When working on demanding job sites, the right equipment can make all the difference. One essential piece is the bucket capacity of your excavators or wheel loaders and understanding how to measure it effectively ensures maximum productivity. Two common methods of measuring bucket capacity are heaped and struck capacity. So, let's dive into what these terms mean, how they’re calculated, and key considerations for measuring excavator bucket capacity.
Heaped Capacity
Heaped capacity refers to the maximum volume a bucket can hold when it’s filled above the rim or top edge, accounting for the natural “mound” or angle of repose of the material. This capacity measurement is ideal for estimating how much material can be loaded beyond the bucket’s internal volume, ensuring optimal efficiency in transporting loose, bulk material. For example,
Calculation
For Wheel Loader Buckets: The typical heaped capacity is calculated at a 2:1 ratio. This means that heaped capacity = struck capacity x 2.
For Hydraulic Excavator Buckets: With excavators, the heaped capacity is usually calculated at a 1:1 ratio. So, heaped capacity = struck capacity x 1.
Given a scenario where if the struck capacity of an excavator bucket is 1 cubic meter, the heaped capacity will also be 1 cubic meter for an excavator. However, if you’re using a wheel loader bucket with a struck capacity of 1 cubic meter, the heaped capacity would be 2 cubic meters. Lastly , heaped capacity is ideal for materials that form a natural peak when loaded, such as loose aggregates, gravel, or soil, and is commonly used for applications where maximizing load volume in each cycle is crucial.
Struck Capacity
Struck capacity measures the bucket volume when filled level to the top edge without any additional mound. This “flat load” measurement is a more straightforward calculation and represents the bucket’s internal volume without considering any extra material volume that could accumulate above the rim.
Calculation
Struck capacity is measured using the bucket’s dimensions:
Struck Capacity = Length x Width x Height
Struck capacity is particularly useful for applications where precise loading is necessary, or in cases where the material may not easily form a stable heap (e.g., heavy or sticky materials like clay or wet sand).
Imagine a construction site where an excavator is working with wet clay —a heavy, sticky material that doesn’t easily form a stable heap. The operator needs to load trucks with a precise, consistent amount to prevent overloading. Using the bucket’s struck capacity ensures each load remains level with the bucket’s top edge, avoiding any extra mound that could fall off or miscalculate the weight. This straightforward, flat measurement is calculated by multiplying the bucket’s length, width, and height (Struck Capacity = Length x Width x Height), giving an accurate and controlled volume for each load. It’s ideal for handling materials like wet sand, clay, or other dense substances that aren’t suited to heaping, allowing for consistent operation on sites where overloading could lead to equipment strain or legal weight compliance issues.
Key Considerations for Measuring Excavator Bucket Capacity
When determining the ideal bucket capacity for your job site, several critical factors come into play:
- Material Weight and Density: The type and density of the material you’re handling will impact both heaped and struck capacity. For example, heavy, dense materials like rocks will require a smaller bucket capacity to avoid overloading the machine.
- Fill Factor: This is the ratio of how much material the bucket can hold compared to its rated capacity. Material types and bucket design impact the fill factor, as some materials are easier to heap and load fully.
- Cycle Per Hour & Hourly Production Rate: The frequency at which your machine can complete a cycle, and the rate at which material is moved per hour, should be considered. A larger heaped capacity may allow for fewer cycles, while a struck capacity might mean more cycles to achieve the same volume.
- Angle of Swing: The swing angle affects how much time each loading and unloading cycle takes. Reducing the angle can optimize cycle times and increase production rates.
- Length of Boom and Equipment Condition: The length of the boom affects reach and loading depth. Additionally, keeping equipment in good condition ensures accurate performance for either heaped or struck capacity measurements.
- Job Site Conditions: Uneven or soft ground can impact load efficiency and cycle times. Job site conditions should influence the bucket capacity decision based on the stability and requirements of the work environment.
Choosing Between Heaped and Struck Capacity: Which One Fits Your Job ?
Choosing between heaped and struck capacity comes down to your specific job requirements. Here’s a quick guide:
Choose Heaped Capacity- if you’re handling loose materials and need to maximize each load for high-efficiency jobs.
Choose Struck Capacity- when dealing with heavy, compact, or non-heapable materials where control over volume and weight is a priority.
Why Eighty Nine Trading Machinery - GP-9 & HD-9 series buckets are the right choice ?
At Eighty Nine Trading Machinery, our GP-9 & HD-9 series buckets are designed with AR400 abrasion-resistant steel to tackle tough conditions with ease. These buckets are engineered for both heaped and struck capacities, providing durable, high-performance solutions that allow you to work efficiently no matter the site conditions or material type.
Final Thoughts
Make the most of every load—select the right capacity for your needs.
Understanding the difference between heaped and struck capacity allows you to make informed decisions that improve productivity, save costs, and optimize your machinery's capabilities. For demanding jobs, choosing the right capacity can lead to more efficient operations and better results for your bottom line.
