, and weight distribution and how they influence the forklift’s ability to handle the load.
When it comes down to it, the main reason you invest in a forklift is to move heavy things from one location to another. Of course, it‘s crucial that the equipment’s load-carrying capacity matches how much weight you usually have to move. It’s just as important to consider a load’s shape, size, and weight distribution since these influence the forklift’s ability to handle it.
The load capacity of a forklift typically is based on a cube-shaped load with its center of gravity lining up with the lift’s load center. The vehicle’s load center is indicated on the data plate and usually is 24” on center from the back of the forks or the mast.
Loads come in different shapes and sizes and weight distributions. If a load’s center of gravity is beyond the forklift’s load center on the horizontal axis, the forklift’s capacity to handle that load will decrease.
It’s like a see-saw. On the playground, the heavier kid needed to sit closer to the middle of the see-saw to balance. If the heavier one sat farther away from the middle, the lighter kid got stuck up in the air.
Like on a see-saw, when a forklift tries to pick up a load with a center of gravity that’s too far from its load center, the lift may tip over to the front. Lateral tip-overs can happen if a load isn’t balanced laterally.
You can see that choosing a forklift for your operation has to involve analysis of what you need to move. We are happy to help you with that analysis—just reach out to your local Morrison Branch.
Load Management Prevents Forklift Accidents
Your forklift operators should understand the basics of load-carrying so they can avoid common load-related accidents like tip-overs, collisions, falling loads, and loss of steering control. To avoid problems, we recommend your operators understand these basic rules:
● Know the equipment and its capabilities. Never exceed a forklift’s rated load capacity. (It’s listed on the data plate or nameplate.) [29 CFR 1910.178(o)(2) ]
● Know where the forklift’s load center is
● Use extra caution when moving a heavy load. [29 CFR 1910.178(o)(1)]
● Consider the load’s orientation. (For example, carry a rectangular load width-wise to shorten the distance from the forklift’s load center to the load’s center of gravity.)
● Load the heaviest weight as close to the forklift’s front wheels as possible.
● Transport loads at the lowest position. (An elevated load is less stable because the center of gravity is farther away from the lift’s load center.)
See the appendix in OSHA’s Powered Industrial Truck Standard for a description of the forces involved in forklift stability. [29 CFR 1910.178 Appendix A]
When you need to train your operators on safely managing loads, we recommend our forklift operator training partner, TrainMOR. They provide classroom, online and train-the-trainer programs for powered industrial equipment such as forklifts and aerial lifts.
Calculating Safe Load Capacity
When you need to figure out what your existing equipment can handle, your dealer or equipment manufacturer is the best source of load-carrying advice. If advice isn’t available when you need it, here’s a way to calculate safe load capacity in the field.
- Let’s assume you have a forklift with 5,000 pound capacity at a 24 inch load center. This truck is going to have to handle a load with a center of gravity that’s 28 inches from the back of the forks.
- To estimate the safe load capacity, take the rated load center and divide it by the actual load center. Then multiply the result by the rated load capacity for an approximate safe load capacity:
24 in/28 in x 5,000 lb = 4,285 lb (approximate safe load capacity)
- If the load exceeds this weight, you may need to reduce or redistribute the weight, consider a different load orientation, or use another forklift that can handle the load.
Attachments and Load Capacity
Sometimes you need to add an attachment to carry a load. Whether a drum carrier, pole, boom or something else, an attachment adds weight to a forklift (which reduces its load capacity). If you need an attachment, be sure your equipment manufacturer re-rates the lift and provides a revised data plate with the new information.
Manufacturers use a combination of mathematical calculation and real-world testing to re-rate their equipment. The formula requires basic information:
A = Truck's basic load 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
G = Distance from carriage face to rear face of load
H = Distance from rear face of load to center of load
Net Capacity = A (B + C) - D (E + F)
E + G + H
If we assume
A = 7,000 lbs
B = 20 inches
C = 22 inches
D = 750 lbs
E = 18 inches
F = 10 inches
G = 8 inches
H = 24 inches
Then the re-rated result is
Net Capacity = 7,000 (20 + 22) - 750 (18 + 10) = 294,000 - 21,000 = 5,460 lbs
18 + 8 + 24 50
This calculation gives you a ballpark estimate of the new load capacity. If this doesn’t meet your needs, you may have to move up to a forklift with a higher load capacity.
Choosing the right forklift for your operation can be complicated. The forklift experts at your local Morrison branch can help you select the one that fits your needs.