For maximum productivity, match the bucket capacity and type to the job.
Buckets serve as the business end of your excavator. Choosing the right size and type of excavator bucket for your application and the material you’re digging or moving can increase production without over-stressing the equipment.
Use this guide to understand how to match excavator bucket sizes and excavator bucket types to your jobs.
Excavator bucket sizes
Size is the first consideration when choosing a bucket. If you’re digging a trench, the width of the trench will dictate the bucket width you need. If you’re digging a foundation or backfilling an excavation, bigger is generally better, within the bucket size recommendations for the excavator. The range of bucket sizes you can use with a particular excavator is dictated by the size of the excavator. The same is true for mini excavator bucket sizes. See the excavator bucket size chart below for details.
Bigger buckets increase productivity since you can move more material in one cycle.
“In general, if you're loading trucks, you get as big a bucket as you can put on the machine,” advised Lee Oldenburg, branch manager for United Rentals’ Heavy Equipment Division in the Boston metro area.
Choose an excavator that can power the largest bucket you want to use
When working in difficult terrain or lifting dense materials, said Oldenburg, “it’s far more important to pick the right size excavator than to pick the right size bucket. You can't use a small excavator and put a heavy duty bucket on it, it won’t make one bit of difference.” You’ll only stress the machine and increase the risk of tipping.
Check the machine’s lifting capacity chart to see how much weight the excavator can safely lift over the side at full reach. Note that the excavator manufacturer may provide several lifting capacity charts to account for different boom and arm lengths, bucket sizes and other factors.
Calculate the lift ratio
To make sure the excavator has enough power to lift the bucket you want to use filled with the material you need to lift, do a little math.
- Note the bucket capacity, which is listed in cubic yards.
- Multiply the it by the material density of the heaviest material you plan to lift. (Consult the manufacturer’s material density chart or any standard reference.)
- Add the weight of any attachments to get the lift weight. (Remember, the bucket weight may or may not already be included in the lifting capacity; if it is, don’t add it here.)
- Take the lift weight and divide it by the adjusted lift capacity, which is the maximum lifting capacity plus the bucket weight. The result is the lift ratio.
If the lift ratio is less than 1, the bucket will work for the material you want to lift. If it’s higher than 1, the bucket will be too heavy for the excavator. You’ll need a smaller bucket — or a larger excavator.
If you’re working with high-density materials and you need to reach out as far as the machine will go, a smaller bucket will be safer, even if you’ve rented the appropriate size excavator. Filling the bucket to capacity with heavy material and extending the stick to the end of its working range can potentially cause the machine to tip.
Excavator bucket size chart
When choosing a bucket size, stay within the bucket width recommendations provided by the manufacturer of your excavator or mini excavator. The recommend bucket widths refer to general purpose and specialty buckets. Grading buckets are listed separately.
|Machine Size||Recommended Bucket Width in Inches||Recommended Grading Bucket Width in Inches|
|< 0.75 ton||6-24||30|
|1 ton-1.9 ton||6-24||36|
|2 ton-3.5 ton||9-30||36|
|5 ton to 6 ton||12-36||36-48|
|7 ton to 10 ton||12-36||48-60|
|15 -29 ton||18-48||60|
The benefits of renting two or more buckets
In some cases, different phases of a job are best handled with different sizes of bucket. If you’re digging a foundation and you hit rock or packed gravel, for example, you may want to switch to a narrower bucket to slice through it more easily.
“The way our machines are set up with these quick couplers, I tell people all the time to take two buckets for not a whole lot more money,” said Oldenburg. “That way, if they’re having trouble getting through the dirt or breaking through frost with a big bucket, they can easily switch buckets.”
Switching buckets can also help you increase productivity. “Let’s say you’re putting a 24-inch pipe into the ground and you've got a 30-inch or 36-inch bucket to dig the trench,” said Oldenburg. “Now you need to pull all of the material from the side of the trench back into the hole. It will take you forever with the same bucket you were using. But if you switch to a 60-inch bucket with a flat edge, you could you double or triple your backfill speed.”
Excavator bucket types
Different excavator bucket types are suited to different tasks. Using the right bucket will help you get the job done efficiently.
General purpose bucket: This is the standard attachment for an excavator and can be used to move loose dirt, loam, mixed gravel and other soil types. A general purpose bucket is often the best solution for digging, loading and cleanup.
Heavy-duty bucket/rock bucket: Excavating abrasive materials such as sand and crushed rock will be easier with a heavy-duty or high abrasion bucket. These buckets resist abrasion and withstand high breakout and impact forces. You can use them for excavating broken slag, sandstone, iron ore and high quartz granite or for loading tightly compacted materials. They may include a spade nose or a straight edge and can accept different types of teeth.
Grading bucket: This wide bucket has a straight edge with no teeth and a flat surface, making it useful for smoothing out soil and aggregates.In addition to landscape work, a grading bucket is excellent for backfilling, sloping, loading material and cleaning ditches. If you’re struggling with whether to choose a ditching bucket vs grading bucket, the answer is easy: They’re the same bucket, used for different purposes.
Trenching bucket: A trenching bucket is a narrow bucket used to dig trenches. Size the bucket for the desired width of the trench.
Tilting bucket: A tilting bucket, also known as an angle tilt bucket, allows for precise angles (up to 45 degrees in both directions) for superior grading and leveling work.
Manufacturers also offer special application buckets. These include skeleton buckets that separate rock from sand and buckets with clamps used to keep materials in the bucket.
What is breakout force?
Breakout force is the amount of force an excavator can exert against the material at its cutting edge. It’s determined by the hydraulic power of the excavator, not the size of the bucket.
Narrower, heavy-duty buckets are the way to go when using an excavator at its maximum breakout force. If you try to use a light-duty bucket for heavy-duty work, you can tear the lip right off the bucket.
“If someone calls me and says ‘I've got a brutal site with rock everywhere, I have to use a hydraulic hammer to break it, I need to be able to rip through some of it,’ I would say ‘let's find a machine with the highest breakout force and then put a narrow bucket on it.’ In other words, oversize the excavator,” said Oldenburg.
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John Ross écrit sur les technologies industrielles, automobiles et de consommation depuis 17 ans.