New Patented Double Tamper Can Be Adjusted While Paver Is Operating

ABG’s double-tamper screeds, unique to the market, now have another significant advantage.

Stroke on the front tamper of the newly patented VDTA-V Screed can be steplessly adjusted by the operator while the paver is working. “You can do it on the fly,” Frank Dörrie, Global Product Manager at ABG, said of the adjustable double tamper Variomatic screed.

Previously, front tamper stroke could only be modified manually and doing so was time consuming. The paver had to be shut down, and the process required some effort. “Because of this, the paving team often did not make changes, even if they would have positively impacted the paving results,” Dörrie said.

Low-temperature asphalt

The VDTA-V is ideal for the challenges presented when paving with low temperature asphalt (LTA). The cooler LTA mix provides a host of benefits, particularly lower CO₂ emissions and fuel savings.

Yet LTA also has a tighter compaction window. The double-tamper system addresses this by striking the material twice for optimised pre-compaction – and the VDTA-V makes that process significantly easier. “The stepless adjustable setting ensures crews can apply the perfect amplitude – and even adapt to the specifics of a jobsite,” Dörrie said.

Double lifts

The on-the-fly responsiveness is a significant benefit to crews who are paving successive layers in a day – for example, a thick base course of 10 cm, followed by a surface lift of 4 cm.

Without a tamper adjustment, one of the lifts would surely be mismatched. Using the amplitude that’s proper for the 4-cm surface lift on the 10-cm base course would result in an undercompacted base. Conversely, the tamper properly set for the thicker base course would be too powerful for the surface lift and lead to overcompaction.

Because tamper changes were so challenging, crews often compensated in other ways, such as tweaking tamper speed. But this was imprecise, impacted the paver’s behaviour, and sometimes created additional problems, such as increased wear.

Now, a modification can be made with a touch of the control panel. Adjustments are stepless, meaning there are no predetermined settings, which ensures precision. Only the front tamper is adjusted, which is all that is needed to optimise pre-compaction. The back tamper remains in its fixed position.

Curves, roundabouts and racetracks

Each of the VDTA-V’s screed sections can be adjusted independently, from a range of 0,5 mm to 10 mm.

Sectional adjustments are important when paving curvy roads and roundabouts. The screed sections on the inside require a lower stroke because they are not covering as much ground as those on the outside. A single setting would either over-compact the inside, or under-compact the outside.

With the new VDTA-V, a crew might set the inside section at about 2 mm, the next section near 4 mm, and so on – all the way to around 10 mm on the outermost panel. Each section across the screed would have the precise tamping needed.

Other benefits

• Tamper bearings on the VDTA-V require no daily greasing. “They are maintenance-free for the paving season,” Dörrie said. Previously, greasing was required every one or two days.

• Front-tamper heating optimises heat distribution.

• A new diagnosis system makes it easier to assess performance of screed heating elements.

The on-the-fly modifications are the latest screed improvement ABG has brought to the market.

First, there were single-tamper screeds, which provided more uniform compaction than a roller. The advent of ABG’s double-tamper screed advanced performance even further.

“Now, with the adjustable tamper, we can realise the full potential of our double-tamper technology by pressing a button,” Dörrie said.

About Ammann

Ammann is a world-leading supplier of mixing plants, machines and services to the construction industry with core expertise in road building and transportation infrastructure.

The family-owned company has enjoyed international success since 1869. Hans-Christian Schneider, Ammann CEO, is the sixth generation to run the business.