Relax and think back ten years. Remember the plume of diesel smoke as it floated in a feathery charcoal cloud from your new earthmover, accompanied by the musical roar of its engine? The sulfur-scented diesel perfume that could bring tears to your eyes? Ah, nothing like a new dozer.
What a difference a decade makes!
When the EPA demanded cleaner diesel engines in off-road vehicles, manufacturers producing heavy-duty construction equipment wisely chose the high road and used the ‘opportunity’ the EPA presented to build vehicles that were not only cleaner but also more comfortable, efficient and easier to run. A quick scan of 1997 dozer brochures doesn’t mention innovations like global positioning systems, engine diagnostics, or automotive-style cabs that are now standard on many dozer models. Onboard computers? If you had asked about the monitor on that ’97 model, they might have thought you were referring to a guy with a clipboard who watches while you work.
That was then, this is now and 160-to 210-horsepower dozers in 2007 are better than ever.
The engines started it
Bernie Winker, manager of marketing and engineering services for Dressta, says the past ten years have been amazing. As the EPA regulations have been laddered into place, Winker says one of the most important major changes in dozers is the fully electronic controlled engine. Engines in use a decade ago used mechanically controlled fuel injections systems. Today’s highly efficient electronically controlled fuel injection systems burn fuel more completely and produce far less toxic emissions. Now diesel engines can burn biodiesel, giving the contractor the flexibility to use whatever diesel blend fuel is most available and economic in his area.
Changes made to meet the EPA emission standards are influencing engineering in other areas of the machines. “The effect on other major sub-systems is pronounced,” says Winker. “On the 190-horsepower Dressta dozer, we have included a more efficient cooling module that provides cooling control for the engine coolant, engine combustion air cooling and powertrain oil cooling – all in one side-by-side package.”
Winker says another by-product of the low emission engines is a decrease in overall noise level because the new engines produce maximum power at several hundred rpms slower than their predecessors.
ECMs, GPS and joysticks
Ten short years ago, midsize dozers were powerful earthmovers that did pretty much just that – moved dirt. Today dozers are sophisticated ‘smart’ machines that can grade dirt within a quarter-inch accuracy, wirelessly alert its owner if the dozer is stolen, analyze the performance of each machine component and troubleshoot service issues before they become problems.
Standard electronics featured in 1997 dozers specs included microprocessor controlled transmissions and electronically activated battery master switches. With the help of improved electronic controls technology and more robust hardware, those microprocessors have grown into equipment control modules that monitor everything from fan speeds to tire pressure to fuel injector timing. ECM’s automatically make the thousands of repetitive mechanical choices that keep the vehicle running smoothly, while the operator uses his skills to do the job instead of babysitting the machine.
Deere’s Speed-in-Grip (SIG) transmission electronic control system in the 850J Series dozer is an example of what that old microprocessor has learned in 10 years. The SIG’s small display panel mounted in the cab lets the operator adjust the machine’s steering rate and modulation, forward and reverse speeds, deceleration response and FNR shift rate to meet the demands of that day’s job. When he’s finished, the system resets itself to the factory default settings. The transmission controller also reads the charge pressure and oil temperature and will limit operations based on previously determined parameters to prevent accidental damage.
Operators can analyze real-time engine diagnostic data to determine how well the machine is running and make adjustments from inside the cab. If the machine shows signs of engine stress, the operator is immediately alerted and can take action before the vehicle is damaged and sidelined. The same data, stored in the dozer’s computer memory or on a portable disk, can be used during regular servicing.
Grading accuracy also benefits from new electronic technologies. Cat’s AccuGrade GPS system, available on the new Cat D6T dozer, uses satellite technology to generate 3D positioning information which, combined with site dimension data, automatically controls the dozer’s hydraulic system and guides the blade’s elevation and angle. The in-cab visual elevation guidance tools allow the operator to direct the dozer to make highly accurate cuts and fills. Caterpillar says the AccuGrade GPS system can determine and perform grades with centimeter-level accuracy.
Asset security is aided by communication systems that are part of the dozer’s brain box. The JDLink system offered by Deere wirelessly sends the dozer’s location, utilization, performance and maintenance data to a remote computer or cell phone. If the system detects the dozer is in use during predetermined off-hours or is being relocated, the system alerts the owner who can then contact security and even shut down the machine remotely from his computer.
Advanced electronic controls are most apparent in how the operator works the dozer. Single lever joystick controls have eliminated the three separate control levers used in older model dozers and can provide all forward and reverse directions, gear range selections and steering functions. On the TD-15M Extra dozer, Dressta integrated pilot pressure hydraulics and electronic controls, combining two-speed geared steering in a single control. Preset travel speed selection and automatic downshift systems are also at the operator’s fingertips. On the Case 1850K dozer, electro-hydraulic controls now let the operator work the blade with one control lever instead of two.
Comfort level
Jim Hughes, marketing manager for Case, says compared to even five years ago, today’s crawlers are increasing their attention on operator comfort and productivity. Life in the dozer’s cab has improved since 1997.
Cabs on midsize dozers are designed to fight the physical and mental fatigue that can rapidly drain an operator’s energy and accuracy. Rusty Schaefer, platform marketing manager for dozers at Case, says cabs on 1997 dozers were built as part of the frame so every bump and vibration was felt throughout the machine. Case and other manufacturers now design their cabs to be separate from the frame and rest on isolation mounts that suppress vibrations transferred from the frame to the cab and reduce the noise in the cab.
Wider doors and more floor space make getting in and out of the cab easier, and give you the personal space you need to work comfortably for hours at a time. Large glass windows and tapered hood designs provide better all around visibility and repositioned seats help the operator watch the blade and ripper work without constantly shifting his body.
Ergonomically designed automotive-style fabric upholstered seats adjust to the operator’s individual size and preferences, providing back support and dampen the effects of day-long jostling. Some dozers in this category offer heated seats for winter comfort.
Instrument panels are positioned within easy reach of the seat and use combinations of visual and audio alerts to grab the operator’s attention. Pressurized air recirculation systems provide clean, filtered heat and air conditioning, while helping suppress engine noise in the cab.
Attention to creature comforts include pre-wired radio mounts, built-in speakers and 12-volt power receptacles for portable audio, computer and phone devices. Easy to reach and lockable storage compartments give the operator a secure spot for personal belongings.
Here’s an overview of today’s mid-size lineup:
Deere 850J
The 850J and 750J models are the first of Deere’s dozers that can be ordered with factory installed hardware, software and wiring that will accommodate any grade control system the customer chooses. The flexible plug and play approach to integrated grade control systems gives customers the option to install a grading system when it suits their timeframe and budget. The 850J dozer is powered by a six-cylinder Tier III certified PowerTech engine that produces 185 horsepower on the LT model and reaches 200 horsepower on the LGP dozer. The 850J has five main frames, twelve track frames and thirteen blade options.
Liebherr PR 724 L Litronic and PR 734 Litronic
Liebherr’s 163-horsepower PR 724 and 200-horsepower PR 734 dozers have the widest tracks in this class measuring 38 inches. Load-sensing power hydraulics and the Litronic electronic speed sensing control match the PR724 and PR734’s steering response to its travel speed. Liebherr has increased its drawbar pull to 51,034 pounds.
Cat D6T
Cat’s new D6T offers the Multi Velocity Program (MVP) that lets the operator select five speed ranges and automated speed control depending on the job’s ground conditions. The D6T C9 ACERT six-cylinder, Tier 3 engine delivers 185 horsepower on the standard model and 200 horsepower on the XL, XW and LGP models. The D6T comes in several undercarriage configurations including the XL (extended length) for better grading capability, the XW with wider track gauge for reduced ground pressure and better floatation in soft ground condition. The low ground pressure configuration is offered for soft ground conditions. All models are equipped with a variable pitch, power angle and tilt (VPAT) blade which manually adjusts for ground conditions. The AccuGrade Ready option includes all the changes needed to machine systems and mounting brackets to accommodate installation.
Dressta TD-15M Extra
At 190 horsepower, the new TD-15M Extra combines the hydraulic control system with advanced electronics to create an electro-hydraulic motion control system. All control functions are activated by moving the joystick or pushing a button on the face of the joystick. The semi-U blades on the standard LT and WT track frames combine the penetration of a straight blade with the additional capacity of short side wings. The semi-U blade has an optional tilt or tilt/pitch feature. Dressta’s angle blade for use on the standard and LT track frames does side casting, backfilling and cuts ditches and also has a two-cylinder blade tilt option. Their six-way hydraulic angle blade on the WT track does finish grading and light land clearing. The straight blade on the LGP is designed for soft, swampy areas and can be equipped with a hydraulic tilt cylinder.
Case 1850K
Case Family IV six-cylinder engines deliver 184 horsepower for the LT and XLT models and 199 horsepower on the LGP configuration. PowerSteer, Case’s electronically controlled dual task hydrostatic transmission gives the operator infinite control of his speed and direction, and delivers maximum power to both tracks. The oscillating undercarriage allows the tracks to follow the terrain, ensuring traction, stability, and blade control in all types of applications. Blade configurations include a six-way power-angle tilt and a semi-U blade configuration, and an outside push beam for reliable dozing in difficult ground conditions. The straight power-tilt blade on the 1850K LGP provides balance in soft conditions. An equistatic compensator on the 1850K reduces stress on the blade and push beam for added durability and machine life.
Komatsu D61 and D65 dozers
Komatsu’s 168-horsepower standard D61PX-15 and LGP D61X-15 dozers feature hydrostatic steering and torqflow transmission, controlled by a single joystick. A single lever blade controller responds to Komatsu’s Palm Command Control System. Daily engine checks are grouped on the left side of the engine compartment and the rear mounted reversible fan swings up for easy access.
