US3448880A - Article grasping device for fork lift trucks - Google Patents

Description

June 10, 1969 w, HOWARD Y 3,448,880

ARTICLE GRASPING DEVICE FOR FORK LIFT muons 7 Filed Feb. 23. 1966 Sheet of 4 INVENTOR WILL/AM E. HOWARD A T TORNE VS June 10, 1969 w. E. HOWARD j 3,448,380

ARTICLE GRASPING DEVICE FOR FORK LIFT TRUCKS Filed Feb. 23, 1966 Sheet 2 of 4 FIG.& 2 I42 June 10,-1969 w. E. HOWARD 3,448,880"- ARTICLE GRASP ING DEVICE FOR FORK LIFT TRUCKS Filed Feb. 23. 1966 Sheet 3 M4 103. ,I i 0 /l0 1 I J/ M m 102 I 42 m 6 as "$6 58 40 32" FIG 9 I I 82 86 v 32 l 74 88 0"} I 1 0 I02 a 1m 70 {03 as 92 l c 102 54 58 54, 1 I :5? 5-7 I f7 36 F' I G. 7

June 10, 196 9 w. E. HOWARD 3,448,880

ARTICLE GRASPING DEVICE FOR FORK LIFT TRUCKS Filed Feb. 23. 1966 Sheet 4 0f 4 FIGJQG United States Patent US. Cl. 214-620 9 Claims ABSTRACT OF THE DISCLOSURE A device attachable to the fork of a fork lift truck permits the truck to grasp, pick up and release an article such as a drum while the operator remains on the truck and without the need for an assistant or powered parts. Two opposing article grasping pads are located on the two prongs of the fork for movement about vertical axes between spread article receiving positions and closed article grasping positions, and are biased toward the article receiving positions so that as an empty fork is moved toward an article the engagement of the pads with the article moves the pads toward their article grasping position. The pads are additionally supported for rotation about axes which are coaxially arranged when the pads are in their article grasping positions to allow the pads and the article grasped thereby to be rotated after the article is picked up by raising the fork. The pads are also supported by carriers which swing about horizontal axes generally parallel to the fork prongs. During an article receiving process the pads are swung upwardly about these latter axes to increase the spacing between the pads, and as the fork is thereafter raised the weight of the article swings the pads downwardly about these axes to decrease the spacing therebetween and to thereby cause the article to be firml grasped.

This invention relates to fork lift trucks, and deals more particularly with a device usable with a fork lift truck to enable the truck to grasp and lift a relatively rigid article.

Conventionally, fork lift trucks are operated to lift articles by inserting the fork of the truck beneath the article or beneath a pallet on which one or more articles are loaded, the fork when lifted vertically supporting the article by engaging the bottom of the article or pallet. When no pallets are used, this method of operation requires either that the articles handled be manually loaded onto and off of the fork or that some special provision be made for allowing the fork to pass freely under the articles during loading and unloading. To overcome this problem, an object of this invention is the provision of a device whereby a fork lift truck, when used to handle relatively rigid articles of a fairly uniform size and shape, may engage and grasp such an article at its sides, and with sufficient clamping force to enable the article to be lifted and manipulated without slipping, thereby eliminating the need for pallets, manual loading or other special provisions. Through the use of a device embodying this invention, a fork lift truck may be used to pick up andreplace an article directly from or onto a floor or similar flat surface without the operator leaving the truck and without any other manual assistance.

In some of its aspects, the invention may be embodied in a device constructed and adapted solely to lift articles, but a further object of the invention is to provide a device of the foregoing character whereby the article after being grasped and lifted may be rotated about a generally horizontal axis to change the orientation of the article. In keeping with this object, a more specific object is to pro- 3,448,880 Patented June 10, 1969 vide a device of the foregoing character especially adapted to handle open-topped trash drums or similar containers, so that without leaving the truck an operator may pick up a container, carry it to another point, rotate it to dump its contents, and then replace it at will at any convenient location in its normal upright position.

Another object of this invention is to provide a device of the foregoing character which may be made as a simple attachment to a standard fork lift truck and which uses the normal movements of the truck to elfect the grasping, release and rotation of the ,handled article, thereby eliminating the need for any additional motors or actuators and associated control mechanisms,

Other objects and advantages of the invention will be apparent from the following description and from the drawings forming a part hereof.

The drawings show a preferred embodiment of the invention and such embodiment will be described, but it will be understood that various changes may be made from the construction disclosed, and that the drawings and description are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

FIG. 1 is a side elevational view of a fork lift truck equipped with an article grasping device of this invention and adapted for handling drums, this view showing the device in its article grasping position relative to a drum resting on the ground;

FIG. 2 is a view generally similar to FIG. 1, but shows the device with the drum raised from the ground and rotated to a dumping position;

FIG. 3 is an enlarged top view of the article grasping device of FIG. 1, the device in this view being shown in its empty or article receiving position;

FIG. 4 is a view similar to FIG. 3, but showing the article grasping device in its article grasping position;

FIG. 5 is a still further enlarged top view of one of the pressure pad assemblies of the article grasping device of FIG. 1, the pressure pad assembly in this view being shown in its article grasping position;

FIG. 6 is a vertical sectional view taken on the line 66 of FIG. 5;

FIG. 7 is a vertical sectional view taken on the line 7--7 of FIG. 6;

FIG. 8 is a view generally similar to FIG. 5, but shows the pressure pad assembly with the parts thereof in the positions occupied at a point intermediate the article receiving and article grasping positions;

FIG. 9 is a vertical sectional view taken on the line 9-9 of FIG. 8;

FIGS. 10a, 11a, 12a and 13a are simplified or schematic front end views of the article grasping device of FIG. 1 and show the sequence of movements involved in moving the device into grasping relation with a drum;

FIGS. 10b, 11b, 12b and 13b are simplified or schematic top views corresponding respectively with the end views of FIGS. 10a, 11a, 12a and 13a.

Turning now to the drawings and first considering FIGS. 1, 2, 3 and 4, a device embodying the present invention is shown attached to a conventional fork lift truck 12 having a vertical mast 14 at its forward end. The mast 14 includes a stationary part of column 16 and a vertically movable part or column 18, the movable part 18 having fixed thereto a fork 20, the portion of the movable part to which the lifting fork is attached being often referred to as a lifting carriage. Raising and lowering movement of the column 18 relative to the column 16, to raise and lower the fork 20, is effected by one or more hydraulic actuators or other conventional motors controlled by the operator of the truck by means of a control lever 22 mounted on the steering column 24, or elsewhere near the steering column, so as to be easily manipulated by the operator while he remains in a driving position on the truck. The fork is of conventional construction and, as shown best in FIGS. 3 and 4, includes two horizontal and transversely spaced prongs 26, 26 which extend forwardly from the mast 14.

The article grasping device of this invention is carried by the prongs 26, 26 of the fork 20 and includes two pressure pad assemblies, indicated generally at 28 and 30. The pressure pad assemblies 28 and 30 are substantially identical to one another, are associated respectively with the two fork prongs 26, 26, and are located directly opposite to one another near the forward ends of the prongs. Each pressure pad assembly includes a pressure pad 32 having an article engaging surface 34 conforming generally to the shape of the side surface of the article to be handled. In the illustrated case, the device is designed for use in handling steel drums, such as the one indicated at 36 in the various figures, and therefore the pressure pads 32, 32 are arcuately curved to provide arcuately curved article engaging surfaces 34, '34 conforming generally to the circular shape of the side walls of the drums which are handled. It should be understood, however, that the invention is not necessarily limited to the handling of drums or other generally cylindrical articles and that by using differently shaped pressure pads articles of other shapes may also be handled. For example, by using pressure pads with substantially planar article engaging surfaces the device of the invention may be used to handle articles such as rectangular boxes having flat vertical side surfaces.

FIG. 3 shows the pressure pad assemblies 28 and 30 in their article receiving positions, and when the assemblies are in such positions the pressure pads 32, 32 are in a generally forwardly diverging relationship to one another so that their forward edges 38, 38 are spaced apart by a distance greater than the thickness of drum 36. Therefore, the drum 36 in FIG. 3 may be moved to a position between the pressure pads by moving the pressure pad assemblies 28 and 30 forwardly toward the drum, this being accomplished by the operator driving the fork truck 12 forwardly. As explained in more detail hereinafter, the pressure pad assemblies 28 and 30 are movable, by engagement with the drum 36, from the receiving positions of FIG. 3 to the grasping positions of FIG. 4. When in their grasping positions, the pressure pads 32, 32 engage diametrically opposite sides of the drum 36, and the spacing between the article engaging surfaces 34, 34 is slightly less than the normal outside diameter of the drum so that the drum is slightly deformed when grasped to produce a large clamping force between the pressure pads and the drum, this in turn creating sulficient friction between the pressure pads and the drum to prevent the drum from slipping vertically relative to the pressure pads as the pressure pads are raised to lift the drum.

In addition to use for merely grasping and lifting a drum from the ground or other support, the pressure pad assemblies 28 and 30 are also designed to permit rotation of the pressure pads 32, 32 about a common transverse axis, after the drum is grasped and raised, for dumping the contents of the drum or for any other purpose. To illustrate this feature, FIG. 1 shows the drum 36 grasped by the grasping device of this invention but with the fork 20 in a lowered position at which the drum rests in its normal position on the ground. From this position, the drum is movable to the position shown in FIG. 2 at which it is raised from the floor and inverted. The drum 36 may, for example, as is often done in machine shops, have an open top and be used as a container for receiving scrap or trash. The device of the invention is therefore conveniently used for picking up such drums and for rotating them to dump their contents into another larger receptacle or conveyance.

The pressure pad assemblies 28 and 30 may be directly attached to the associated fork prongs 26, 26, but as shown in the illustrated case, they are preferably carried by a separate frame which fits over the prongs and which is quickly and easily attached to and removed from the prongs to allow the truck 12 to be quickly converted from normal use to use with the grasping device, and vice versa. The frame may take various different forms and as shown comprises two channel members 40, 40 each of which in use overlies and receives a respective one of the prongs 26, 26. Each channel member 40 is slightly shorter than the associated prong and extends from the forward end of.the prong to a point spaced slightly from the vertical rear portion of the prong. To the top surface of each channel member is Welded a spacer plate 42 which extends rearwardly beyond the channel member and which is engageable with the vertical rear portion of the prong to properly locate the channel member on the prong.

The two channel members 40, 40 are connected to one another by a third channel member 44 extending transversely between the members 40, 40 and welded at each end to the adjacent member 40. For releasably holding the frame to the fork prongs, each channel member 40, adjacent its rear end, threadably receives a retaining screw 46 provided with a handle enabling it to be easily turned by hand. Each screw 46 passes through the associated channel member 40 and is engageable at its lower end with the top surface of the associated prong. Directly beneath each retaining screw, as shown in FIGS. 1 and 2, the associated channel member 40 includes a plate 48 extending transversely across the bottom of the prong and welded to the side flanges of the channel member. Therefore, by tightening the screw 46 the associated prong is tightly clamped between the screw 46 and the associated plate 48 to firmly retain the frame on the prongs.

The details of the construction of the pressure pad assemblies 28 and 30 may be best understood by reference to FIGS. 3 to 9. FIGS. 5 to 9 are enlarged views of the right-hand assembly 30, and the left-hand assembly 28 is substantially an exact mirror image counterpart of the right-hand assembly except that the assembly 30 includes a semi-circular segment 50 of a V-grooved pulley used in cooperation with a cable 52 to rotate the pressure pad assemblies, as described in more detail hereinafter. Referring to these figures, each pressure pad assembly inchides a base plate 54 which rests flatly on top of another bearing plate 56 welded to the top surface of the associated channel member 40. Adjacent the laterally inner edge of the bearing plate is a vertical pivot pin 58 which isfixed to the bearing plate 56. The pin 58 extends upwardly loosely through an opening in the base plate 54 and restrains the latter to pivoting movement relative to the associated prong 26 about the vertical axis of the pivot pin 58. Welded to the channel member 40 adjacent thelaterally outer edge of the bearing plate is an L-shaped retaining member 57 having an upper horizontal leg, see FIGS. 6 and 9, which is spaced above the bearing plate to form a channel for receiving the laterally outer end portion of the base plate 54. This latter leg of the member 57 is therefore engageable with the base plate to prevent its outer end from being moved upwardly by the weight of the drum.

Movement of the base plate 54 about the pivot pin 58 is limited to movement between the two positions shown in FIGS. 3 and 4, and suitable stop-means are provided for arresting the movement of the base plate in both directions. In the illustrated case, these stop means include an upstanding lug 58 provided on each channel member 40 behind the associated base plate and engageable with the base plate, as shown in FIG. 3, to limit the movement of the base plate toward its article receiving position. Another stop lug 60 extends upwardly from the forward edge of each bearing plate 56 and is engageable with the adjacent edge of the base plate to limit the movement of the base plate in the direction toward its article grasping position of FIG. 4. Each base plate is biased toward the article receiving position of FIG. 3 by a helical tension spring stretched between the base plate and an arm on the associated stop lug 58.

The base plate 54 of each pressure pad assembly includes two vertically extending ears 64 and 66 which are spaced from one another along the length of the associated channel member 40 when the base plate is in the article grasping position shown in FIGS. 4, 5 and 8. Between the two base plate ears 64 and 66 is a U-shaped carrier 68 having two upwardly projecting legs spaced laterally from one another when the base plate 1s in ts article grasping position. Adjacent the bottom of its laterally outer leg the carrier 68 is pivotally connected to the ears 64, 66 of the base plate by a horizontal plvot pin 70. The carrier 68 is therefore capable of pivotal movement relative to the base plate about the ax s of the pivot pin 70 between a normal or lowered position, as shown in FIG. 6, and a raised position, as shown 1n FIG. 9. Movement of the carrier toward the raised position of FIG. 9 is arrested by a stop post 71 carried by the base plate ear 66.

The carrier 68 rotatably supports an intermediate part 72 for rotation about an axis located above and arranged generally perpendicular to the axis of the pivot pin 70.

More particularly, the intermediate part 72 includes a' generally cylindrical shank portion 74 which passes loosely through conforming openings in the two arms of the carrier so as to be rotatable relative thereto. The shank portion 74 is externally threaded along a part of its length and is axially fixed relative to the carrier by a thrust bearing 76, two locking nuts 78, 78 and a collar 80, the collar 80 being releasably fixed to the outer end of the shank portion by a set screw or similar means. ThlS arrangement allows the intermediate part 72 to be moved to various different positions of axial adjustment relative to the carrier 68, by shifting the locking nuts 78, 78 and the collar 80, to vary the spacing between the two pressure pads 32, 32 to allow the device to be used for handling drums or other articles of various different sizes. In FIG. 5, for example, the solid lines show the pressure pad 32 at one position of adjustment of the intermediate part 72, and the broken lines show the same pad at another adjusted position of the intermediate part.

At its inboard end the intermediate part 72 of each pressure pad assembly includes a head 82 having two flat parallel side surfaces engaged respectively by two parallel spaced ears fixed to the pressure pad '32 and pro ecting laterally outwardly therefrom. The pressure pad 32 is pivotally connected to the head 82 by a pivot pm 86 passing through the cars 84, 84 and through the head 82. Normally the pin 86 is positioned with its axis horizontal and parallel to the axis of the carrier pivot pm 70. As shown in FIGS. 6 and 9, the movement of the pressure pad relative to the head 82 is limited in both directions by two generally inwardly facing surfaces 88 and 90 on the inner end of the head 82, the surface 88 being engageable with the outer surface of the pad 32 to limit movement of the pad in one direction and the surface 90 being engageable with the outer surface of the pad to limit its movement in the other direction. A biasing spring 92 is received in a blind opening in the head '82 and works between the head and the pressure pad 32 to urge the pressure pad to the position shown in FIG. 6 whereat the movement of the pad is arrested by the stop surface 88, the pad 32 in this position being generally perpendicular to the axis of the intermediate part 72. In FIGS. 6 and 9 the pad ear 84 facing the viewer has been omitted to more clearly show the structure of the head '82 and the arrangement of the spring 92.

As mentioned, the pivot pin 86 is normally parallel to the pivot pin 70, and to hold the head 82 in the position required to achieve this orientation of the pin 86, a biasing means is provided between the carrier 68 and the intermediate part 72. In the illustrated case, this biasing means, as shown best in FIG. 7, comprises a spiral torsion spring '94 surrounding the shank portion 74 of the part 72 and having a radially inwardly directed inner end received in an axially elongated slot 96. The outer end of the spring is formed into a circular loop surrounding a post 98 fixed to the inboard leg of the carrier. As the intermediate part 72 is adjusted axially relative to the carrier 68, the inner end of the spring 94 may slide in the slot 96. The spring 94 is so designed as to have a normal undeformed shape such as shown in FIG. 7 so that when no torque is imposed between its ends the spring holds the intermediate part 72 in the FIG. 9 position. The spring 94 therefore resists movement of the intermediate part 72 in either direction about its axis from its neutral position at which the pivot pin 86 is horizontal and parallel to the pin 70. When the pressure pads 32, 3-2 are rotated, however, to invert the grasped article, the two intermediate parts 72, 72 are rotated about their axes and the two springs 94, 94 are deformed and provide a restoring force for later returning the article to its normal position.

As will be evident from FIG. 4, when the two pressure pad assemblies 28 and 30 are in their article grasping positions, the axes of the two intermediate parts 72, 72 are colinear so that the drum 36 or other grasped article may be rotated by rotating the two parts 72, 72 simultaneously about their common axis. The means for effecting the rotation comprises the previously mentioned V- grooved pulley segment 50 which is welded or otherwise secured to the outwardly facing side of the associated pressure pad 32. The segment 50' is arranged, generally concentric with the axis of the part 72. It is approximately 180 in angular extent and is located forwardly of a vertical plane passing through the axis of the part 72, when the pressure pad is positioned as in FIG. 1. The cable '52 normally passes over the pulley segment 50 and has its outer end fixed to a lug 99 attached to the outer surface of the pad 32 adjacent the upper end of the segment 50. From the bottom end of the segment 50 the cable 52 passes rearwardly through a housing 100* containing a roller or pulley 101 and beyond the housing '100 has its rear end fixed to the stationary column 16 of the mast 14, the attachment point being shown at 104.

Referring to FIGS. 1 and 2, the drum 36, as it is lifted from the FIG. 1 position, retains its upright or FIG. 1 orientation until all slack is taken up in the cable 52. Thereafter, continued raising of the fork 20 causes the cable to be pulled from the segment 50, rotating the segment and in turn rotating the pressure pads and the drum to the FIG. 2 position or to any other position involving a lesser degree of rotation, the amount of rotation depending upon the height to which the fork is raised.

Each pressure pad assembly 28 and 30 also includes a catch device for releasably holding the base plate 54- of the assembly in its article grasping position and which catch is released in response to the upward swinging movement of the associated carrier 68. In the illustrated case, this catch device comprises a latch member 102 pivotally connected to the horizontal leg of the associated retaining member 57 by a pivot screw 10'5 passing vertically loosely through the forward end of the latch 102 and threaded at its lower end into the retaining member 57, a spacer 106 being received on the screw 104 between the member 57 and the latch 102 to space the latch 102 some distance above the retaining member 57. A torsion spring 103 biases the latch member 102 about the pivot screw 104 toward the latched position shown in FIG. 5 and resists its movement in the opposite direction. In FIGS. 5 and 6, the carrier 68 is shown in its lowered position and when the carrier is in this position, a finger 108 on the rear end of the latch member is engageable with the rearwardly [facing surface of the base plate ear 66 to hold the base plate in its article grasping position. The latch member 102 is further so designed so as to include a laterally inwardly extending swell or protrusion 110 which is engageable with the outwardly facing surface of the outer leg of the carrier 68. When the carrier 68 is moved to its raised position, as shown in FIGS. 8 and 9, the outer leg of the carrier 68, by engagement with the swell 110, moves the latch 102 outwardly to an unlatched position relative to the base plate ear 66 so that the base plate is thereafter free to move to its article receiving position.

Before turning to a more complete description of the operation of the device, it should be noted, by referring to FIGS. 6 and 9, that the arrangement of the parts is such that from the article grasping position of FIG. 6 the pressure pad 32 may be moved in the direction away from the grasped article, and away from the opposite pressure pad, by simultaneously rotating the carrier 68 about its pivot pin 70 and rotating the pressure pad 32 about its pivot pin 86 to the positions shown in FIG. 9.

Having now described the construction of the illustrated device, its operation may be more easily understood by reference to FIGS. 10a to 13b which somewhat schmetically show the device at various stages in the process of moving into grasping relationship with a drum. Turning to these figures, FIGS. 10a and 10b show the device with the pressure pad assemblies in their article receiving positions and moved to a point whereat the drum 36 is partially received between the pressure pads 32, 32. This position is reached by the operator of the truck 12 moving the truck forwardly toward the drum. At this time the operator of the truck also controls the elevation of the fork so that the two pressure pads 32, 32 are located at such a height as to be vertically positioned between the two chimes 112, 112 of the drum.

The operator then drives the truck further forwardly to cause the pressure pads 32, 32 to engage the drum and to thereby rotate the two base plates 54, 54 part way toward the final article grasping positions of FIG. 4. Before such final positions are reached, however, the pressure pads 32, 32 reach the positions of FIGS. 11a and 11b whereat the engagement of the pressure pad with the drum tends to resist further rotation of the base plates. When this position is reached, the operator lowers the fork of the truck slightly to the position shown in FIG. 12a and while doing so also moves the truck still further forwardly relative to the drum. The lowering of the fork causes the carriers 68, 68 of the two pressure pad assemblies to be swung to their raised positions to increase the space between the pressure pads, thereby allowing the further forward movement of the truck which rotates the base plates to the positions shown in FIG. 12b. During the movement of the parts from the FIG. 11a to the FIG. 12a positions, the pressure pads 32, 32 are prevented from moving downwardly relative to the drum by engagement with the lower barrel chime 112 and/or by the friction existing between the pressure plates and the drum.

After the base plates 54, 54 are moved to the positions shown in FIG. 12b, the operator again raises the fork to the position shown in FIG. 13a. As this latter movement takes place the carriers 68, 68 are returned to their normal lowered positions, and as a result of this the pressure pads 32, 32 are moved inwardly toward the drum and tightly clamp the drum therebetween as shown in FIG. 13b. As the final article grapsing position of FIGS. 13a and 13b is reached, the two latches 102, 102 of the two pressure pad assemblies move to their latched position to prevent rotation of the base plates. Thereafter, the fork may be raised above the level of FIG. 13a to lift the drum from the ground or floor and, as previously described, after the drum is raised to a given point, the cable 52 and segment 50 operate to rotate the drum for dumping its contents or for other purposes.

After the drum 36 has been lifted by the device of this invention, it may be disengaged from the device and placed in a normal position on the ground or other supporting surface by following the reverse procedure described in connection with FIGS. 11a to 1311. That is, the fork is first lowered to bring the bottom end of the drum to rest against the ground and is then lowered further to raise the carriers 68, 68 to the positions shown in FIG. 12a, the raising of the carrier to this position spreading the pressure pads 32, 32 to remove the clamping pressure from the drum and also moving the associated latches 102, 102 from their latched conditions. The operator then may back the truck 12 away from the drum 36 and as this i done, the pressure pads 32, 32 slide around the outer surface of the drum and they and the associated base plates are moved to the article receiving positions of FIG. 10b and FIG. 3 by the associated tension springs 62, 62, the drum thereby being released from the grasping device and the device conditioned for use in receiving and grasping another drum.

From this description of the operation of the device. it will be understood that the operator of the truck may operate the truck to cause the device to grasp a drum or other article, to lift the article, to dump the drum, to return the drum to its normal position, and to then re lease the device from engagement with the drum, all without the operator leaving the truck 12 or requiring any manual assistance. It should also be noted that the height at which the drum 36 is rotated for dumping may be readily controlled by varying the length of the operating cabel 52 and/or by fixing the rear end of the cable to different points along the length of the stationary column 16.

Returning to FIGS. 3 and 4, these figures show an alternative means which may be used in conjunction with, or in place of, the stop lugs 60, 60 for limiting the move ment of the base plates 54, 54 to their article receiving positions. This alternative means comprises a cable 112 having its opposite ends fixed to lugs 114, 114 located respectively adjacent the rear edges of the two pressure pads 32, 32. The cable 112 is of such length as to be slack when the pressure pad assemblies are in the article receiving positions of FIG. 3, and when the pressure pads are moved to their article grasping position relative to the drum 36, the cable 112 is stretched tightly between the lugs 114, 114 and against the rear surface of the drum to prevent further movement of the pressure pad assemblies and also to positively prevent the drum from moving rearwardly beyond the position shown in FIG. 4. It should also be noted that the pressure pads 32, 32 in the illustrated example are preferably comprised of curved pieces of plate steel with the inner surfaces of the steel pieces forming the article engaging surfaces 34, 34. If desired, however, the inner surfaces of the steel pieces may be lined with rubber or other material for increasing the friction between the pads and the articles to be handled. Such friction increasing material is not, however, necessary in the illustrated case since the chimes 112, 112 of the drums being handled positively prevent any undue slippage between the drums and the pressure pads while the drum is lifted.

In the case of some fork lift trucks such as small trucks of the non-riding type, the forks customarily used with the trucks may have their prongs too closely spaced to accommodate the drums or other articles to be lifted. The present invention may however be readily used with such trucks by removing the conventional fork and using a pronged frame which is attached directly to the lifting carriage or equivalent part of the truck in place of the conventional fork, the prongs of the frame in turn carrying the pressure pad assemblies in the same manner as the prongs of the illustrated frame. It should therefore be understood that in the claims which follow the term fork is used to refer to either the fork conventionally used with the truck or to a special fork shaped frame attached to the truck in place of the conventional fork.

The invention claimed is:

1. An article grasping device for use with a fork truck having a vertically movable fork with two generally horizontal transversely spaced prongs, said device when attached to such a fork truck comprising two pressure pads each associated with a respective one of said prongs, said pressure pads being located directly opposite from one another and having generally vertical article engaging surfaces generally facing one another, and having a shape conforming generally to the side surfaces of the article to be grasped, means supporting each of said pressure pads for movement about a generally vertical axis to permit said pads to be moved between article receiving positions and article grasping positions, said two pads when in their article receiving positions having their article engaging surfaces diverging forwardly so that the forward edges thereof are transversely spaced by a distance greater than the thickness of the article to be grasped and said two pads when in their article grasping positions being I arranged to engage opposite sides of said article, means supporting each of said pressure pads for swinging movement upwardly and laterally outwardly relative to the associated prong during movement of said pads from said article receiving positions to said article grasping positions to increase the spacing between said pads and to thereby allow said pads to loosely receive said article therebetween, said pads when said fork is thereafter raised being swung downwardly and laterally inwardly by the weight of said article to decrease the spacing between said pads and to thereby cause said pads to tightly grip said article therebetween, means supporting said pressure pads for movement about a common axis extending transversely of said prongs when said pads are in their article grasping positions, and means for rotating said pads about said common axis to rotate the grasped article in response to vertical movement of said fork after said fork is raised above a predetermined level.

2. An article grasping device for use with a fork truck having a vertically movable fork with two generally horizontal transversely spaced prongs, said device when attached to such a fork truck comprising two pressure pads each associated with a respective one of said prongs, said pressure pads being located directly opposite from one another and having generally vertical article engaging surfaces generally facing one another, and having a shape conforming generally to the side surfaces of the article to be grasped, means supporting each of said pressure pads for movement about a generally vertical axis to permit said pads to be moved between article receiving positions and article grasping positions, said two pads when in their article receiving positions having their article engaging surfaces diverging forwardly so that the forward edges thereof are transversely spaced by a distance greater than the thickness of the article to be grasped and said two pads when in their article grasping positions being arranged to engage opposite sides of said article, means supporting each of said pressure pads for swinging movement upwardly and laterally outwardly relative to the associated prong during movement of said pads from said article receiving positions to said article grasping positions to increase the spacing between said pads and to thereby allow said pads to loosely receive said article therebetween, said pads when said fork is thereafter raised being swung downwardly and laterally inwardly by the weight of said article to decrease the spacing between said pads and to thereby cause said pads to tightly grip said article therebetween, means supporting said pressure pads for movement about a common axis extending transversely of said prongs when said pads are in their article grasping positions, means for biasing said pads to a normal angular position relative to said common axis, and means for rotating said pads and the grasped article about said common axis and against the biasing force of said biasing means in response to raising movement of said fork beyond a predetermined level, said biasing means serving to rotate said pads and the grasped article back to said normal position of said pads upon subsequent lowering movement of said fork.

3. An article grasping device as defined in claim 2 further characterized by said means for rotating said pads comprising an arcuate member fixed to one of said pads in concentric relation to said common axis, and a flexible tension member having one end fixed relative to said arcuate member and its other end fixed to a part of said truck which is stationary relative to said fork, said flexible tension being trained over a part of said arcuate member when said pads are in said normal position and being so arranged as to be pulled off of said arcuate member as said fork is raised above a given level relative to said stationary part of said truck.

4. An article grasping device for use with a fork truck having a vertically movable fork with two generally horizontal transversely spaced prongs, said device when attached to such a fork truck comprising two pressure pads each associated with a respective one of said prongs, said pressure pads being located directly opposite from one another and having generally vertical article engaging surfaces generally facing one another, and having a shape conforming generally to the side surfaces of the article to be grasped, means supporting each of said pressure pads for movement about a generally vertical axis to permit said pads to be moved between article receiving positions and article grasping positions, said two pads when in their article receiving positions having their article engaging surfaces diverging forwardly so that the forward edges thereof are transversely spaced by a distance greater than the thickness of the article to be grasped and said two pads when in their article grasping positions being arranged to engage opposite sides of said article, means supporting each of said pressure pads for swinging movement upwardly and laterally outwardly relative to the associated prong during movement of said pads from said article receiving positions to said article grasping positions to increase the spacing between said pads and to thereby allow said pads to loosely receive said article therebetween, said pads when said fork is thereafter raised being swung downwardly and laterally inwardly by the weight of said article to decrease the spacing between said pads and to thereby cause said pads to tightly grip said article therebetween, said means supporting each of said pressure pads for movement about a generally vertical axis comprising a base member supported on the associated prong for movement about said vertical axis, latch means for releasably holding said base member in the position corresponding to the article grasping position of the associated pressure pad when said pad is in its downwardly swung position, and means for releasing said latch means in response to the upward swinging movement of said pad to allow said base member to be moved to the position corresponding to the article receiving position of the associated pressure pad.

5. An article grasping device as defined in claim 4 further characterized by biasing means associated with each of the base members of the two pressure pads for biasing said base members to the positions corresponding to said article receiving positions of said pressure pads.

6. A device for use with a fork truck having a vertically movable fork with two generally horizontal trans versely spaced prongs, said device when attached to such a fork truck comprising two pressure pad assemblies located respectively on said two prongs directly opposite from one another for releasably grasping an article received therebetween, each of said pressure pad assemblies including a base supported for movement relative 'to the associated prong about a generally vertical axis fixed relative to said associated prong between an article receiving position and an article grasping position, a carrier pivotally connected with said base for movement between raised and lowered positions about a generally horizontal carrier axis fixed relative to said base, said carrier axis when said base is in its article receiving position being generally parallel to said associated prong, a pressure pad for engaging the adjacent side of an article received between said pressure pad assemblies, means pivotally connecting said pressure pad to said carrier to enable said pad to pivotally move relative to said carrier about a horizontal axis parallel to said carrier axis as said carrier is swung between its raised and lowered positions, means for biasing said base to its article receiving position, a catch for holding said base in its article grasping position when said carrier is in its lowered position, and means for releasing said catch to allow movement of said base about said vertical axis, in response to movement of said carrier from its lowered to its raised positions.

7. A device as defined in claim 6 further characterized by. said means for connecting said pressure pad to said carrier comprising an intermediate part carried by said carrier and supported thereby for rotation about an axis which is hoizontal when said carrier is in its lowered position and which is in a plane perpendicular to said carrier axis, means for biasing said intermediate part to a normal angular position relative to said carrier, and means pivotally connecting said pressure pad to said carrier for movement about an axis which is parallel to said carrier axis when said intermediate part is in its normal angular position.

8. A device as defined in claim 7 further characterized by means for adjustably positioning said intermediate part to various different positions along its axis relative to said carrier to vary the spacing between the two pressure pads of said two pressure pad assemblies.

9. A device as defined in claim 7 further characterized by means associated with one of said pressure pad assemblies for rotating its intermediate part relative to the associated carrier, when an article is grasped between said pressure pad assemblies, in response to vertical movement of said fork above a predetermined level.

References Cited UNITED STATES PATENTS 2,683,546 7/1954 Sherriff 214-652 2,706,060 4/1955 Ferrario 214-652 2,713,431 7/1955 Koehler 214-710 2,755,949 7/1956 Sehenkelberger 214-653 2,812,089 11/1957 Purpura 214-620 2,842,275 8/1958 Kughler 214-653 2,877,911 3/1959 Arnot 214-147 2,877,913 3/1959 Arnot 214-147 2,915,332 12/1959 Cotesworth 294-106 X 3,112,835 12/1963 Gierhart 294-110 X 3,180,512 4/1965 Moss 214-620 3,319,815 5/1967 Vik 214-620 FOREIGN PATENTS 1,150,322 6/1963 Germany.

GERALD M. FORLENZA, Primary Examiner.

R. B. JOHNSON, Assistant Examiner.

US. Cl. X.R.

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