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Understanding Cargo Capacity

See Also: Rated Load Capacities by Product


What are Pound-Feet?

Overloading any system, be it as large as a train or as small as a cargo carrier, can lead to a failure of that system. For systems with two or more support points, like train cars, trucks, and autos, weight as represented by pounds can be a suitable measure of Carrying Capacity. For cantilevered systems with a single support point, such as most bumper-mounted cargo accessories and the bumpers that support them, a more accurate measure of Carrying Capacity is the pound-foot (see also A pound-foot is equal to one pound supported one foot away from the support point. Two pounds supported one foot away from the support point is two pound-feet just as one pound supported two feet away from the support point is also two pound-feet.

Put simply: Weight times Distance equals Load.

A great example of this is a diving board; the further out on it you walk, the more it depresses. Because bumper-mounted cargo accessories and the bumpers that support them utilize a single support point, pound-feet more accurately describe Carrying Capacity than do pounds. It is for this reason that we test and rate our products using pound-feet.  To determine your cargo’s Load, multiply the number of feet the center of your cargo is from the bumper times the weight.

Calculating Load in Pound-Feet is Easy!

Generator Photo ExampleAs mentioned before, Weight times Distance equals Load. Using the example in the image to the right, we see two 50 pound generators on a tray. The center of the nearer generator – left-most in image – is 0.625 feet (7.5 in/12) from the bumper, giving us 31.25 pound-feet of Load (0.625 ft. x 50 lbs.). The center of the farther generator – right-most in image – is 1.67 feet (20 in/12) from the bumper, giving us 83.3 pound-feet (1.67 ft. x 50 lbs.). Adding the two values together gives us a total Load on the tray of 114.6 pound feet.

Tongue Weight vs. Carrying Capacity

Most hitches are rated for Tongue Weight in pounds due to their origins as towing devices; Tongue Weight is the downward force of a trailer’s tongue onto the hitch and is calculated in pounds. To convert Tongue Weight to Carrying Capacity, use 0.5 feet as the distance to the center of the Load (as this is the distance most hitch balls are from the hitch body) and the Tongue Weight as the Load. As an example, 500 pounds of Tongue Weight equals 250 pound-feet of Carrying Capacity (0.5 ft. x 500 lbs.).

Should you have questions understanding or calculating load as pound-feet, please feel free to contact us.

Rated Load Capacities by Product

Capacity by Item ID

Installed on Undamaged
Factory-Installed Bumper

1SNUHD: 400 pound-feet
1SSNHD: 400 pound-feet
1SMWHD: 400 pound-feet

Capacity by Item ID

Single Pressure Plate with
Pressure Bolt @ 20 ft-lbs torque

1H4HZ: 300 pound-feet
1H5HZ: 300 pound-feet
1H6HZ: 300 pound-feet

Double Pressure Plates with
Pressure Bolt @ 40 ft-lbs torque

1H4HZD/HC40HZ: 400 pound-feet
1H5HZD/HC53HZ: 400 pound-feet
1H6HZD/HC60HZ: 400 pound-feet

GennyGo Generators and Cargo Carriers

Capacity by Item ID

Support Arms
1GSAA: 125 pound-feet/pair
1GSAS: 200 pound-feet/pair

Cargo Tray Kits
1GGKA: 125 pound-feet
1GGKH: 200 pound-feet
1GGKS: 200 pound-feet
1GHKA: 250 pound-feet
1GHKH: 400 pound-feet
1GHKS: 400 pound-feet

Aftermarket RV Bumpers and RV Bumper Accessories

Capacity by Item ID

10UBK: 500 pound-feet
10VBK: 500 pound-feet
10MBK: 600 pound-feet
10HBK: 600 pound-feet

1HHAB, 1HH53B, 1HH60B:
200 pound-feet/pair

Frame Extenders
1000 pound-feet/pair*

*Assumes mounting to Frame using 6 Mounting Bolts per Frame Extender with the distance for Pound-Feet calculation starting at rear-most Mounting Bolt.
combining Frame Extenders in series, use forward-most Frame Extender to calculate Pound-Feet!