skip to main content
The Comprehensive Guide to Reading Crane Load Charts

The Comprehensive Guide to Reading Crane Load Charts

Cranes have been in use on construction sites for millennia and have been instrumental in building our modern world and infrastructure. Being a contractor or construction project manager is all about planning effectively. You have to plan every aspect of your project, from start to finish and beyond. Regardless of the size of the project, the details matter. 

If a crane is expected on a job site, everyone involved from the operators, supervisors, and planners, needs to know the chosen equipment capabilities and limits. 

There are many types of cranes available on the market, and knowing which one fits the job needed can be difficult.

How To Determine Your Crane’s Lifting Capacity and Read Load Charts

The first step in understanding crane loads and determining what machine you need on site is to determine precisely what you need to lift accurately. This includes how heavy it is, from where you need to lift it, and to where you’re delivering it. We’ll take this question from the point of view of someone looking to rent a crane, but the same applies if you are interested in owning a dedicated crane for your company.

When it comes to jobs that require cranes, one of the first questions your crane rental company will ask is the maximum total weight of any load you expect to lift and the average weight. You need to know several things about calculating a load's weight before you rent a crane. This is especially relevant if you plan on performing a critical lift - a lift performed at 75% or more of the crane's capacity. 

Calculating Total Load

calculating total load

Load calculation refers to the way in which you determine how much weight the crane will be lifting. While it can be relatively straightforward, at times, you will need to do some math and work with formulas in order to find the numbers your crane rental company will need.

Load calculations should take into account the weight of everything to be lifted, including:

  • All lifting gear
  • Hooks and rigging
  • Ropes and harnesses
  • Construction materials on the load

These weights need to be as accurate as possible. Manufacturers are an excellent source for this information for individual parts that you can then add together. 

You can also physically weigh an example load using an industrial scale. It is worth investing in a dynamometer to allow you to measure each load before each lift. These devices can be attached directly to the rigging to give you an accurate measure and can be a great safety measure for your crane operator and riggers as conditions and needs change on site.

How To Read a Load Chart

Once you have your measure of load weight, it is time to start looking at load charts and determining if the crane you have selected can operate safely under the given parameters. Cranes have a maximum load, but that maximum applies to only the most optimal conditions, which rarely occur during normal operations. Ground stability, physical obstructions, and weather can all affect a lift and reduce a crane's load capabilities. 

Every crane model will come with its own load chart. Review each section carefully to ensure you understand the machine's capabilities and limits. These charts diagram exactly what a crane can and cannot accomplish. And in the hands of an experienced crane operator, it should be reviewed for every lift undertaken on-site.

1. Dimension and Weight

The first thing to look at on the load chart is the specifications concerning the crane itself. Each chart will show the dimensions and weight of the crane, along with information concerning standard operation features like outriggers. 

This data is crucial for understanding how the crane will sit on the site and determining any space constraints and special considerations for site prep if you need to work in a severely confined space that won’t allow the use of outriggers, which will significantly influence the stability of the crane and lower the maximum capacity.

2. Effect of Lift Range and Angle

Effect of Lift Range and Angle

Before you get into looking at what your lift load capacity is, you need to understand how you are going to be moving the load. Lift range is the determination of how far the boom is going to need to extend to pick up and lift a load taking into account distance and height.

For every lift, you want to carefully calculate this and select your max capacity based on the farthest range of extension that will be required.

Cranes rarely lift loads straight up and down. Lift angle plays a significant role in determining maximum lift capacity as well. 

The greater the extension of the boom arm, the higher the angle needed for a lift to complete safely and the lower the maximum capacity. This angle places strain on the stability of the crane itself, and exceeding lift angle capacity greatly increases the chances of tipping.

3. Movement of the Crane

While many lifts might be completed with a relatively stationary crane, many times, some movement or rotation is required for a lift to navigate obstacles. The distance and speed you intend to perform this movement will have an impact on the lift capacity of the crane. 

Movement, especially with heavier loads, puts the entire crane at a much higher risk of tipping over. As such, you’ll find the load chart will limit the lift capacity in these cases.

4. Lift Capacity

Once you have knowledge of what you would like to lift and the path it will take, you can use that load information, range, and angle planning to determine if you can safely operate within the crane's lift capacity. Follow the respective informational axis for distance and angle, and the load chart will indicate the appropriate maximum load weight. 

Remember that this lift capacity is representative of the ideal lift. That means a situation with fully extended outriggers, perfectly prepped ground, minimal obstructions, and non-inclement weather. For this reason, if you are planning a lift that exceeds 75% of the determined lift capacity, a critical lift plan must be formed and followed. 

5. Load Chart Visuals

Crane lifts are generally limited by one of two factors, the structural strength of the crane and its stability. As such, load charts are visually split in half by a bold line. On one side, you will find the capacities limited by structure, and on the other by stability.

Each axis on the chart (exact layout will vary by manufacturer) corresponds to either the lift radius or the length of the boom. You will need to find the cell where those two meet, that value is your crane’s given load capacity for that needed lift. Usually included below the capacity is also the boom angle. 

If one parameter needs to be altered, like you must do a heavier lift, you’ll need to adjust the other factors, like boom length or angle, until a safe lift is possible. 

Selecting the Right Crane for the Job

Knowing how to read and regularly consulting a Load chart before using a crane is a vital part of utilizing these pieces of machinery in your projects. All site managers and supervisors should have competency in how to read and determine if the crane is up to a task. Lifting loads that are above capacity can be extremely dangerous, resulting in broken machinery, damaged structure, injuries, and worker death.

No matter the job, using the right tool makes all the difference. Make sure you select a crane that fits your job site requirements for the safest and most effortless experience. 

Serving the Carolinas for over 40 years, Parker’s Crane Service can help you get equipped with the right crane for the job. With a fleet of well-maintained hydraulic truck cranes, we offer not only the best equipment but can help with:

  • Pre-Lift Job Assessments
  • Daily Risk Assessments
  • On-Site Hazard Analysis
  • Routine Management Audits

Our crew is OSHA and MSHA-compliant to ensure your site and crew safety. Browse our list of available cranes to see if we have the right crane for your job. And contact our team to discuss any services or equipment we can help you select for your project.