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CONSTRUCTION WORLD
JUNE
2017
HAMM offers over 30 different rollers with oscillation - including
machines with Tier 3 and Tier 4 engines.
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
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.
A HAMM HD+ 120i OV tandem roller compacting
the surface course of a busy highway.
Oscillation involves two unbalance shafts rotating
synchronously. The unbalances are offset by 180°
relative to one another.