January-February 2009

Two Machines In One

The backhoe-loader offers versatility fore and aft, so choosing the right machine for the job may require twice as much time.

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Because backhoe loaders are just about the most versatile construction machines you’ll find on any job site, the grading and excavation contractor needs to consider a significant number of performance capabilities and design attributes when trying to choose the right backhoe model for the job whether purchasing or renting one. If you think of this workhorse as two machines in one—a combination of a compact front-end loader and a mini-excavator—it only makes sense to devote twice as much time and thought to the specification process.

Several industry experts shared with Grading & Excavation Contractor important concepts to consider in order to make as informed a decision as possible. With so many factors to think about, sophistication is the contractor’s ally. Although the contractor must rely heavily upon a dealer’s expertise, it’s a good idea to keep in mind the various items that the experts list so as to ensure that the machine’s capabilities can handle so many wide-ranging demands.

Advantages, Disadvantages
The first decision is whether or not the backhoe suits the job to begin with. Scott Cowan, president of Knox Tenn Rental in Knoxville, TN, points out that the most likely substitute for excavation is the mini-excavator, which has seen increased adoption in recent years. “One of the things that people love about the mini-excavator is the stability factor,” says Cowan, whose company rents Allmand Brothers and John Deere backhoes. But, he adds, the backhoe provides tremendous mobility and often can be driven from one site to a nearby one without the need for a trailer, maximizing machine utilization. “The one thing that steers contractors toward a backhoe versus a mini-excavator is jobs that have distance between them; that and the ability to haul material in the front bucket.”

Photo: JCB The 1 CX 8 skid-steer from JCB has a dig depth of 8 feet and 4 inches. Its 47-net-horsepower engine provides a loader-lift capacity of 1,345-pounds.

Tom Gray, president of Industrial Contracting Services, Holland, OH, says the versatility of his company’s two Terex 760 backhoes is perfect for the company’s most common project: rail grading. “It’s the versatility of having the ability to load and excavate,” Gray says. “When you work around the tracks, you’ve got to stone them back in and you can rough grade with the bucket.”

Marcello Bargellini, product specialist for Volvo Construction Equipment, adds that backhoes can travel upward of 20 miles per hour. For jobs that do not involve operation in tight spaces or extremely hilly terrain, the backhoe is the right choice and can dig, backfill, grade, crane, load and unload, and perform other functions. Tom Reith, product manager for Terex Construction Americas, adds site preparation, trenching, installing, concrete breakup, posthole digging, and site cleanup to the list.

Starting Points
Once the contractor determines that the backhoe suits a particular project or future projects, the next step is choosing the right model. The primary criterion for rating backhoe models in North America is digging depth, says Bargellini. Digging depth is measured as the maximum distance achievable from the ground line to below grade at the tips of the bucket teeth and typically is expressed as “digging depth 2-foot flat bottom” and “8-foot flat bottom.” These expressions refer to a flat-bottom trench that is actually excavated 2 feet deep and 8 feet long. Standard rated digging depths are 14, 15, 16, and 17 feet.

Bargellini reports that the most popular dig-depth segment is 14 feet, the rating of about 80% of all backhoes sold in North America. In the past few years, he adds, the 15-foot dig-depth backhoe has been gaining in popularity and currently accounts for about 15% to17% of the North American market. Making up most of the remainder of the market, he adds, are “compact backhoes” with dig depths of 8 to13 feet. Bargellini recommends that the contractor first select a backhoe by dig-depth class and price range in addition to various features, options, specifications and attachments that are appropriate for most projects. Other important items are productivity, fuel efficiency, safety, serviceability, operator comfort and dealer service support, he adds.

Paul Grohsmeyer, backhoe-loader marketing manager for Caterpillar Inc., contends that a couple of factors complicate the issue of digging depth, though. Adding an extendable stick to the rear boom can expand the digging depth by as much as 4 feet, Grohsmeyer points out. Another variable affecting the digging depth is the bucket size, he adds.

Bargellini contends that digging depth is a starting point and that one of the most important backhoe specifications is bucket breakout—or digging—force. This is the maximum calculated force in pounds applied at the tip of the bucket teeth. Calculations of breakout force are based on the highest system relief valve setting. Both the bucket digging force and dipper digging force are factors in determining work output. The other factor that determines output, Bargellini says, is speed, which is determined by available hydraulic flow.

Lowell Stout, senior product manager, and Tom Reith, product manager for Terex Construction America, prioritize horsepower, bucket breakout force and stick force because all of these contribute to the machine’s ability to move and lift material, says Stout. Reith adds that knowledge of typical soil types is valuable in determining the necessary bucket or stick breakout force. Although horsepower affects how quickly the machine can work, Reith says, the right power-to-weight ratio is a more accurate predictor of productivity.

Hydraulic capability is a key factor in overall backhoe capability, so this aspect of machine performance will likely come up several times during the specification process. In recent years, manufacturers have spent a great deal of effort to make their hydraulics more powerful and intelligent.

Bargellini notes that almost all manufacturers now offer optional or standard pilot controls as opposed to mechanical “wobble sticks.” Besides being light to the touch and less tiring for the operator, pilot control joysticks can be fitted with many other control switches, such as the roller proportional switch to control operation of a four-in-one extendable dipper. Additionally, these controls can be converted from backhoe to excavator control with the switch of a lever, usually located inside the cab, eliminating the need to have a service technician change mechanical rods for these different operating modes. In its E-Series loaders, Caterpillar incorporated a flow-sharing valve that was designed as an improvement over hydraulic fluid flow sharing through individual joysticks. This proportioning system is designed to provide smooth movements when multiple functions are used.

Digging depth and capacity are two items to specify early in the decision process. An issue related to digging depth, and often considered a factor in productivity, is the reach of the rear boom because, the thinking goes, the greater the machine’s reach, the less often it needs to be repositioned during trenching operations. Bargellini reports that reach from the swing pivot is measured as the distance, at the ground line, from the backhoe swing pin line to the end of the bucket teeth with the backhoe fully extended.

Grohsmeyer says that contractors now realize that they can get greater digging depth with the extendable stick and that this feature also provides greater horizontal reach. This greater reach allows digging a longer trench in fewer machine redeployments and after the final pass, the operator can backfill by reaching across the spoil pile. “We handle some heavy materials that extend out quite a ways; we handle rail with the boom,” says Gray, adding that concerns about stability accompany a desire for long reach. “We handle that by filling the bucket with stone to balance it out.” Cowan adds that some advancements have addressed machine stability. For example, he has noticed that many backhoes now have wider footprints, lower profiles, and lower centers of gravity.

Besides the unit’s sheer power and reach capabilities, Stout says, determining the appropriate machine configuration for typical jobs is important. He says the contractor should consider specifying an extendable stick and perhaps a multipurpose bucket for the front of the machine, depending on need. Determining the machine’s carrying capacity goes a long way toward matching the backhoe to the typical project, as does the size of buckets and their possible compatibility with such specialty buckets as clam-style four-in-ones, side-dumpers, and logging buckets equipped with grapples on the front.

Bargellini indicates that the machine’s physical and operating dimensions are an important consideration. The dimensions are important relative to typical working area footprints and nearby obstructions. These dimensions include:

• Overall length
• Overall width
• Ground clearance
• Operating height
• Bucket rotation
• Swing arc
• Leveling angle
• Dump angle
• Dump height
• Dump reach fully raised
• Maximum rollback at ground
• Maximum rollback at carry position and fully raised
• Wheelbase
• Overall and bucket width
• Tread width
• Maximum grading bucket angle
• Operating weight
• Cycle times (raise, lower, dump)
• Loader clearance circle
• Front- and rear-axle load rating (static and dynamic)

Grohsmeyer argues that the backhoe’s versatility has been positively affected by the evolution of the skid-steer into an integrated tool carrier in many cases. For nearly 15 years, he notes, Caterpillar has included a hydraulic coupler that is optimized to the loader linkage on its backhoes, giving the machines the ability to operate a wide variety of attachments on the front and back, including hydraulic tools, side-dump buckets, and brooms. A recent development for backhoes is the fact that the back-end capability has increased from 50% to 100%, Grohsmeyer estimates. As the demand for tools such as vibratory compactor plates and hammers and even augers for installing posts has increased, Caterpillar has added thumbs to the rear boom to accommodate a wider variety of tools by essentially adding grappling functionality to a bucket.

Cowan cautions that quick-couplers have undergone increased scrutiny in recent years. Indeed, the Occupational Safety and Health Administration (www.osha.gov) has published Safety and Health Information Bulletin SHIB 07-22-2005, which stresses the need to follow manufacturer instructions regarding the installation, use, testing, inspection, and maintenance of quick-coupling devices and provides insight into ways to prevent unintended releases. Additionally, the National Institute for Occupational Safety and Health has issued Department of Health and Human Services Publication No. 2004-107, “Preventing Injuries When Working with Hydraulic Excavators and Backhoe Loaders.”

Photo: Komatsu Komatsu offers a steep slope on the engine hood, a corner-mounted exhaust stack, and a front roof cutout for visibility.

Photo: Yanmar Construction Equipment Yanmar Construction's new CBL40 compact backhoe-loader is designed for advances in productivity and fuel efficiency.

Recently, fuel costs have become a major concern for contractors who operate heavy equipment. As a result, manufacturers have focused on ways to reduce fuel consumption in recent years. Bargellini cautions that fuel efficiency varies greatly in backhoes because it depends to a great extent on how the machine is operated—whether used mostly in excavation work, loading work, or driven for long distances, for examples—and how it is equipped. Such manufacturers as Volvo feature closed-center, load-sensing systems with variable-displacement piston pumps in their backhoes, in contrast with open-center systems with fixed-displacement gear pumps. The former configurations tend to be more fuel efficient, Bargellini points out, because they supply oil only “on demand,” meaning when the load-sensing system on the pump detects that oil flow is not required, the system reduces pump flow and horsepower to conserve fuel.

Grohsmeyer says that maximizing productivity per gallon of fuel consumed, not sheer fuel efficiency alone, is Caterpillar’s goal. He actually includes fuel efficiency, along with comfort and performance, as a top-three purchase criterion in a backhoe. Automatic engine-speed control, he says, idles the engine to a lower rpm when the operator stops digging with the back boom for a few seconds. Grohsmeyer also points out that Caterpillar’s axial piston pumps are designed to stop pumping hydraulic oil if the hydraulic system is not being used, which extends the life of the oil, prevents heat buildup inside the machine, and prevents backward resistance. A gear pump setup, in contrast, is a side-loaded pressure system that causes wear and decreased pressure over time. With this hydraulic system, Grohsmeyer says, the company’s backhoes are able to lift material off a trailer and deposit it at ground level or in an excavation while the engine runs at idle speed.

There are other items to consider that either the contractor or the dealer should raise during the specification process. Aubrey says that the contractor should try to determine if limitations to size and weight of the machine exist relative to truck and trailer capacities. Also, the contractor should think ahead to determine what the backhoe’s future requirements might be, particularly in regard to attachments, because auxiliary hydraulics capable of providing adequate pressure and flow to run those attachments might be necessary.

Finer Points
As backhoes have matured as heavy work tools, manufacturers have focused on responding to increasingly sophisticated marketplace demands and differentiating their equipment when possible. As in any competitive market, though, truly differentiating features in backhoes usually do not maintain their novelty for long, and manufacturers work harder to seek new differentiators—to the benefit of the customer. Features that manufacturers have stressed in recent years include operator comfort and productivity, safe operation, machine uptime, and maintenance.

For several years, in response to marketplace concerns about worker retention and an OSHA focus on ergonomics, manufacturers have devoted arguably more time and effort to the operator cab than any other component of construction machines. Cowan describes the ease of control from the cab now compared with earlier versions of backhoes as the difference between power steering and standard steering in a car. The use of servohydraulics, he notes, has gone a long way toward making control of the front and rear components smoother, not to mention less of a physical endeavor for the operator who often used to be exhausted at the end of a shift.

Bargellini notes that the fingertip control possible via the use of pilot controls is only one of the fatigue-reducing advancements provided by the market in recent years. A cab component that the manufacturer has enhanced is the seat, which is available in heavy-duty or air-suspension versions and often has an available heat switch. Aubrey adds that the seat and controls are commonly adjustable now, allowing each operator to work in a customized position; control towers in Komatsu models, he points out, can be locked in any position along the arc of movement. Other features that contribute to operator comfort, Bargellini adds, include tilt steering; separate heating and air-conditioning systems; a one-piece, excavator-style rear window; and flat cab glass that opens partially or fully.

Another development driven by operator comfort is Caterpillar’s addition of fully automatic shifting mode on power-shift transmissions, says Grohsmeyer. Because the operator does not have to shift from first to second gear in this mode, Grohsmeyer points out, more attention can be paid to machine functions other than shifting. This feature also allows the operator to put the machine into an automatic ride-control mode for the purpose of driving the machine over medium distances.

Advancements in machine and operator safety have similarly grown in recent years. Aubrey notes that manufacturers have been focusing on noise levels, operational and safety labeling, and backup alarms. For road use, he adds, work lights, highway lights, turn-signal lights, emergency flashers, and rotating beacons are also available. The market has also enhanced the operator’s ability to view obstacles out the front, side, and rear of the machine, Aubrey adds. Komatsu, for example, has designed a steep slope on the engine hood, a corner-mounted exhaust stack, and a front roof cutout to give the operator better visibility.

Grohsmeyer notes that such seemingly minor design features as proper openings, steps, and handles for operator ingress and egress have become more common. Other items include wear-resistant, punched-steel skid plates and an overall increase in cab space. Machine speeds of 25 miles per hour are now common, Grohsmeyer notes, and a major safety advancement in recent years has been that of more powerful braking systems, such as those featuring commonly available power-boost brakes. Caterpillar, for example, developed a two-wheel-drive, all-wheel braking system that locks the differential for greater stopping power. Bargellini lists such Volvo safety developments as an SAE-certified cab/canopy; three-point contact entry; multiple-disc, oil-immersed, self-adjusting brakes; stabilizer anti-drift/balance valves; and a hydraulic boom lock.

These machines’ high versatility and dual functionality can create challenges in tight spaces, so manufacturers have also focused a great deal upon maneuverability. Bargellini says that the best indicator of maneuverability is expressed as turning radius, aka “curb turning circle,” the maximum diameter of the tire path at the track, or center, of the tire. Manufacturers have published turning circles with and without brakes applied, he notes.

Terex’s Stout says that four-wheel drive is a key tool in machine maneuverability because it provides access to work areas that a two-wheel-drive machine would have difficulty negotiating. It also improves loader performance by providing additional loading effort going into the pile, he points out. “We want the four-wheel drive,” Gray insists. “And the Terex backhoes have larger tires on the front, which makes it easier to get over obstacles.” Another key maneuverability-enhancing feature is that of all-wheel steer, which gives larger loaders comparable performance to small front-end loaders in this area, Stout says. Many manufacturers have addressed machine length, notes Grohsmeyer. For example, he says, many have reduced machine length by pulling the rear boom tighter to the machine body, a configuration that also provides better stability when the front bucket is being used.

Increasingly, contractors have scrutinized their machines not only as workhorses but also as financial assets. Keeping them moving dirt is a key to company profitability; uptime is at a premium, and manufacturers have responded to this demand by minimizing the need for maintenance of some components and making other required maintenance more efficient.

In the past five years or so, manufacturers have incorporated bearings that distribute grease around high-pressure points, Grohsmeyer says. He adds that Caterpillar’s new E-stick uses high-density plastic shims and wedges and has an “oil-impregnated design” that prevents the attraction of dirt that causes wear. Additionally, he says, oil and filter intervals have almost doubled in the past five to seven years due to the use of new longer-lasting oils and better filter media. Other maintenance-saving design changes that the company have made include the use of o-ring face seals to mitigate dust ingress; locating all daily maintenance ports in an elevated position on the machine to keep them away from mud, dirt, water, and other contaminants; a cyclonic filter cleaner; locating fuel filters in a position in the engine to more easily get the water out of the system better; and plumbing air filter gauges or fuel filter gauges into the instrument panel for more timely monitoring. Grohsmeyer points out that electronically controlled Tier III engines have made diagnostics more intelligent by providing the ability to pick more diagnostic information out of a machine and even allow trouble alerts to be sent to management wirelessly.

Bargellini argues that if maintenance is not made easy, it will not get done. He points to developments that have addressed this concept, such as one-piece, rear-tilting hoods that can be opened with a latch rather than by unscrewing bolts and side panels; pivot joints that are designed to accept grease weekly rather than daily; and grease fittings (zerks) placed on one side of the machine for easier access. Cowan notes that lubrication intervals on bushings have increased, for example. Aubrey adds that Komatsu clusters many daily checkpoints inside the engine compartment and the hydraulic tank site gauge is at eye level when the operator stands beside the machine. Other enhancements include strong guarding for the front driveshaft, location of the steering cylinder high and behind the front axle, and tire valve-stem protection.

Latest and Greatest
Below are just a few of the newest backhoe models currently available on the market.

Photo: Caterpillar Caterpillar's E-Series loaders incorporate a flow-sharing valve designed as an improvement over individual joysticks.

Photo: Terex Corp. Terex's TX760B offers excavator and front-end functionality along with the power of an 86-horsepower Perkins turbo-induction engine.

Allmand Bros.’ four-wheel drive TLB has an Extended Service Life (ESL) design and a hydrostatic, 65-horsepower-rated, servo-controlled transmission. Its 35-horsepower, liquid-cooled, Isuzu diesel engine is driven by an axial piston motor designed to run at higher pressures and rpms. The ESL system features oversized pins with composite bearings and urethane lip seals in all working joints to reduce friction. An exclusive heavy-duty boom lock can be easily engaged or disengaged from the operator’s seat. A load-sensing hydraulic steering system requires hydraulic flow only when the operator turns the steering wheel. The ESL models also feature hydraulically cushioned swing cylinders to prevent the backhoe from crashing into its swing stops when the backhoe boom is moved laterally.

Just in time for the 2008 World Of Concrete show in Las Vegas, Case CE launched its M Series 3 line of loader-backhoes. The latest upgrade to the Case legacy of rugged, durable loader/backhoes, the new M Series 3 lineup—the 580M, 580 Super M, 580 Super M+, 590 Super M and 590 Super M+—with Case Family IV Tier III engines ranging from 79 to 109 net horsepower, featuring dig depths from 14 feet and 3 inches on the standard backhoe up to 20 feet and 4 inches with the Extendahoe. For increased fuel efficiency, Case has added high-pressure, common-rail injection on the Super M and Super M+ models, as well as pressure-compensated, load-sensing hydraulics on its Super M+ machines. Case’s one-touch idle allows the operator to select idle or return to the operating rpm setting at the touch of a button.

Caterpillar has introduced its new E-Series backhoes—the 416E, the 420E and the 430E—replacing the D-Series models. The 420E and 430E are designed as high-performance machines and are offered in integrated tool-carrier configurations for applications benefiting from parallel-lift loader linkage and requiring quick work-tool changes. The 416E is designed for value at a competitive price. A variable displacement piston pump and closed-center, load-sensing hydraulics and new flow-sharing hydraulic valves are included in these models. A new cab with curved glass is incorporated to provide high visibility. Standard pilot-operated joystick controls are configured for easy use and reduced operator fatigue. New mainframes have a wheelbase 4 inches longer for improved balance and machine stability. A new extendible stick has an external slider design for reported best-in-class performance, digging forces, and versatility. An AccuGrade BHL site reference system for checking depth and grade has been incorporated for greater productivity.

JCB offers the broadest range available of backhoe-loaders throughout the world today. At the small end of the spectrum, the 1CX 8 skid-steer backhoe has a dig depth of 8 feet and 4 inches and a 1,345-pound loader-lift capacity with its 47-net-horsepower engine. At the other end of the scale is JCB’s 4CX 17 four-wheel-drive, four-wheel-steer backhoe-loader featuring a 21-foot, 6-inch dig depth and a 12,638-pound loader breakout force with its 97.6-net-horsepower JCB Dieselmax 444TC engine. The middle of the line is anchored by JCB’s 3CX 15, with a dig depth of 20 feet and 1 inch on its extended-boom option. As with the 4CX model, the loader breakout force is 12,638 pounds.

The TX760B tractor loader backhoe from Terex combines excavator and front-end loader functionality. An 86-horsepower Perkins turbo induction engine and a powershift transmission are designed to provide high power and easy, clutch-free operation. A front counterweight for greater fore and aft stability is standard. The unit’s stabilizer legs feature lock-out valves in the circuit so they remain down during operation, providing better stability when operators are working 90 degrees of the side of the machine. The bucket linkage design allows operators to drive into a pile and roll back 45 degrees. This machine is able to dump at 57 degrees for greater fill capacity and discharge. The backhoe end features advanced pilot controls for fine control in trenching and grading. The ergonomically designed joystick with adjustable armrests is intended to increase productivity.

Yanmar Construction Equipment Co.’s new CBL40 compact backhoe-loader is designed for advances in productivity and fuel efficiency. The manufacturer reports that, according to tests, the machine performs up to 67% more work with 32% less fuel in backhoe work and up to 41% more work with 32% less fuel in loader work than a couple of competing brands. A heavy-duty, single-frame chassis like those used on larger units is incorporated into this model. A 180-degree swivel seat is included in the cab for easy access to both loader and backhoe controls. A Yanmar 3TNV84T diesel engine reportedly produces 37.2 horsepower and is capable of propelling this 7,750-pound machine to a forward speed of 13.7 miles per hour and 7.8 miles per hour in reverse. Variable displacement axial piston hydraulic pumps allow for smooth work operation.

Author's Bio:  Don Talend is a print and e-content developer specializing in technology and innovation.