two machines in one

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Two Machines in One

Posted By Don Talend On January 1, 2009 @ 12:00 am In Construction | No Comments

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

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

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Advantages, DisadvantagesThe 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 forexcavation is the mini-excavator, which has seen increased adoption in recent years. “One ofthe 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 backhoeprovides tremendous mobility and often can be driven from one site to a nearby one withoutthe need for a trailer, maximizing machine utilization. “The one thing that steers contractorstoward a backhoe versus a mini-excavator is jobs that have distance between them; that andthe ability to haul material in the front bucket.”

Tom Gray, president of Industrial Contracting Services, Holland, OH, says the versatility ofhis 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. “Whenyou work around the tracks, you’ve got to stone them back in and you can rough grade withthe bucket.”

Marcello Bargellini, product specialist for Volvo Construction Equipment, adds that backhoescan travel upward of 20 miles per hour. For jobs that do not involve operation in tight spacesor 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 TerexConstruction Americas, adds site preparation, trenching, installing, concrete breakup,posthole digging, and site cleanup to the list.

Starting PointsOnce 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 inNorth America is digging depth, says Bargellini. Digging depth is measured as the maximumdistance achievable from the ground line to below grade at the tips of the bucket teeth andtypically is expressed as “digging depth 2-foot flat bottom” and “8-foot flat bottom.” Theseexpressions refer to a flat-bottom trench that is actually excavated 2 feet deep and 8 feetlong. 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 about80% 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% ofthe 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

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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. Otherimportant items are productivity, fuel efficiency, safety, serviceability, operator comfort anddealer service support, he adds.

Paul Grohsmeyer, backhoe-loader marketing manager for Caterpillar Inc., contends that acouple of factors complicate the issue of digging depth, though. Adding an extendable stick tothe 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 importantbackhoe specifications is bucket breakout-or digging-force. This is the maximum calculatedforce in pounds applied at the tip of the bucket teeth. Calculations of breakout force arebased on the highest system relief valve setting. Both the bucket digging force and dipperdigging force are factors in determining work output. The other factor that determinesoutput, Bargellini says, is speed, which is determined by available hydraulic flow.

Lowell Stout, senior product manager, and Tom Reith, product manager for TerexConstruction America, prioritize horsepower, bucket breakout force and stick force because allof these contribute to the machine’s ability to move and lift material, says Stout. Reith addsthat knowledge of typical soil types is valuable in determining the necessary bucket or stickbreakout 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 machineperformance will likely come up several times during the specification process. In recentyears, manufacturers have spent a great deal of effort to make their hydraulics morepowerful and intelligent.

Bargellini notes that almost all manufacturers now offer optional or standard pilot controls asopposed to mechanical “wobble sticks.” Besides being light to the touch and less tiring for theoperator, pilot control joysticks can be fitted with many other control switches, such as theroller 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 changemechanical rods for these different operating modes. In its E-Series loaders, Caterpillarincorporated a flow-sharing valve that was designed as an improvement over hydraulic fluidflow sharing through individual joysticks. This proportioning system is designed to providesmooth movements when multiple functions are used.

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

Grohsmeyer says that contractors now realize that they can get greater digging depth withthe extendable stick and that this feature also provides greater horizontal reach. This greaterreach 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 materialsthat extend out quite a ways; we handle rail with the boom,” says Gray, adding that concernsabout stability accompany a desire for long reach. “We handle that by filling the bucket withstone to balance it out.” Cowan adds that some advancements have addressed machinestability. For example, he has noticed that many backhoes now have wider footprints, lowerprofiles, and lower centers of gravity.

Besides the unit’s sheer power and reach capabilities, Stout says, determining theappropriate machine configuration for typical jobs is important. He says the contractor shouldconsider specifying an extendable stick and perhaps a multipurpose bucket for the front ofthe machine, depending on need. Determining the machine’s carrying capacity goes a longway 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 importantconsideration. The dimensions are important relative to typical working area footprints andnearby 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 theevolution 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 linkageon its backhoes, giving the machines the ability to operate a wide variety of attachments onthe front and back, including hydraulic tools, side-dump buckets, and brooms. A recentdevelopment for backhoes is the fact that the back-end capability has increased from 50% to100%, Grohsmeyer estimates. As the demand for tools such as vibratory compactor platesand hammers and even augers for installing posts has increased, Caterpillar has addedthumbs to the rear boom to accommodate a wider variety of tools by essentially addinggrappling 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[2]

) has publishedSafety and Health Information Bulletin SHIB 07-22-2005, which stresses the need to followmanufacturer instructions regarding the installation, use, testing, inspection, andmaintenance of quick-coupling devices and provides insight into ways to prevent unintendedreleases. Additionally, the National Institute for Occupational Safety and Health has issuedDepartment of Health and Human Services Publication No. 2004-107, “Preventing InjuriesWhen Working with Hydraulic Excavators and Backhoe Loaders.”

Recently, fuel costs have become a major concern for contractors who operate heavyequipment. As a result, manufacturers have focused on ways to reduce fuel consumption inrecent years. Bargellini cautions that fuel efficiency varies greatly in backhoes because itdepends to a great extent on how the machine is operated-whether used mostly inexcavation work, loading work, or driven for long distances, for examples-and how it isequipped. Such manufacturers as Volvo feature closed-center, load-sensing systems withvariable-displacement piston pumps in their backhoes, in contrast with open-center systemswith 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 pumpflow and horsepower to conserve fuel.

Grohsmeyer says that maximizing productivity per gallon of fuel consumed, not sheer fuelefficiency alone, is Caterpillar’s goal. He actually includes fuel efficiency, along with comfortand 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 theback boom for a few seconds. Grohsmeyer also points out that Caterpillar’s axial pistonpumps 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 preventsbackward resistance. A gear pump setup, in contrast, is a side-loaded pressure system thatcauses wear and decreased pressure over time. With this hydraulic system, Grohsmeyersays, the company’s backhoes are able to lift material off a trailer and deposit it at groundlevel 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 duringthe specification process. Aubrey says that the contractor should try to determine iflimitations 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 requirementsmight be, particularly in regard to attachments, because auxiliary hydraulics capable ofproviding adequate pressure and flow to run those attachments might be necessary.

Finer PointsAs backhoes have matured as heavy work tools, manufacturers have focused on respondingto increasingly sophisticated marketplace demands and differentiating their equipment whenpossible. As in any competitive market, though, truly differentiating features in backhoesusually do not maintain their novelty for long, and manufacturers work harder to seek newdifferentiators-to the benefit of the customer. Features that manufacturers have stressed inrecent years include operator comfort and productivity, safe operation, machine uptime, andmaintenance.

For several years, in response to marketplace concerns about worker retention and an OSHAfocus on ergonomics, manufacturers have devoted arguably more time and effort to theoperator cab than any other component of construction machines. Cowan describes the easeof control from the cab now compared with earlier versions of backhoes as the differencebetween 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, notto mention less of a physical endeavor for the operator who often used to be exhausted atthe end of a shift.

Bargellini notes that the fingertip control possible via the use of pilot controls is only one ofthe fatigue-reducing advancements provided by the market in recent years. A cab componentthat 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 andcontrols are commonly adjustable now, allowing each operator to work in a customizedposition; control towers in Komatsu models, he points out, can be locked in any positionalong the arc of movement. Other features that contribute to operator comfort, Bargelliniadds, 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 automaticshifting mode on power-shift transmissions, says Grohsmeyer. Because the operator does nothave to shift from first to second gear in this mode, Grohsmeyer points out, more attentioncan be paid to machine functions other than shifting. This feature also allows the operator toput the machine into an automatic ride-control mode for the purpose of driving the machineover medium distances.

Advancements in machine and operator safety have similarly grown in recent years. Aubreynotes 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 enhancedthe operator’s ability to view obstacles out the front, side, and rear of the machine, Aubreyadds. 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, andhandles for operator ingress and egress have become more common. Other items includewear-resistant, punched-steel skid plates and an overall increase in cab space. Machinespeeds 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 thosefeaturing 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-pointcontact entry; multiple-disc, oil-immersed, self-adjusting brakes; stabilizer anti-drift/balancevalves; 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 thatthe 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. Manufacturershave 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 itprovides access to work areas that a two-wheel-drive machine would have difficultynegotiating. It also improves loader performance by providing additional loading effort goinginto the pile, he points out. “We want the four-wheel drive,” Gray insists. “And the Terexbackhoes have larger tires on the front, which makes it easier to get over obstacles.” Anotherkey maneuverability-enhancing feature is that of all-wheel steer, which gives larger loaderscomparable performance to small front-end loaders in this area, Stout says. Manymanufacturers 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, aconfiguration that also provides better stability when the front bucket is being used.

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

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

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

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

Allmand Bros.’ four-wheel drive TLB has an Extended Service Life (ESL) design and ahydrostatic, 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 higherpressures and rpms. The ESL system features oversized pins with composite bearings andurethane 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 hydraulicsteering system requires hydraulic flow only when the operator turns the steering wheel. TheESL models also feature hydraulically cushioned swing cylinders to prevent the backhoe fromcrashing 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 Series3 line of loader-backhoes. The latest upgrade to the Case legacy of rugged, durableloader/backhoes, the new M Series 3 lineup-the 580M, 580 Super M, 580 Super M+, 590Super M and 590 Super M+-with Case Family IV Tier III engines ranging from 79 to 109 nethorsepower, featuring dig depths from 14 feet and 3 inches on the standard backhoe up to 20feet 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 idleallows the operator to select idle or return to the operating rpm setting at the touch of abutton.

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-performancemachines and are offered in integrated tool-carrier configurations for applications benefitingfrom parallel-lift loader linkage and requiring quick work-tool changes. The 416E is designedfor 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-operatedjoystick controls are configured for easy use and reduced operator fatigue. New mainframeshave a wheelbase 4 inches longer for improved balance and machine stability. A newextendible stick has an external slider design for reported best-in-class performance, diggingforces, and versatility. An AccuGrade BHL site reference system for checking depth and gradehas been incorporated for greater productivity.

JCB offers the broadest range available of backhoe-loaders throughout the world today. Atthe small end of the spectrum, the 1CX 8 skid-steer backhoe has a dig depth of 8 feet and 4inches and a 1,345-pound loader-lift capacity with its 47-net-horsepower engine. At the otherend of the scale is JCB’s 4CX 17 four-wheel-drive, four-wheel-steer backhoe-loader featuringa 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 3CX15, with a dig depth of 20 feet and 1 inch on its extended-boom option. As with the 4CXmodel, the loader breakout force is 12,638 pounds.

Check out Forester Media's directory [3] for detailed information from our partners in grading& excavation: construction equipment, insurance, materials, safety, software and trucks &trailers. For additional information from our grading & excavation partners, visit our Grading

& Excavation Directory.[3]

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

Yanmar Construction Equipment Co.’s new CBL40 compact backhoe-loader is designed foradvances in productivity and fuel efficiency. The manufacturer reports that, according totests, the machine performs up to 67% more work with 32% less fuel in backhoe work andup to 41% more work with 32% less fuel in loader work than a couple of competing brands. Aheavy-duty, single-frame chassis like those used on larger units is incorporated into thismodel. A 180-degree swivel seat is included in the cab for easy access to both loader andbackhoe controls. A Yanmar 3TNV84T diesel engine reportedly produces 37.2 horsepower andis 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.

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