Machine Matters More

|  February 07, 2011 |

Keeping Compactors on a Roll

The trend is to size up when buying, and try to work that soil roller more often, says product specialist

By Mike Anderson

The dozer’s done its job, the dirt’s in place, and now you need that compactor to come along.

But, regardless of brand (and there’s a healthy choice), what size or even type of roller do you need?

Including the Sakai SV510T-III model, 84-inch-wide single padfoot drum compactors weighing in at 10 metric tons and up are more likely to be working in site-prep conditions, because they can be used in a variety of applications. Including the Sakai SV510T-III model, 84-inch-wide single padfoot drum compactors weighing in at 10 metric tons and up are more likely to be working in site-prep conditions, because they can be used in a variety of applications.

“If you make the generalization it’s a padfoot out following a dozer, that’s an incorrect conclusion,” says Bob Marcum, Volvo road machinery product specialist for compaction. “That choice would solely be dictated by the type of soil. A padfoot roller is used on cohesive or clay-type materials, whereas if a dozer was spreading a granular or a sandy-type material, we’d be there with a smooth-drum roller.”

Many site-prep contractors Marcum has worked with will size up on their single-drum soil compactors – in contrast to many other equipment types in which the tendency is to do more work with less iron. “In fact, most of the people would go up to a 10-ton-class or 84-inch-wide roller,” he says. “Real world, contractors tend to use a roller that may be one size too big.

Rollers follow, literally, the work of crawler dozers in site-prep applications, compacting the soil moved into place by the dozers.

“Yet, what we find is that with a soil roller 700 hours a year is nornal usage, because they don’t run them eight hours a day, five days a week. The dozer will run that long, but the roller won’t. They may spread material for three or four hours in the morning and they’ll run a compactor before lunch; then they’ll start spreading in the afternoon, and they’ll seal it off before they shut down at the end of the day. You’re not using a roller at 100-percent efficiency by the amount of hours that are put on it, but you’re using it to accomplish what your job is.”

Sizing up a machine could on the surface be considered dramatic, Marcum says, but considering the lower utilization of a soil compactor, the tradeoff of opportunity for additional applications is, he believes, worth it. He recounts a conversation with a grading and paving contractor who tackled both private and public work in the Southeast. “He bought 84-inch rollers because he could do any job with them, whereas with a 66-inch or 7-ton roller, there are some jobs where it was not productive enough. He could use an 84-inch machine and get the work done, and it gave him a better utilization of his fleet. Even though some of it was overkill – that was recognized – it allowed him more versatility and to not have to move machines around as much to get the right machine on the right job.”

One of the few OEMs to offer both dozers and compaction equipment, and as such a single dealer source for sales and service, Caterpillar has a different perspective. “Our range of both dozers and compactors allows contractors to properly size their machines for efficient operation together,” reports Jon Sjoblad, Caterpillar Global Paving marketing communications. “Having the correct-sized machines to match the production goals is crucial. For example, you don’t want a dozer that works faster than the soil compactor can keep up with. If it gets too far ahead, problems can arise, such as the moisture content of the material may become detrimental to the compaction process. Conversely, if the soil compactor can work faster than the dozer, it is inefficient because the compactor will be waiting.”

A shell game

While not a perfect solution for achieving 100-percent efficiency of a machine during actual operation, a shell kit as offered by all manufacturers does provide overall machine utilization advantages that Volvo’s Marcum sees for today’s contractor who is likely to be moving around to different soil conditions.

Since there are fewer jobs and the contractor is going further to find work that he can be effective on, his machine this month may be on one type of soil and next month on a different type of soil,” says Marcum. “By having the shell kit, he can convert from one configuration to the other, get the job done, and improve the utilization of his machine.”

The versatility of a shell kit does have some production cost associated with it, he advises. “By increasing the weight of the drum by adding the shell kit,” says Marcum, “since the amount of energy is fixed and the mass increases, the ability to throw that drum or the amplitude diminishes. How much? Probably 15, 20 percent. When you have a pure padfoot machine and it takes you four passes over the material to get the specified density, it may take you five passes over the material if you put a shell kit on the machine to get the same density.

“If you take the two machines, put them on the same job side by side, the shell kit machine is most likely to take an extra pass or two to get the density. The utilization of the machine outweighs the compromise in productivity.”

For an equipment type only used perhaps 20 percent of the day anyway, the extra passes won’t keep the roller from missing other assignments, as compared to an excavator or loader where maximized production may be key to a job’s financial success.

Marcum says: “My advice is, buy the machine that you’re going to use 80 to 85 percent of the time. Get the shell kit or rent a machine that you need to the other 15 to 20 percent of the job.”

Besides pure market share – there are more smooth drum rollers in the field across the United States – there is another reason why most shell kits convert from smooth to padfoot, says Marcum. “The tires that come on a smooth drum roller 95 percent of the time are diamond tread tires – a high-flotation tire – because these machines are working in sand and gravel. When you get a padfoot machine, you get a tractor-type or a lug-type tire for the extra traction that you need when working in clay. If I put a smooth drum shell on a padfoot roller, and I’m compacting sand or gravel, then what that lug-type tire does is kick up the material that I have just compacted. The more aggressive tread undoes some of the compaction that the drum has previously accomplished.” EW

The following roundup of single padfoot drum vibratory compactors showcases models available in the 10- to 15-metric-ton range.

HAMM

3410 P

• 10.88 metric tons operating weight

• 84-inch drum capacity

• 134 gross horsepower

• 50,625 pounds maximum centrifugal force

3412 P

• 12.0 metric tons operating weight

• 84-inch drum capacity

• 134 gross horsepower

• 57,600 pounds maximum centrifugal force

In addition to an articulation joint with three pivot points, Hamm compactors leverage Hammtronic technology in control of drive, vibration, oscillation and engine speed, automatically monitoring front and rear drives to prevent spinning. Working from a seat that swivels from side to side and rotates, the operator is able to use either hand to apply all functions, thanks to dual, seat-mounted, five-in-one control levers.

CATERPILLAR

CP56

• 11.36 metric tons operating weight

• 84-inch drum capacity

• 156 gross horsepower

• 63,300 pounds maximum centrifugal force

CP64

• 14.3 metric tons operating weight

• 84-inch drum capacity

• 156 gross horsepower

• 63,300 pounds maximum centrifugal force

According to Caterpillar, its larger vibratory soil compactors are enhanced by exclusive features: a dual pump propel system provides greater performance and traction on grades and in thick lifts; a pod-style vibratory system reduces maintenance needs; and an oval-shaped pad design provides deeper lift penetration and better compaction performance than conventional square-faced pads.

JCB

VM115PD

• 11.6 metric tons operating weight

• 82.7-inch drum capacity

• 130 gross horsepower

• 63,396 pounds maximum centrifugal force

VM132PD

• 13.4 metric tons operating weight

• 82.7-inch drum capacity

• 145 gross horsepower

• 68,567 pounds maximum centrifugal force

VM146PD

• 14.9 metric tons operating weight

• 82.7-inch drum capacity

• 161 gross horsepower

• 71,264 pounds maximum centrifugal force

As part of the JCB Vibromax line, the single padfoot drum vibratory rollers feature the Switchable Anti-Slip System (SASS) providing enhanced gradeability for high compaction performance on slopes. Center articulation joints are lifetime-lubricated and maintenance-free, and loaded rubber isolators prolong the life of drum components and reduce the number of drum service intervals required, says JCB.

CASE

SV212 Padfoot

• 11.51 metric tons operating weight

• 87-inch drum capacity

• 148 gross horsepower

• 65,250 pounds maximum centrifugal force

SV216 Padfoot

• 14.27 metric tons operating weight

• 87-inch drum capacity

• 148 gross horsepower

• 73,037 pounds maximum centrifugal force

With its single-drum compactors, Case employs a high-traction hydrostatic drive system in which the rear wheels are synchronized with the front drum for enhanced gradeability. With a lower center of gravity, these machines are adept working across steeper slopes also, says Case, adding that the center joint oscillates as well as articulates for effective compaction on uneven or difficult terrain.

SAKAI

SV505T-I

• 11.03 metric tons operating weight

• 84-inch drum capacity

• 130 gross horsepower

• 55,120 pounds maximum centrifugal force

SV510T-III

• 11.03 metric tons operating weight

• 84-inch drum capacity

• 148 gross horsepower

• 55,120 pounds maximum centrifugal force

Suited for medium to high compaction jobs including highway and airport subbases, embankments and dams, the 84-inch Sakai dual-amplitude, dual-frequency soil compactors boast shock isolation systems, three braking choices, and drum and axle drives for traction. Gradeability of 62 percent is possible for the SV510T-III model, which is also available in a blade-equipped SV510TB-III version.

BOMAG

BW211 PD-40

• 11.7 metric tons operating weight

• 83.9-inch drum capacity

• 133 gross horsepower

• 61,875 pounds maximum centrifugal force

BW213 PDH-40

• 12.69 metric tons operating weight

• 83.9-inch drum capacity

• 160 gross horsepower

• 61,825 pounds maximum centrifugal force

BW213 PDH-4

• 12.87 metric tons operating weight

• 83.9-inch drum capacity

• 160 gross horsepower

• 67,500 pounds maximum centrifugal force

Dual vibration amplitude and frequency optimize compaction quality, says BOMAG. In particular, for the cohesive soils better suited to a padfoot roller, high amplitude and low frequency is the desired combination. For maintenance of BOMAG rollers, a vertically-opening hood provides access to the engine and hydraulic points. Visual fluid indicators and no grease points further cut maintenance time.

VOLVO

SD100F

• 11.4 metric tons operating weight

• 84-inch drum capacity

• 130 gross horsepower

• 59,300 pounds maximum centrifugal force

SD105F

• 11.4 metric tons operating weight

• 84-inch drum capacity

• 130 gross horsepower

• 78,000 pounds maximum centrifugal force

SD116F

• 11.4 metric tons operating weight

• 84-inch drum capacity

• 160 gross horsepower

• 61,000 pounds maximum centrifugal force

A built-in feature of the SD116F single padfoot vibratory compactor, the full-time Ultra-Grade traction system enhances grade climbing grip, extending machine performance to the most difficult terrain, says Volvo. Heavy-duty drum drive components and a rear axle featuring No-Spin differential provide additional application flexibility. Ultra-Grade is optionally available on the SD100F and SD105F models.

STONE

SD84XC

• 13.0 metric tons operating weight

• 84-inch drum capacity

• 130 gross horsepower

• 62,946 pounds maximum centrifugal force

As part of its Rhino line of ride-on vibratory rollers, compact and mid-sized construction equipment specialist Stone offers an 84-inch, 12-ton single drum model, additionally available in a padfoot shell version. A single four-in-one lever controls vibration and direction. A hydraulically-driven fiberglass hood provides access to all service points, and reduces jobsite noise.

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