With dirt-moving profit margins now down to a measly 5 percent, using a dozer skillfully is an economic necessity for contractors engaged in site prep applications. The majority of dozers in the 85- to 130-horsepower classes are used for fine grading work, while approximately 20 or 30 percent are engaged in combinations of applications. These include slot or production dozing, side banking, pioneering, trench backfilling for utilities, foundation and backfilling for residential and commercial buildings.
Production and finish grade models define these classes
Dozers in the 85 to <130 horsepower classes may be categorized into two types: production dozers and finish grade machines, most of which are fitted with six-way blades. Production dozers are capable of limited finish grade work. But if this is your primary application, a finish grade unit equipped with a variable power angle tilt blade (VPAT or PAT blade) is a wiser choice.
Rippers are less common on dozers in these classes than they are on larger machines. But they remain a valuable tool for contractors using these size dozers, says A. John Holmes, product specialist, John Deere. "Taking a few minutes to rip highly compacted, dry, hard material can reduce the time required to cut an area by three to five times," he explains. "You can save fuel and component wear since you're not forcing your blade to cut through the material, and you can also reduce undercarriage and cutting edge wear."
Trucks waiting? Spec a larger dozer
Application as well as environment plays a role in preparing a dozer to be productive. “Obviously, you have to consider how much material must be moved or what area must be struck to final grade and how long you have to complete this task,” says Joel Fritts, senior project engineer, small track-type tractors, Caterpillar. “Make certain that the dozer you spec is the proper size for the task at hand. On tight jobsites, you may have to use a smaller machine than would normally be required for the volume of material that has to be moved in order to maneuver the dozer in the space available.”
On the other hand, Holmes notes, there are disadvantages to spec’ing too small a dozer for a job. “If your machine isn’t large enough, it’s going to cost you money,” he says. “Always spec the largest dozer you can safely maneuver around the jobsite. If the machine is too small, you’re going to inflict excessive undercarriage wear on it by making too many cycles attempting to cover the area.” Another sign that you need a larger dozer is if you’ve got trucks waiting with fill material because the dozer can’t spread and shape the delivered fill quickly and efficiently enough.
Optimize undercarriage length, width
Your next step should be to determine what type of material is prevalent on the site and what your operating conditions are. “Choose a narrow track if you’ll be working in dry conditions,” Fritts says. “Narrow tracks will give you proper grouser penetration into the soil for better traction when pushing dirt.”
In rocky operating conditions, your dozer should be equipped with the narrowest track pads available, Holmes stresses. “This is more important today because most dozers now use sealed and lubricated tracks,” he says. “Operating over rocky terrain with wide track pads increases the flex forces on pin seal joints. Over time, these increased stresses can lead to leaking joints and reduced pin and bushing life.”
If you find yourself in soft or wet underfoot conditions, Rusty Schaefer, marketing manager, Case Construction Equipment, suggests opting for the extra flotation provided by a tractor with a low ground pressure undercarriage. “LGP tracks are typically longer than conventional undercarriages,” he explains. “But even on these longer tracks, a narrower shoe is still preferable. Try to select the narrowest shoe available that will give you the flotation required for the job to maintain optimal ground penetration. And going with as narrow a shoe as possible may help to increase the life of your undercarriage, since you won’t have a wide track pad putting additional loads on your track link joints.”
Coach your operators and technicians to pay close attention to a dozer’s track sag adjustment, Holmes suggests. “Running a dozer with the tracks too tight increases fuel consumption while reducing undercarriage life,” he says. “In wet, soft materials, you should increase track sag to reduce popping.”
Another aspect some contractors fail to take into consideration is working on flat land versus slope work, Fritts says. “If you commonly work on slopes, consider spec’ing a track guiding guard for your machine,” he suggests. “Based on the incline of the slope, your dealer can provide simple guards for less severe slopes and full track length guiding packages for steeper slopes. Both will help to reduce lateral wear on the undercarriage and extend its life.”
And if you’re working in sandy or abrasive soils or conditions, it’s a good idea to spec long-life tracks, like Case’s CELT, Schaefer says. “This type of undercarriage has a hardened bushing, free to rotate, over the regular bushing, reducing excessive wear and ultimately extending track life. In applications in northern Michigan we’re seeing dozers work in extremely sandy soil for 2,000 hours with no track wear evident.”
Cat’s Rotating Bushing Track (RBT) is also designed for abrasive soil types. “RBT is a bushing that rotates around the pin when it is in contact with the sprocket,” Fritts explains. “But the area between the bushing and pin is sealed and lubricated. This reduces the internal wear between the bushing and inflicts less wear on the pin. It also eliminates the noise produced by a grinding dry joint.”
Track dozer productivity daily for hard data
The traditional approach for measuring dozer productivity is the amount of loose cubic yards of material moved per hour. Some contractors have also used the amount of material moved per gallon of fuel burned. “These methods work fine for production machines, but they don’t give us an accurate picture when gauging productivity for smaller dozers and fine grade machines,” Fritts cautions. “These machines are better measured by the number of square meters or yards finished in a period of time.”
Some contractors use their own variations of this approach, Fritts says, such as the number of building pads that can be cut and finished in an eight-hour shift or the amount of time required to finish a particular job. “Many of these productivity measures are based on years of experience,” he says. “A contractor might decide that his goal for backfilling a foundation and finish grading a 3/4-acre housing lot is eight hours. Or he’ll expect his operator to spread and final grade 20 truckloads of fill dirt (at 14 yards per load) on a building pad in 1 1/2 hours. In either case, these are both very achievable goals with experienced operators running your dozer.”
“Productivity must be measured with survey instruments,” says Ed Warner, dozer product manager, Komatsu. “There’s really no simple way, in my opinion. To be absolutely certain about your dozer’s numbers, you need to profile the machine’s existing productivity, then profile its final production numbers and compare the two. To do this, you need to track dozing and ripping production each and every day. Only then will concrete trends appear.”
Spinning tracks? Try adjusting blade pitch
A good dozer operator is more of an artist than a technician. But no matter how long you or your operators have been running these machines, there are some common mistakes that can be avoided on a jobsite. And avoiding these mistakes can help put more money in your pocket at the end of the day.
First off, let nature help you out, Holmes says. “Push downhill and avoid uphill pushes whenever possible,” he advises. “Also remember to adjust the blade pitch on your dozer so that it meets your current application. Pitch the blade forward to reduce the tumbling action of base stone and improve the separation of fine material from the stone. More aggressive cutting can be obtained by pitching the blade forward in hard-to-penetrate materials, or back to improve cutting and rolling action in compacted soils and to increase dirt-moving production.”
Also check blade sizes to ensure good productivity, Fritts says. “A common mistake is fitting too wide a blade on a dozer in the mistaken belief that it will increase production or decrease the number of passes required on a job,” he says. “But if you have more cutting edge out there than the tractor can handle, the blade will tend to ‘suck you in’ to the ground once it starts to penetrate the soil. Too large a blade will also impede corner loading since its extra length acts as a large lever and will try to turn the tractor.”
If your dozer is spinning its tracks constantly, it’s a good indicator that something isn’t right with either the size or the pitch of the blade. Both Holmes and Fritts note that sometimes contractors think they have too large a blade when really the blade is set at the wrong pitch. “Before you replace a blade, try tweaking its pitch setting to see if that makes it more or less aggressive, depending on your needs,” Fritts says. “It’s an easy way to increase productivity.”
Slow, steady and precise are the keys
There are other common-sense dozing practices you can instill in your operators. One is to stop cutting when you’ve got a full blade. Most operators don’t do this. But, in actuality, they’re not adding any productivity and they’re costing you money by burning extra fuel. Remind them that it takes more horsepower to cut than to carry.
Your operators should also make it a point to keep as much of the undercarriage as possible on the ground at all times. Some operators want to be extra productive by taking a big bite out of the soil and pushing the tractor to go as fast as possible. That’s not a good idea, Warner says. “Slow down,” he advises. “Be precise and let the dozer work efficiently. If you lower the blade deep into the ground to make a big cut, you’re forcing the front half of the track roller frame off the ground. And you just eliminated half of its available traction. Simply slowing the dozer down and taking the right size cuts can work wonders for your bottom line and timetable.”