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Vibrations under Control?

TIRSCHENREUTH/GERMANY, December 9, 2014 - When it comes to compaction in city areas Hamm AG completely relies on its VIO- drum.  Compactors are also considered a good thing at Hamm – if they are mounted on a Hamm drum roller. According to Hamm, they sell 16.000 drum rollers worldwide, per year so they can draw on firsthand experience, not only in the applications technology area.


by Hendrik Stellmach

Hamm sees no cause for concern in the discussion started earlier this year, about compaction quality and base course layer compaction. When it comes to the question of appropriate machine technology, head of marketing Gottfried Beer argues fundamentally:“There is no application in the traditional earthworks industry which could not be covered by a drum roller.“ In city areas there are of course situations where the power of the big machines has to be handled with care, he adds. Enormous compaction powers up to 40 or 50 tons are generated by a drum roller, Reiner Bartsch, product manager at Hamm's earthworks section, explains. “Vibrations are a general problem within the cities “, Beer says.

VIO helps protect the proximity

That is why Hamm swears by its VIO- drum at such compaction works. The Bavarians are convinced that it can meet all requirements conceivable in city area compactions. “With the oscillation technique you only get 15 percent of the vibrations you have with vibration technique.“ Beer says. “Compaction can be done dynamically without transferring vibrations to buildings. The drum roller can compact neatly right up to the edges. Damages in inhabited areas often occur because compaction has not been done sufficiently.”

Beer considers the VIO- technology an especially intelligent form of compaction when compacting dynamically without damaging the proximity.

“With oscillation you can find vibrations mainly beneath the drum respectively  they spread slightly to the rear and to the front“, Beer confirms.

Hamm H13 i with attached plate compactor in action

At the facility extension works of Hamm AG a 13 ton drum roller H 13 i with attached plate compactor compacted the frost protection and gravel layers. | photo: Hamm

Plate compactors where appropriate

The main compaction work is not appropriate for the plate compactor, Beer says, because the principle of directed vibration has disadvantages compared to the circuit oscillator of drum rollers.
 “The circular movements direct thrust forces into the ground which help the stones to relocate“, Beer explains.

The only function of the plate compactor is to seal the top layer well. Nonetheless it has its disadvantages in narrow and city areas. “We wouldn't recommend Hamm's drum roller with attached plate compactor to customers for these kinds of applications, because the attached plate compactor has its disadvantages in terms of overall view and maneuverability.” Hamm presented their attached plate compactor at the INTERMAT 2012. The combination of drum roller and plate optimizes the compaction process and its results, especially on non- cohesive soils.
The drum roller achieves good depth penetration with its drum at low frequencies and high amplitude.

The plate compactor directly behind the drum  stops the upper soil sections from re-loosening by its large contact surface. Thus the drum roller achieves the required load capacities after two passes in most cases.   
And what about high frequency technology? Does it not have advantages compared to machines which work more slowly, like Stehr claims?
Beer knows this kind of compaction from the USA but instantly waves dismissively. „You can't trick physics. You may drive faster with high frequency technology but you can't compact faster. You have to drive more rounds, because you can't get the energy into the ground.“ In the USA the machines have to compact at higher frequencies because they drive faster to save costs.

Profitability?

Bartsch would not hear of the alleged energy waste when using single drums. “The energy distribution is managed by Hammtronic. “The optimum performance is provided, no more no less.“ The compaction performance generated in the drum is completely directed into the ground. And also the engine power is mainly used for the traction drive, for example on difficult, cohesive soils or on slopes – not exclusively for the vibration of the drum. Despite different kinds of machine construction concepts, Beer is certain, that the technology which promises best profits at low costs will succeed on the market.