Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Sgn/RL/2538~ z~5333
Feed arrangement or a harvester
Roy present invention relates to an arrangement for the
feeding and guiding of tree trunks in logging machines
comprising two interacting moving friction webs in the form
of feeding belts which are in contact with the tree trunk
on opposite sizes of -the trunk.
Mechanized timber felling makes use of suckled
harvesters, whose task is to cut the tree intended for
felling at the root, and then to remove branches from the
tree and to cut the tree trunk into convenient lengths. The
feeding of the tree trunk for delimbing presents certain
problems in this respect. The delimbing operation itself is
performed with the help of delimbing knives, which follow
the tree trunk and against which it is fed butt end first.
Testing has revealed that considerable force is required
for the feeding operation, partly in order to overcome the
resistance of the delimbing itself, i.e. the cutting of of
the brunches from the tree, and partly in order to overcome
the frictional forces and accelerating forces which arise.
One major problem associated with felling using harvesters
has its background in the requirement for the rapid feeding
of the tree trunk without damage being caused to the bark
or the surface layer of the trunk. In order to avoid damage
to the trunk, the bark layer must remain undamaged as far
as possible. Partial barking of the trunk loads to uneven
drying out and cracking during storage of the timber. The
so-called spiked rollers which were used previously suffer
from disadvantages due to their tendency to slip and to
cause damage in other respects to the surface layer of toe
trunk. feud wheel with a friction web of rubber in
,, : ,
2 So
combination with an anti-skid device in the form ox chain
elements to some extent avoids the aforementioned
disadvantages associated with the previously used spiked
rollers, although weed wheels of this wind also suffer from
S shortcomings due to their small friction surface and the
high wear on the rubber web, one consequence of which is
high costs.
lo previously disclosed is the equipmen~.of the harvester
with a so-called belt feed system. In this case the tree
trunk is fed with the help of moving belts which make
contact with the trunk under the effect of friction. In
order Jo achieve an adequate friction surface with the help
of these essentially flat belts, the belts are equipped
with spikes or combs to provide increased grip on the
trunk. Damage to the trunk similar to that caused by the
use of spiked rollers occurs in this case, too.
Feed wheels with a friction web consisting of chain
netting, either alone or in combination with an elastic
support web in accordance with Patent applications SE-
8902493-3 and SE-9000590-1, have been found to produce a
significant improvement in that the friction web of the
feed wheels is able to adapt with greater flexibility to
the form of the tree trunk as it passes through the
harvester as the diameter reduces progressively towards the
top end of the trunk. These feed wheels are nevertheless
still beset by the fundamental problem what the feed wheels
are required to exert a relatively high frictional force
against the trunk in order to feed it at the required
speed. Since the feed wheels are in contact wit the trunk
only over a limited area, it is necessary Jo exert a
considerable force against the trunk in order to produce
the required frictional o'er. It is necessary at all
times, however, to take into account the risk of slipping
and surface damage to the trunk
3 I I
The object of the present invention is to eliminate the
aforementioned disadvantages and to make available a feed
arrangement which ensures the necessary feed force whilst
exerting a relatively low specific surface pressure against
the trunk. This is achieved by a feed arrangement of the
kind indicated by way of introduction through the
characteristics in accordance with the accompanying Patent
Claim 1.
Because the contact pressure of the feed belt against the
trunk is distributed over a relatively large area, the
specific contact pressure will be relatively low, even if
a considerable frictional force is exerted in full between
the feed belt and the trunk. The concentrated application
of force against the trunk, with the associated risk of
damage to it, is avoided in this way.
The feed belt is flexibly supported on the feed wheels and
is attached along each of its free edges to a drive chain
intended to engage with the respective toothed rings on
each feed wheel. In order to achieve the desired
flexibility of the feed belt, the toothed rings are non-
pivotal mounted on the shafts of thy feed wheels, but in
a manner which permits their axial displacement.
alternatively, only one ox the toothed rings may be capable
of axial displacement. By changing the axial distance
between the toothed rings, the feed belt can be made to
adapt to the varying diameter of the tree trunk.
The tree trunk is fed in its longitudinal direction with
the help of the fee belt, which is set in motion with the
help of a hydraulic motor connected to each feed wheel.
In order to facilitate the adaptation of the feed belt to
varying diameters of the tree trunk, the wheel discs ox the
feed wheels with their associated toothed rings may be
4 I 33~
connected to the drive shaft of the feed wheel via a
threaded union. These threaded unions have a mutually
opposing pitch arranged in such a way that the wheel discs
are screwed towards one another under -the rotating load
from the shaft of the feed wheel until the weed belt
between the wheel discs develops sufficient contact
pressure to counteract the rotation of the wheel discs
relative to the shaft, that is to say in such a way that
the wheel discs are caused to rotate in the same direction
as the shaft and to feed the trunk via the belt.
In this, as in the preceding form of execution, spring
devices in the form of cup springs (Belleville spring
washers) are fitted between the wheel discs with the effect
of forcing the wheel discs in a direction away from one
another. because the wheel discs in the last-mentioned form
of execution are connected to the drive shaft ox the feed
wheel via threaded unions, the distances between the wheel
discs will be adapted in such a way that the feed belt has
its largest contact surface at the hull end of the trunk,
where the maximum feed force is required, whereas the
distance between the wheel discs is increased towards the
top end of the trunk, where a smaller feed force is
required. This automatic adjustment of the wheel discs and
the feed belt maps it possible to achieve effective
feeding of the tree trunk even where there is a
considerable difference in diameter between the butt end
and the top end, but without the wheel discs on the feed
wheel coming into contact with one another.
us an alternative to threaded unions, the use ox tooth
couplings in which one half of the coupling is attached to
the drive shaft of the feed wheel and the other half is
attacked to the wheel disc is also conceivable. the teeth
of the coupling are executed in this way with the
engagement flanks of the teeth inclined at an angle to the
Jo 3~3
axis of the coupling such that the tooth coupling operates
in a corresponding fashion to the threaded union described
above, that is to say an axial displacement of that half of
the coupling which is connected to the wheel disc takes
place above a certain torque level.
The feed belt included in the arrangement may vary in its
execution. Use may thus be made of a chain net of familiar
execution, with runs of chain intersecting one another and
connected to one another at the points of intersection,
which runs of chain extend, for example, at opposing angles
of inclination to the longitudinal direction of -the feed
belt. Any other chain pattern which permits appropriate
adaptation to the tree trunk may also be used, however. Of
particular interest as an alternative to the chain net are
feed belts consisting of intersecting bands of steel which
extend a mutually opposing angles of inclination to the
longitudinal direction of the feed belt and are attached to
its drive chains. In order to permit the unhindered
adaptation of the feed band formed in this way as it
changes its form as it passes over the feed wheels, these
metal bands are attached only at their ends to the drive
chains and are free to move relative to one another at the
points of intersection.
It is appropriate and desirable in many cases to provide
the elements of the feed belt with an elastomers coating.
If necessary, this coating ma be executed in the Norm of
a continuous strip into which the chain net or the
aforementioned steel bands are mounded.
the invention is described below in the form of
illustrative embodiments and with reference to the
accompanying drawings.
3~3
Figure 1 is a schematic end view of a harvester viewed in
the direction I-I in Figure 2. Figure 2 shows the unit in
schematic plan view. Figure 3 is a side view of a feed
wheel belonging to the harvester in the laden condition.
Figure 4 shows the feed wheel in contact with a tree trunk.
Figure 5 is a partially sectioned plan view of the feed
wheel in accordance with Figure 4. Figure 6 is a partial
side view of the friction web with drive chains connected
viewed along the line VI-VI in Figure 5. Figure 7 shows a
further embodiment of the feed wheel with the wheel discs
connected via threaded unions, to a larger scale. Figure 8
shows the schematic engagement between a feed wheel and the
top end of a tree trunk.
Figures 1 and 2 illustrate schematically a harvester 2 for
feeding a tree trunk 1 in the direction of the arrow shown
in Figure 2. The unit has a cutting unit 3 for cutting the
actual tree, a feed arrangement 4 for feeding the tree
trunk, and a delimbing unit 5 for the purpose ox removing
the ranches of the tree as the tree trunk is fed through.
The cutting and delimbing units are previously disclosed
elements and are not discussed in any greater detail in
this context.
Mounted on the frame 6 of the harvester are two feed
arrangements 7, 7 intended to be forced against each side
owe the tree trunk 1. Each feed arrangement is articulately
supported at coupling points 10 via arms 9, 9 and bearing
shafts 11 on the frame 6. The arms 9 are able to pivot
tout the respective shaft 11 and are connected at their
ends which face away prom the feed wheels via points ox
articulation 13~ 13 to the opposite ends of a pressure
cylinder 12. The two feed arrangements 7, 7 with their
associated arms are symmetrical in relation to the centre-
line of the trunk 1. The arms 9, 9 are caused Jo pivot about the shafts 11, 11 by the expansion of the pressure
7 ~S33~S
cylinder 12, so that the feed arrangements 7, 7 are forced
against the trunk 1.
Each feed arrangement comprises two feed wheels 7, 7. The
execution of the feed arrangement can be appreciated in
more detail from Figures 3 to 6. Each feed wheel is
constructed around a central shaft 16 which is rotatable
supported in bearings on upper and lower supporting plates
8, which form the supporting structure for the feed wheels.
The supporting plates are articulately connected to the
respective arms 9 at the aforementioned coupling points
10. The shaft 16 ! which is rotatable mounted in the
supporting plates 8, supports a feed wheel 7 consisting of
an upper and a lower wheel disc 15. These wheel discs are
non-pivotally mounted, for example Bohemians of splints 17
on the shaft 16, and are capable of axial displacement on
that shaft. Present between the two wheel discs is a set of
cup springs (Belleville spring washers) 19, the effect of
which is to force the wheel discs in a direction away from
one another. In the position shown in Figure 3, the wheel
discs are in contact with respective bearing bushings in
the supporting plates 8.
The wheel discs 15 are executed at their periphery in the
form of toothed rings intended to engage with the
respective drive chains 20 which link together the feed
wheels 7, 7 in each pair. feed belt 22 in the form of an
endless belt extends between the drive chains for each pair
of feed wheels. The drive chains are illustrated in the
Figure as roller chains, although any other type of flat
link chain can be used. The feed belt illustrated is
executed in thy form of a chain net a SO-called diagonal
net is shown in the Figure - although the feed belt can
also consist of a chain net to some other pattern which is
suitable for forming a support web and can be connected to
any drive chains I which may be present. The feed belt can
8 33
also be constructed from intersecting bands of steel or
some other suitable metal, which bands extend at respective
opposing angles of inclination to the longitudinal
direction of the feed belt. In order to permit the
necessary adaptation of the belt as it moves in the feed
web, the individual elements of the belt are connected to
the drive chains only at their end points and not to one
other at the points of intersection. The roller chain 20
shown in Figure 6 is connected to the lateral edge 23 of
the chain new with the help of clamps 21.
In order to feed the trunk 1, one of the feed wheels 7 in
each pair to either side of the trunk is caused to rotate
with the help of, for example, a hydraulic motor 18. m e
linking together of the two feed wheels in each pair with
the help ox the drive chains 20 ensures the even and equal
feeding of the two edges of the chain net.
Figure 3 shows the feed belt in the Walden condition. When
70 the feed heel is forced against the! trunk 1, as shown in
Figure 4 (a corresponding feed wheel is assumed to be
arranged symmetrically on the opposilce side of the trunk),
the feed belt 22 will be forced in towards the centre ox
the feed wheel, in conjunction with which the belt 22 draws
the two wheel discs 15, 15 towards one another under axial
guidance in the splinted union 17. The feed belt I now
comes into approximate contact with the surface of the
trunk 1 under the effect of friction against it. When the
feed belt is extending essentially in a rectilinear fashion
along the trunk 1 for a distance corresponding to the
distance between the shafts of the feed wheels, a
considerable friction surface is produced between the net
and the trunk. This friction surface ensures the necessary
frictional force for feeding the trunk, even at a
relatively low specific surface pressure. The risk of
surface damage to the trunk is avoided in this way. The
I 333
axial adjustment of the two wheel discs of the feed wheel
ensures that the chain net adapts appropriately to the form
of the trunk.
on embodiment in accordance with Figure 7 can be applied
with advantage in order further to improve the attachment
of the friction web to the tree trunk, and to permit the
feeling of tree trunks with a considerable difference in
diameters between the butt par and the top part. The same
reference designations as in the above embodiment are used
in Figure 7 for identical parts of the arrangement.
according to Figure 7 the shaft 16 is rotatable, as in the
previous embodiment, with the help of a motor 18 and is
guided in bearings on the support plates 8, 8. attached to
the shaft 16 in this case are threaded sleeves 25, which
engage via threaded unions 29 with the respective wheel
discs 26. These threaded unions have mutually identical but
opposing pitches. The threads in the union are preferably
square threads or trapezoid threads with the ability to
absorb a high axial load. A spacer sleeve 26 is inserted
between the threaded sleeves US, I spring device 19
lion example, a sex of cup springs (Belle~ille spring
washers)) between the wheel discs 26,-26 exerts an axial
force against the wheel discs 26, 26 via spacer washers 28
in a direction such as to move these aware from one
another.
Toe l~ft-hand half of Figure 7 shows the eddy wheel with
the wheel discs in their outer end position with the chain
net 22 extended between the wheel discs. The right-hand
halt of the Figure shows the feed wheel during engagement
with a tree trunk with the feed wheels brought together
against the effect of the spring device 19 to a position in
which the feed belt 22 is essentially in contact along its
rectilinear part with the tree trunk.
I
This arrangement works in the following way. It is assumed
that a corresponding feed wheel engages with the trunk 1 on
the right-hand side.
In the initial position in accordance with the left-hand
half of Figure 7, the linked pair of feed wheels with the
rectilinear net part extended between them is brought into
contact with the trunk 1. The shaft 16 with the threaded
sleeves 25, 25 rotates. During a starting phase, the wheel
discs with the net in contact with the trunk remain in
position without the wheel discs rotating, whilst the wheel
discs are brought towards one another by means of the
threaded unions 29 and compress the spring device 19.
Further displacement of the wheel discs and compression of
the spring device finally leads to a position of
equilibrium in which the peripheral component of the force
transferred to the wheel disc is sufficient to cause the
wheel disc to rotate and, by so doing, to advance the trunk
1. The pitch of the opposing threaded unions 29 and the
execution and the sliding friction in the threaded union
require to be adapted in this case in relation to the
developed spring force, in such a way that the desired feed
force is obtained at the adjusted axial distance between
the wheel discs.
us mentioned above, the required feed force is greatest at
thy butt end of the trunk, as it it necessary at this point
to take account of significant acceleration of the tree and
frictional losses with the ground, etch The fact that the
wheel discs 26 are moved closer together, because of the
relatively greater feed resistance as the weed wheel is
applied to the butt end of the trunk, means that the
friction web moves into relatively close contact with the
surface of the trunk during the starting phase of the feed,
which is advantageous for the uniform distribution of the
contact pressure of the net against the trunk.
So
it the end of the weed operation, on the other hand, when
the necessary feed force is significantly reduced, the
wheel discs will be moved further apart under the effect of
the spring device 19, which is possible because the
threaded union is not self-bra~ing. As will be appreciated
from Figure I the friction web 22 will be extended in this
way, and the distance between the periphery of the feed
wheels 26 will be extended. The risk of the weed wheels
approaching too closely to one another or coming into
contact with one another is avoided in this way if a trunk
of low diameter is fed through.
The feed wheels thus adapt themselves automatically to the
force required for feeding a trunk of varying diameter.
In a simplified alternative it is also possible to attach
one of the wheel discs 26 securely to the shaft 16 of the
feed wheel, whilst the other wheel disc is supported as
shown in Figure I above. The feed wheel in this case
operates in principle in the same way as described above,
although the height of the trunk 1 changes us the axially
movable wheel disc 26 is adjusted. This may be observed as
the trunk is guided through the harvester.
us can be appreciated from the foregoing, the friction web
in contact with the trunk as it is being fed can exhibit
different executions. Where high demands are imposed with
regard to the surface of the processed trunk, a friction
web consisting of a supporting layer which is mounded into
a suitable elastomers such as rubber, or a plastic material
of adequate softness, etc., is preferred The supporting
layer then consists of a chain net or, alternatively, of
intersecting band elements, for example, in conjunction
Whitehall which the supporting elements of the layer either can
be coated separately with an elastomers or can be included
in an elas~omer strip in the form of moulded-in reinforcing
12 I
elements. In those cases in which no special requirements
are imposed on the surface of the processed trunk, a chain
net, for example, can form the friction web directly
without any special coating.
S
