Trommel Project Benefits
From Brevini Expertise & Support
Delivering robust and reliable machinery to the mining industry
is a specialist task that requires components designed for the
job, as well as experience in producing equipment for harsh
environments. For one trommel manufacturer in the UK, this
meant teaming up with Brevini in order to create a pair of 20 meter
machines destined for an iron ore processing facility in Trinidad.
esigned to separate
materials by size, a trommel
is a key piece of equipment
within an ore processing
facility, but dealing with
hundreds of tonnes of rock every hour
means that the design must be very
robust. Designing and manufacturing
a complete package requires several
manufacturers to cooperate successfully
in order to deliver a properly integrated
solution that is both reliable and efficient.
For this particular trommel, the power
required for normal running would be
520 kW and this would be used to power
four drives that would produce a gearbox
output speed of 70 rpm. Due to the size
and weight of the screens, the initial startup procedure would require 680 kW for
around 15 seconds in order to accelerate
the machine up to working speed. This
additional power requirement would
affect the specification of the drives and
gearboxes being supplied by Brevini.
The Holborne Group is a specialist
engineering company that has
considerable experience in designing
and manufacturing trommels. Based in
Shropshire, the engineering team has
worked closely with its supply partners to
design and construct the latest machine.
Brevini was contracted to develop the
complete drive package, which included
the motors, gearboxes, couplings and
electrical control system.
The gearboxes were designed around
the Posired 2 helical drive units that
incorporate a two stage reduction, giving
an output ratio of 16:1. All of the units
were supplied with identical handling of
the input and output shafts, which allowed
the gearboxes to be installed in any of the
drive positions on the rotary screen. This
rationalisation of the design simplifies the
installation and reduces the amount of
essential spares required.
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The reduction gears are housed in a
bespoke, fabricated steel housing - as
opposed to the more usual cast casing.
This arrangement ensures that the
gearboxes will fit easily into the restricted
space of the trommel design and also
eliminates the need for an angled base
plate, which reduces the material costs
and the manufacturing time for the
components.
The design of the couplings also posed a
challenge to the Brevini engineers since
the maximum diameter was limited to
280 mm. Considering the substantial
torque that has to be transmitted, the
designers created a coupling using a
special hardened material that formed
fully crowned and barrelled gear teeth
giving ±2 degrees of misalignment per
gear mesh.
The hubs and flanged covers were
manufactured from high tensile steel
which provided a higher torque capacity
and enabled standard couplings to be
used for heavy shrink fit applications. All
of the components were manufactured to
extremely high standards using precision
machines; the tight tolerances allowing
complete interchangeability.