Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
20fi4885
The present invention refers to a track for track-type
vehicles, in particular for track-type vehicles used for
preparing skiing pistes, comprising a plurality of bands
extending parallel to one another, said bands being aligned
in the direction of motion and having transversely secured
thereto a large number of steel crosspieces, which, when
seen in cross-section, are equipped with a U-shaped yoke
composed of two U-legs and of a connection web extending
therebetween, the first U-leg being provided with a con-
necting leg, which extends inwards via a bend, and, after an
additional bend, with a sword following said connecting leg
and extending approximately parallel to said first U-leg.
A steel crosspiece of the above-mentioned type is known from
FR-A-2094636. it is primarily used on hard ground, e.g. on
icy pistes. It is constructed as an open profile and has an
asymmetrical cross-section. In view of the fact that the
shear center in the case of this open profile is located
outside of the geometry, high torsional stress will cccur.
Likewise, high bending stress will occur as well.
The known steel crosspiece consists of two sheet-metal
blanks, which overlap each other in the area of the U-shaped
yoke and which are secured to the track by means of a screw.
The two U-legs have approximately the same length, and they
are welded together at their ends. Due to the asymmetrical
structural design of the steel crosspieces, said crosspieces
often have to be readjusted, and this can result in a for-
mation of capillary cracks.
Due to the asymmetrical nature of the profile, it is
AMENDED SHEET
A
2064885
2
necessary to produce separate steel crosspieces for the left
and for the right track, and this increases the manufac-
turing costs.
Other problems arise in connection with the fastening of the
track crosspieces to the guide yokes for driving as well as
in connection with the bands.
In particular when driving on a piste, the bands are
affected at the point of connection with the crosspieces and
they are partly destroyed. The guide plates and spike
holders normally provided on such crosspieces are arranged
in a disadvantageous manner on the known crosspieces and
cannot be secured optimally.
Light metal crosspieces used for tracks and belonging to a
different class of device are known from practical ex-
perience as well; these light metal crosspieces are already
provided with a symmetrical profile. Most of them are
manufactured as an extruded part, and they are equipped with
a comparatively thickened base portion tapering towards the
sword. In order to be able to provide a sufficient connec-
tion between the light metal crosspieces and the bands, the
crosspieces are equipped with a central web, which is nor-
mally provided with a tapped hole for the fastening screws.
Light metal crosspieces of this type are used in soft snow.
They offer the advantage of low weight and of a high moment
of resistance. They are, however, not cheap and they wear
within a comparatively short period of time.
The present invention is based on the task of providing a
steel crosspiece for tracks of the type mentioned at the
beginning, which can be manufactured at a reasonable
price and in a simple manner and which has better
AMENDED SHEET
A
2064885
shape-retaining properties.
In accordance with the present invention, this task is
solved by the features that the second U-leg merges with a
second connecting leg via a bend, the end of said second
connecting leg being welded to the bending point defined by
the first connecting leg and the sword, a hollow space
having a houselike cross-section being thus formed between
the first and second U- and connecting legs, and that the
whole profile is bent by making use of one sheet metal
blank.
The present invention provides a solution for contrary aims.
On the one hand, the costs for producing a steel crosspiece
are to be reduced; on the other hand, said steel crosspiece
is to be improved with regard to its wear resistance and it
is intended to be used for providing better fastening to the.
bands.
According to the present invention, there is provided a track
for track-type vehicles, in particular for track-type vehicles
used for preparing skiing pistes, comprising a plurality of
bands extending parallel to one another, said bands being
aligned in the direction of motion and having transversely
secured thereto a large number of steel crosspieces, which,
when seen in cross-section, are equipped with a U-Shaped yoke
composed of two U-legs and of a connection web extending
therebetween, the first U-leg being provided with a connecting
leg, which extends inwards via a bend, and, after an additional
bend, with a sword following said connecting leg and extending
approximately parallel to said first U-leg, characterized in
that the second U-leg merges with a second connecting leg via
a bend, the end of said second connection leg being welded to
the bending point defined by the first connecting leg and the
sword, a hollow space having a house-like cross-section being
thus formed between the first and second U- and connecting
AMENDED SHEET
A
2064885
3a
legs, and that the whole profile is bent by making use of one
sheet metal blank.
In the case of the present invention, the extension of the
second leg simultaneously serves several purposes: the
profile is closed so that there is also the possibility of
providing it with a symmetrical structural design. At the
same time, a hollow space is created, which has an approxi-
mately houselike cross-section and which, as will still be
explained hereinbelow, serves to safely secure the steel
crosspiece to the bands because it provides the necessary
free space within which the fastening screws can be arranged
and secured in position and on the basis of which it is also
possible to secure additional accessory parts, such as guide
plates and spike holders, to the crosspieces. Moreover, the
houselike hollow space provides high resistance values and
guarantees a torsional stress which is lower than that which
occured in the case of the former steel crosspieces.
When the steel crosspiece according to the present invention
is provided with a symmetrical structural design, it will no
longer be necessary to manufacture separate left and right
AMENDED SHEET
A
~~s4~$~
steel crosspieces, as is required in the case of the prior
art.
One advantageous further development of the present inven-
tion provides the feature that the steel crosspiece consists
of a high-strength fine-grained steel. Such a steel is
weldable and it can also be welded at the place of use, i.e.
in situ. It has excellent mechanical values even in the case
of low temperatures. This is particular important when it is
used on snow. A heat treatment is no longer necessary, and,
consequently, the hitherto required readjustment can be
dispensed with as well. The fine-grained steel can be cold
rolled. The radii at the locations of connection between the
connection web and the U-legs can be kept very small, when
an adequate rolling operation is carried out. This will
enlarge the area of contact between the connection web and
the bands. Hence, the use of support means, which have
hitherto protected the retention holes for the fastening
screws, is no longer necessary.
An additional advantage is to be seen in the fact that the
steel crosspiece can be produced from a cold-rolled steel
sheet and that the thickness of material can be the same
throughout the whole steel crosspiece.
In the case of the known steel crosspieces, holes for in-
serting the fastening screws for the bands are already
provided in the connection web of the U-shaped yoke. The
present invention offers the advantageous possibility of
providing the holes with aprons projecting into the hollow
space as well as of arranging a female thread therein. These
aprons can be produced e.g. by a flow drilling process. In
the case of said process, a fast rotating mandrel is in-
troduced into the material. It penetrates the sheet metal
and forms the aprons in question at the location of exit.
zos4ss~
The aprons can subsequently be provided with the thread.
It is, however, also possible to subject the steel cross-
piece to hot rolling and to form, in the course of said
hot-rolling process, a thicknend strip on the inner side in
the area of the intended holes; the holes for the fastening
screws are then provided in said thickened strip.
In the case of another variant, at least one insert, e.g. an
insert strip, provided with tapped holes is arranged in the
hollow space for interconnecting the steel crosspieces and
the bands. In this case, it will suffice to provide the
connection web simply with through holes. The actual
anchoring of the fastening screws is effected with the aid
of the insert strip.
An advantageous further development of the present invention
provides the feature that at least one of the two connecting
legs has a reduced thickness of material in comparison with
the U-legs. Such a reduction can be carried out e.g, by
providing at least one of the connecting legs with a recess
on its inner side associated with the houselike hollow
space. The reduction of the wall thickness of the connecting
legs can serve several purposes. The houselike hollow space
within the steel crosspiece is one of the factors deter-
mining the moment of resistance of said crosspiece. The U-
shaped yoke with its two U-legs serves as the reinforcing
backbone of the crosspiece. A reduction of the thickness of
material of one or of both connecting legs will result in an
advantageous combination between the dimensionally stable U-
shaped yoke on the one hand and the softer V-shape of the
connecting legs on the other. When a load is applied to the
sword, a connecting leg having a reduced wall thickness will
be able to absorb the load forces in a dampening manner.
.
2os4ss~
6
This is especially true in the case of shocks. Depending on
whether only one of the connecting legs has a reduced
thickness of material, or whether both connecting legs have
such a reduced thickness of material, a symmetrical or an
asymmetrical dampening effect will be produced. The forces
will be transmitted from the connecting legs to the U-legs,
which are able to yield elastically outwards.
It follows that the reduction of the material of one or of
both connecting legs offers not only the advantage of lower
weight, but also the important advantage of better dampening
within the steel crosspiece. Said dampening will result in a
mode of driving which is less detrimental to the environment
and, at the same time, in more comfort for the vehicle.
A double function is obtained due to the fact that, on the
one hand, the connecting leg or the connecting legs having a
reduced thickness of material cause a dampening effect and
that, on the other hand, the U-shaped yoke defines an es-
sentially dimensionally stable backbone, which, in spite of
the dampening effect achieved, retains the shape of the
steel crosspiece and, consequently, also of the sword and
causes the driving forces to be taken up.
Some embodiments of the connection will be described herein-
below on the basis of a drawing, in which
Fig. 1 shows a side view of a steel crosspiece according to
the present invention,
Fig. 2 shows a vertical section through a mounted steel
crosspiece according to Fig. 1, which has been
machined in accordance with the flow-drilling method
and which is provided with a guide plate,
~0~488~
Fig. 3 shows a fragmentary side view of a steel crosspiece
according to Fig. 1 and 2,
Fig. 4 shows a fragmentary top view of a track equipped
with steel crosspieces according to the invention,
Fig. 5 shows a vertical section through an additional
embodiment of the present invention, which consists
of a hot-rolled steel section equipped with a spike,
Fig. 6 shows a front view of the spike of Fig. 5,
Fig. 7 shows a side view of an additional embodiment of the
present invention in the case of which the steel
crosspiece is provided with guide plates on both
sides and has in its hollow space a similar strip
for accommodating the fastening screws, and
Fig. 8 shows a cross-section through a steel crosspiece
according to the invention whose connecting legs
have a reduced thickness of material.
The embodiment according to Fig. 1 shows a steel crosspiece
1 of the type provided for tracks 2 according to Fig. 4.
These tracks are used for track-type vehicles, which, during
the summer, are used in the fields of agriculture and forest
economy, whereas, during the winter, they are mainly used
for preparing pistes and cross-country skiing courses.
The track shown in Fig. 4 is equipped with a total number of
five rubber bands 3, which extend parallel to one another
and which are aligned in the direction of motion, said
rubber bands having transversely secured thereto a plurality
of steel crosspieces 1. When seen in cross-section, each
206488
steel crosspiece comprises a U-shaped yoke 4, which is com-
posed of two U-legs 5 and 6 as well as of a connection web 7
extending therebetween. The U-legs are aligned parallel to
each other and they extend at right angles to the connection
web 7. An important point is that the radii 8 in the corners
between the U-legs and said connection web are comparatively
small. This can be achieved by a rolling operation. The
small radii have the effect that the area of contact between
the connection web 7 and the rubber band associated
therewith is enlarged. It follows that, other than in the
case of the known solutions, it is no longer necessary to
use support means for making this area of contact suffi-
ciently large and for avoiding damage at the location of
connection between the steel crosspiece and the rubber band.
The first U-leg 5 has a connecting leg 10 as an extension
which is directed upwards, i.e. away from the rubber band,
said connecting leg 10 extending slightly inwards via a bend
9. The length of this leg is slightly greater than that of
the U-legs 5 and 6.
Subsequent to an additional bend 11, a sword 12 is provided,
which projects outwards at right angles with respect to the
connection web 7 and which, in the present case, has
approximately the same length as the U-legs 5 and 6. The
free end of the sword defines the actual contact surface
with which the steel crosspiece rests on the ground.
Via a bend 13, the second U-leg 6 is provided with a second
connecting leg 14, which is bent inwards as well and the
free end of which is durably connected, e.g. by means of
welding, to said first connecting leg 10 in the area of the
bend il.
The U-shaped yoke with its U-legs 5 and 6 and its connection
2064885
web 7 as well as the connecting legs 10 and 14 define be-
tween them a hollow space 21 having the shape of a house
which is provided with an acute-angled saddle roof.
In the present case, the steel crosspiece has a symmetrical
structural design with respect to the vertical. It defines a
closed profile, whereby advantageous resistance values and a
low torsional stress are guaranteed. In view of the fact
that the profile of the steel crosspiece is symmetrical, the
crosspiece can be used equally for the left as well as for
the right track of the vehicle.
The steel crosspiece according to Fig. 1 is made of a high-
strength, fine-grained steel, which is particularly suitable
for cold-working processes and which is adapted to be
welded. This steel is also well suited for the production of
the small radii desired in the area of the connection web.
In order to be able to connect the steel crosspiece with the
rubber bands 3, an apron 15, which projects inwards into the
hollow space, was formed with the aid of the flow-drilling
method in the case of the present embodiment in the bi-
secting line outlined in Fig. 1. This apron can be seen in
Fig. 2. When flow drilling is carried out, the steel sheet
of the steel crosspiece is pierced at the desired drilling
point with the aid of a fast rotating mandrel, whereupon,
due to the flow of material, the displaced material will.
build up inwards in an apronlike manner. A thread can be
inserted in the apron, e.g, by stamping, whereby the
material in the area of the apron will be further compacted.
With the aid of flow drilling, fastening can be achieved at
any desired location of the steel crosspiece, no matter
whether the steel crosspiece is to be anchored in the rubber
bands, or whether the elements to be anchored are additional
10
2064885
accessory parts, e.g. guide plates 16 or spikes 17. This is
advantageous especially insofar as it is thus possible to
utilize - without making use of any special additional ele-
ments - the cavity of the steel crosspiece for the purpose
of anchoring specific parts.
Fig. 3 shows a side view of a steel crosspiece according to
Fig. 1 and 2, which has already been fully mounted on the
rubber bands 3. In connection with Fig. 2, it can be seen
that the guide plates 16, which have a triangular shape when
seen in a top view, are each provided with two fastening
screws in the area of the sword 12 as well as with one
fastening screw in the base area thereof. The last-mentioned
base area is anchored through a fastening screw, which, in
turn, is screwed into an apron formed in the interior hollow
space according to the flow-drilling method.
From Fig. 2 and 3, it can be seen that the heads of the
fastening screws rest on supports 18, which serve as an
intermediate layer towards the bands 3.
Whereas the steel crosspiece according to Fig. 1 to 3 is
made of a cold-rolled steel sheet having approximately the
same thickness of material throughout its whole surface, the
steel crosspiece according to Fig. 5 is produced by means of
hot rolling. Fundamentally, it has the same structural
design as the steel crosspiece according to Fig. 1. Hence,
identical parts are provided with identical reference
numerals. In order to connect the fastening screws 19 with
this embodiment of the steel crosspiece, a strip 20 has been
formed on the inner side of the connection web 7 during the
hot-rolling process, said strip 20 thickening said connec-
tion web 7 and having inserted therein, according to
requirements, a tapped hole for the fastening screws 19.
The strip extends along the whole length of the web.
11
206488
Fig. 5 shows in addition the attachment of a spike 17. Fig.
6 shows a side view of said spike 17. Analogously with the
guide plate, said spike has an approximately triangular
shape. Its upper, broader end is equipped with two fastening
screws, whereas its lower end has provided therein one
fastening screw. In the case shown, said one lower fastening
screw extends through the hollow space 21 and is anchored by
a counternut only in the area of the second U-leg 6.
Fig. 7 shows an additional embodiment of the invention.
Fundamentally, it can again be said that this steel
crosspiece has the same structural design as the embodiment
according to Fig. 1 to 3. Identical parts are provided with
identical reference numerals.
In the case of this embodiment, the steel crosspieces are
anchored to the bands 3 with the aid of inserts having each
the form of an insert strip 22. With respect to its
cross-section, said insert strip is adapted to the inner
form of the connection web 7, and, for providing a
sufficient thickness of material for tapped holes, it is
provided with a thickened portion 23 projecting inwards into
the hollow space 21. The insert strip 22 offers the ad-
vantage that the steel crosspiece has to be provided with
through holes only at the necessary locations, whereas the
actual anchoring of the fastening screws 19 takes place be-
tween the supports 18 and the tapped holes provided in the
insert strip 22.
Fig. 8 shows an additional embodiment of the steel cross-
piece according to the invention. For the sake of
simplicity, identical parts are provided with the same
reference numerals as in the case of the preceding
embodiments. In the following, only the differences will
be discussed.
12 2os4s8~
In the case of the steel crosspiece according to Fig. 8,
both connecting legs 10 and 14 are legs having a reduced
thickness 'of material. Both said legs are provided with cup-
shaped recesses 23, which have a U-shaped cross-section and
which, in the present case, extend along almost the whole
length of said two connecting legs. The recesses are
arranged symmetrically with respect to the plane of the
sword 12 so that the profile of the steel crosspiece has an
axially symmetrical structural design.
The reduction of the thickness of material is chosen such
that the connecting legs 10, 14 are softer than the U-legs 5
and 6 of the U-shaped yoke 4. This results in a very advan-
tageous combination between the dimensional stability of the
U-shaped yoke 4 and the shock-absorbing capacity of the con-
necting legs 10 and 14 converging in a V-shape.
If an asymmetric dampening effect is to be achieved, there
will be the possibility of weakening the thickness of
material of only one of the two connecting legs, or the
possibility of providing different thicknesses of material
in the case of the two connecting legs.
The present invention is not limited to the embodiments
shown. In particular, it will also be possible to vary the
wall thickness of the U-legs e.g. for achieving a dampening
effect in this area as well. It follows that, in the case of
the steel crosspiece according to the invention, a combi-
nation of such a nature is imaginable that one or both
connecting legs have an unreduced wall thickness, whereas
the wall thickness of one or of both U-legs is reduced so as
to produce a dampening effect.
If the elements reduced in thickness are only the connecting
legs, the U-shaped yoke will define the dimensionally stable
13
backbone; if, however, the U-legs are reduced in thickness,
the V-shape of the connecting legs will be able to offer a
dimensionally stable support. Combinations of the variants
just mentioned are possible, if the dimensional stability on
the one hand and the absorption behaviour on the other are
to be varied within the houselike hollow space 21.
