Dynapac’s first foray into oscillation on a tandem drum roller came two years ago with the 9.9-ton CO4200 VI. At the recent ConExpo show, the company showed it’s expanding the compaction method in a bigger way.
Dynapac’s new CO5200 VI tandem roller, like the CO4200, features vibration on the front drum and oscillation on the rear. It represents the company’s largest roller, at 11.7 tons and a 77-inch compaction width, to offer oscillation.
But it won’t be Dynapac’s last oscillation model, or its largest for long.
Fredrik Akesson, rollers product portfolio manager, revealed that the company plans to introduce a 6200 model, at 13.7 tons and 84-inch compaction width, in the third quarter. A smaller 2200 model, at 8.4 tons and a 59-inch compaction width, is also expected to launch around the same time.
Akesson says that before going with oscillation, which compacts by horizontal movement instead of vertical vibration, the company first had to solve two main problems that it saw on early oscillation machines.
For one, oscillation creates a rubbing action that can lead to quick wear on the drum shell. To combat that, Dynapac made the drums out of Hardox 450 steel, which Akesson says is the hardest steel that can be shaped into a drum shell.
The other problem was the lengthy and difficult process of changing the timing belts for the oscillating drum’s off-centered eccentric weights. Akesson says that’s typically a two-day job that must be done in the shop, involving dismantling the drum. Instead, the timing belts on Dynapac’s oscillating drums can be replaced in two hours and can be done in the field if necessary, according to Akesson. A demonstration of the belt-changing process can be seen in this video below:
Solving those problems, he says, enabled the company to delve into oscillation with confidence.
The result is a vibrating drum that can provide in-depth compaction, and an oscillating drum that delivers a gentler compaction closer to the surface. The operator can also switch to only oscillation. Akesson says uses for oscillation include bridge decks and joints, as well as near foundations and concrete structures, and for better performance on thin asphalt layers.
The CO5200 VI runs on a 130-horsepower turbo Cummins Tier 4 Final engine. Vertical oscillation is plus or minus 7 degrees. Nominal amplitude is .031 – .012 inches, and vibration frequency is 3,060 – 4,020 vibrations per minute.