U.S. patent number 3,796,505 [Application Number 05/320,652] was granted by the patent office on 1974-03-12 for drag roller.
This patent grant is currently assigned to Ratrac AG. Invention is credited to Manfred Buhler.
United States Patent |
3,796,505 |
Buhler |
March 12, 1974 |
DRAG ROLLER
Abstract
A drag roller, especially for grading or levelling ski pistes,
with a roller body rotatably supported upon an axle. The axle is
composed of a number of partial axle components which are coupled
with one another by joints having 1.degree. of freedom of movement,
the pivot axes of which extend approximately parallel to the
direction of travel. At least a number of the partial axle
components each carry a respective roller body. The end face of one
of two neighboring roller bodies is formed by a substantially ball
or spherical head which merges with the outer surface of such
roller body, and this ball head engages with the neighboring roller
body which is constructed at its neighboring end face in the manner
of a ball socket.
Inventors: |
Buhler; Manfred (Pfaffikon,
CH) |
Assignee: |
Ratrac AG (Wallisellen,
CH)
|
Family
ID: |
4183593 |
Appl.
No.: |
05/320,652 |
Filed: |
January 2, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
404/132; 180/20;
301/1 |
Current CPC
Class: |
E01H
4/02 (20130101) |
Current International
Class: |
E01H
4/00 (20060101); E01H 4/02 (20060101); E01h
004/00 () |
Field of
Search: |
;404/132,124,122,123,125,126,127,128 ;301/1,5,36WP,36R
;280/DIG.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Byers, Jr.; Nile C.
Attorney, Agent or Firm: Kleeman; Werner W.
Claims
1. A drag roll arrangement especially for levelling ski pistes,
comprising an axle consisting of a number of partial axle
components, a respective joint having a single degree of freedom of
movement for interconnecting neighboring partial axle components
with one another, each said joint having a pivot axis which extends
substantially parallel to the direction of travel of the drag roll
arrangement, and at least a portion of the partial axle components
each carrying a roller body, the end face of one of two neighboring
roller bodies being formed by a substantially ball-like head which
merges with the outer surface thereof, and the neighboring roller
body being provided at its end face confronting the end face of the
other roller body with a ball socket, said ball-like head engaging
with
2. The drag roller arrangement as defined in claim 1, wherein three
roller
3. The drag roller arrangement as defined in claim 2, wherein each
of the
4. The drag roller arrangement as defined in claim 3, wherein a
respective further free partial axle component merges at each side
with the partial
5. The drag roll arrangement as defined in claim 1, wherein the
outermost partial axle components are provided with means for
mounting each of the same to be axially displaceable at a drag
frame and pivotably about an axis extending substantially parallel
to the direction of travel of the
6. The drag roll arrangement as defined in claim 5, wherein the
drag frame possesses a substantially rectangular configuration and
carries a coupling member which is pivotably mounted about an axis
extending approximately
7. The drag roll arrangement as defined in claim 1, wherein the
partial axle components incorporate locking means in order to block
the associated joints in a predetermined position, and means for
actuating the locking
8. The drag roll arrangement as defined in claim 7, wherein the
partial axle components are at least partially hollow, and the
locking means incorporates a locking bolt displaceably guided in
one of two neighboring hollow partial axle components, and said
actuating means comprises a fluid-actuated cylinder containing a
piston therein, said piston being operatively connected with the
locking bolt.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a new and improved construction of
drag roller or roll, especially for levelling or smoothing ski
pistes, by means of a roller body rotatably mounted upon an axle or
shaft.
Drag rolls for levelling or smoothing ski pistes have been utilized
for quite some time, and generally are suspended at a snow vehicle
equipped with crawler tracks. A state-of-the-art construction of
drag roll contemplates rotatably mounting the roller body in a
frame, the width of the roller corresponding approximately to the
working width or gauge of the crawler tracks.
Economical tending or servicing of the ski pistes continually
requires larger working widths of the crawler track vehicles,
wherefore the grading or levelling drag rollers also increase in
width. On the other hand, it has been found that the actual
levelling or smoothing action of the prior art drag rollers tends
to decrease as the width thereof increases, although increasing
such width is accompanied by an increase in weight. This is
predicated upon the fact that the transverse profile of the base
surface or stratum with working widths which exceed about 2 meters
-- notwithstanding the smoothing action of the layer of snow -- for
the most part has portions of the terrain which are to be treated
exhibiting considerable irregularities. This in effect means that
the drag roll only bears with one portion -- oftentimes a rather
insignificant portion -- of its width upon the blanket of snow.
Hence, in an attempt to overcome this unsatisfactory operation of
the equipment, proposals have been made to level the working width
of the traction vehicle by using a number of smaller rolls which
are divided over the width and which are movable independently of
one another.
According to a know arrangement in the art which is equipped with a
number of drag rolls, there are symmetrically arranged in the
direction of travel of the vehicle, two further rollers behind a
first roller which is guided approximately centrally of the
vehicle. Although the operable working zone of the individual
rollers in their width joins one another without any intermediate
space or gap, or in fact even overlaps, the edges of the rear
rollers have been found to form tracks or grooves in the processed
ski piste. Since these tracks or grooves are formed by compacted
snow, they constitute disturbing irregularities for the skier and
form a potential source of danger as concers ski accidents.
SUMMARY OF THE INVENTION
Hence, it should be recognized from what has been discussed above,
that this particular field of technology is still in need of an
improved construction of drag roll for the treatment of ski pistes
which is not associated with the aforementioned drawbacks and
limitations of the prior art constructions. Therefore, it is a
primary object of the present invention to provide a drag roll
construction which satisfies the needs still existing in the art
and is not associated with the aforementioned drawbacks and
limitations of the prior art proposals.
Another and more specific object of the present invention relates
to a new and improved construction of drag roll which is capable of
accommodating itself to the transverse profile of the terrain and
nonetheless can level or smooth the skiing piste without the
formation of the undesirable stepped portions or irregularities
across the working width of the traction vehicle.
Yet a further significant object of the present invention relates
to a new and improved construction of drag roller arrangement for
use at a vehicle for the treatment of ski pistes which is
relatively simple in construction and design, economical to
manufacture, extremely reliable in operation, and versatile in use
in that it can adapt itself during use to different encountered
transverse profiles of the terrain over which it travels.
Now in order to implement these and still further objects of the
invention, which will become more readily apparent as the
description proceeds, the new and improved construction of drag
roll of this development contemplates that the axle is composed of
a number of partial axle components or members which are coupled
with one another by joints having one degree of freedom of
movement, the pivot axes of which extend approximately parallel to
the direction of travel. Further at least a portion of the partial
axle components each carry a roller body. The end face of one of
two neighboring roller bodies is formed by a ball head which merges
with the outer or jacket surface thereof and this ball head engages
with the end face of the neighboring roller body which is
constructed in the form of a ball socket.
Due to this construction of drag roller, which is believed to be
unique in the art, it is possible to level or grade the snow
surface during a single pass of the traction vehicle dragging such
roller over the effective working width thereof. Moreover, due to
the interengagement of the individual roller bodies, there is
advantageously avoided the formation of the aforementioned
undesired tracks, and owing to the coherency of the roller bodies
by means of their partial axle components, there are also smoothed
the steps in the transverse profile of the terrain which are formed
during travel of the crawler track vehicle.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be better understood and objects other than
those set forth above, will become apparent when consideration is
given to the following detailed description thereof. Such
description makes reference to the annexed drawing wherein:
FIG. 1 schematically illustrates a preferred constructional
embodiment of drag roller designed according to the teachings of
this invention, partially in elevation, and partially in axial
sectional view:
FIG. 2 is a top plan view of the drag roller or roll depicted in
FIG. 1:
FIG. 3 is an enlarged detail sectional view of embodiments drag
roller: and
FIG. 4 is a further enlarged detailed sectional view of a different
portion of such drag roller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Describing now the drawing, in FIGS. 1 and 2 reference character 2
designates a substantially rectangular-shaped frame which carries
at its narrow sides 4 extending in the direction of travel a
respective bearing body 6. The frame beam 8 which leads in the
direction of roller travel carries at its central portion a
frame-like headpiece or member 10 in which extends a pivot journal
or pin 12 parallel to the narrow sides 4 of the frame 2. A coupling
element 14 is seated upon the pivot pin 12 and is connected
therewith through the agency of a conventional Neidhart spring. The
coupling element 14 serves as a convenient connection means with
the end of a non-illustrated crane-like beam or overhang which is
secured to the traction vehicle and is directed rearwardly with
regard to the direction of travel thereof. The expression "traction
vehicle" is intended to mean a vehicle, such as a crawler track
snow vehicle, to which the drag roller is secured for dragging
same.
Each of both bearing bodies 6 contains a crosspiece 16 which
engages by means of pivot pins 18 in bearing sleeves or bushings
20. The crosspiece 16 is pivotable in the bearing sleeves or
bushings 20 secured to the associated bearing body 6 about an axis
which extends essentially parallel to the pivot pin 12 and the
narrow sides 4 of the frame 2. Each crosspiece 16 contains a bore
22 which extends perpendicular to the pivot pins 18, bore 22
receiving the free end of an associated outer situated partial axle
component 24.
Between both of the outermost situated partial axle components 24
there is disposed an intermediate partial axle component 26 which
is connected with each neighboring end of the associated one of the
outer situated partial axle component 24 by means of a respective
joint or hinge arrangement 28 having one degree of freedom of
movement. The partial axle components 24 are displaceable in the
bores 22 and can be secured against rotation, by any suitable and
therefore not particularly illustrated means, in a position in
which the pivot axes of the joints 28 of one degree of freedom of
movement extend parallel to the pivot pins 18.
The partial axle components 24 and 26 are of hollow design. The
partial axle components 24 each contain a substantially
cylindrical-shaped intermediate portion 30 which, in turn, closes a
fluid cylinder 32 secured therein. In the fluid cylinder 32, there
is displaceably arranged an actuation piston member 34, the piston
rod 36 of which is coupled with a locking bolt 38, as best seen by
referring to FIGS. 1 and 4. Opposite faces of the piston 34 can be
impinged with a pressurized fluid medium, such as pressurized oil,
by means of lines or conduits 40 and 42 which are connected with
the cylinder 32, so that the locking bolts 38 can be displaced out
of the retracted position depicted in FIG. 1 and shifted into the
locking bolt 38 which is displaceably guided in the end of the
associated partial axle component 24 connected with the joint 28
having a single degree of freedom carries at its free end a
conically tapered portion 39. In the locked position, the locking
bolt 38 also extends into the neighboring hollow partial axle
component 26 and thus froms a connection, which is rigid against
bending, between both of the partial axle components 24 and 26: the
joint 28 therefore becomes ineffectual. In the retracted position
of the locking bolt 38, the conically tapered portion or end 39
just extends into the partial axle component 26, so that the joint
28 has free single freedom of movement.
Although with the illustrated exemplary embodiment, the angle
through which the partial axle components 24 and 26 can pivot to
both sides out of the coaxial position is limited by the conical
tapered portion 39, it would be also conceivable to provide stops
at the cooperating components of the single freedom of movements
joint which limit the maximum angling or deflection. In the
illustration of FIG. 1, both of the partial axle components 24 and
26 are depicted in the position of maximum deflection or angling: a
pronounced deflection is prevented because the conically tapered
portion 39 of the locking bolt 38 bears against the inner wall of
the neighboring partial axle component 26.
Each partial axle component 24 and 26 carries a roller body 44 and
46 respectively, wherein such roller bodies are provided with a
suitable contour or profile, and are supported through the agency
of bearing sleeves or bushings 48 rotatably upon the associated
partial axle component. The bushings 48, which are secured at the
roller bodies, cooperate with non-illustrated stop shoulders at the
partial axle components in order to prevent axial displacement of
the associated roller body.
As will be best seen by referring to FIG. 1, the ends or end faces
of the roller body 46 are formed by substantially ball or spherical
heads 52 (only one of which is shown in the drawing) which directly
merge with the outer surface or jacket 50 thereof, and wherein the
center point of the radius thereof is located at the pivot axis of
the neighboring joint 28. On the other hand, the end faces of the
roller bodies 44 which confront the roller body 46 forms recesses
or depressions 54 in the manner of ball sockets, the radius center
point of which again is located at the pivot axis of the
neighboring joint 28, wherein the radius thereof is greater by a
small amount from that of the ball head. However, the difference in
radius is chosen to be just so great that the required movement
play for the pivoting of the partial axle components 24 and 26 with
regard to one another as well as possible rotation of the roller
bodies 44 and 46 with different peripheral speeds is insured
for.
If the drag roller is employed for levelling or grading a ski
piste, then it is connected by means of the coupling element 14 at
an elevationally displaceable overhang or beam of the traction
vehicle, which, as a general rule, is a crawler track vehicle, and
the coupling element possesses nonillustrated locking means of any
suitable design. Both of the conduits or lines 40 and 42, which can
be constructed as flexible hoses, are coupled with an oil pump and
a control device which is provided at the traction vehicle,
preferably capable of actuation from the driver's cabin. If a
terrain is to be treated which in transverse profile is completely
level, then the control device can be actuated such that both of
the locking bolts 38 are shifted by means of the associated piston
34 so as to assume their locked position depicted in FIG. 4. As a
result, the drag roll behaves in the manner of a rigid roller
construction. This type of mode of operation of the equipment is
especially possible in the case of a levelled surface, as such
would be found for instance at the run-out regions of ski jumps and
ski pistes.
On the other hand, if the transverse profile of the piste to be
levelled is irregular or uneven, then such is processed with the
locking bolts 38 located in retracted position, so that the
individual roller bodies can accommodate themselves to the
transverse profile of the terrain. Hence, if at one side of the
roller or at the region of one roller there is present a greater
contact pressure than at the other roller bodies, then this roller
will upwardly deflect or deviate since the partial axle components
are pivotably connected with one another, and wherein at the same
time both of the crosspieces will accommodate themselves to the new
position of the partial axle components 24. If the irregularities
at the terrain are in the form of bumps or moguls which extend in
the lengthwise profile thereof, then when such exceed a certain
magnitude, the frame 2 will also be pivoted or rocked about the pin
12 extending in the direction of travel of the vehicle and the drag
roller and against the action of the Neidhart spring means, wherein
the pre-biased Neidhart spring means will insure that the roller
body will be thereby guided at the run-off side of the mogul in
such a manner that the frame will again return back to its starting
position. In FIG. 1 the frame is shown in a deflected position, as
such would arise when tavelling over moguis which exceed a certain
height.
Whereas the roller bodies are conjointly axially displaceable by
means of their partial axle components in the bores 22 of the
crosspieces 16, the partial axle components 24 carry at their free
ends impact or stop rings 56 which limit the axial displacement
upon contact with the crosspieces 16. Due to the axial
displaceability of the partial axial components in the cross pieces
16, there is simultaneously insured that there can occur the
displacement at the crosspieces 16 which is necessary during their
angling or deflection.
Instead of mounting the crosspieces 16 in housing or bearing bodies
6 which are rigidly connected with the frame, it would also be
possible to suspend such at guides connected with the frame and
which are pivotable about shafts extending in the direction of
travel. The guides could then be connected with the frame again by
Neidhart springs in order to retain such in a preferred direction
of extent. The guides can also extend in the rest position, for
instance at an angle of 45.degree. with regard to the outer roller
bodies a more pronounced deflection, without necessarily having to
pivot the frame about the pivot 12.
A similar mode of operation could also be attained if, for
instance, the partial axle components 24 themselves were not
articulated at the crosspieces 16, rather shorter auxiliary pieces
which likewise would be connected with the partial axle, components
24 through the agency of joints 28 having a single freedom of
movement. Finally, it also would be possible to arrange the
crosspieces 16 displaceably in the housing body 6 in order to
insure for a greater freedom of angling or deflection of the outer
roller bodies 44.
Although in the illustrated exemplary embodiment all of the joint
axes as well as also the pivot axes of the crosspieces and the
frame extend in the direction of travel and are parallel to one
another, the axes of the crosspieces could enclose a slight angle
with respect to the plane of the frame 2, whereby the pivot axes of
all single degree of freedom of movement joints 28 would extend
parallel to the axes of the crosspieces. This arrangement would
facilitate the deflection of the roller bodies relative to one
another upon travelling over moguls and, if desired, would render
possible a more rapid accommodation of their position to the change
in the shape of the terrain.
While there is shown and described present preferred embodiment of
the invention, it is to be distinctly understood that the invention
is not limited thereto, but may be otherwise variously embodied and
practiced within the scope of the following claims.
Accordingly,
* * * * *