Excavator Tech: How Engines, Hydraulics and Hybrids Are Evolving the Mini Ex Market

Volvo Mini Excavator

The long arm of a mini excavator has become a pretty powerful and popular tool for American contractors. Fitted with a bucket, hammer, brush cutter, thumb, grapple or [insert favorite attachment here], a compact excavator can tackle a ton of applications on any number of jobsites. That versatility continues to get upgraded each year but not just by adding more implement options. High-tech electronic engines, sophisticated hydraulic systems, next-gen grade controls and advanced monitoring services are just some of the things allowing small excavators and their operators ever-increasing precision, comfort, efficiency and ease of operation.

“Contractors are looking for new ways to do more work with fewer machines in order to keep their costs down and their productivity up,” explains Jeff Jacobsmeyer, Kubota CE product manager for excavators, tractor loader backhoes and wheel loaders. “Technologies like our Advanced Load-Sensing Hydraulic System deliver increased efficiency by providing optimum oil flow to each cylinder. We also place a high priority on fuel economy and environmental preservation. For example, Kubota’s standard Eco Plus feature allows operators to increase fuel savings by simply activating the Eco Plus switch. Combine that with our Auto Idling feature, and the operator reduces fuel consumption and contributes less machine noise on the jobsite.”

Compact excavators may look small (ranging up to 6 or 8 metric tons in size), but their ability to work harder and smarter is not dependent on their size. It’s dependent on how their engines, hydraulics, pumps, tracks and other systems are seamlessly engineered. Competition in the market has created groundbreaking technologies like Kobelco’s one-of-a-kind, eco-friendly iNDr+E cooling system, which ensures quiet operation and protection from dust. Demand has pushed JCB to offer 500-hour greasing intervals on its minis, which can save up to 47 tubes of grease and 49 hours of labor per 1,500 hours. EPA regulations have pushed Volvo to offer lower horsepower in its diesel engines while not sacrificing performance; on the EC35D and ECR40D, Volvo was able to reduce the horsepower from 36 to 24, while increasing performance in lift capacity and breakout/tearout forces via things like high-tech hydraulics.

As manufacturers are seeing a lot of sales of U.S. mini excavators, they are launching some pretty amazing products and technologies to serve it. And we mean a lot — as in at least 20 different brands — Bobcat, Case, Caterpillar, Doosan, Gehl, Hitachi, Hyundai, IHI, JCB, John Deere, Kobelco, Komatsu, Kubota, Mustang, New Holland, Takeuchi, Volvo, Wacker Neuson and Yanmar. These mobile excavators are going into an assortment of applications, digging basements, burying downspout lines, installing electrical services, trenching service lines, augering holes for trees or grappling obscenely big, decorative rocks. And before we worry about all those fancy advanced technologies, the very first thing a buyer or renter should determine is application.

“The application and the kind of jobs the machine will be performing are probably among the first considerations,” says John Comrie, utility product manager for Volvo Construction Equipment. “Customers should consider the weight of the machine — their truck can only tow so much weight, so that could restrict the type of excavator they rent or purchase. Dimensions are another important factor — if you’re a utility contractor and are going to be working in backyards with tight access points, dimensions should be taken into consideration. If you’re planning on using attachments, oil flow should be a point of consideration. The more oil flow you need, the more horsepower you’re going to need.”

Mini Excavator Hydraulics

Advanced hydraulic systems are powering machines more efficiently and giving contractors precise power (sometimes automated) for all types of applications (digging to hammering).


Compact excavators are made powerful from the gallons of fluid coursing through their hydraulic veins. Using up to four pumps, mini excavators use pressurized oil to propel tracks, swing the house, move the boom, run attachments and basically move the machine. Hydraulic efficiency has been a big concentration point for manufacturers. Efficiency is a result of improved system designs which are capable of higher pressure, increased cooling and optimized use of the available oil flow. The lower engine horsepower found in some machines has also created a need to do more with less, making more efficient hydraulics a requirement.

Caterpillar’s E2 models have what Cat calls “high-definition hydraulics,” which utilize streamlined valves that reduce heat, thereby making the fluid more stable, functional and precise in its control.

“The HDH system was originally developed for our Asia markets,” explains Greg Worley, Cat product expert for mini excavators. “When you have extremely high fuel prices, such as those in China, you need to provide highly efficient machines that still deliver power and control. More power equals more fuel burn. More hydraulic control equals more fuel burn. The HDH system delivers power and control while being very fuel efficient to meet the customer’s needs. With the technology working so well, why not bring the benefits to our customers worldwide? The HDH system was introduced on our 7- and 8-ton models a few years ago, and now we have introduced it on all our models from the 3.5 ton and up.”

High-tech hydraulics fuel attachments, and that’s a large part of a compact excavator’s success. A mini excavator’s hydraulic system specifications — gpm and psi — will help determine the size and power of attachments available. Depending on the excavator model, attachments range from general purpose and grading buckets to rock wheels, augers, hammers and thumbs. In order to run attachments like augers and grapples, excavators can be plumbed with two-way hydraulics and/or equipped with a diverter value to enable quick use of a thumb (without reworking hoses). Certain manufacturers will also have unique technologies and options.

“Our newest machines have nine hydraulic modes to toggle between, ranging from low idle to max engine speed within the categories: Light, Eco, Heavy and Heavy+,” explains Jordan Dey, compact excavator product manager with JCB. “This allows for tailored operation depending upon the machine’s current application. Light and Eco are ideal in soft ground whereas the Heavy modes are designed for applications on more arduous grounds. These machines are able to house a versatile array of attachments, whether it be a simple auger or a thumb and four-way angle blade.”

Mini Excavator Engine

This Perkins 403F-E17T engine is designed to help mini excavators meet EPA emissions regs while burning less fuel and providing big power.


Every year it seems like engine manufacturers are breaking new ground with innovative, emissions-compliant, off-highway diesel engines. As painful and expensive as engine emissions regulations are, they are forcing the industry to innovate on a massive scale. Here’s a refresher: The most stringent yet of the EPA’s regulations for off-highway diesel engines, known as Tier 4 Final, hit the majority of small diesel engine power ranges in 2015 and 2016. Tier 4 Final has diesel designers from Kubota to Perkins creating smarter, more complex and cleaner-burning power plants for hydraulic excavators, but these engines will come at a significant price increase and may include new technologies, maintenance and fluids (but also more advanced features, fuel efficiency and cleanliness).

“There are a wide range of options available, with various degrees of impact on the output when it comes to engines,” says Dey. “It’s very important to consider the requirements for machines to now reach Tier 4 Final emissions regulations. With this in mind, buyers should ask about an excavator’s engine, the maintenance required on that engine and whether the machine requires a diesel particulate filter [DPF] to accurately select the best machine for their needs.”

Many small excavator units rely on emissions-reducing exhaust filters in aftertreatment systems, also known as DPFs, which require periodic cleaning (regeneration). Bigger units require SCR technology, which stands for selective catalytic reduction technology. It’s a Tier 4 Final system aimed at cleaning up emissions too, and it requires bigger excavator owners to use an extra liquid (diesel exhaust fluid or DEF) at about one third the ratio of fuel. What we’re seeing most from manufacturers is the mission to stay below the 25-hp threshold on popular units, which allows them to bypass EPA regulations.

“Engines, like hydraulics, are very significant in pushing the market to evolve,” says Comrie. “Due to recent changes in emissions regulations, manufacturers need to look for ways to stay within certain horsepower ranges [like below 25 hp] without requiring any additional purifying systems on the machines. To achieve this, engineers have to match engine power with the hydraulics — ensuring enough hydraulic power to operate the attachment, while getting the same or better overall performance.”

Other High-Tech Accouterments

Tail Swing: Choose from three different types of tail swing. Conventional-style compact excavators continue to share space with minimum and zero tail swing designs (excavators that are designed to keep their cabs within the width of their tracks).

Retractable Undercarriage:
In addition to an excavator’s many features (enclosed cabs, backfill blades, extendable sticks), retractable undercarriages are available on the smallest units in the market. This can allow minis to go indoors or into the back of yards.

Increasing Power: Even smaller compact excavator models can feature bucket breakout forces that can top 6,000 lbs. The overall range goes from 2,000 to 18,000 lbs, depending on how you categorize compact. That’s plenty of power for lots of operations.

Cab Options: Do you want an enclosed cab with heat, air conditioning and satellite radio? How about a digital display (capable of various languages) that can automate attachments or utilize telematics? Hey, what about strobe kits, travel motion alarms or a heated seat? Cab options abound.


Despite the glut of products on the market, high technologies are producing some really unique units out there right now. Caterpillar for instance offers the 304.5E2 XTC — a mini hydraulic excavator with an innovative attachment coupler interface engineered into where the dozer blade normally sits; Cat also offers the 300.9D VPS (Versatile Power System) unit, which in conjunction with its separate hydraulic power unit can work either with its diesel engine or from a remote electrical power source.

Wacker Neuson offers its 803 Dual Power Excavator (which can go electric) and the unique Vertical Digging System (available on the EZ28, EZ38 and 50Z3), which enables operators to tilt the excavator for level operation on uneven terrain, improving function and comfort. Takeuchi just announced its first hybrid with the TB216H, featuring both an electric motor and diesel engine with its own pump group to power the hydraulics. The product offerings just keep growing, as the mini excavator sector is one of the most competitive areas of the global construction equipment market today.

“The compact mini market in the U.S. has increased more than 27 percent in the last five years,” says George Lumpkins, national service manager for Kobelco Construction Machinery USA. “Much of this increase can be attributed to the expanded versatility and production capability of the mini excavator for the small- to mid-size contractor. With the current and projected growth of both residential and non-residential construction, we expect more mini excavators will be a must have for contractors on the jobsite.”

Keith Gribbins is associate publisher of Compact Equipment.

The Basics

Kubota Mini Excavator

A great way to experience multiple units is to rent machines.

Compact excavators are competitively judged on lots of criteria. Popular mini ex specs include: operating weight, digging depth, bucket breakout force and maximum reach. There are a slew of features that make certain models unique or pedestrian, ranging from six-way dozer blades and quick-attach mounting systems to high-tech digital control panels and keyless start.

“When looking at acquiring a compact excavator, all buyers should take notice of the machine’s required specifications for their particular applications,” suggests Jordan Dey, compact excavator product manager with JCB. “The overall build and configuration of the machine, from horsepower to arm length, will influence the way in which the machine works and performs.”

A great way to experience multiple units is to rent machines from a local dealer. Operate a variety of units. Step onto the house structure of each compact excavator, which contains the operator’s compartment, and get a feel for its comfort and utility. Are the controls intuitive? Is there enough space to stay comfortable for 10 hours? Is entry and exit quick and uncomplicated?

“Our most popular rental machine is the U35, tight tail swing machine,” says Tim Boulds, Kubota CE product operations manager, tractor loader backhoes and wheel loaders. “Cost to rent is around $1,100 per week and $2,500 per month.”

When evaluating production time, be sure to work both the boom and backfill blade to determine the smoothness, accuracy and featherability of a unit’s joysticks and their control patterns. Ensure that switching from pilot controls to the traditional backhoe configurations (ISO to SAE) is simple (this writer is old and prefers backhoe pattern). Jump off and kick the rubber on the undercarriage, inspecting the tracks, drive sprockets, rollers and idlers. Do you need steel tracks or maybe even a wheeled unit? Those might be available — though often in larger models. For added digging depth, choose a compact excavator with long-arm or extendable arm options; normal dig depths can range from 5 to 20 plus ft.

“The best overall product quality and performance for the price is key in selecting a machine,” says George Lumpkins, national service manager for Kobelco Construction Machinery USA. “Although there are many manufacturers offering similar products in the market, not all mini excavators are equal. Ease of maintenance, operator comfort, re-sale value and most of all the product support should all be reviewed closely before purchasing.”

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