U.S. patent number 3,807,064 [Application Number 05/264,418] was granted by the patent office on 1974-04-30 for snow plow.
This patent grant is currently assigned to Firma Ing. Alfred Schmidt. Invention is credited to Alfred Schmidt, Jr..
United States Patent |
3,807,064 |
Schmidt, Jr. |
April 30, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
SNOW PLOW
Abstract
The present snow plow is especially adapted for attachment to
the front end of a carrier vehicle. In order to adapt the plow
blade to varying plow widths, there is provided a main blade and
extension blade means attached to one or both lateral ends of the
main blade. Power means are provided for moving the extension blade
means back and forth between an extended operating position and a
retracted rest position or to any desired intermediate position. In
a preferred embodiment the extension blade means comprise
telescoping sections which are driven by a piston cylinder
arrangement. Further, a power driven journal means is provided for
tilting the extension blade means. The telescoping and tilting
movements may be performed simultaneously.
Inventors: |
Schmidt, Jr.; Alfred (St.
Blasien, DT) |
Assignee: |
Firma Ing. Alfred Schmidt
(Blasien, DT)
|
Family
ID: |
5833884 |
Appl.
No.: |
05/264,418 |
Filed: |
June 20, 1972 |
Foreign Application Priority Data
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Jan 25, 1972 [DT] |
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2203271 |
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Current U.S.
Class: |
37/283; 37/105;
37/281; 172/815 |
Current CPC
Class: |
E01H
5/063 (20130101) |
Current International
Class: |
E01H
5/04 (20060101); E01H 5/06 (20060101); E01h
005/00 () |
Field of
Search: |
;37/41,42,44,50,117.5,105,106,104,46
;172/276,782,784,796,802,804,805 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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205,537 |
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Mar 1959 |
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OE |
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857,370 |
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Dec 1960 |
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GB |
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Primary Examiner: Pulfrey; Robert E.
Assistant Examiner: Eickholt; Eugene H.
Attorney, Agent or Firm: Fasse; W. G.
Claims
What is claimed is:
1. A snow plow comprising main blade means having lateral ends, a
snow facing forward surface and an opposite rear surface, lateral
extension blade means also having a respective snow facing surface
and a rear surface, journal shaft means operatively interposed
between said main blade means and said lateral extension blade
means for movably attaching said lateral extension blade means to
any of said lateral ends of said main blade means, hydraulic rotary
piston power drive means effectively interposed between said main
blade means and said journal shaft to drive the journal shaft for
journaling said extension blade means back and forth between a
working position in which the extension blade means form a working
extension of the main blade means and a rest position in which the
extension blade means are retracted, said snow plow further
comprising a bearing drum secured to said rear surface of said main
blade means at any of said lateral ends thereof, said driven
journal shaft being supported in said bearing drum and having an
upper end and a lower end extending out of said bearing drum, and
two rocker arms, each rocker arm being secured at one end thereof
to the extension blade means and at its opposite end to the
respective end of said journal shaft.
2. The snow plow according to claim 1, further comprising hinging
means secured to said main blade means substantially intermediate
the ends of the main blade means, connecting rod means connected at
a carrier vehicle, and means at the ends of said main blade means
for securing one of said ends at a time to the carrier vehicle
whereby the main blade may be tilted to the right or left.
3. The snow plow according to claim 1, wherein said driven journal
shaft extends in a vertical direction.
4. The snow plow according to claim 1, wherein said driven journal
shaft extends at an angle relative to the vertical.
5. The snow plow according to claim 4, wherein said blade means
have a longitudinal axis, said driven journal shaft extending at an
angle relative to a plane extending perpendicularly to said
longitudinal axis, said angle inclining the journal shaft in such a
manner that its upper end is inclined forwardly relative to an
advance direction of the blade means, whereby an outer end of said
extension blade means is lifted upwardly and reardly when the
extension blade means is tilted toward said rest position.
6. The snow plow according to claim 1, wherein said hydraulic
rotary piston power drive means are located in said bearing drum,
said journal shaft comprising an upper stump and a lower stump
connected to said power drive means and extending out of said
bearing drum.
7. The snow plow according to claim 6, wherein said rotary piston
hydraulic power drive means comprise two rotary pistons, one of
which is connected to said upper stump and the other of which is
connected to the lower stump.
8. The snow plow according to claim 7, further comprising hydraulic
control means operatively connected to said hydraulic rotary piston
power drive means to control said drive means for holding said
extension blade means in a yieldable manner in any position between
a fully extended position and a fully retracted position.
9. The snow plow according to claim 8, further comprising means for
adjusting said control means of said power drive means whereby the
extension blade means will yield in response to an applied external
force exceeding a predetermined force.
10. The snow plow according to claim 1, further comprising damping
means arranged relative to said extension blade means to cushion
the movement of the extension blade means into a fully extended
position and into a fully retracted position.
11. The snow plow according to claim 10, wherein said hydraulic
rotary piston power drive means act as said damping means for
gently moving said extension blade means into their respective
fully extended and fully retracted position.
12. The snow plow according to claim 1, further comprising
connecting means including a carrier frame of tubular frame members
extending longitudinally along said rear surface of said extension
blade means which are secured to said carrier frame.
13. A snow plow comprising main blade means having lateral ends, a
snow facing forward surface and an opposite rear surface, lateral
extension blade means also having front and rear surfaces and an
outer end, connecting means operatively interposed between said
lateral extension blade means and any of said lateral ends of said
main blade means whereby the lateral extension blade means are
movable relative to the main blade means, controlled power drive
means operatively connected to said extension blade means for
moving said extension blade means back and forth between an
extended position and a retracted position, said snow plow further
comprising automatic control means responsive to external forces
exerted on said extension blade means and operatively associated
with said controlled power drive means for automatically moving
said extension blade means in response to said external forces.
14. The snow plow according to claim 13, wherein said extension
blade means comprise a number of sections, said apparatus further
comprising telescoping means connected to and cooperating with said
extension blade sections for moving one of said sections relative
to the other.
15. The snow plow according to claim 14, wherein said extension
blade sections include at least an end section and an intermediate
section arranged between said end section and said main blade means
in such a manner that the rear surface of the end section overlaps
the snow facing front surface of the intermediate section.
16. The snow plow according to claim 15, wherein said controlled
power drive means comprise a piston cylinder arrangement connected
to said extension blade sections for effecting a substantially
horizontal stroke.
17. The snow plow according to claim 16, further comprising a
telescoping frame structure including a corresponding number of
sections, and connecting means operatively interposed between said
frame structure and said blade sections for connecting said blade
sections to a respective telescoping frame section.
18. The snow plow according to claim 13, wherein said outer end of
the lateral extension blade means comprises laterally outwardly
extending sensing means.
19. A snow plow comprising means having lateral ends, a snow facing
forward surface and an opposite rear surface, lateral extension
blade means also having a respective snow facing surface and a rear
surface, journal shaft means operatively interposed between said
main blade means and said lateral extension blade means for movably
attaching said lateral extension blade means to any of said lateral
ends of said main blade means, drive means connected to said
journal shaft to rotate the journal shaft for journaling said
extension blade means back and forth between a working position in
which the extension blade means form a working extension of the
main blade means and a rest position in which the extension blade
means are retracted, said extension blade means comprising a
plurality of sections and telescoping means operatively interposed
between adjacent ones of said sections for movably interconnecting
said sections to each other whereby said sections are movable
relative to each other.
20. The snow plow according to claim 19, wherein said journal shaft
extends in a vertical direction.
21. The snow plow according to claim 19, wherein said journal shaft
extends at an angle relative to the vertical.
22. The snow plow according to claim 21, wherein said blade means
have a longitudinal axis, said journal shaft extending at an angle
relative to a plane extending perpendicularly to said longitudinal
axis, said angle inclining the journal shaft in such a manner that
its upper end is inclined forwardly relative to an advance
direction of the blade means, whereby an outer end of said
extension blade means is lifted upwardly and rearwardly when the
extension blade means is tilted toward said rest position.
23. The snow plow according to claim 19, further comprising a
bearing drum secured to said rear surface of said main blade means
at any of said lateral ends thereof, said journal shaft being
supported in said bearing drum and having an upper end and a lower
end extending out of said bearing drum, and two rocker arms, each
rocker arm being secured at one end thereof to the extension blade
means and at its opposite end to the respective end of said journal
shaft.
24. The snow plow according to claim 23, wherein said drive means
are located in said bearing drum said journal shaft comprising an
upper stump and a lower stump connected to said power drive means
and extending out of said bearing drum.
25. The snow plow according to claim 24, wherein said drive means
comprise two rotary piston hydraulic drive means, and means for
securing said journal shaft stumps to the respective rotary piston
means.
26. The snow plow according to claim 19, further comprising
hydraulic control means operatively connected to said drive means
to control said drive means for holding said extension blade means
in a yieldable manner in any position between a fully extended
position and a fully retracted position.
27. The snow plow according to claim 26, further comprising means
for adjusting said control means of said drive means whereby the
extension blade means will yield in response to an applied external
force exceeding said predetermined force.
28. The snow plow according to claim 19, further comprising
connecting means including a carrier frame of tubular frame members
extending longitudinally along said rear surface of said extension
blade means which are secured to said carrier frame.
29. The snow plow according to claim 19, wherein said plurality of
extension blade sections includes at least an end section and an
intermediate section arranged between said end section and said
main blade means in such a manner that the rear surface of the end
section overlaps the snow facing front surface of the intermediate
section.
30. The snow plow according to claim 19, wherein said drive means
comprise power drive means operatively connected to said journal
shaft means for journaling said extension blade means, said snow
plow comprising further power drive means operatively connected to
said telescoping means for moving said extension blade sections
relative to each other.
31. The snow plow according to claim 19, wherein said telescoping
means comprise a frame structure including a corresponding
plurality of frame sections which are operatively connected to
respective ones of said extension blade sections.
32. The snow plow according to claim 19, wherein the lateral
extension blade means comprise lateral sensing means connected to
said lateral extension blade means at the outer end thereof.
33. The snow plow according to claim 19, further comprising
automatic control means responsive to external forces exerted on
said extension blade means and operatively associated with said
drive means for automatically journaling said extension blade means
in response to said external forces.
34. The snow plow according to claim 19, comprising further drive
means connected to said telescoping means for moving the extension
blade sections relative to each other, and automatic control means
responsive to external forces exerted on said extension blade means
and operatively associated with said further drive means for
automatically moving said extension blade means in response to said
external forces.
Description
BACKGROUND OF THE INVENTION
This invention relates to a snow plow, preferably for attachment to
the front end of a carrier vehicle.
In order to make an efficient use of snow plows it is desirable to
clear with each advance as wide a swath as possible especially
where rather wide surfaces are to be cleared, for example,
multi-lane highways, plazas, airport runways or the like.
Heretofore, snow plows with a conventional blade must make three
runs in order to clear, for example, a three lane turnpike. In
order to increase the efficiency of conventional snow plows, and
thus reduce the number of required carrier vehicles, and shorten
the time required for the clearing it has been suggested heretofore
to provide in addition to the snow plow supported at the front end
of the vehicle, further auxiliary snow plows attached to the sides
of the vehicle. Such auxiliary snow plows are attached to one or
both sides of the vehicle and are journaled approximately
intermediate the ends of the vehicle for an inward and outward
tilting of the auxiliary plow blades. This tilting movement is
controllable by the operator from the operator cabin. This makes it
difficult for the operator to visually monitor the positioning of
the auxiliary plow blades.
Another disadvantage of this arrangement is seen in that where
auxiliary snow plow blades are attached to both sides of the
vehicle it is not possible to transport the snow uniformly in one
direction. In other words, while the main plow blade and one
auxiliary blade would transport the snow in one direction, the
other auxiliary snow blade would have to transport the snow in the
opposite direction. Besides, additional receiving or holding
devices must be provided for securing the auxiliary plow blades to
the vehicle.
OBJECTS OF THE INVENTION
In view of the foregoing, it is the aim of the invention to achieve
the following objects singly or in combination:
TO PROVIDE A SNOW PLOW HAVING A BLADE WITH AN ADJUSTABLE SNOW
CLEARING WIDTH;
TO PROVIDE A SNOW PLOW CAPABLE OF CLEARING A SWATCH OF VARIABLE
WIDTH IN SUCH A MANNER THAT ALL THE REMOVED SNOW IS CLEARED AWAY IN
THE SAME DIRECTION;
TO ARRANGE THE PLOW BLADE IN SUCH A POSITION THAT THE OPERATOR MAY
HAVE THE ENTIRE WIDTH OF THE BLADE UNDER CONSTANT DIRECT VISUAL
OBSERVATION FROM HIS CABIN;
TO PROVIDE A MAIN PLOW BLADE WITH EXTENDABLE ENDS WHICH ENDS MAY
YIELD FROM A FULLY EXTENDED POSITION TO A SOMEWHAT MORE RETRACTED
OR FULLY RETRACTED POSITION WHEN A BLADE EXTENSION SHOULD CONTACT
AN OBSTACLE, PREFERABLY, THE YIELDING SHOULD BE JUST SUFFICIENT TO
CLEAR THE OBSTACLE;
TO PROVIDE POWER MEANS FOR THE RETRACTION OF THE EXTENSION BLADE
MEANS;
TO PROVIDE A COMBINATION OF TELESCOPING EXTENSION BLADE MEANS WHICH
MAY SIMULTANEOUSLY BE TILTED INTO A REST POSITION;
TO PROVIDE AUTOMATIC CONTROL MEANS WHICH WILL ASSURE A YIELDING IN
RESPONSE TO EXTERNAL FORCES EXERTED ON THE EXTENDABLE BLADE MEANS
SO THAT THESE MAY YIELD AUTOMATICALLY WITHOUT ANY ACTION BY THE
OPERATOR; AND
TO PROVIDE FURTHER CONTROL MEANS WHICH WILL ENABLE THE OPERATOR TO
ALSO CONTROL THE MOVEMENT OF THE EXTENSION BLADE MEANS.
SUMMARY OF THE INVENTION
According to the invention there is provided a snow plow or an
attachment snow plow in which the main blade is extended beyond the
width of the vehicle on one or both lateral sides or ends of the
main blade by lateral extension blade means whereby the movability
of these extension blade means is accomplished by telescoping means
and/or by journal hinge means.
Where telescoping means and journal hinge means are employed in
combination it is preferable to operate both moving means; namely,
the telescoping means as well as the hinging means simultaneously
whereby the length of the radius of a cricle is reduced which is
described by the outer end of the extension blade means. The
journal axis for the hinge means may take up a vertical position or
in an aternative embodiment it may be slightly inclined in a
forward direction. This has the advantage that the swinging of the
extension blade into its retracted position simultaneously lifts
the outer end of the extension blade slightly upwardly whereby
obstacles may be cleared.
According to the invention the main blade may be extended by the
length of the extension blade or by the length of two extension
blades one of which is attached to each end of the main blade. If
the road to be cleared is of normal width, the extension blade or
blades are tilted into a rest position backwardly toward the
vehicle. The extension blades are kept in this retracted position
also when the vehicle moves along a road without the need of
clearing it, for example, from a garage to a place where clearing
is to be performed.
Where the extension blade means comprise several sections, it has
been found to be advantageous that an end section overlaps with its
rear surface the snow facing front surface of an intermediate
section located between the main blade and the end section. In this
instance the several sections of the extension blade means are
connected to each other by telescoping means so that an end section
will slide along the front face of an intermediate section when the
end section is retracted.
BRIEF FIGURE DESCRIPTION
In order that the invention may be clearly understood, it will now
be described, by way of example, with reference to the accompanying
drawings, wherein:
FIG. 1 illustrates a top plan view of the front portion of the
carrier vehicle having attached thereto a snow plow according to
the invention;
FIG. 2 is a top view similar to that of FIG. 1, however, on a
slightly enlarged scale and omitting the vehicle as well as most of
the main blade; only the left hand end of which is shown;
FIG. 3 shows a rear view onto the extension blade means as it would
appear substantially from the vehicle and viewing in a forward
direction;
FIG. 4 is a view similar to that of FIG. 3, however, illustrating
the left hand end section of the extension blade means;
FIG. 5 shows a side view of the end section according to FIG. 4 as
viewed from its free end; and
FIG. 6 is a hydraulic circuit diagram for the actuation of the
extension blade means according to the invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
FIG. 1 illustrates a top plan view onto the carrier vehilce 1 to
the front end of which there is attached a snow plow 2 by means of
arms 3 and 4. The position of these arms 3 and 4 is adjustable in a
conventional manner for adjusting the elevational position of the
snow plow 2. Further, one end of each arm 3 and 4 is hinged to a
vertical axis 11. The opposite end of the arms 3 and 4 is coupled
to the front end of the vehicle by coupling means 5 and 6. As
shown, the snow plow 2 is tilted for removing the snow from left to
right. However, by disconnecting the latching means 7 and 9 from
each other, tilting the plow about the vertical axis 11 and
connecting latching means 8 and 10 to each other, the plow will be
in a position for removing the snow from right to left. The
latching means 7 to 10 may comprise secured bolts extending through
respective holes in a conventional manner.
The vehicle 1 will advance in the direction indicated by the arrow
F and the above mentioned directions of snow removal are to be
understood with respect to such direction of vehicle advance.
The snow plow 2 comprises a center piece 12 to which is attached
the main blade comprising several sections 13, 14, 15, 16, and 17.
According to the invention extension blade means 18 are movably
attached to the left hand end 23 of the main blade of the snow plow
2. The extension blade means 18 are hinged to a journal axis
19.
The retracted or rest position of the extension blade means 18 is
shown in FIG. 1 by dash-dotted lines. The extension blade means 18
will also be kept in the retracted position where the length of the
main blade is sufficient for accomplishing the desired clearing
width. If desired, extension blade means 18 may be attached to one
end of the main blade as shown in FIG. 1 or to both of the main
blade, or merely to the opposite end.
The extension blade means 18 comprise, for example, two blade
sections 25 and 26. The extension blade section 25 has a rear
surface 20 and an outer end 21. The extension blade section 26 has
a rear surface 26' and forms an intermediate blade member. The
blade sections 25 and 26 are movably connected to each other for a
telescoping movement whereby the entire extension of the extension
blade means may be reduced by the length B shown in FIG. 1. It has
been found to be satisfactory to select the telescoping length B so
it corresponds approximately to the maximal height H of the segment
of the circle K along which the outer tip 21 of the extension blade
section 25 moves when the extension blade means are tilted about
the axis 19. The just mentioned segment and thus its height H is
defined by a line extending in parallel to the forward direction of
vehicle advance and through the tip 21 of the end section 25, when
the latter is in its fully extended position.
The retracting of the end section 25 simultaneously with the
backward tilting of the extension blade means 18 as will be
described in more detail below, has the advantage that the backward
tilting may be accomplished even if the available space as defined
by the circle K is not available. This may, for example, be the
case where the road runs along adjacent to a wall or where a lane
extends along a separating boundary wall.
The outer end 21 of the outer blade section 25 is preferably
provided with a supporting means or element 22 such as a skid or a
supporting roller schematically indicated at 22. Such a skid or
roller will prevent that the outer end of the extension blade means
becomes interlocked with a lateral obstacle. When the skid or
roller 22 contacts a lateral obstacle, an external force will be
exerted on the extension blade means and such force may be employed
to control automatically the withdrawal of the extension blade
means.
Incidentally, the entire snow plow including the main blade and the
extension blade means may be supported on the ground by means of
wheels, preferably wheels provided with air tires. Such wheels are
conventional and therefore not shown.
FIG. 2 illustrates the extension blade means 18 in a plan view of a
somewhat larger scale as compared to FIG. 1. The main blade of the
snow plow 2 is provided with an adapting end portion 23 and the
intermediate section 26 of the extension blade means 18 is held in
such a position that it contacts the left hand edge of the portion
23 in a flush manner to form an abutting contact 24. In FIG. 2 the
extension blade means are shown in their fully extended position in
which the rear surface 20 of the outer end extension section 25
overlaps the front surface of the intermediate blade section 25 to
the extend L. The extension blade means 18 are rigidly connected to
a shaft 37 by means of a double arm rocker bracket 27 which will
journal with its shaft 37 about the axis 19. In this manner the
extension blade means are tiltable as described above with
reference to FIG. 1.
It has been found that the just described overlap of the end
section 25 in front of the intermediate section 26 has the
advantage that a strong but nevertheless movable connection may be
accomplished between the two extension blade sections so that
external forces may be taken up, presumably because the
intermediate section provides a guide for the outer end
section.
The movable interconnection between the extension blade sections 25
and 26 is accomplished by a telescoping frame structure to be
described below and by a piston cylinder arrangement 29 positioned
for a substantially horizontal stroke. The cylinder 30 is connected
to the frame structure 47 of the intermediate blade section 25 by
hinge means 31. The piston rod 32 is connected to the frame
structure 55 of the end section 25 by hinge means 33. The
dash-dotted lines in the lower right hand corner of FIG. 2 indicate
the rest or retracted position of the extension blade means 18.
There are several possibilities of movably connecting the extension
blade means to the main blade. One possibility is illustrated in
FIG. 3 wherein journal means are provided for hinging the rocker
bracket 27 for a tilting movement about the axis 19. The journal
means comprise a bearing drum 34 which is rigidly connected to the
rear surface of the main blade. Two drive motors, for example,
rotary piston hydraulic drive motors 35 and 36 are supported in the
bearing drum 34. The drive motor 35 has an upwardly pointing stump
37 which is rigidly connected through a bushing 39 to an upper arm
41 of the rocker bracket 27. The drive motor 36 has a downwardly
extending shaft stump 38 connected through the bushing 40 to the
lower arm 42 of the rocker bracket 27. The shaft stumps or ends 37,
38 are rigidly connected to the bracket 27 so that rotation of the
shafts 37, 38 about the axis 19 will journal the entire bracket 27.
The bracket 27 comprises in addition to the upper arm 41 and the
lower arm 42 vertical connecting means including tubular members
43, 44, 45, and 46. A horizontal tubular member 47 of the above
mentioned frame structure is rigidly connected to the rocker
bracket 27 between the vertical tubular members 44 and 45, for
example, by respective weldments. A further tubular member 48 of
the frame strucutre is welded to the bracket between the tubular
members 45 and 46. The frame structure further comprises vertical
ribs 49 and 50 secured to the rear surface 26' of the intermediate
extension blade section 26. The horizontal tubular members 47 and
48 are rigidly connected to these vertical ribs 49 and 50. The
vertical members 43 and 44 of the bracket 27 are releasably
connected to each other by means of flanges 51 and 52 in order to
facilitate the assembly. The end section 25 of the extension blade
means 18 is similarly supported. A frame structure comprising
vertical ribs 53 and 54 and horizontal tubular members 55 and 56
support the end section 25. Thus, the vertical ribs 53 and 54 are
rigidly connected to the rear surface 20 of the end section 25. The
horizontal tubular members 55 and 56 are in turn rigidly connected
to the vertical ribs 53 and 54. The outer dimensions of the tubular
members 55 and 56 are such that these members fit into the tubular
members 47 and 48 of the frame structure secured to the
intermediate blade section 26. Accordingly the two sections 25 and
26 may telescope relative to each other. This has the advantage
that the radius of the tilting arc K may be reduced and thus the
retraction of the extension blade means 18 may be accomplished
within the clearing width. The right hand ends 57 and 58 of the
horizontal tubular members 55 and 56 respectively reach to the
extent shown in FIG. 3 into the tubular members 47 and 48.
Depending upon the length of the stroke of the hydraulic piston
cylinder arrangement 29, the end section 25 may be drawn-in to the
extent A as shown in FIG. 3 until the vertical rib 54 touches the
left hand edge 59 of the intermediate blade section 26.
Accordingly, the extent or length A determines the maximum
shortening of the extension blade means including the end section
25. In order not to interfere with the sliding movement of the
tubular members 55 and 56, the vertical rib 50a which is connected
to the rear surface of the adapting end portion 23, is provided
with apertures 28a and 28b.
FIG. 4 illustrates a rear view of the end section 25 disconnected
from the intermediate section 26. This view shows still more
clearly the connection of the vertical ribs 53 and 54 to the rear
surface 20 of the blade section 25 and the connection of the
tubular telescoping frame members 55 and 56 to the ribs 53 and 54.
Hollow sectional members 60 and 61 are welded in an abutting
fashion to the rear surface 20 of the blade section 25. Further,
these hollow sectional members 60 and 61 are welded to each other
to form a T. These sectional members 60 and 61 bear with their
surface facing the viewer against the front surface of the
intermediate blade section 26 whereby the length of overlap depends
upon the instantaneous telescoped position of the two blade
sections relative to each other. In any event, even in the fully
extended position, the overlap L shown in FIG. 2 will be
maintained. Further, the blade section 25 is provided along its
lower side with a clearing edge 63 gliding along the ground 62.
FIG. 5 shows a side view of the end section 25 with its clearing
edge 63 and the carrier frame including the tubular members 55 and
56 as well as the rib 53. The rib 54 is not seen since it is
located in back of rib 53. The tubular members 55 and 56 are
connected by a cross piece 64 which also may be of tubular cross
section. The hinge means 33 comprise two connecting pieces 65 and
66 welded to the cross piece 64. The left hand end of the piston
rod 32 is connected to these pieces 65 and 66. The piston cylinder
arrangement 29 is not seen in FIG. 5. The above mentioned channel
members 60 and 61 which preferably have a U-cross-sectional shape
not only act as guide means but also reinforce the extension blade
25 since these guide and reinforceing channel members 60 and 61 are
welded to the rear surface 20 of the blade section 25. The lower
rear side of the blade section 25 is further forified by a channel
member 67 having an extension 68. The channel member and the
extension are preferably welded to the lower edge of the blade
section 25.
Referring further to FIG. 5, there is illustrated a preferred
position for the journal axis 19. In this embodiment the journal
axis 19 is slightly inclined at an angle .alpha. in the forward
direction F and relative to a plane P extending perpendicularly to
the longitudinal extension of the snow plow blades. This slightly
forwardly inclined position of the journal axis 19 has the
advantage that the outer end of the extension blade means 18 is
raised when the extension blade means 18 are tilted backwardly
whereby minor obstacles, for example, protruding man hole covers
may be easily cleared.
Referring to the hydraulic circuit diagram of FIG. 6 the operation
of the present snow plow will now be described. By means of the
hydraulic control circuit it is possible to journal the extension
blade means 18 back and forth and to telescope the extension blade
sections 25 and 26 relative to each other.
If the extension blade means 18 of the snow plow contact an
obstacle protruding from the ground, a pressure increase will be
produced in the hydraulic system which maintains the outwardly
tilted position of the extension blade means 18. This hydraulic
system includes the rotary piston motors 35 and 36 as well as the
pressure supply means connected thereto. These pressure supply
means include a safety valve 69 which may be adjustable to a
selectable minimum response pressure, for example, about 120 bar.
As soon as such preadjusted pressure is exceeded, the safety valve
69 opens the conduit 72 between the storage 70 and the oil sump 71.
Corresponding to the rearward tilting of the extension blade means
18 in response to the movement of the vehicle against the obstacle,
oil is displaced from the hydraulic motors 35 and 36 into the sump
71. Simultaneously, the pressure in the storage 70 which contains a
gas bubble is increased due to the pressure increase in the conduit
system. Depending upon whether or not the obstacle may be cleared
by the backward tilting of the extension blade means, the latter
will yield only partially or completely until the rest position is
reached as indicated by the dash-dotted lines in FIG. 1. Thus, the
extension blade means 18 will be yieldingly held in any
intermediate position. In other words, the larger the external
force in excess of a certain predetermined minimum force, the
extension blade means will yield to that extent and will then be
held in any intermediate tilted position by a hydraulic counter
force so that damage to the equipment is avoided.
As mentioned above, due to the forwardly tilted position of the
axis 19 it is possible to clear a relatively low obstacle by merely
slightly tilting the extension blade means backwardly whereby the
outer end thereof is lifted sufficiently for clearing such a
relatively low obstacle. However, where higher obstacles must be
cleared the extension blade means may have to be tilted backwardly
to a larger extent or even completely. In any event, the pressure
build up in the storage 17 will maintain the extension blade means
under a yielding counter force as described above. When the
obstacle has been cleared, the operator may return the extension
blade means into their fully extended position by interrupting the
conduit circuit 73 through the biasing valve 72'. Whereas in the
shown position of the conduit circuit 73 and the valve 72' the pump
74 may operate without pressure. In the interrupting position of
the valve 72' hydraulic fluid is supplied through the conduit 75
and the pilot or control valve 76 to the conduit 77 and thus to the
motors 35 and 36. It is assumed that the valve 76 is in its open
position rather than in its shown neutral position. The just
described supply of hydraulic fluid to the rotating piston motors
35 and 36 accomplishes the journaling of the rocker bracket 27 and
thus the tilting of the extension blade means 18 in an outward
direction.
In addition to the above described automatic inward tilting and the
operator controlled outward tilting, the operator may also effect
an intentional inward tilting. In this case the conduit 73 is again
closed or interrupted by the valve 72 and the pilot or control
valve 76 is moved into its closed position. The pump 74 then
removes hydraulic liquid from the drive motors 35 and 36 through
the conduits 78 and 79 whereby the removed liquid is returned into
the oil sump 71. A pressure limiting device 80 which may be an
adjustable valve similar to valve 69 is connected to the pump 74
and to the conduit 75 on the one hand to the sump 71 on the other
hand. This pressure limiter 80 assures the safety of the
system.
The telscoping of the extension blade sections 25 and 26 relative
to each other is, as described above, controlled by the piston
cylinder arrangement 29 also schematically shown in FIG. 6. The
pressure in cylinder 30 is maintained continuously through the
conduit 81 so that the end section 25 will normally be kept in its
fully extended position. If the end section 25 hits a lateral
obstacle with its skid or roller 22, an external force is exerted
on the piston rod 32 and thus on the respective piston so that the
latter will be moved to the right whereby the pressure in the
system is increased. The hydraulic fluid which is displaced by the
rightward movement of the piston 32 in the cylinder 30 is collected
in the storage 82. When the obstacle has been cleared and the
external force on the end section 25 is removed, the pressure in
the storage 82 will cause a back flow of the hydraulic liquid into
the cylinder 32 whereby the piston is again moved to the left. As a
result, the end section 25 is again telescoped outwardly into its
original extended position.
In order to compensate for leaking losses which will cause a
pressure decrease in the conduit 81, a pressure monitoring device
83 is connected to the conduit 81. This pressure monitoring device
83 controls the biasing valve 84 in such a manner that the valve is
switched from its shown position in which the conduit is
interrupted to its open position in which the conduit 81 is
connected to the conduit 75 and thus to the pump 74. This
connection of the conduit 81 to the pump 74 is accomplished in
response to a pressure decrease below a predetermined pressure as
ascertained by the pressure monitor device 83. As a result, the
pump will restore the desired pressure by supplying hydraulic
liquid to the pressure conduit 81 whereby such restored pressure
will have a value above the minimum pressure to which the
monitoring device 83 will respond.
Incidentally, the end skids or roller 22 may be employed as sensing
means for transmitting a signal to the operator's cabin in response
to contacting an obstacle.
As described above with regard to the intentional control of the
outward tilting of the extension blade means 18 by the operator, it
is also possible to provide in addition to the automatic restoring
movement a control for intentionally telescoping the end section 25
outwardly. In other words, the operator would have a control means
for actuating the piston cylinder arrangement 29. For this purpose
there would be provided a pilot or control valve similar to valve
76 for controlling the supply and the removal of hydraulic liquid
from the cylinder 30. The control means will usually be arranged in
a housing attached to the front end of the carrier vehicle.
Moreover, these control means will be connected to the source of
hydraulic power conventionally present in such vehicles.
Although the invention has been described with reference to
specific example embodiments, it is to be understood that it is
intended to cover all modifications and equivalents within the
scope of the appended claims.
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