US3807064A

US3807064A - Snow plow

Info

Publication number: US3807064A
Application number: US00264418A
Authority: US
Inventors: Alfred Schmidt Jr
Original assignee: Ing Alfred Schmidt GmbH
Current assignee: Ing Alfred Schmidt GmbH
Priority date: 1972-01-25
Filing date: 1972-06-20
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: JPS5038407B2; NO133816C; CA958885A; CH536392A; JPS4886333A; FR2176477B1; DE2203271B2; FR2176477A1; DE2203271A1; NO133816B; IT951250B; AT320010B

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.

Description

[451 Apr. 30, 1974 SNOW PLOW Alfred Schmidt, Jr., St. Blasien, Germany [73] Assignee: Firma Ing. Alfred Schmidt, Blasien,

Germany 22 Filed: June 20, 1972 21 Appl. No.: 264,418

[75] Inventor:

[30] Foreign Application Priority Data Jan. 25, 1972 Germany 2203271 [52] US. Cl 37/41, 37/50, 37/105, 172/805 [51] Int. Cl E0lh 5/00 [58] Field of Search 37/41, 42, 44, 50, 117.5,

FOREIGN PATENTS OR APPLICATIONS 205,537 3/1959 Austria ..37/42 857,370 12/1960 Great Britain 172/804 Primary ExaminerRobert E. Pulfrey Assistant Examiner-Eugene H. Eickholt Attorney, Agent, or FirmW. G. Passe [5 7] 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.

34 Claims, 6 Drawing Figures FATENTEUAPR 30 m4 3807064 vSHEET 1 [IF 6 PATENTEUAPR 30 1974 07, 4

sum 3 OF 6 APR 30 I974 3 807 064 sum u or 6 FIG 4 PATEMTED APR 3 0 I974 sum 5 BF 6 w @I E RAW I I 1 I I x a w M R w I. J T T 1 E U g E om w I Um mowzww @mbmwwmm mxfi 2 3 k mm 5 SNOW PLOW BACKGROUND OF THE INVENTION 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 1 l. 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 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 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 toselect 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 re tracted 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 assemblyv 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

tubularmembers

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 2812.

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. I-Iollow 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 1.. 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 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-crosssectional 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 a 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 tilt ing 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 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 operators 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.

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. 1

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. I

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 forwardlyrelative 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.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,807,064 Dated April 30, 1974 Alfred Schmidt. Jr.

Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Assignee: Firma Ing. Alfred Schmidt, St. Blasien, Germany Column 8, line 65 after "at" insert -one end thereof to said hinging means and at the other end to Column 10, line 36 after "comprising" insert -main blade- Signed and sealed this 17th day of September 1974.

(SEAL) Attest:

C. MARSHALL DANN MCCOY M. GIBSON JR. Attesting Officer Commissioner of Patents USCOMM-DC 60376-P09 w u 5. GOVERNMENT PRINYING OFFICE: was 0-!68-334,

F' ORM PO-1OS0 (10-69)

Claims

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.

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.

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.

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.

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.