Plow Attachment for a Forklift Truck

This invention relates in general to an attachment for a forklift truck, and more particularly to a plow attachment for a forklift truck which can be easily and quickly secured to the tines of the forklift truck to facilitate the moving of material along the ground with the forklift, such as the removal and clearing of snow.

Heretofore, it has been well known to use plow attachments on the front of vehicles such as light and heavy-duty trucks for moving materials along the ground, such as snow removal and clearing and for other purposes. It has also been known to attach a plow to a forklift truck. For example, U.S. Pat. No. 3,470,631 shows a floating hitch construction for a snowplow attachment for a self-powered lift truck. However, such devices available on the market are bulky, complex, and relatively expensive. Accordingly, there is a need for an inexpensive and simple plow attachment for a forklift truck which can be easily and quickly attached and detached from the tines of the forklift truck. Moreover, since such a device may only be infrequently used, the device should be compact, requiring minimum storage space when not in use.

The present invention overcomes the above problems in providing a plow attachment for a forklift truck which has a simple, inexpensive, and compact construction, which requires little storage space, and which can be easily attached to or detached from the tines of a forklift truck to remove or clear snow or other materials.

More particularly, the plow attachment of the present invention includes a frame which is adapted to be releasably connected to the tines and a blade assembly connected to the frame at the end opposite the tines. The frame generally includes spaced-apart elongated tubular members or tubes adapted to releasably receive the tines. The tubular members are interconnected by three spaced-apart transversely extending crossbars. Each tubular member has a ground-engaging member extending downwardly from the bottom of each tube to the ground, and each ground-engaging member includes a replaceable plastic shoe for engagement with the ground. The blade assembly including a blade and replaceable resilient sweep member, is pivotally attached to the tubular members of the frame. A shear pin assembly is connected between the blade and the frame to accommodate abnormal forces subjected to the blade by obstructions in the path of the blade by releasing the blade from the plow position thereby protecting the blade against damage. A further embodiment of the invention includes a hinged connection between the tubular members and the crossbars to allow the angling of the blade in either direction.

It is therefore an object of the present invention to provide a plow attachment for a forklift truck which has a simple, compact, and inexpensive construction.

A further object of the present invention is to provide a plow attachment for a forklift truck which can be easily attached to and detached from the tines of the forklift truck.

A further object of the present invention is to provide a plow attachment for a forklift truck which prevents damage to the blade by obstructions on the ground.

Another object of the present invention is to provide a plow attachment for a forklift truck for removing and clearing snow from the ground.

Another object of the present invention is to provide a plow attachment for a forklift truck which requires little storage space when not in use.

A further object of the present invention is to provide a plow attachment for a forklift truck which can be easily assembled and disassembled.

A still further object of the present invention is to provide a plow attachment for a forklift truck which is easily adjusted on the tines of the forklift truck to vary the angle of the blade.

Other objects, features, and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts.

FIG. 1 is a perspective view of the plow attachment of the present invention mounted on the tines of a standard forklift truck which is shown in fragmentary;

FIG. 2 is a side view of the plow attachment;

FIG. 3 is a rear view of the plow attachment;

FIG. 4 is a top plan view of the plow attachment;

FIG. 5 is a bottom plan view of the plow attachment;

FIG. 6 is an enlarged sectional view of the locking mechanism on the tubular member of the plow attachment positioned on a tine and taken substantially along line 6--6 of FIG. 4;

FIG. 7 is an enlarged cross-sectional view of the knuckle joint and shear pin assembly on the frame taken substantially along line 7--7 of FIG. 2;

FIG. 8 is a cross-sectional view of the shoe mounted on the foot of the ground engaging member taken substantially along line 8--8 of FIG. 2;

FIG. 9 is a perspective view of a further embodiment of the plow attachment of the present invention mounted on the tines of a forklift truck and having an adjustably anglable blade;

FIG. 10 is an enlarged fragmentary top plan view of the hinge joint between the crossbar and the tubular member of the plow attachment of FIG. 9;

FIG. 11 is a enlarged cross-sectional view of the hinge assembly attaching the blade to the tubular member of the plow attachment of FIG. 9 taken substantially along line 11--11 of FIG. 9; and

FIG. 12 is a enlarged cross-sectional view of the hinge joint taken substantially along line 12--12 of FIG. 10.

Referring now to the drawings, and particularly to FIGS. 1 to 5, the plow attachment of the present invention for use on a forklift truck, generally indicated by numeral 20, is releasably attachable to a conventional forklift truck 22. The forklift truck 22 includes a main body or vehicle supported by ground engaging wheels 24, a lifting and tilting mechanism 26 attached to the front of the main body, and a fork defined by two tines 28 and 30 extending substantially horizontally from the front of the lifting mechanism 26. The tines 28 and 30 may be vertically raised and lowered, tilted forward and backward to some degree, and moved closer or farther apart. The plow attachment 20 includes a frame 40 which is adapted to be releasably connected to the tines 28 and 30 and a blade or plow assembly 42 connected to the frame 40. The frame and the blade assembly of the plow forklift attachment of the present invention may be made from suitably strong steel which will withstand the forces subjected by the forklift truck and the tines. It should be appreciated that the plow attachment of the present invention could be made from other suitable materials or a combination of materials such as tough and/or light-weight plastics.

The frame 40 of the plow attachment 20 generally includes two parallel spaced-apart elongated tubular members or tubes 44 and 46 interconnected by three spaced-apart transversely extending crossbars 48, 50, and 52. The frame 40 further includes ground-engaging members 54 and 56, respectively, which are attached to the bottom of each tube. More particularly, the rectangular elongated steel tubular members 44 and 46 have top walls 44a and 46a, bottom walls 44b and 46b, interior side walls 44c and 46c, and exterior side walls 44d and 46d, respectively, as best illustrated in FIGS. 3 and 6. The crossbars 48, 50, and 52 are likewise formed from tubular steel members, the ends of which are attached to and between the interior walls 44c and 46c of tubes 44 and 46. The crossbars may be attached to the tubes by welding, or alternatively could be attached by other suitable methods such as by conventional connectors or brackets. Tubes 44 and 46 have openings 58 and 60 sized to receive the tines 28 and 30, as seen in FIGS. 1, 3, and 6. Tubes 44 and 46 are preferably of a sufficient length and size such that they freely receive a significant portion of the length of the tines when the tines are inserted into the tubes. This enables the operator of the forklift to control the height and tilt of the plow attachment through the movement of lift mechanism 26 and the tines 28 and 30.

The tubes 44 and 46 further include locking mechanisms 64 and 66 for releasably connecting or securing the tubes to selected positions on the tines after the plow attachment 20 is mounted on the tines. More specifically, locking mechanism 66, as seen in greater detail in FIG. 6, includes a threaded shaft 70 which is threadedly received in a conventional hex nut 72 having an interior screw-threaded surface. The bottom surface of the hex nut 72 is welded or otherwise suitably secured to the upper surface of the top wall 46a of tube 46 and is positioned above an aperture 74 formed in the top wall 46a. The aperture 74 is sized larger than the shaft 70 to allow the shaft to freely rotate into and out of tube 46. Alternatively, the top wall 46a could be constructed with an aperture having an interior screw-threaded surface for threadedly receiving the shaft 70, thereby eliminating the need for the hex nut 72. For either case, the shaft 70 has two ends, one end disposed inside tube 46 and the opposite end disposed outside the tube 46 above the top wall 46a. A handle 76 for rotating the shaft is suitably attached to the exposed or outer end of the shaft 70. A hold-down plate 78 is suitably attached to the opposite end of shaft 70 which is disposed within the tube 46. The hold-down plate 78 is circular, although it may have any suitable configuration. Once the tine 30 is inserted into the tube, the handle 76 is manually rotated clockwise to lower the hold-down plate 78 into tightened engagement with the tine 30, thereby locking the plow attachment 20 to the forklift truck 22. Depending upon the length of the tines, the end of the tines may engage the interior surface of the end wall 46c in each tube. Also depending upon the length of the tines, the ends of the tubes adjacent openings 58 and 60 may abut against the lift member 26. The bottom surface of the hold-down plate 78 is adapted to engage the top surface of the tine 30 to maintain the tube at a preselected position on the tine. When the user desires to remove the plow attachment from the forklift, the hold-down plate 78 is disengaged from the tine 30 by manually rotating the handle 76 counterclockwise, thereby raising the hold-down plate 78 away from the tine. The tine may then be removed from the tube. The bottom surface of the hold-down plate may be suitably formed or provided with a material to increase the frictional engagement between the hold-down plate and the tine.

As noted above, the frame 40 includes ground-engaging members 54 and 56 extending downwardly from the tubes 44 and 46, respectively. The ground-engaging members 54 and 56 are constructed from steel tubular front legs 80 and 82 and steel tubular rear legs 84 and 86, all of which are suitably attached to the bottom walls 44b and 46b of the tubes 44 and 46, such as by welding. The rear legs 84 and 86 extend substantially vertically downwardly from the tubes while the front legs 80 and 82 extend downwardly at an angle and rearwardly toward the rear legs. This allows space for the blade to pivot backward when the blade hits an obstruction in its path and the shear pin breaks, as discussed below. The lower ends of the front and rear legs are suitably connected to steel tubular ground-engaging feet 88 and 90, respectively. The feet 88 and 90 extend substantially horizontally between the front and rear legs and engage the ground when the plow attachment 20 is unattached to the forklift truck. These ground-engaging members 54 and 56 maintain the tubes in a substantially horizontal position prior to and during the insertion of the tines into the tubes to facilitate the insertion and removal of the tines from the tubes.

The feet 88 and 90 have removable and/or replaceable shoes 92 and 94 which are snugly snapped or mounted thereon for engaging the ground as the plow attachment moves or slides along the ground. As further illustrated in FIG. 8, shoe 94 is an elongated U-shaped member which includes a ground-engaging sole 96, two spaced-apart upstanding side members 98 and 100 connected to the sole 96 at substantially right angles, and two opposing spaced-apart flanges or tongues 102 and 104 connected to the top ends of the sides 98 and 100 at substantially right angles. Shoe 94 is thereby adapted to snap on to the foot 90 and, when the sole is worn, snap off the foot prior to replacement. The shoes 92 and 94 are preferably made from a plastic material having a low coefficient of friction and/or a self-lubricating plastic material. In addition to reducing the friction between the plow attachment and the ground, the shoes protect the pavement and legs against metal-to-pavement contact, thus providing a replaceable wear element. An example of the material used for the shoe would be Delrin, which is a registered trademark of E. I. Du Pont de Nemours & Co., Inc. of Wilmington Del. The shoes may be formed in other suitable configurations and may be made from other suitable materials. Further, the entire ground-engaging member could be made of plastic.

The plow attachment 20, as noted above, has a blade assembly 42. The blade assembly 42 includes a standard blade 110 suitably sized and bent in a concave shape for clearing snow or other materials. The blade is preferably made of steel, but could be made of other suitable materials. A conventional resilient sweep member 112 made of rubber or plastic as is well known in the blade art is attached to the bottom of the blade for engaging the ground. The resiliency of the sweep member allows the blade to engage protrusions and/or minor obstructions without damage to the blade as well as preventing excessive wear to the blade. The sweep member 112 is preferably replaceable. The bottom of the blade assembly and the ground-engaging members are aligned in substantially the same plane such that the plow attachment standing alone rests in a substantially horizontal position. Moreover, when the plow attachment 20 is lowered by the forklift into engagement with the ground to clear materials such as snow, the ground-engaging members coact to cause the blade to contact the ground at the appropriate angle without the blade digging into the ground.

The blade assembly 42 is pivotally attached to the frame 40 by conventional knuckle joints 120, 122, and 124. Knuckle joints 120 and 122 are attached to the closed ends 44e and 46e of the tubes 44 and 46 and provide a pivotal connection at the back of the blade 110. The knuckle joints 120 and 122 are attached to the blade at a level to properly position the blade on the frame such that the blade will properly engage the floor during operation. The knuckle joints 120 and 122 include male projections 120a and 122a and female projections 120b and 122b, respectively. Each of the projections have horizontally aligned disposed eyes or slots (not shown) adapted to receive a pin (not shown) in a conventional manner to pivotally connect the blade to the tubes. While the female projections are shown attached to the blade and the male projections are shown attached to the tubes, their positions could be reversed. Moreover, other conventional fastening methods could be employed to pivotally attach the blade to the frame 40 on a horizontal axis.

The third knuckle joint 124 is attached to the back of the blade at a lower horizontal level than knuckle joints 120 and 122, as seen in FIG. 2. More specifically, the female projections 124b of the knuckle joint 124 are attached to the blade and the male projection 124a is attached to one end of a shear bar 130 to pivotally connect the blade to the bar. The tubular steel shear bar 130 extends at an angle from the blade upwardly and is pivotally connected to the crossbar 50 by a further knuckle joint and shear pin assembly 132, as illustrated in FIG. 7. This knuckle joint and shear pin assembly 132 includes a pair of female projections 134a and 134b attached to and extending downwardly from the bottom of the crossbar 50, and a single male projection 136 attached to the end of the shear bar 130. The male and female projections define corresponding horizontally extending eyes which are adapted to receive a conventional shear pin 138. When the ground is too steep and or when the blade hits or engages an obstruction in its path, the force of which is greater than the strength of the shear pin 138, the shear pin breaks and the blade pivots backward about knuckle joints 120 and 122 to avoid damage to the blade. The blade does not engage the front legs 80 and 82 because they are angled toward the rear of the plow attachment. After the shear pin is broken, the blade must be pivoted back to its original position, the broken shear pin pieces must be removed, and a new shear pin must be inserted to continue to use the plow. In such situations, adjustment of the height and/or angle of the tines may be necessary to replace the shear pin and/or to continue plowing operations. This simple construction significantly reduces the costs of the plow attachment of the present invention and prevents the blade from being damaged. It will be appreciated that the shear pin may have a head on one end and a standard C-ring lock on the other end to maintain the pin in the knuckle joint.

An alternative embodiment of the plow forklift attachment of the present invention, generally indicated by numeral 100, is illustrated in FIGS. 9 to 12. The forklift attachment 100 is similar to forklift attachment 20 except that it includes hinge assemblies 152 for pivotally connecting the crossbars 48, 50, and 52 to the tubular members 44 and 46, and hinge assemblies 170 for attaching the frame 40 to the blade assembly 42 for pivotal movement on both horizontal and vertical axes.

Each hinge assembly 152 may consist of a knuckle joint as described above, or may be similar to a door-type hinge as further illustrated in FIGS. 10 and 12 to allow suitable pivot movement between the crossbars and tubular members. For example, hinge 152 connecting tube 44 and crossbar 52 includes a pair of semi-cylindrical projections 154a and 154b attached to the interior wall 44a of tube 44 and a pair of semi-cylindrical projections 156a and 156b attached to the end of the crossbar 52. These projections define vertically extending eyes or apertures through which a pin or a bolt 158 is inserted to connect the crossbar to the tube. The pin 158 preferably includes a slot 160 for a linchpin 162 or other suitable locking means which releasably locks the pin 158 in place while allowing for the removal of the pin and easy disassembly of the plow attachment 150. If a bolt is employed, a standard collar, lock washer and nut could be used to complete the hinge assembly.

Forklift attachment 150 further includes hinge assemblies 170 for connecting the frame 40 to the blade 110 which define both horizontal and vertical pivot axes to allow pivotal movement horizontally and vertically, as illustrated in FIGS. 9 and 11. Hinge assembly 170 includes a pair of female projections 174a and 174b attached to and extending from the end of tubular member, opposite opening 60, and a male projection 172 attached to and extending from one side of a bracket 176. The projection 172 has a vertically extending eye adapted to align with eyes in projections 174a and 174b for suitably receiving pin 177. The opposite side of bracket 176 has a male projection 178 adapted to mate with two female projections 180a and 180b attached to the blade 110. This arrangement defines a universal connection that provides for the angling of the blade in conjunction with the frame and for the pivoting of the blade relative to the frame. This type of hinge assembly also connects the shear bar 130 to both the blade and the crossbar 50. It should be appreciated that the construction of the hinges or joints could vary in keeping with the present invention.

This hinged arrangement of the plow attachment of the present invention enables the user to place the tubes on the tines at different positions to angle the blade as desired, as specifically shown in FIG. 9. This allows the user to push the snow or other materials straight ahead, or either to the right or left of the truck, depending on the location desired for the plowed material. This also allows the user to change the direction of the blade at any time during use, and it will be appreciated a lever arrangement could be provided to assist in angling the plow.

This hinged construction further facilitates the shipment of the plow attachment to the customer unassembled, as pins and linchpins may be used at each pivot connection, and allows the customer to easily and quickly assemble the plow attachment. Likewise, this construction allows the plow attachment to be disassembled when not in use. When disassembled, the plow attachment would use a minimum of storage space.

Although not shown in FIGS. 1 to 12, a further embodiment of the present invention includes one or more tine stopping pins or members which may be inserted into the tubular member for preventing the tine from moving forward in the tubular members due to the force of the blade against pushing the material such as show. More particularly, one or more sets of aligned vertical holes may be formed in the top and bottom walls of the blade end of tubular members. A pin or bolt may be inserted in and suitably secured in the set of aligned holes to provide a stop member in the tube which is adapted to engage the end of the tine. This stop member would prevent the tines from sliding further into the tube due to forces on the blade during normal operation.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.