Note: Descriptions are shown in the official language in which they were submitted.
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Cutting Drum for Borer Miner
15
Field of invention
The present invention relates to a cutting drum for a borer miner and in
particular, although
not exclusively, to a bottom cutting drum configured to work cooperatively
with
forwardmost primary cutting rotors of a borer miner to both cut and facilitate
rearward
transport of cut material.
Background art
Continuous mining machines have been developed to provide uninterrupted
continuous
mining. Typically, the continuous miner has a mining head to abrade material
at the mine
face which is gathered and deposited onto a rearward extending conveyor
projecting from
a forward to a rearward region of the mining machine.
Borer miners may be crawler mounter full-face continuous miners, capable of
powerful
and rapid forward advancement into rock and being either manually driven or
remote
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control operated. Typically, a borer miner is used to drive entries and
headings, mine
rooms and extract pillars as fast as haulage equipment can remove the material
from the
region of the miner. Usually, a borer miner includes a cutting head having one
or more
pairs of forwardmost primary cutting rotors with rotational axes aligned
generally parallel
with a main length of the machine. Top and bottom cutting drums are positioned
in the
lengthwise direction of the machine immediately behind and respectively at the
upper and
lower regions of the primary rotors. These cutting drums provide a dual
operation to cut or
abrade rock at the mine face that is untouched by the rotors in addition to
providing further
cutting of material fragments already cut by the rotors.
However, conventional borer miners whilst being effective for rapid forward
cutting, are
typically energy inefficient, in part, due to the operation of the bottom
cutting drum. In
particular, existing bottom drums are not adapted to gather and clear material
at the lowest
most regions of the miner resulting in an accumulated mass of cut material at
the forward
and lower regions of the machine. This material is periodically reengaged by
the lower
cutting drum and primary rotors and reground. Accordingly, additional and
unnecessary
energy is consumed by this regrinding and the forward pushing of the already
cut material
at the mine floor. Additionally, and as will be appreciated, accelerated wear
of the
working parts of the rotors and drums is a common problem. Accordingly, what
is
required is a borer miner and a cutting drum for a borer miner that at least
in part addresses
these problems.
Summary of the Invention
It is an objective of the present invention to provide a borer miner cutting
drum and a borer
miner offering enhanced gathering and rearward transport of cut material from
the
forwardmost cutting head of the machine. It is a specific objective to provide
a borer
miner cutting drum to reduce motor power demand and to increase productivity
of the
mining machine. It is a further specific objective to reduce secondary
crushing of the borer
miner and the maximised gathering and rearward transport of cut material at
the mine face.
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The objectives are achieved via a cutting drum for a borer miner mountable
immediately
behind and at the lower region of forwardmost primary cutting rotors having a
plurality of
material transport blades extending between cutting pick holders (and cutting
picks). The
blades are adapted specifically to provide multiple modes of operation and
function. In a
first mode of operation, the blades collate and temporarily hold material cut
primarily by
the lower drum and then transport and discharge this material directly to the
rearward
transport conveyor of the miner. In a second mode or function the blades are
adapted to
gather, transport and propel material already cut by the primary rotors (or
even the cutting
drums) into the path of the primary rotors for indirect supply to the rearward
conveyor.
Additionally, the present bottom drum via the material transport blades is
adapted to gather
cut material at the very lowermost regions of the mine being specifically the
region
immediately underneath the prime rotors at the mine floor. The plates are
adapted
specifically to both gather cut material and then to transport the material
(in the rotational
direction of the drum around the drum longitudinal axis) such that cut
material is
transported (by rotation) upwardly and then ejected from the drum either into
the path of
the primary rotors or directly onto the miner conveyor. Advantageously, the
blades are
orientated at the drum so as to release the cut material from rotation about
the drum into
the path of the primary rotors or onto the conveyor such that the material
does not
accumulate at the drum and/or is ejected from the drum back at an undesirable
position i.e.,
towards the mine floor or other regions of the mine or borer miner.
According to a first aspect of the present invention there is provided a
cutting drum for a
borer miner having a longitudinal axis to extend transverse or perpendicular
to rotational
axes of forwardmost primary cutting rotors of the borer miner, the drum
comprising: a
.. main body centred on the longitudinal axis and having an external facing
drum face; a
plurality of cutting pick holders projecting outwardly from the drum face to
mount
respective cutting picks at the main body; characterised by: a plurality of
material transport
blades each having a respective outward facing blade face being raised
radially from the
drum face, each of the blades extending generally lengthwise along the drum
between the
.. pick holders and positioned side-by-side in a circumferential direction
around the drum to
cover the drum face.
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Optionally, each blade face may be generally planar. Optionally, each blade
face
comprises a generally rectangular shape profile in which a main length of the
blade extends
lengthwise along the drum and generally parallel to the longitudinal axis of
the drum.
Preferably, in a cross sectional plane perpendicular to the longitudinal axis,
each blade face
is declined in a circumferential (rotational) direction of the drum such that
a first
lengthwise side is positioned radially beyond an opposite second lengthwise
side i.e., at a
greater radial separation from the drum axis. Such a configuration is
advantageous to
gather and capture cut material for partial rotational transfer around the
longitudinal axis of
the drum. The angle of the decline is configured specifically to provide a
desired and a
predetermined distance of angular transport as the material is cut and/or
gathered by the
drum, rotated and then ejected either into the path of the primary rotors
(involving a
generally upward and possibly forward material transfer) or onto the
rearwardly extending
conveyor (involving upward and rearward transport of the material around and
from the
drum) relative to the drum longitudinal axis and a main length of the miner.
Optionally, an
angle by which each blade face is declined relative to the radius of the drum
is in a range
35 to 85 , 40 to 80 , 45 to 75 or 50 to 70 . This angled orientation of the
blade face
(relative to the radial spokes of the drum) provides the desired capture,
retention and
release characteristics of the drum and specifically avoids cut material
accumulating
around the drum which would otherwise be continuously rotated and accordingly
increase
power consumption.
Preferably, the blades extend over a majority of the surface area of the drum
face between
the cutting pick holders (and the picks). This majority may be greater than
50%, 60%,
70%, 80%, 90% or 95% of the surface area of the drum face being the outward
facing
generally cylindrical drum face extending at a central region of the drum
axially between a
pair of arms that mount the drum at the miner cutting head. In particular, and
preferably,
the blade faces cover a majority of the drum face in both an axial and a
circumferential
direction between the pick holders. The surface area of uncovered and exposed
drum face
is therefore minimised to avoid accumulating cut material that is not
otherwise transported
.. into the primary rotors or to the conveyor.
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Preferably, the drum further comprises a plurality of cutting picks mounted at
the pick
holders, each of the picks having a cutting tip, the blades positioned at the
main body such
that a radial separation distance between the cutting tips and a radially
outermost part of
the blades is in a range 20 to 80 mm, 25 to 75 mm, 30 to 70 mm or 35 to 65 mm.
This
separation distance between the cutting tips and outermost portions of the
blades provides
an optimised compromise between forward penetration rate of the borer miner
and power
consumption. That is, the separation distance provides a sufficient length of
the pick
cutting tips extend in a radial direction of the drum to be capable of
penetrating and
abrading the rock whilst avoiding or minimising direct contact between the
blades and
rock. The present drum therefore is configured both for effective rock
cutting/abrading
and also to gather and transport cut material either into the path of the
primary rotors or
directly onto the rearward conveyor.
Preferably, the blades are arranged into sets in which each set comprises a
plurality of
blades positioned side-by-side in the circumferential direction, each of the
sets being
separated axially by a plurality of pick holders. Distributing the blades into
sets is
advantageous to maximise surface area coverage at the drum between the pick
holders
projecting radially outward from the drum face. Optionally, the drum comprises
in a range
4 to 16, 4 to 14, 4 to 12 or 8 to 12 of the sets. Optionally, at least some of
the sets extend
over an angular distance in the range 60 to 120 , 70 to 1100 or 80 to 100 .
Optionally, a
length of each blade or at least some of the blades within each set are
different.
Optionally, a length of the blades within each set is the same. Preferably,
the drum
comprises blades of different lengths to fit appropriately between the pick
holders both in
the longitudinal and circumferential directions at the drum face. Optionally,
where the
drum comprises sets of material transport blades, each blade may be
individually mounted
within each set. Optionally, the blades within each set may be integrally
formed such that
each set may be independently changeable at the drum with respect to other
sets.
Optionally, the number of blades within at least some of the sets is
different.
Preferably, the drum, at least at selected axial sections of the drum,
comprises pick holders
arranged along a single helical path. Optionally, the pick holders may extend
over the
drum face following two or multiple helical paths. A single helical path is
preferred to
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maximise the arrangement and distribution of the plates so as to reduce drive
power
consumption as cut material is effectively and efficiently gathered and
transported
rearward from the mine face to eliminate or minimise undesirable regrinding.
Optionally, the drum may be divided axially to comprise a central section and
a first and a
second end section, wherein the blades are mounted at the central section.
Preferably, the
first and second end sections comprise respective material conveyor fins
projected radially
outward from the drum face and extending helically over the drum face around
the axis.
Preferably, the end sections are devoid of the material transport blades. Such
a
configuration is advantageous to optimise the effectiveness of the material
conveyor fins at
the drum end sections to transport axially cut material towards the drum
central section, for
subsequent transport and transfer into the path of the primary rotors and/or
to the miner
conveyor.
Optionally, the material transport blades are removably mounted at the drum to
represent
wear parts capable of convenient interchange at or between servicing intervals
of the borer
miner. Optionally, regions of the material transport blades including
preferably radially
outer regions comprise welded seams, coatings or reinforcement to protect
against
accelerated frictional wear or rock abrasion damage.
According to a second aspect of the present invention that is provided a borer
miner
comprising: a plurality of primary cutting rotors positioned axially
forwardmost at the
miner and having respective rotational axes aligned generally in a lengthwise
direction of
the miner; and a cutting drum as claimed herein positioned such that the
longitudinal axis
of the drum extends widthwise across the miner, the drum mounted in a
lengthwise
direction of the miner behind and at a lower region of the cutting rotors.
Preferably, the miner further comprises a top cutting drum having a
longitudinal axis and
mounted at the miner such that said longitudinal axis extends widthwise across
the miner,
the top cutting drum mounted in a lengthwise direction of the miner
immediately behind
and at an upper region of the cutting rotors. Preferably, the borer miner is a
crawler
mounted full-face continuous miner configured for use in demanding
environments.
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Optionally, the miner is configured for manual or remote control in which the
cutting drum
is capable of manual or automatic powered control.
Brief description of drawings
A specific implementation of the present invention will now be described, by
way of
example only, and with reference to the accompanying drawings in which:
Figure 1 is a perspective view of a crawler mounted boring-type continuous
miner having a
top and bottom cutting drum positioned immediately behind a pair of
forwardmost primary
cutting rotors according to a specific implementation of the present
invention;
Figure 2 is a perspective view of the bottom cutting drum of the borer miner
of figure 1;
Figure 3 is a lengthwise side view of the cutting drum of figure 2;
Figure 4 is a cross sectional view through A-A of figure 3;
Figure 5 illustrates a section of the drum of figures 2 and 3 in a plane
perpendicular to the
drum longitudinal axis according to a specific implementation of the present
invention.
Detailed description of preferred embodiment of the invention
Referring to figure 1, a crawler mounted boring type full-face continuous
miner 10
comprises a main frame and chassis 12 mounting crawler tracks 13 and a
rearward
transport conveyor 14 extending lengthwise along the miner 10 from a forward
to a
rearward position. A cutting head 11 is positioned at forward end of miner 10
and
comprises a pair of primary cutting rotors 15a, 15b having respective
rotational axes 33a,
33b aligned parallel with a main length of miner 10 and conveyor 14. A pair of
elongate
cutting drums 16, 17 are positioned immediately behind rotors 15a, 15b (in a
lengthwise
direction) with the first (bottom) drum 16 mounted at a lower region of miner
10 and
second (top) drum 17 mounted at an upper region of miner 10. Each drum 16, 17
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comprises a respective longitudinal axis 18a, 18b aligned perpendicular to the
respective
rotational axes 33a, 33b of primary rotors 15a, 15b. Accordingly, cutting drum
16, 17
extend widthwise across miner 10 at head 11 so as to define a maximum cutting
width of
head 11. As will be appreciated, miner 10 is effective via the cutting head 11
to abrade
.. rock continuously as miner 10 is advanced forward via tracks 13. Primary
rotors 15a, 15b
provide an initial and primary cutting of the rock and the drums 16, 17
provide a secondary
and supplementary cutting action. Miner 10 is typically configured for
creating drive
entries, headings, mine rooms and to extract pillars continuously for rapid
advancement
rates. Efficient forward cutting is achieved via the direct rearward transport
of cut material
from cutting head 11 to a stock pile at the rearward lengthwise end of machine
10 via
material transport conveyor 14. In particular, as primary rotors 15a, 15b are
rotated about
axes 33a, 33b in respective rotational directions Ri and R2, material is cut
and driven into
the axial centre of head 11. The forwardmost end of conveyor 14 emerges at the
axial
centre of head 11 immediately behind rotors 15a, 15b. Further cutting and
transport of cut
.. material into the axial centre of head 11 is achieved via the respective
bottom and top
drums 16, 17 rotating respectively about axes 18a, 18b in respective
rotational directions
R3 and R4. In particular, bottom cutting drum 16 is specifically adapted
according to the
present invention to greatly facilitate collation and transport of cut
material into the axial
centre of the head 11 and to the forwardmost end of conveyor 14 for efficient
rearward
transport and to avoid specifically regrinding of the cut material by the
rotors 15a, 15b and
drums 16, 17 as described below.
Referring to figures 2 and 3 bottom cutting drum 16 comprises a generally
elongate
configuration centred on axis 18a. An outward facing drum face 21 is generally
cylindrical
.. about axis 18a. Drum 16 is mounted at cutting head 11 via a pair of gear
box arm
mountings 27 (only one is shown in figure 2 and 3) so as to maintain the drum
16 in
rotational mounted position at the lower region of miner 10 and immediately
behind the
lower region of rotors 15a, 15b. Drum 16 is divided in this lengthwise
direction to
comprise a pair of first and second axial end sections 19 separated by an
axial central
section 20, with the sections 19, 20 separated axially by gear box arms 27. A
plurality of
cutting pick holders 22 are distributed at the end 19 and central 20 sections
to mount
respective cutting picks 23, with each pick having a respective cutting tip 24
configured to
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abrade the rock for forward advanced cutting of the continuous miner 10 as
drum 16 is
rotated about axis 18a in direction R3. According to the specific
implementation, pick
holders 22 are mounted and project from drum face 21 to follow helical paths
around axis
18a. In particular, pick holders 22 and picks 23 at the drum end sections 19
are arranged to
follow two separate helical paths and at central section 20 to follow a single
helical path
around axis 18a (from a first end to a second end of central section 20)
between the pair of
gear box arms 27.
A pair of elongate conveyor fins 26 (alternatively termed blades) project
radially from
drum face 21 at each end section 19. The conveyor fins 26 are arranged to
follow
respective helical paths approximately aligned with the helically distributed
pick holders
and picks 22, 23 at the respective end sections 19. Conveyor fins 26 are
adapted to
facilitate axial transport of cut material towards the axial centre of drum 16
and in
particular the central section 20. This axial transport is achieved via the
helical path of fins
26 at drum face 21.
Drum central section 20 further comprises a plurality of material transport
blades 25 that
cover substantially the drum face 21 (at central section 20). Each of the
blades 25,
according to the specific implementation, comprise a respective radially
outward facing
blade face 28, with each face 28 being elongate in the axial direction of drum
16. In
particular, each blade face 28 comprises a main length aligned with the drum
axis 18a and
a corresponding width extending in the circumferential direction around axis
18.
Accordingly, each blade face 28 is defined by respective first and second
lengthwise ends
29c, 29d with each end 29c, 29d positioned approximately at respective axially
separated
pick holders 22. Each blade face 28 is further defined by a pair of opposite
lengthwise
sides 29a, 29b that are separated in the circumferential direction around drum
16 within
central section 20. The blades 25 are mounted at drum 16 in a side-by-side
arrangement
with the respective lengthwise sides 29a, 29b of neighbouring blades 25 being
generally
parallel with one another and in touching or near touching contact.
Accordingly, the
outward facing drum face 21 is substantially and generally covered by the pick
holders 22
and the blades 25, with the blades 25 positioned axially and in a
circumferential direction
between the helically extending pick holders 22 (and picks 23).
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Referring to figure 4 in combination with figures 2 and 3, the blades 25 may
be considered
to be divided into a plurality of sets 32a, 32b at drum central section 20
with the sets 32a,
32b being defined by their different respective positions at the drum face 21
relative to the
pick holders 22, the axial ends of the central section 21 and the pair of
gearbox arms 27.
Each set indicated generally be reference 32a, 32b may be defined as
comprising a
plurality of blades 25 with each of the blade lengthwise sides 29a, 29b
positioned side-by-
side with a respective neighbouring blade 25 (of the same set) so that the
blades within
each set extend substantially continuously in a circumferential direction
around axis 18a to
.. effectively fill the gap at the external facing side of the drum 16 between
the pick holders
22. The number of blade 25 within each of the sets 32a, 32b may be different
depending
upon the position of each respective set 32a, 32b at drum central section 20
as indicated
above. For example, set 32a is axially closest to gear box arms 27 and
comprises three
blades 25, with each blade comprising a respective blade face 28 defined by
lengthwise
ends 29c, 29d and lengthwise sides 29a, 29b.
Each blade set 32a, 32b extends over an angular distance 0. According to the
specific
implementation, the axially outer sets 32a (positioned immediately inboard of
the gear box
arms 27) extends over an angular distance 0 being 80 to 100 . The axially
inner set 32b
comprising more blades than sets 32a may extend over an angular distance 0 in
a range
140 to 190 . Optionally, the axially outer sets 32a may comprise three blades
and the
axially inner set 32b may comprise four, five, six, seven, eight or more
blades 25.
Each blade 25 at drum 16, according to the specific implementation, comprises
a
respective rib 30 having a main length extending axially over drum face 21 and
a width
extending radially at drum 16 being aligned on a respective drum radius.
Accordingly,
each rib 30 comprises a width that protects radially outward from drum face 21
and a
length that extends axially between respective pick holders 22 within the
single helical
path at drum face 21. Each blade 25 further comprises a blade plate 29 having
a respective
blade face 28 defined by lengthwise sides 29a, 29b and lengthwise ends 29c,
29d. Each
blade plate 29 is mounted at and extends in a circumferential direction
between adjacent
blade ribs 30 via the plate lengthwise sides 29a, 29b. According to the
specific
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implementation, blades 25 are rigidly mounted at neighbouring ribs 30 (in the
circumferential direction) via welded seams 31. Seams 31 are further
advantageous to
reinforce and provide frictional wear resistance to the blades 25 against
abrasion induced
wear. According to the specific implementation, each blade plate 29 is mounted
at an
angled or declined orientation in a circumferential direction around axis 18a
relative to
drum face 21. In particular, a first lengthwise side 29a is separated from
axis 18a by a first
radial separation distance R' which is greater than a corresponding radial
distance R" of a
second respective lengthwise side 29b. As illustrated in figure 4, each blade
plate 28 is
declined relative to each blade rib 30 at a declined angle a. According to the
specific
implementation a is in a range 50 to 70 . Accordingly, a radial separation
distance
between the first and second lengthwise sides 29a, 29b of each blade plate 28
may be in a
range 35 to 65 mm (corresponding to the difference between R' and R").
Referring to figure 5, blades 25 are mounted at drum 16 such that they are
positioned in a
radial direction entirely inboard of cutting tips 24 and the cutting picks 23,
or at least a
majority of a radial length of each pick 23. Such a configuration is required
to achieve the
desired penetration of picks 23 into the rock and to avoid rock fouling of the
blades 25 as
drum 16 is rotated in direction R3. Accordingly, each pick tip 24 is
positioned at a radial
distance R" which is greater than the radial distance R'. In particular, the
radial separation
difference h between R" and R' according to the specific implementation is in
a range 35 to
65 mm. Such a configuration is advantageous to achieve a desired maximum
forward
penetration rate of miner 10 whilst avoiding fouling and accelerated
frictional wear of
blades 25.
In use, as drum 16 is rotated in direction R3 different sections along the
length of drum 16
are required to provide different cutting and transport functions as
determined by their
different respective axial positions at drum 16 relative to the forwardmost
primary rotors
15a, 15b. That is, drum end sections 19 generally project outward beyond the
radial
cutting paths of rotors 15a, 15b and in turn make a significant contribution
to the cutting of
fresh rock as miner 10 is advanced. Material cut by picks 23 at end sections
19 is
transported axially along drum 16 to the central section 20 via helical
conveyor fins 26.
The axially outermost sets 32a of blades 25 may be considered to be positioned
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immediately behind the radial cutting path of rotors 15a, 15b so as to
encounter already cut
material. The blades 25 at these axial positions (immediately axially inboard
of gear box
arms 27) are effective to transport cut material in a rotational direction R3
around axis 18a
and then to eject the material upwardly into the radial cutting path of rotors
15a, 15b. The
material ejected from blade sets 32a is then transported by rotors 15a, 15b
into the axial
centre of head 11 and onto the forward end of conveyor 14. The blades 25 at
and towards
the axial centre of drum 16 (represented, in part, by blade set 32b) are
positioned outside
the radial cutting path of rotors 15a, 15b and accordingly encounter a wall of
uncut rock.
The material cut primarily by bottom drum 16 at the axial central region of
drum section
.. 20 is gathered and transported by blades 25 (within sets 32b) in the
rotation direction R3 so
as to be transported upwardly and then to be ejected rearwardly into the axial
centre of
head 11 and onto the forward end of conveyor 14 (without being delivered to
the cutting
path of rotors 15a, 15b). Accordingly, the blades 25 at the different axial
positions of drum
16 provide a different respective function for material cutting, gathering and
rotational
transport depending upon their respective axial positions relative, for
example, to the
rotational cutting paths of primary rotors 15a, 15b. Accordingly, the declined
angle a by
which each blade plate 28 is aligned to extend in a circumferential direction
relative to
blade ribs 30 is configured to retain cut material for a sufficient time
period as it is
transported in rotational direction R3 so as to be capable of being ejected
both into the
rotational paths of rotors 15a, 15b and also in the rearward direction from
axis 18a onto the
forward end of conveyor 14. Blades 25 being configured to substantially
completely cover
drum face 21 are effective to deliver cut material into the cutting paths of
rotors 15a, 15b
and onto conveyor 14 and specifically to minimise or avoid unnecessary
regrinding of
material in addition to greatly facilitating rearward transport of cut
material via conveyor
14.
Again referring to figure 4, the present arrangement of blades 25 is further
advantageous to
minimise a separation distance S between the blades 25 and the mine floor 34.
Effectively,
the free volume below the bottom drum 16 is reduced by a radial volume of the
blades 25
that are arranged at drum 16 to occupy a majority of otherwise free volume
between the
picks 23 in both the axial and circumferential directions. The blades 25
occupying this free
volume are effective to gather and collate cut material at the mine floor 35
to avoid
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material accumulating at the lower region of the cutting head 11. Material
accumulated at
this lower region is undesirable as it reduces material cutting efficiency and
significantly
increases power demand of the miner 10. That is, with conventional borer
miners, material
collected at the lower region of the cutting head 11 is effectively carried
forward with the
forward advancement of the miner 10 and periodically introduced into the
cutting path of
the rotors 15a, 15b and drum 16 where it is reground. Blades 25 minimise and
preferably
eliminate material stock piling below drum 16 that reduces power consumption
of cutting
head 11 and increases service lifetimes of the active components of the
cutting head 11
including picks 23, pick holders 22 as well as gear box components 27. The
respective
radial separation distance h between R' and R" accordingly represents a
compromise
between forward penetration rates and power consumption with the present
arrangement of
blades 25 representing an appropriate compromise with a specific focus on
minimising
power consumption.
