The Goldilocks Zone

Excavators that aren’t too big, or too small—they’re just right.

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Credit: Caterpillar
The Caterpillar 323
It’s the Goldilocks tale of the heavy construction industry: some excavators are too large; some excavators are too small. You know the rest.

There are two or three common size classes (8 metric ton, 20 metric ton, and 35 metric ton), but the middle size class would probably be the 20- to 24-metric-ton size class, speculates Jonathan Spendlove, product marketing manager, excavators, John Deere and Hitachi. “A 20-metric-ton excavator covers a lot of bases, whether that’s loading trucks, placing pipes, or general excavation. For Deere and Hitachi, that size class is covered by the 210G and ZX210-6, respectively.”

Most contractors have had a 20- or 21-ton in their fleet, Todd Dohnal, dealer development manager for Kobelco USA, believes. Many also have a 14- or 15-ton. “This is primarily due to transportation restrictions and overall capabilities for those sizes on job sites.”

Why is this size so popular? This size “strike[s] an excellent balance of performance, versatility, and transportability,” says Brian Stellbrink, product application specialist for Caterpillar. In other words, they are large enough to do high-production work but are sized to maneuver around congested job sites and are easily transportable between jobs. That versatility helps contractors do more with less. “The most common size excavator contractors have in their fleets [is] typically in the 50,000- to 85,000-pound weight range. For Caterpillar, these include the 320–336 model range.”

Credit: Hitachi
The Hitachi ZX60USB-5

Komatsu’s PC210 LC-11 to PC490-LC11 fall into the 20-ton to 50-ton mid-range excavator and dozer line. It’s a popular class for residential, non-residential, and infrastructure markets. Andrew Earing, product marketing manager, hydraulic excavators, Komatsu America Corp., thinks that’s because they blend productivity and transportability. “A contractor wants the largest machine he can get his hands [on] that’s still easy to move from job site to job site with minimal to no permits.” Larger sizes are common in quarries and mines because they stay at the site, he notes.

Easy to transport and to afford, this mid-range class also offers productivity by reducing the amount of equipment and ground crew needed and by incorporating semi-autonomous intelligent machine control. In addition, another feature is easy access to pattern change controls for the hydraulics, Earing says.

Versatility is a desired attribute. “It’s not uncommon for operators to use a machine’s quick coupler to change attachments to best match the digging or trenching conditions,” observes Aaron Kleingartner, marketing manager for Doosan Infracore North America LLC, whereas larger crawler excavators tend to be paired with a specific bucket that stays on that machine day in, day out.

Credit: John Deere
The John Deere 210G LC

Excavators in 22- to 25-metric-ton size class size class, such as the Doosan DX225LC-5 and DX235LCR-5, can be transported more easily than larger excavators and are used in many day-to-day construction applications, Kleingartner continues. This is the most common size of excavators, used for excavating, trenching, and grading duties, he states. “One of the most common applications, according to our data, is site development and building. When paired with a bucket and a hydraulic clamp, the excavators are ideal for land-clearing tasks and prepping ground for a new commercial building. They are also used to dig footings or basements in some residential construction markets.”

Another benefit is that this size class tends to be more nimble than larger models, but customers must also identify their lifting capability and productivity needs. “The question is, ‘How much dirt do I need to move?’” advises Spendlove. “Or, ‘How much weight do I need to lift?’”

For utility work, site preparation, and other medium construction projects, the mid-sized excavators are ideally suited. “These excavators are great for applications like general excavation, site preparation, brush-cutting, trenching, hammering, and shearing,” says Sung Sook Kim, product manager, excavators, Volvo Construction Equipment. “Once you get into a production environment, like aggregates, you’d start to get into the larger size excavators.”

Volvo classifies excavators based on operating weight and considers between 10 metric tons to 33 metric tons mid-sized. For Volvo, this covers nine total crawler models, including conventional-swing machines, ranging from the EC140E up to the EC300E, and short-swing models from ECR145E up to ECR355E. They also offer a newly expanded wheeled excavator lineup with five models that would fall into the mid-sized excavator class, ranging from the new short-swing EWR150E up to the new conventional-swing EW220E.

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One of the most popular features in this size class, Kleingartner believes, is reduced tail swing. “Reduced-tail-swing excavators are quite popular in this size because they are versatile on many road and bridge construction job sites,” he explains. It enables an operator to work within one lane width on a road so there’s no need to close two lanes of traffic. In addition, the design might reduce damage to adjacent structures because there is less overhang with the operator rotates the house and workgroup to load a truck. Doosan’s offering is the DX235LCR-5.

From an operation standpoint, Spendlove believes that customers are looking for smooth hydraulics, fast swing speed and boom up speed, bucket breakout force, and stability. “It doesn’t hurt to have a comfortable cab either. John Deere and Hitachi now offer a comfortable leather seat with heating and cooling functions—just like you have in your truck.”

Cab comfort is an important feature, Earing confirms. Customers look for Bluetooth and heated seats to keep operators comfortable and productive. “Skilled operators are in demand, so you want to keep them happy and comfortable.”

Many heavy construction equipment manufacturers have enhanced technology for operators by upgrading cabs with larger display screens and cameras. Doosan “-5” excavators offer standard rearview and side-view cameras that allow operators to have better visibility all around the machine. A split-screen option on Doosan excavator LCD screens allows operators to see both views at the same time.

A unique Volvo feature designed to increase productivity is the boom float, which relieves hydraulic pressure from the cylinders while lowering the boom. “This has several unique benefits,” says Kim, such as “faster cycle times, more accurate grading, and improved fuel efficiency.”

Similarly, Volvo’s straight travel pedal allows the operator to control the line with one pedal rather than two pedals. Not only does this increase productivity, but it also improves accuracy.

One additional feature is Volvo’s integrated work modes. Rather than having two separate dials for engine speed and pump flow, they integrated them into one. This allows operators to get the perfect balance of power and controllability while burning as little fuel as possible.

Overall, Stellbrink concludes, contractors are looking for a machine that helps them get the most work done at the lowest operating cost. They want a machine that provides a safe and comfortable working environment.

“Contractors are asking for more performance, both from the core machine and onboard technology,” says Stellbrink. For example, many contractors seek advantages such as more lift, faster cycle times, balance, and more breakout force. They are also asking for usable technology to help them be more productive, efficient, and safe. A few examples include machine grade control systems, payload systems, and e-fence features.

Contractors are also asking for machines with lower operating costs, such as lower fuel consumption and lower maintenance costs. Safety and comfort are also key considerations for most contractors when choosing a mid-size excavator.

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Often used for site prep, utility work, and brush cutting, excavators are known as the “Swiss Army knife” of the construction industry—even more so when versatility is enhanced by attachments, enabling the machines to dig basements, demolish buildings, and do much more. It gives excavators “range” by enabling them to switch tools and not be limited by any one configuration. This saves on manpower, fuel, equipment, and the time it takes to get permits, Earing says. Contractors no longer have to purchase multiple machines.

Attachments enable excavators to become very versatile and efficient in many different applications, such as underground utilities, demolition, and land clearing, according to Stellbrink. He says some of the most common hydraulic attachments are hammers, thumbs, compactors, shears, and multi-processors.

There exists a wide range of work tool attachments to further enhance the versatility of these mid-size excavators. Kim believes attachments are one reason for the growth in the excavator market. He lists popular attachments as hydraulic thumbs, hammers, and a brush-cutter/mower attachment.

Another attachment gaining popularity among customers is the Steelwrist tiltrotator. This enables an operator to rotate the bucket 360 degrees and tilt plus or minus 45 degrees, which increases the machine’s versatility and reduces repositioning time. It can be used with a variety of attachments including buckets, compactors, grapples, sweepers, and a variety of work tools.

The most common attachments used with mid-size excavators, Kleingartner says, are buckets, clamps, and quick couplers. Additional attachments may include hydraulic breakers and plate compactors.

Hydraulic thumbs are in demand because they allow an operator to pick up and handle material, eliminating the need for ground crew. “Hydraulic thumbs are by far the number 1,” insists Donhal. Breakers, mowing heads, and some other higher-flow-capacity attachments are starting to be requested more and more, he adds. However, Donhal points out, auxiliary hydraulics are a necessity with the increased use of thumbs and quick couplers.

When it comes to attachments, Earing says, they vary by region. However, a quick coupler comes in handy when changing attachments. When changing them manually, he estimates that it takes 20–60 minutes, but with the coupler, it’s only 15–20 seconds—and it requires just one person. Done in the cab, the quick coupler promotes safety.

Quick couplers and different sizes and types of buckets enable contractors to excavate efficiently, Stellbrink interjects.

Volvo’s excavators allow an operator to digitally store presets on pressure and flow for up to 20 different attachments inside the cab, Kim indicates. This increases uptime and the machine’s versatility.

Credit: Volvo CE
The Volvo ERC355EL on the job site

Tech Talk: Telematics
With a new generation of owners and operators joining the industry, adoption of evolving technology has become almost routine. In fact, many are demanding the latest technology—specifically, telematics.

Telematics—the ability to understand how your machine is being used, where it is being used, and any potential service issues that may impact uptime—is a key feature, Spendlove states. “JDLink and Service Advisor Remote are two telematics technologies that come standard on every John Deere model in this size class.”

Telematics is definitely an area gaining interest among contractors, according to Kim. “What sets Volvo apart in the industry is that we offer telematics support at the OEM level with our ActiveCare Direct program.” ActiveCare Direct is an around-the-clock, 365 days a year machine monitoring and monthly reporting solution. Rather than sending a flood of undiagnosed fault codes to the customer, Volvo’s proprietary system diagnoses fault codes in near-real time and sends case alerts to the customer and their dealer with the probable cause, the recommended solution, and the potential consequence of not taking action. This allows the owner to take action immediately rather than spending time trying to diagnose fault codes.

Similarly, Doosan offers the DoosanCONNECT telematics management system to help owners better utilize their equipment and partner with their dealer to ensure they are operating in an efficient manner. Kleingartner offers an example: a construction firm called Branch Civil, based in Roanoke, VA, specializes in road and bridge construction. The company opened a situational awareness room in June 2018 and uses three 65-inch television screens to monitor the company’s earthmoving equipment. He says the logistics foreman partners with a communication employee to ensure machines are transported properly to their intended destination. The company is also using the data provided by telematics to monitor fuel consumption and service-related decisions.

Kleingartner says the equipment superintendent at Branch Civil wants to “be on top of things” and efficiently track and monitor their equipment—not just the tracking, but the data from certain manufacturers. They import machine fault codes into their communication board and situational awareness room, where they make decisions daily on working alerts that may otherwise go unnoticed.

Tech Talk Two: Grade Control
Grade management is another technology that has become important. Both Deere and Hitachi offer a grade-ready option that allows customers to pair their excavator with their choice of grade technology provider.

Contractors are looking for reliable technology that can help them directly increase productivity, increase safety, and increase operator efficiency while helping lower their operating costs. Caterpillar’s Stellbrink explains that two- and three-dimensional integrated machine grade control systems help contractors dig to grade more quickly and stay on grade with a high degree of accuracy while eliminating or greatly minimizing traditional ground labor around the machine. “These grade systems can significantly increase the operational efficiency of that machine on a given job site, ultimately getting more work done at a lower cost, with an enhanced focus on safety.”

Contractors are also looking for more efficient ways to move and track material. On-board excavator payload systems help them load trucks with material that is moved offsite. “These systems ensure truck payloads are achieved without the risk of costly over- or underloading,” continues Stellbrink. They also track productivity.

In addition, contractors are always looking for ways to enhance job site safety. Thus, they want machines with increased visibility, as well as camera systems that can provide a complete 360-degree view of what exists around the machine at all times. “Contractors often work on very constricted job sites, including overhead obstacles,” says Stellbrink. They are looking for ways to avoid certain areas within the working range of the excavator. Caterpillar Next Gen Excavators offer a number of e-fence features that help operators avoid pre-defined work areas.

Credit: Kobelco
Dirt moving with a Kobelco SK270SR

More and more, Kim says, contractors are asking about machine control systems. Volvo offers Dig Assist—an intuitive machine control solution offered on the Co-Pilot touchscreen display that provides a real-time 3D view of the machine’s movements. This allows the operator to use follow-the-line guidance for trenching, as well as check real-time progress against target grade and depth, ensuring the job is done right the first time. In-Field Design functionality also allows the operator to select from pre-built digging profiles or draw custom digging profiles to work from.

Dohnal concurs that grade control has become “a big request,” which is why Kobelco works closely with Trimble on “one of the most advanced control systems on the market today.” All the operator has to do is raise the boom and the GPS system will control the arm and bucket function to ensure the proper grade is achieved.

The system does not use specialized electronic sensor cylinders or mechanically controlled position sensors; instead, it utilizes newly developed state-of-the-art gyroscopic sensors similar to those used in modern airliners and stability systems on automobiles.

Its three levels of usage include:

  • Grade Assist—the operator will be able to monitor the position of the bucket or working tool in relation to the machine.
  • 2D Machine Control—with the assistance of a laser system and additional sensors, this is able to provide a height and/or slope reference to the operator. The system and operator can manually or automatically control the machine to recreate the programed elevations.
  • 3D Machine Control—with the addition of a Global Navigation Satellite System, receivers, and pre-programmed engineering plans, the machine can be manually or automatically controlled to match a 3D set designed for the groundwork. With this system, multiple machines can work together to meet the engineer’s design.

Benefits of intelligent machine control (3D GPS guidance) include eliminating or reducing waste by enabling the operator to dig straight to grade; fleet optimization through reduction of the need for machine support; and freeing up the ground crew because there’s no need for grade or stake checkers—a safety benefit. Factory-installed and fully integrated, it is precise. Komatsu’s Earing cites case studies that indicate 50–80% productivity increases when intelligent machine control is used.

Earing references other case studies indicating that use of 3D GPS guidance reduces the number of hours needed to complete jobs by 50% or more. Reducing the hours on the machine, in turn, reduces the amount of maintenance required. “In North America, you would move on to the next job.” Komatsu’s KOMTRAX service—which monitors hours and maintenance needs—is the only OEM service that doesn’t include a subscription fee for the life of the machine.

Hydraulic excavators are one of the most versatile pieces of construction equipment, and mid-size excavators are the very center of this, Stillbrink believes. They can be used effectively across a wide range of applications and are very productive, yet easy to transport.

They are common pieces of equipment in road construction, commercial site preparation, heavy infrastructure, underground utilities, land clearing, and demolition. As tracked machines, they can work in challenging terrain, weather, and ground conditions. In addition, they can be configured with many different options to further expand their versatility.

The increasing use of technology in these machines adds to their versatility. This can help contractors free up other machines and labor for different jobs.

Often considered more versatile than larger crawler excavators, this size range is frequently used in general construction activities such as site prep and digging basements or footings. “They can also be used for everyday digging or lifting,” states Kleingartner.

Excavators in the 20- to 24-metric-ton size class are highly versatile, Spendlove emphasizes. “They are among the more transportable mid-sized excavators, and they can be paired with a wide variety of buckets, couplers, thumbs, hammers, and other attachments.”

They continue to evolve every year, Dohnal notes. “With new attachment innovations and a deeper understanding of what an excavator can do, end-users continue to find additional ways to utilize excavators on their job sites.” GX_bug_web

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