Load Chart Fundamentals
Reading and interpreting crane load charts - radius, boom length, configuration, capacity tables, footnotes, and structural vs stability limits.
- Identify the key components and layout of a crane load chart
- Explain how radius and boom length affect rated capacity
- Distinguish between on-outrigger and on-rubber load charts
- Interpret jib charts, deductions, and load chart footnotes
- Differentiate between structural and stability limited capacities
Lesson 1
Anatomy of a Crane Load Chart
The Most Critical Document
The load chart is the single most critical document for crane operating limits. It defines the maximum rated capacity for every combination of boom length, radius, and configuration. Every lift must be planned and executed within the load chart limits - exceeding them risks catastrophic failure.
Never Exceed the Load Chart
The load chart is specific to each crane make, model, and serial number. Using the wrong chart, ignoring footnotes, or exceeding rated capacities can result in structural failure, tipping, or both. The chart must be in the cab and legible at all times.
Load Chart Components
Every crane load chart contains these essential elements:
| Component | What It Tells You |
|---|---|
| Crane identification | Make, model, serial number range the chart applies to |
| Configuration | Boom type, counterweight amount, outrigger position |
| Capacity table | Rated loads at each radius and boom length intersection |
| Operating radius | Horizontal distance from center of rotation to load center |
| Boom length | Available boom lengths in the configuration |
| Footnotes | Critical conditions, limits, exclusions, and deductions |
Reading the Capacity Table
The capacity table is arranged as a grid with operating radius along the left side and boom lengths across the top. The value at each intersection is the gross rated capacity in pounds or tons for that specific combination. Blank cells indicate that the combination is not permitted.
The Role of Footnotes
Load chart footnotes contain critical limits, conditions, and exclusions that modify the capacity values in the main table. Footnotes may specify:
- Minimum boom angle requirements
- Required counterweight configurations
- Reeving (parts of line) requirements
- Wind speed limitations
- Deductions for stowed or erected jibs
- Whether capacities are structural or stability limited
Always Read the Footnotes
Footnotes are not supplementary information - they contain critical limits and conditions that can change the rated capacity. Ignoring footnotes is one of the most common causes of crane overload incidents.
The load chart is the most critical document for crane operating limits. It must match the specific crane and configuration. Always read the footnotes - they contain critical conditions that affect capacity values in the main table.