Loads of Attachment Options
A Multitude of Implements to Make Your Excavator More Productive
By Jason Morgan
 On a utility jobsite, where machines of all kind productively scurry around, the excavator is king. With its long-reaching arm, the excavator easily tackles dig-and-place operations, but there’s more than one way to dig a trench and lay pipe. The excavator’s ultimate ability is its versatility. With the excavator’s ability to swap buckets and grapples (among a wide range of other application attachments) some might consider it the “Swiss Army Knife” of the utility jobsite.
When you’re surveying your excavator attachment options, start with the digging implement. Standard dirt buckets are used in most common digging applications. Trenching for underground utilities such as water, electric, gas, sprinkler systems, drain tiles and sewer systems are the most popular. The bucket size and type may very on the width of trench desired. Soil conditions, such as black dirt, sand, clay or rock, can dictate the size of machine required, as well as the size and type of bucket.
“Depending on the size of the excavator, standard dirt bucket widths from 6 to 30 in. are available,” says JCB Inc.’s General Manager Chris Giorgianni. “The bucket depth varies by machine class, as it is important to properly match bucket capacity with the machine size and operating capacity. Ditching and grading buckets are also available from 39 to 60 in., allowing operation in more specialized applications.”
Typically, compact (1 to 6 metric tons) and mid-sized (7 to 12 metric tons) excavators are the diggers on utility sites. For these excavators, standard-duty, heavy-duty, cemetery/bellhole, ditching and grading are the buckets of choice.
“The type of bucket for installing or repairing an underground utility would depend on the type of digging conditions, as well as the utility being installed or repaired,” says Lowell Stout, Senior Product Manager, Terex Construction Americas. “Normally, a standard- or heavy-duty type bucket would be selected. Widths of 12 to 30 in. are most common for this type of work.”
Buckets can be attached to excavators in two different ways. The most common attachment is through a direct pin-on system in which the bucket attaches directly to the excavators’ pins.
A quick-coupler option is also available, providing a faster change between buckets and other attachments. The quick-coupler attachment is permanently pinned to the compact excavator attachment mounting points, allowing for less time in between attachment revisions.
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| Excavators come in all shapes and sizes -- one of the smallest is JCB’s Micro Series excavators. |
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There are also mechanical and hydraulic quick-couplers. The mechanical couplers use an over-center lever mechanism to latch the attachments. With hydraulic quick-couplers, the hydraulic controls located in the operator’s station are used to fasten and unlock the coupler to the attachments. The majority of quick couplers work by hooking one of the bucket pins and then capturing the other pin with an over-center latching mechanism, explains Ron Grimstad, Product Manager for CEAttachments. A locking pin is provided and is required to be installed to prevent accidental bucket release.
With a new bucket attached, the operator may notice a few small changes in the excavator’s productivity ebb and flow. The first difference an operator might notice is that he or she may be able to get more production by installing a larger-capacity bucket if handling lighter weight material, says Stout. Or, he may get increased versatility by installing a 4-in-1 bucket, which gives him the option of moving items like rocks, timbers, trash and other types of material that may need to be moved before excavation can occur.
“Moving from a standard capacity digging bucket to a ditching bucket adds mostly functionality not weight,” says Jay A. Baudhuin, Compact Equipment Product Manager for Wacker Neuson. “All ditching, 4-in-1 or quad buckets are reduced capacity to adjust for the added weight from the material and or the bucket construction.”
Of course, like any piece of machinery, you’ll want to keep your buckets in tip-top shape to keep them cutting productively, especially when bucket attachments are an investment of anywhere from $300 to $2,000, depending on manufacturer, size and type. Bucket cutting edges, side cutters and cutting teeth are all wear items. Many teeth are bolt on or are pinned to shanks that are either bolted or welded onto the bucket, explains Giorgianni. Digging performance is greatly affected by maintaining buckets in good working conditions.
“The most common overlooked maintenance task for a bucket is applying grease to the attaching pins and bushings,” says Stout. “Normally, when you are near an excavator that is digging and you hear the bucket slapping back and forth, that is the result of insufficient lubrication or improper shimming.”
Just because your trench is etched in the earth, it doesn’t mean that the excavator’s job is done. You’ve got to get your pipe in the trench and the trusty mechanical arm of your excavator is your tool of the trade. There are several common attachments that help you do this. In the way of actual attachments, you can take your pick between mechanical or hydraulic thumbs (see sidebar on p. 28), grapples or 4-in-1 combination buckets. These attachments allow the operator to quickly grab, rotate and position the pipe for accurate placement.
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| Standard dirt buckets are used in most general digging applications. Trenching for underground utilities such as water, electric, gas, sprinkler systems, drain tiles and sewer systems are most popular. |
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A more simplistic system is a pipe strap — which typically connects to a craning eye on the backside of the bucket.
“The pipe strap should be attached to the craning eye so that strap can in no way be placed into a pinch point,” recommends Stout.
“If craning without a bucket, then a hook should be pinned to the bucket pin and the strap attached to it.
A major concern is that the pipe strap is properly attached to the machine. If not correctly installed, there is a possibility that the load can become disconnected. Always follow all guidelines and instructions for lifting, as outlined in the operator’s manual.”
4-in-1 combination buckets and grapples all have size limitations, says Giorgianni. Pipe straps, depending on their length, can accommodate pipe of any size or length. The limiting factor becomes the size and capacity of the compact to mid-sized excavator.
Another attachment that is growing in popularity is a pipe lift. This is basically a jaw that clamps around the outside of the pipe that can be either fully automatic or semi automatic, making the job a lot easier for the handler on the ground. A pipe lift attachment can also speed up the task by not requiring slings or other devices that require manipulation by the ground handler. The pipe lifts can be matched to pipes having diameters of 4 to 54 in. while the pipe hooks normally handle pipes with diameters of 8 to 36 in.,
says Stout.
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| The bucket size and type may very on the width of trench desired. Soil conditions, such as black dirt, sand, clay or rock, can dictate the size of machine required, as well as the size and type of bucket. |
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Regardless of your attachment selection, you have to be careful not to overload the excavator’s lifting capacity. A long, heavy pipe can be an awkward load for an excavator to move and place. It’s also important to remember that the further from the excavator you extend the arm, the less lifting capacity the machine has. Larger pipes can often be more weight than a bucket full of material. It is important that the operator understands what the stability limit is for his machine, as well as what weight it can safely handle at a given distance from the machine.
“If an operator attempts to lift too much pipe or is using too small of machine, the machine may become unstable,” says Giorgianni. “If the operator attempts to move the pipe too quickly, it could cause the pipe to swing side to side, which becomes very dangerous.”
There are two ways to move the material once it’s lifted: 1) stick-and-boom or 2) lifting the load and tracking the machine. You want the machine positioned as close to the hole as possible because when you lift the load, you’ll lose stability. The stick-and-boom movement technique is the optimal procedure to keep the machine in one place. It’s also safer than moving the entire loaded excavator. If you can place the pipe without rolling the tracks, that’s probably the easiest and safest bet.
Another common error is not properly installing the craning strap. Some operators will simply put the strap across the teeth or around the bucket’s hinge point, says Stout. In both cases, there is a good possibility that the pipe could be released. And endangering the lives of his crew and himself is the last thing any good excavator operator wants to do.
Jason Morgan is Associate Editor of Utility Contractor.
All Thumbs
Examining the Mechanical Appendage
By Pam Stask
A thumb attachment is an excellent way to move pipe and materials around the jobsite. Thumbs are used to complement a bucket, turning it from a dig-only attachment to a piece of equipment capable of lifting and shifting materials around the work area. Similar to the thumb on a person’s hand, the attachment is able to snatch items up and hold them firmly in the bucket — enabling an operator to reposition the bucket’s contents throughout the busy jobsite.
Operators can use thumb and bucket combos to handle a variety of worksite materials such as pipe and manholes. By adding a thumb to a bucket, the combination can act like a grapple attachment, performing similar tasks without removing and attaching other equipment — saving time and hassle on the jobsite.
“Thumbs have an advantage over grapples due to the fact that when retracted they lay against the bottom of the stick until neede, out of the way for normal digging operations of the excavator bucket,” says Ron Grimstad, Product Manager for CEAttachments.
There are two types of thumb attachments — rigid and hydraulic.
Rigid thumbs pivot and are put into position and locked manually. The operator must exit the machine to place the thumb in the desired work position.
A mechanical link arm grips the thumb into place, allowing the thumb to work at different angles to the bucket or to be stored against the excavator stick for regular digging work.
Hydraulic thumbs are designed with a hydraulic cylinder that puts the thumb into position hydraulically. Operators are able to reposition the thumb from inside the machine through a hydraulic control. Since the two different thumbs feature contrasting characteristics, each type is better suited for a variety of tasks. Jobs that require lifting and moving items that are the same size and shape are ideal for rigid thumbs, given its fixed position. Longer jobs are desirable for rigid thumbs since they allow the operator to stay in the machine and work, rather than readjust the thumb’s position.
“Rigid thumbs make sense in applications where the thumb will be in use for extended periods of time in repetitive operations such as moving or loading material like rocks, timbers and brush or demolition debris,” says Grimstad.
When the project requires lifting and moving items of various sizes — like sewer or drainage pipe — hydraulic thumbs provide the most relief.
Since the hydraulic thumb is put in place hydraulically and doesn’t require the operator to get out of the machine, it is suited for jobs that require the thumb to be used between short
digging jobs.
Prices for rigid thumbs range from $1,600 to around $2,800. Hydraulic thumbs cost around $2,000 on smaller excavators and $3,500 for a larger machine.
There are some guidelines when pairing a thumb and bucket attachment. Grimstad notes that the thumbs are designed so that the end of the thumb mates with the tip or cutting edge of the bucket. Based on this design, the thumb should match the tip radius of the bucket. To assure proper sizing and operation, thumb and bucket attachments may also be purchased from the compact excavator OEM manufacturer, resulting in the two attachments matching correctly. |
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