Construction World June 2017

HAMM offers over 30 different rollers with oscillation - including machines with Tier 3 and Tier 4 engines.

A HAMM HD+ 120i OV tandem roller compacting the surface course of a busy highway.

in 2016, around 40% of all DV+ series rollers were delivered with oscillation drums. The oscillation rollers for the compact class from 2,5 to 4,5 t also experience great market demand. Hardly surprising, because HAMM is the world’s only manufacturer in this market segment. This also applies for earthwork. Customers worldwide seeking a solution for compactors with the facility to choose between oscillation and vibration find that only HAMM has the answer in the form of its VIO drums. The oscillation principle But what exactly happens in an oscillation drum, and how does oscillation differ from vibration? With vibration, a single unbalanced shaft generates the upward and downward movement of the drum, causing it to strike the ground at a rapid rate. In oscillation drums, two unbalanced shafts rotate synchronously, driven by a toothed belt. The unbalances are offset by 180° relative to one another. As a result, the drum performs a rapidly alternating forward/backward rotary movement. Due to this movement, the drum directs the compaction force into the substrate tangentially to the front and rear in the form of shear forces. Here, unlike with vibrating drums, the compaction force acts continuously on the substrate because the drum is in contact with the ground at all times. This is why oscillation rollers compact dynamically as well as statically with their intrinsic weight the whole time. Maximum wear resistance HAMM’s experience of more than 30 years is also reflected in the way in which the technology is incorporated in the design. An example of this is the drum shell. On oscillation drums, it is inevitably subject to greater stresses, due to the constant ground contact, than is the case with vibrating drums. Thanks to ongoing product and material development, the operating life of HAMM oscillation drums is today nearly the same as that of vibrating drums. Low-maintenance operation A glance at the exciter system drive inside the oscillation drum also shows that it is based on a great deal of experience. HAMM has continuously optimised the position of the unbalanced weights in the oscillation drum to enable the resulting forces to be utilised as effectively as possible. At the same time, HAMM’s oscillation drums are designed to require very little maintenance. The toothed belt, the core element of the drive, has been perfectly attuned to the overall system: its operating life corresponds to that of the entire drum. Checking the belt tension after 2000 operating hours is all that is recommended. Use for all layers Oscillation rollers can be used to compact all earthwork and road building layers. They come into their own in earthwork, where re- loosening of the upper layers has to be effectively prevented, such as in garden and landscaping work. Another important application is the compaction of soils in vibration-sensitive areas, for example above gas, water and other pipework. In asphalt paving, base courses, binder courses and surface

Oscillation involves two unbalance shafts rotating synchronously. The unbalances are offset by 180° relative to one another.

courses can be reliably compacted with oscillation rollers. They perform especially well in the compaction of generally hard-to- compact asphalts such as SMA or in the case of polymer-modified material mixes. This is because, in contrast to vibration compaction, the effective direction of the vibrations during oscillation promotes the desired redistribution of long-chain binding agents. Six benefits of oscillation Oscillation offers a wide range of benefits, enhancing efficiency, quality, productivity and profitability. Here are the most important ones: • High compaction power – great efficiency. • Easy operation. • Smooth, skid-resistant surfaces. • Low vibration emissions.

• Material-friendly compaction. • Wider temperature window. 

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CONSTRUCTION WORLD JUNE 2017