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(11) | EP 2 154 294 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Extendible scraper blade |
| (57) A bottom blade of a working vehicle, comprising a main blade (1) provided with a
first cutting edge (2) and slide guides (3) in the direction of the main blade. A
slide frame (4) has been directed to move in the direction of the main blade in the
guidance of the slide guides (3). An extension blade (5) has been connected to the
slide frame (4) to move relative to the main blade between a first position (I) and
a second position (II). In the first position (I), the extension blade (5) is protruded
outside the end of the main blade (1). In the second position (II), the extension
blade (5) is retracted to a position where the extension blade and the main blade
are disposed substantially one upon the other. A second cutting edge (6) is provided
in the lower part of the extension blade. A power means (7) acts between the slide
frame (4) and the main blade (1) to move the extension blade (5) between the first
position (I) and the second position (II). The extension blade (5) is jointed to the
slide frame (4) by a joint (7) to turn about a pivoting axis (X) in the direction
of the main blade (1) so that in the first position (I) of the extension blade when
the main blade is pressed against the underlying ground (R) the extension blade (5)
turns relative to the main blade to a turned position (A) in which the second cutting
edge (6) is aligned with the first cutting edge (2).
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FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION
[0002] Bottom blades are used in working vehicles, such as trucks and tractors, in road maintenance to shape and/or work on the masses.
[0003] The bottom blade is provided under the frame of a vehicle between the axles. The bottom blade may be used both in summer and winter. In winter, plowing the snow, grading thick ice and removing the slush may be performed by a bottom blade simultaneously with the other road maintenance tasks. In summer, working on gravel roads, moving and grading of gravel and other masses can be performed efficiently with a bottom blade.
[0004] Known from the prior art is a bottom blade of a truck comprising a main blade provided with a first cutting edge in the lower part thereof to be contacted with the underlying ground. A slide frame has been directed to move in the direction of the main blade in the guidance of slide guides. An extension blade has been connected to the slide frame to move relative to the main blade between a first position and a second position. In the first position, the extension blade is protruded to a distance outside the end of the main blade. In the second position, it is retracted to a position where the extension blade and the main blade are disposed one upon the other. The extension blade is provided with a second cutting edge in the lower part thereof to be contacted with the underlying ground. An extending/shortening type power means, such as a hydraulic cylinder, has been arranged to act between the slide frame and the main blade to move the extension blade between the first position and the second position.
[0005] A problem with the known bottom blades provided with an extension blade is that when the extension blade is protruded, it is disposed on the front or back side of the main blade during use, depending on which side of the main blade it has been provided on. In this case, the cutting edges of the main and the extension blade are not aligned with to each other. This causes discontinuity in the work result, so that at the extension blade the working depth is different, for example deeper or lower, than at the main blade. In addition, the difference in the working depths varies according to the angle in which the main blade is tilted relative to the underlying ground.
OBJECTIVE OF THE INVENTION
[0007] In particular, the objective of the invention is to disclose a bottom blade in which the cutting of the extension blade is always aligned with the cutting edge of the main blade on the same cutting level during use, irrespective of the current angle relative to the underlying ground set for the main blade.
SUMMARY OF THE INVENTION
[0008] The bottom blade according to the invention is characterized by what has been presented in claim 1.
[0009] According to the invention, the extension blade is jointed by a joint to the slide frame to turn about a pivoting axis parallel to the main blade so that in the first position of the extension blade when the main blade is pressed against the underlying ground the extension blade turns relative to the main blade to a turned position in which the second cutting edge is aligned with the first cutting edge.
[0010] The advantage of the invention is that the second cutting edge of the extension blade always works in alignment with the first cutting edge of the main blade on the same cutting level, irrespective of the current angle set for the main blade relative to the underlay so that the extension blade and the main blade always provide the same cutting depth.
[0011] In one embodiment of the bottom blade, the extension blade is on the front side of the main blade and the slide frame is on the back side of the main blade.
[0012] In one embodiment of the bottom blade, a stop is mounted to the main blade and fitted to stop the turning of the extension blade in the position where the first cutting edge and the second cutting edge are aligned with each other.
[0013] In one embodiment of the bottom blade, the joint is above the main blade and on the back side thereof.
LIST OF FIGURES
[0014] In the following section, the invention will be described in detail by means of examples of its embodiments and with reference to the accompanying drawing in which
Fig. 1 is a perspective side view of a part of one embodiment of the bottom blade according to the invention as seen obliquely from the back,
Fig. 2 shows the bottom blade of Fig. 1 when the extension blade is in a retracted position,
Fig. 3 shows the bottom blade of Fig. 2 when the extension blade is in a protruded position,
Fig. 4 shows the bottom blade of Fig. 2 and 3 pressed against the ground,
Fig. 5 is a side view of the bottom blade in the position of Fig. 2 or 3,
Fig. 6 is a side view of the bottom blade in the position of Fig. 4, and
Fig. 7 illustrates tilting of the bottom blade of Fig. 6.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Fig. 1 is a view of the left side end of a bottom blade mountable under a working vehicle, such as a truck or a tractor. Fig. 2 to 4 illustrate the bringing of an extension blade 5 of the bottom blade into a service position.
[0016] Referring to Fig. 1 to 4, the bottom blade comprises a main blade 1. The lower part of the main blade 1 is provided with a first cutting edge 2 to be contacted with the underlying ground. Arranged on the back side of the main blade 1 are slide guides 3 in the direction of the main blade to guide a slide frame 4 to move in the direction of the main blade 1. A hydraulic cylinder 7 is connected at one end to the main blade and at the other end to the slide frame 4 to move an extension blade 5 between a first position I and a second position II. The extension blade 5 has been connected to the slide frame 4 to move relative to the main blade 1 between the first position I and the second position II.
[0017] In the first position I presented in Fig. 3 and 4 the extension blade 5 is protruded to a distance 1 outside the end of the main blade 1.
[0018] In the second position II presented in Fig. 1 and 2 the extension blade 5 is retracted to a position where the extension blade 5 and the main blade 1 are disposed substantially one upon the other so that the extension blade 5 is on the front side of the main blade 1. The lower part of the extension blade 5 is provided with a second cutting edge 6 to be contacted with the underlying ground.
The figures show that the first cutting edge 2 and the second cutting edge 6 are so-called stud blades, but it is apparent that any cutting edge suitable for the current task, such as a flat blade, perforated blade, serrated blade, is applicable.
[0019] The extension blade 5 has been jointed to the slide frame 4 with a joint 7 to turn about a pivoting axis X in the direction of the main blade 1. The joint 7 is positioned above the main blade 1 on the back side thereof. The joint 7 is formed by a shaft mounted to the extension blade 5 and a bushing mounted to the slide frame 4, the shaft being fitted with a bearing to rotate inside the bushing.
[0020] As seen from Fig. 4, when the extension blade 5 is in the protruded first position I and the main blade is pressed against the underlying ground R, the extension blade 5 turns back relative to the main blade 1 to a turned position A in which the second cutting edge 6 is aligned with the first cutting edge 2.
[0021] As seen from Fig. 1, 5 and 6, mounted to the back side of the main blade 1 is a stop 8 formed by two flanges welded to the main blade. The stop 8 stops the turning of the extension blade 5 so as to not turn further than the position A where the first cutting edge 2 and the second cutting edge 6 are aligned with each other as presented in Fig. 6.
- a main blade (1) provided with a first cutting edge (2) in the lower part thereof to be contacted with the underlying ground (R) and comprising slide guides (3) in the direction of the main blade,
- a slide frame (4) directed to move in the direction of the main blade in the guidance of the slide guides (3),
- an extension blade (5) connected to the slide frame (4) to move relative to the main blade between a first position (I) and a second position (II), so that in the first position (I) the extension blade (5) is protruded to a distance (1) outside the end of the main blade (1) and in the second position (II) the extension blade (5) is retracted to a position where the extension blade and the main blade are disposed substantially on upon the other, the extension blade being provided with a second cutting edge (6) in the lower part thereof to be contacted with the underlying ground, and
- an extending/shortening type power means (7) arranged to act between the slide frame (4) and the main blade (1) to move the extension blade (5) between the first position (I) and the second position (II), characterized in that the extension blade (5) has been jointed to the slide frame (4) with a joint (7) to turn about a pivoting axis (X) in the direction of the main blade (1) so that in the first position (I) of the extension blade when the main blade is pressed against the underlying ground (R) the extension blade (5) turns relative to the main blade to a turned position (A) in which the second cutting edge (6) is aligned with the first cutting edge (2).