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CAPITAL EQUIPMENT NEWS
MAY 2017
30
COMPACTION
HAMM’S OSCILLATION COMPACTION
PROWESS
Over 30 years ago, HAMM became the first roller manufacturer to offer an oscillation drum for tandem rollers, and they
have become an integral part of its product offering. In the past five years alone, the compaction technology specialist
has delivered more than 3 000 machines with this innovative technology.
T
oday, one in four of the tandem rollers
made by HAMM is equipped with an
oscillation drum. With more than 30
models to choose from, HAMM claims
to have the widest offering of oscillation
rollers in the world. The company is said
to be the only OEM that builds oscillation
tandem rollers in the compact class, as
well as soil compactors with oscillation
compaction capability.
The HAMM portfolio encompasses
tandem rollers for asphalt paving ranging
from 2,5 to 15 t. When it comes to the pivot-
steered rollers in the DV+ series, a popular
choice for demanding road building projects,
the share of oscillation rollers is particularly
high: in 2016, around 40% of all DV+ series
rollers were delivered with oscillation drums.
Why oscillation rollers?
Oscillation rollers make for fast, cost-
effective and high-quality dynamic
compaction. In particular, tandem rollers
with one oscillation drum and one vibrating
drum achieve at least the same degree
of compaction as double vibrating drum
rollers, but with fewer passes.
Another benefit is the very low vibration
provided by oscillation, making dynamic
compaction on bridge overlays, of thin layers,
and in sensitive areas, such as near hospitals,
city centres, rail tracks, or industrial plants,
possible for the first time. The scope of
applications is enormous.
Another bonus is that oscillation rollers can
start dynamic compaction directly behind the
paver (breakdown phase). They can then also
deal with the main compaction (intermediate
phase). And even with lower asphalt
temperatures at the end of compaction (finish
phase), oscillation ensures an increase in
compaction without crushing the aggregate.
Overall, when using oscillation rollers, the
time available for compaction is significantly
greater than with vibratory rollers.
How it works
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, on the other
hand, 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.
Benefits of oscillation
Oscillation offers a wide range of benefits,
enhancing efficiency, quality, productivity
and profitability. Here are the most
important ones:
Benefit 1:
High compaction power – great
efficiency. Oscillation rollers compact very
quickly. Or to put it differently: their compaction
power is very high. The reason for this is the
superimposition of dynamic shear forces with
the permanent load from the roller’s own
weight. As a result, considerably fewer passes
are needed, especially on large areas.
Benefit 2:
Easy operation. HAMM uses
the laws of physics to generate vibrations
in such a way that the oscillation roller is
extremely easy to operate. Simply switch
the machine on, and there’s nothing more
for the operator to do. The appropriate
amplitude is set automatically according to
the rigidity of the material to be compacted.
This happens so quickly that compaction
is always adjusted perfectly, even with
varying substrates. In this way, HAMM has
eliminated the risk of operating errors due
to incorrect settings.
Benefit 3:
Smooth, skid-resistant surfaces.
Oscillation rollers produce surfaces with
excellent longitudinal evenness, resulting
from the drum remaining in contact with
the ground at all times. Surface rippling, on
the other hand, does not occur, not even at
high working speeds. Asphalt compaction
with oscillation also provides good initial
skid resistance, because the oscillating
movement of the drum rubs off asphalt from
the top surface of the pavement.
b
A HAMM HD+ 120i OV tandem roller
compacting the surface course of a busy
highway.