CA2093031C - Drag for snow grooming - Google Patents
Drag for snow groomingInfo
- Publication number
- CA2093031C CA2093031C CA 2093031 CA2093031A CA2093031C CA 2093031 C CA2093031 C CA 2093031C CA 2093031 CA2093031 CA 2093031 CA 2093031 A CA2093031 A CA 2093031A CA 2093031 C CA2093031 C CA 2093031C
- Authority
- CA
- Canada
- Prior art keywords
- drag
- frame
- snow
- blade
- tongue
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01H—STREET CLEANING; CLEANING OF PERMANENT WAYS; CLEANING BEACHES; DISPERSING OR PREVENTING FOG IN GENERAL CLEANING STREET OR RAILWAY FURNITURE OR TUNNEL WALLS
- E01H4/00—Working on surfaces of snow or ice in order to make them suitable for traffic or sporting purposes, e.g. by compacting snow
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Cleaning Of Streets, Tracks, Or Beaches (AREA)
Abstract
A drag for snow grooming includes a frame having a front, a back and two sides and two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface. Blades are connected to the frame and are disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag. The drag also includes a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle. The drag is designed to be towed over a snow surface by a towing vehicle, such as a tractor, for removal of snow from bumps on the snow surface by the blades, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface.
Description
. 1238-2 _ DRAG FOR S~OW GROOMING 2 o 9 3 0 31 FIELD OF INVENTION
The present invention relates to a drag for snow grooming which can be towed behind a vehicle for the purpose of grooming a snow surface such as a snowmobile trail.
BACKGROUND OF THE INVENTION
Much snowmobiling takes place on snowmobile trails.
Snowmobile trails are covered with snow which often accumulates so as to form bumps and depressions. It is often desired, however, that snowmobile trails be as smooth as possible. Much time, effort and money is therefore spent in removing such bumps and filling such depressions by grooming the snow surfaces of snowmobile trails.
The grooming of a snowmobile trail is often accomplished by using a vehicle such as a tractor to tow a drag over the snow surface. A drag typically consists of a tongue similar to that found on a trailer, a metal frame that slides over the snow surface, one or more blades to remove snow bumps, and a pan for compacting the snow removed by the blade. The theory is that the blades remove snow from the bumps, snow that accumulates in the drag is deposited in depressions in the snow surface, and snow thus deposited is compacted by the pan. In practice, however, drags often fail effectively to remove bumps or fill in depressions; in fact, additional bumps are sometimes created.
SUMMARY OF THF INVENTION
The object of the present invention is to provide an improved drag for snow grooming.
According to the invention, there is provided a drag for grooming snow surfaces comprising: a frame having a front, a back and two sides; two generally parallel, spaced apart rails depending from the sides of the ~rame, each rail having a front A ~
209'3031 end substantially proximate the front of the frame and being slidable on a snow surface; blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle; wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface.
In an embodiment of the invention, there is provided a drag for grooming snow surfaces comprising: a frame having a front, a back and two sides; two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface; blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle; wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface; further comprising a first B
'- 20g3~31 pivoting means capable of pivoting the tongue relative to the frame, and also capable of allowing the tongue to pivot downward freely relative to the frame.
In a further embodiment of the invention, there is provided a drag for grooming snow surfaces comprising: a frame having a front, a back and two sides; two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface; blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle; wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface; wherein the blade means comprises a pair of leading blades depending from the frame; each leading blade having an adjacent end and a free end, the adjacent end being substantially adjacent one rail and the free end being angled towards the back of the frame; each leading blade having a generally horizontal lower edge disposed generally below the frame; the adjacent end of one leading blade being substantially proximate the front end of one rail, and the adjacent end of the other leading blade being substantially proximate the front end of the other rail.
BRIEF DESCRIPTION OF THE DRAWINGS 2 o 9 3 o 31 The embodiments of the invention will now be described with reference to the accompanying drawings, in which:
Figures la to lf are schematic diagrams of prior art drags in operation;
Figures 2a to 2f are schematic diagrams of an embodiment of the present invention in operation;
Figure 3 is a plan view of one embodiment of the present invention;
Figure 4 is a plan view of the tongue of the embodiment of Figure 3;
Figure 5 is a side view of the tongue of the embodiment of Figure 3;
Figure 6 is an end view of the wheel assembly of the embodiment of Figure 3;
Figure 7 is a plan view of the wheel assembly of the embodiment of Figure 3;
Figure 8 is a side view of the wheel assembly of the embodiment of Figure 3;
Figure 9 is a perspective view of the embodiment of Figure 3;
Figure 10 is a side view of the embodiment of Figure 3.
Similar references are used in different figures to denote similar components.
B
There are many problems with prior art drags. One problem, illustrated in Figure la, is that bumps are often incompletely removed by the drag. To obtain a smooth trail, one must therefore tow the drag over the bumps twice or more, which is time consuming and therefore costly. One reason why drags often l ~C~ ~ !
fail to remove a bump completely is that the frame rides up on the bump, causing the blade to become airborne prior to contacting the bump. The blade therefore removes the top of the bump, leaving the bottom intact.
Some problems are associated with drags that are too long.
Figures lb and lc, for example, illustrate what can happen when a long drag crests a hill. Figure lb shows the snow that has accumulated in the drag being deposited just before the crest of a hill, thus creating a bump. Figure lc shows a long drag "scalping" the crest of a hill, that is, removing all the snow from the hill, thus exposing the ground beneath the snow and rendering the trail unsuitable for snowmobiling.
Other problems are associated with drags that are too short.
Illustrated in Figure ld is a drag that is stuck in the snow by virtue of its failure to bridge a depression in the snow surface.
Figure le shows that a drag that is too short can remove snow from a trail without removing the bumps or filling in the depressions. Similarly, Figure lf shows a short drag failing to deposit much snow prior to ascending a hill.
Figures 2a to 2f correspond to Figures la to lf, and depict how the present invention overcomes the problems associated with the prior art.
Referring now to Figure 3, the drag 1 includes a frame 2 which is essentially constructed from welded square steel tubing.
Welded to the frame 2 are two rails 3, on the bottom of each of which is a replaceable wear plate 4. At the front of each rail 3 is a point 5 which pierces snow bumps (not shown) during operation of the drag 1.
Because the points 5 will pierce a bump, the leading blades 6 are able to contact the bump near its base and thus remove the entire bump. Without the points 5, the rails 3 would ride up on the bump, thus preventing the leading blades 6 from contacting the base of the bump; alternatively, unless the snow were very soft, the rails 3 would become stuck in the bump.
The proximity of the leading blades 6 to the rails 3 also contributes to the characteristic of the rails 3 not riding upon bumps. Firstly, the leading blades 6 are located near the front of the rails 3 so that the bump is substantially removed shortly after the initial contact between the point 5 and the bump; thus, the trailing part of the rail 3 does not have a chance to ride up on the bump. Preferably this distance is in the range of 0-50 cms. Secondly, the leading blades 6 and the following blades 7 are located adjacent to the rails 3 so that a path through a bump is effectively cleared for the trailing part of the rail 3.
Preferably the distance between each rail and the adjacent end of the associated leading blade and following blades is in the range of 0-10 cms.
To improve cutting performance, the blades 6,7 are angled so that they are not perpendicular to the direction of travel of the drag 1. The blades 6,7 are also angled so as to direct the snow towards the centre of the drag 1 so that the snow can be mixed and then compacted onto the trail. Preferably the acute angle between each rail and the associated leading blade and each following blade is in the range of 60-75~.
The leading blades 6 are oriented in a side by side fashion so that they are able to contact a bump very shortly after the points 5 contact the bump. A side by side orientation also avoids the twisting effect on the drag 1 that would be caused by staggered leading blades 6. In a staggered orientation, one
The present invention relates to a drag for snow grooming which can be towed behind a vehicle for the purpose of grooming a snow surface such as a snowmobile trail.
BACKGROUND OF THE INVENTION
Much snowmobiling takes place on snowmobile trails.
Snowmobile trails are covered with snow which often accumulates so as to form bumps and depressions. It is often desired, however, that snowmobile trails be as smooth as possible. Much time, effort and money is therefore spent in removing such bumps and filling such depressions by grooming the snow surfaces of snowmobile trails.
The grooming of a snowmobile trail is often accomplished by using a vehicle such as a tractor to tow a drag over the snow surface. A drag typically consists of a tongue similar to that found on a trailer, a metal frame that slides over the snow surface, one or more blades to remove snow bumps, and a pan for compacting the snow removed by the blade. The theory is that the blades remove snow from the bumps, snow that accumulates in the drag is deposited in depressions in the snow surface, and snow thus deposited is compacted by the pan. In practice, however, drags often fail effectively to remove bumps or fill in depressions; in fact, additional bumps are sometimes created.
SUMMARY OF THF INVENTION
The object of the present invention is to provide an improved drag for snow grooming.
According to the invention, there is provided a drag for grooming snow surfaces comprising: a frame having a front, a back and two sides; two generally parallel, spaced apart rails depending from the sides of the ~rame, each rail having a front A ~
209'3031 end substantially proximate the front of the frame and being slidable on a snow surface; blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle; wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface.
In an embodiment of the invention, there is provided a drag for grooming snow surfaces comprising: a frame having a front, a back and two sides; two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface; blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle; wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface; further comprising a first B
'- 20g3~31 pivoting means capable of pivoting the tongue relative to the frame, and also capable of allowing the tongue to pivot downward freely relative to the frame.
In a further embodiment of the invention, there is provided a drag for grooming snow surfaces comprising: a frame having a front, a back and two sides; two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface; blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle; wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface; wherein the blade means comprises a pair of leading blades depending from the frame; each leading blade having an adjacent end and a free end, the adjacent end being substantially adjacent one rail and the free end being angled towards the back of the frame; each leading blade having a generally horizontal lower edge disposed generally below the frame; the adjacent end of one leading blade being substantially proximate the front end of one rail, and the adjacent end of the other leading blade being substantially proximate the front end of the other rail.
BRIEF DESCRIPTION OF THE DRAWINGS 2 o 9 3 o 31 The embodiments of the invention will now be described with reference to the accompanying drawings, in which:
Figures la to lf are schematic diagrams of prior art drags in operation;
Figures 2a to 2f are schematic diagrams of an embodiment of the present invention in operation;
Figure 3 is a plan view of one embodiment of the present invention;
Figure 4 is a plan view of the tongue of the embodiment of Figure 3;
Figure 5 is a side view of the tongue of the embodiment of Figure 3;
Figure 6 is an end view of the wheel assembly of the embodiment of Figure 3;
Figure 7 is a plan view of the wheel assembly of the embodiment of Figure 3;
Figure 8 is a side view of the wheel assembly of the embodiment of Figure 3;
Figure 9 is a perspective view of the embodiment of Figure 3;
Figure 10 is a side view of the embodiment of Figure 3.
Similar references are used in different figures to denote similar components.
B
There are many problems with prior art drags. One problem, illustrated in Figure la, is that bumps are often incompletely removed by the drag. To obtain a smooth trail, one must therefore tow the drag over the bumps twice or more, which is time consuming and therefore costly. One reason why drags often l ~C~ ~ !
fail to remove a bump completely is that the frame rides up on the bump, causing the blade to become airborne prior to contacting the bump. The blade therefore removes the top of the bump, leaving the bottom intact.
Some problems are associated with drags that are too long.
Figures lb and lc, for example, illustrate what can happen when a long drag crests a hill. Figure lb shows the snow that has accumulated in the drag being deposited just before the crest of a hill, thus creating a bump. Figure lc shows a long drag "scalping" the crest of a hill, that is, removing all the snow from the hill, thus exposing the ground beneath the snow and rendering the trail unsuitable for snowmobiling.
Other problems are associated with drags that are too short.
Illustrated in Figure ld is a drag that is stuck in the snow by virtue of its failure to bridge a depression in the snow surface.
Figure le shows that a drag that is too short can remove snow from a trail without removing the bumps or filling in the depressions. Similarly, Figure lf shows a short drag failing to deposit much snow prior to ascending a hill.
Figures 2a to 2f correspond to Figures la to lf, and depict how the present invention overcomes the problems associated with the prior art.
Referring now to Figure 3, the drag 1 includes a frame 2 which is essentially constructed from welded square steel tubing.
Welded to the frame 2 are two rails 3, on the bottom of each of which is a replaceable wear plate 4. At the front of each rail 3 is a point 5 which pierces snow bumps (not shown) during operation of the drag 1.
Because the points 5 will pierce a bump, the leading blades 6 are able to contact the bump near its base and thus remove the entire bump. Without the points 5, the rails 3 would ride up on the bump, thus preventing the leading blades 6 from contacting the base of the bump; alternatively, unless the snow were very soft, the rails 3 would become stuck in the bump.
The proximity of the leading blades 6 to the rails 3 also contributes to the characteristic of the rails 3 not riding upon bumps. Firstly, the leading blades 6 are located near the front of the rails 3 so that the bump is substantially removed shortly after the initial contact between the point 5 and the bump; thus, the trailing part of the rail 3 does not have a chance to ride up on the bump. Preferably this distance is in the range of 0-50 cms. Secondly, the leading blades 6 and the following blades 7 are located adjacent to the rails 3 so that a path through a bump is effectively cleared for the trailing part of the rail 3.
Preferably the distance between each rail and the adjacent end of the associated leading blade and following blades is in the range of 0-10 cms.
To improve cutting performance, the blades 6,7 are angled so that they are not perpendicular to the direction of travel of the drag 1. The blades 6,7 are also angled so as to direct the snow towards the centre of the drag 1 so that the snow can be mixed and then compacted onto the trail. Preferably the acute angle between each rail and the associated leading blade and each following blade is in the range of 60-75~.
The leading blades 6 are oriented in a side by side fashion so that they are able to contact a bump very shortly after the points 5 contact the bump. A side by side orientation also avoids the twisting effect on the drag 1 that would be caused by staggered leading blades 6. In a staggered orientation, one
2~9~031 leading blade 6 would contact a bump first, causing the drag 1 to shift to one side, only to be shifted back again when the other leading blade 6 made contact.
The following blades 7 are oriented in an alternating fashion to assist in the mixing of the snow which has been rémoved from the trail.
Mixing the snow improves the trail in two ways. Firstly, the grain size of pieces of compacted snow and ice is reduced.
Secondly, different types of snow (for example, granular, powdery, wet, etc.) are mixed so as to form a more homogeneous product.
Each blade 6,7 is capable of pivoting approximately about its centre line. The ability of each blade 6,7 to pivot is restricted, firstly, by a blade stop 8 which prevents the bottom edge of the blade 6,7 from pivoting towards the front of the drag 1, and secondly, by springs 9 which bias the blade 6,7 against the blade stop 8.
The stiffness of the springs 9 (that is, the spring coefficient) is such that the blade 6,7 will only pivot (or "trip") when the blade 6,7 contacts a highly resilient object such as a large rock or tree stump. Fracture of the blade 6,7 is thus avoided.
Each spring 9 is anchored to the frame 2 such that when the blade 6,7 is resting against the blade stop 8, the centre line of the spring 9 is positioned approximately tangentially to the arc of rotation of the top of the blade 6,7.
The steel from which the blades 6,7 are made must not be too brittle, as the blades 6,7 must be able to withstand impact with fixed objects such as rocks or tree stumps.
B
20930~1 Pivotally attached to the front of the frame 2 is a tongue 10 which is capable of pivoting downward relative to the frame 2, but which is prevented from pivoting upward by a tongue stop 11. The pivoting action of the tongue is controllable by a front hydraulic ram assembly 12. This arrangement has two advantages.
Firstly, the front hydraulic ram assembly 12 can be used to adjust the height of the front of the drag 1. Consequently, the front of the drag 1 can be lifted clear of the ground (during transportation, for example). Similarly, the front of the drag 1 can be lowered so that the blades 6,7 contact the snow; in this way, blade depth is also controllable. Secondly, the tongue stop 11 allows the drag 1 to bend in an inverted-v-shape, but not in a v-shape. The result is that the length of the drag 1 is self-adjustable; that is, the drag 1 is shorter when it spans a convex surface, and longer when it spans a concave surface.
A drag with a self-adjusting length is important for several reasons. Firstly, if the length is too short, the drag will not affect undulations, that is, the drag will plane the entire surface equally. What is desired is to plane off bumps and fill in depressions. Secondly, if the length is too long, the drag will perform poorly over hills. Some problems are that the drag will teeter-totter at the top of the hill, scalp the top of the hill (that is, remove all the snow off it), dump the snow accumulated in the drag just before the top of the hill thus leaving a bump, and be unable to negotiate tight corners, especially in the forest.
A drag with a self-adjusting length is versatile, as it can perform effectively on a relatively flat trail (such as a rail bed) or on winding, undulating trails (such as may be found in a forest). Furthermore, since it is self-adjusting, little operating skill is required.
Attached to the back of the drag 1 is a flat pan 13 which, due to the weight of the drag 1, compresses the snow which has been planed and mixed by the blades 6,7.
Depending from the pan 13 are two skegs 14 which improve the tracking of the drag 1.
The depth to which the skegs 14 extend below the pan 13 is adjustable. Generally softer snow would indicate a need to have the skegs 14 extend deeper into the snow.
A wheel assembly 15, which includes a pair of wheels 16, trails the pan 13 and can be hydraulically pivoted up and down by a rear hydraulic ram assembly 17. It is preferable that the wheels 16 trail the pan 13, as wheels positioned before the pan 13 may interfere with the passage of snow through the drag 1.
During grooming, the wheel assembly 15 is pivoted up so that the wheel assembly 15 does not contact the snow. During transportation of the drag 1 (across a road, for example), the wheel assembly 15 is pivoted down so that the wheels 16 extend below the pan 13 and the drag 1 is lifted off the ground. Also during transportation, the front hydraulic ram assembly 12 is activated so as to lift the front of the drag off the ground (see Figure 10).
The tongue 10 consists of two sections linked together with a shear bolt 18. If the drag 1 jams against something (a tree, for example), the shear bolt 18 will break, and damage to the towing vehicle (not shown) and drag 1 will thus be limited.
When the tongue 10 comes apart, the rip-away hydraulic hoses 19 separate without a loss of fluid or damage to the hoses 19.
The length of the drag 1 is approximately 15 feet, as compared with the common prior art drags which are approximately 20 feet in length. As a result, the drag 1 is relatively light.
A light drag causes less wear on a tractor, and will let it perform better (in tight corners, for example, where a tractor tends to lose traction due to the rearward force exerted by the drag).
B
',_ Referring now to Figure 9, attached to the top of the drag 1 is a snowmobile platform 20 designed for ease of parking and removal of a snowmobile (not shown). The platform 20 is positioned high enough above the drag 1 so that it does not interfere with the snow passing through the drag 1. It is important to be able to carry a snowmobile both for safety and convenience reasons.
Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above with departing from the scope of the invention, which is defined in the claims.
B
The following blades 7 are oriented in an alternating fashion to assist in the mixing of the snow which has been rémoved from the trail.
Mixing the snow improves the trail in two ways. Firstly, the grain size of pieces of compacted snow and ice is reduced.
Secondly, different types of snow (for example, granular, powdery, wet, etc.) are mixed so as to form a more homogeneous product.
Each blade 6,7 is capable of pivoting approximately about its centre line. The ability of each blade 6,7 to pivot is restricted, firstly, by a blade stop 8 which prevents the bottom edge of the blade 6,7 from pivoting towards the front of the drag 1, and secondly, by springs 9 which bias the blade 6,7 against the blade stop 8.
The stiffness of the springs 9 (that is, the spring coefficient) is such that the blade 6,7 will only pivot (or "trip") when the blade 6,7 contacts a highly resilient object such as a large rock or tree stump. Fracture of the blade 6,7 is thus avoided.
Each spring 9 is anchored to the frame 2 such that when the blade 6,7 is resting against the blade stop 8, the centre line of the spring 9 is positioned approximately tangentially to the arc of rotation of the top of the blade 6,7.
The steel from which the blades 6,7 are made must not be too brittle, as the blades 6,7 must be able to withstand impact with fixed objects such as rocks or tree stumps.
B
20930~1 Pivotally attached to the front of the frame 2 is a tongue 10 which is capable of pivoting downward relative to the frame 2, but which is prevented from pivoting upward by a tongue stop 11. The pivoting action of the tongue is controllable by a front hydraulic ram assembly 12. This arrangement has two advantages.
Firstly, the front hydraulic ram assembly 12 can be used to adjust the height of the front of the drag 1. Consequently, the front of the drag 1 can be lifted clear of the ground (during transportation, for example). Similarly, the front of the drag 1 can be lowered so that the blades 6,7 contact the snow; in this way, blade depth is also controllable. Secondly, the tongue stop 11 allows the drag 1 to bend in an inverted-v-shape, but not in a v-shape. The result is that the length of the drag 1 is self-adjustable; that is, the drag 1 is shorter when it spans a convex surface, and longer when it spans a concave surface.
A drag with a self-adjusting length is important for several reasons. Firstly, if the length is too short, the drag will not affect undulations, that is, the drag will plane the entire surface equally. What is desired is to plane off bumps and fill in depressions. Secondly, if the length is too long, the drag will perform poorly over hills. Some problems are that the drag will teeter-totter at the top of the hill, scalp the top of the hill (that is, remove all the snow off it), dump the snow accumulated in the drag just before the top of the hill thus leaving a bump, and be unable to negotiate tight corners, especially in the forest.
A drag with a self-adjusting length is versatile, as it can perform effectively on a relatively flat trail (such as a rail bed) or on winding, undulating trails (such as may be found in a forest). Furthermore, since it is self-adjusting, little operating skill is required.
Attached to the back of the drag 1 is a flat pan 13 which, due to the weight of the drag 1, compresses the snow which has been planed and mixed by the blades 6,7.
Depending from the pan 13 are two skegs 14 which improve the tracking of the drag 1.
The depth to which the skegs 14 extend below the pan 13 is adjustable. Generally softer snow would indicate a need to have the skegs 14 extend deeper into the snow.
A wheel assembly 15, which includes a pair of wheels 16, trails the pan 13 and can be hydraulically pivoted up and down by a rear hydraulic ram assembly 17. It is preferable that the wheels 16 trail the pan 13, as wheels positioned before the pan 13 may interfere with the passage of snow through the drag 1.
During grooming, the wheel assembly 15 is pivoted up so that the wheel assembly 15 does not contact the snow. During transportation of the drag 1 (across a road, for example), the wheel assembly 15 is pivoted down so that the wheels 16 extend below the pan 13 and the drag 1 is lifted off the ground. Also during transportation, the front hydraulic ram assembly 12 is activated so as to lift the front of the drag off the ground (see Figure 10).
The tongue 10 consists of two sections linked together with a shear bolt 18. If the drag 1 jams against something (a tree, for example), the shear bolt 18 will break, and damage to the towing vehicle (not shown) and drag 1 will thus be limited.
When the tongue 10 comes apart, the rip-away hydraulic hoses 19 separate without a loss of fluid or damage to the hoses 19.
The length of the drag 1 is approximately 15 feet, as compared with the common prior art drags which are approximately 20 feet in length. As a result, the drag 1 is relatively light.
A light drag causes less wear on a tractor, and will let it perform better (in tight corners, for example, where a tractor tends to lose traction due to the rearward force exerted by the drag).
B
',_ Referring now to Figure 9, attached to the top of the drag 1 is a snowmobile platform 20 designed for ease of parking and removal of a snowmobile (not shown). The platform 20 is positioned high enough above the drag 1 so that it does not interfere with the snow passing through the drag 1. It is important to be able to carry a snowmobile both for safety and convenience reasons.
Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above with departing from the scope of the invention, which is defined in the claims.
B
Claims (17)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A drag for grooming snow surfaces comprising:
a frame having a front, a back and two sides;
two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface;
blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle;
wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface.
a frame having a front, a back and two sides;
two generally parallel, spaced apart rails depending from the sides of the frame, each rail having a front end substantially proximate the front of the frame and being slidable on a snow surface;
blade means, connected to the frame and disposed generally below the frame and between the rails, for contacting a snow surface during operation of the drag; and a tongue having a pivot end and a hitch end, the pivot end of the tongue being attached to the front of the frame to permit free downward pivotal movement of the frame and the tongue with respect to each other and including a stop to restrict upward pivotal movement of the frame and the tongue with respect to each other, and the hitch end of the tongue being adapted to attach to a towing vehicle;
wherein the drag is capable of being towed over a snow surface by a towing vehicle for removal of snow from bumps on the snow surface by the blade means, passage of snow thus removed between the rails and underneath the frame, and deposition of snow thus removed on the snow surface and in depressions in the snow surface.
2. A drag as defined in claim 1, wherein the upward pivotal movement of the tongue with respect to the frame is restricted beyond a substantially horizontal position.
3. A drag as defined in claim 1, further comprising a first pivoting means capable of pivoting the tongue relative to the frame, and also capable of allowing the tongue to pivot freely downward relative to the frame.
4. A drag as defined in claim 3, wherein the first pivoting means comprises a hydraulic ram assembly.
5. A drag as defined in claims 1, 2, 3 or 4 wherein:
the blade means comprises a pair of leading blades depending from the frame;
each leading blade having an adjacent end and a free end, the adjacent end being substantially adjacent one rail and the free end being angled towards the back of the frame;
each leading blade having a generally horizontal lower edge disposed generally below the frame;
the adjacent end of one leading blade being substantially proximate the front end of one rail, and the adjacent end of the other leading blade being substantially proximate the front end of the other rail.
the blade means comprises a pair of leading blades depending from the frame;
each leading blade having an adjacent end and a free end, the adjacent end being substantially adjacent one rail and the free end being angled towards the back of the frame;
each leading blade having a generally horizontal lower edge disposed generally below the frame;
the adjacent end of one leading blade being substantially proximate the front end of one rail, and the adjacent end of the other leading blade being substantially proximate the front end of the other rail.
6. A drag as defined in claim 5, wherein:
the blade means further comprises a plurality of following blades depending from the frame;
each following blade having an adjacent end and a free end, the adjacent end being substantially adjacent one rail and the free end being angled towards the back of the frame;
each following blade having a generally horizontal lower edge disposed generally below the frame;
the following blades being in staggered formation and being disposed between the leading blades and the back of the frame.
the blade means further comprises a plurality of following blades depending from the frame;
each following blade having an adjacent end and a free end, the adjacent end being substantially adjacent one rail and the free end being angled towards the back of the frame;
each following blade having a generally horizontal lower edge disposed generally below the frame;
the following blades being in staggered formation and being disposed between the leading blades and the back of the frame.
7. A drag as defined in claim 6, wherein there are four following blades.
8. A drag as defined in claim 5, wherein the distance between the front end of each rail and the adjacent end of the associated leading blade is in the range of 0 to 50 centimetres.
9. A drag as defined in claim 6, wherein the distance between each rail and the adjacent end of the associated leading blade and each following blade substantially adjacent thereto is in the range of 0 to 10 centimetres.
10. A drag as defined in claim 6, wherein the acute angle between each rail and both the associated leading blade and each following blade substantially adjacent thereto is in the range of 60 to 75 degrees.
11. A drag as defined in claim 6, further comprising a plurality of springs, wherein each leading blade and each following blade is pivotable about a generally horizontal axis, one or more springs bias one blade against a stopping means which prevents the blade from pivoting from its rest position to a position wherein the lower edge of the blade would be closer to the front end of the frame.
12. A drag as defined in claim 1, wherein the front ends of the rails are generally pointed and are thereby adapted to cut into bumps on a snow surface during operation of the drag.
13. A drag as defined in claim 1, further comprising a pan rigidly attached to the back of the frame and having a generally flat bottom surface adapted to compress snow, and at least one skeg depending from the pan to improve the tracking of the drag.
14. A drag as defined in claim 13, wherein the distance each skeg extends below the pan is adjustable.
15. A drag as defined in claim 13, further comprising:
a wheel assembly rollable in a direction generally parallel to the rails and attached to the back of the drag, such that the wheel assembly trails the pan, and such that the wheel assembly is pivotable in a generally vertical plane between first and second positions, the wheel assembly being above the snow surface in the first position, and the wheel assembly extending below the snow surface in the second position; and a second pivoting means capable of causing the wheel assembly to pivot between the first and second positions;
the arrangement being such that in the first position, the wheel assembly is out of contact with the snow surface, and in the second position, the back end of the drag is out of contact with the snow surface.
a wheel assembly rollable in a direction generally parallel to the rails and attached to the back of the drag, such that the wheel assembly trails the pan, and such that the wheel assembly is pivotable in a generally vertical plane between first and second positions, the wheel assembly being above the snow surface in the first position, and the wheel assembly extending below the snow surface in the second position; and a second pivoting means capable of causing the wheel assembly to pivot between the first and second positions;
the arrangement being such that in the first position, the wheel assembly is out of contact with the snow surface, and in the second position, the back end of the drag is out of contact with the snow surface.
16. A drag as defined in claim 15, wherein the first pivoting means comprises a hydraulic ram assembly.
17. A drag as defined in claim 1, further comprising wear plates removably attached to the bottom surfaces of the rails, the wear plates being slidable on a snow surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2093031 CA2093031C (en) | 1993-03-31 | 1993-03-31 | Drag for snow grooming |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2093031 CA2093031C (en) | 1993-03-31 | 1993-03-31 | Drag for snow grooming |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2093031A1 CA2093031A1 (en) | 1993-06-19 |
| CA2093031C true CA2093031C (en) | 1998-06-30 |
Family
ID=4151392
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2093031 Expired - Lifetime CA2093031C (en) | 1993-03-31 | 1993-03-31 | Drag for snow grooming |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2093031C (en) |
-
1993
- 1993-03-31 CA CA 2093031 patent/CA2093031C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2093031A1 (en) | 1993-06-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20130402 |
|
| MKEC | Expiry (correction) |
Effective date: 20131009 |