US 3683821 A
Stacked empty pallets having registering sockets in adjoining surfaces are interlocked by latch members carried by yieldable arms extending from the mid sections of the sockets and yieldably projecting from the socket of one pallet into the corresponding socket of an adjoining pallet.
Description (OCR text may contain errors)
United States Patent Mangold [4 1 Aug. 15, 1972  PALLET 3,363,540 l/l968 Cloyd et a]. l08/53 Inventor: T. I e't Rd., Erie Pa. 16506  Filed: Sept. 24, 1970  Appl. No.: 75,120
Related U.S. Application Data 1  Continuation-impart of Ser. No. 38,778, May
521 u.s.cl. ..10s/s3,'10s/5s [51 lnt.Cl ..B65d 19/38, 865d 21/00  FieldofSearch ..10s/51-ss; 220/84 Primary Examiner-James T. McCall Assistant Examiner-Glenn O. Finch Attorney-Ralph Hammar socket of one pallet into the corresponding socket of w an adjoining pallet,
3 Claims, 9 Drawing Figures PATENTEDAUB l 5 I972 SHEET 1 0F 2 IN V EN TOR. WM T PATENTEDAUB 15 m2 SHEET 2 OF 2 I I! If If I! If I! F IG.8
24 flzr FIG. 6
ATTORNEY PALLET This invention is a continuation in part of application Ser. No. 38,778 filed May 19, 1970.
This invention is an improvement on US. Pat. No. 3,363,590, simplifying the latch construction for interlocking empty pallets so as to hold them in stacked relation.
In the drawing,
FIG. 1 is a perspective of a stack of empty pallets,
FIG. 2 is a fragmentary bottom plan view of one of the pallets,
FIG. 3 is a section on line 3-3 of FIG. 2,
FIG. 4 is a view similar to FIG. 3 of a modification using a strip spring to urge the latch member upward,
FIG. 5 is a fragmentary view showing the manner in which the strip spring is secured to the socket,
FIG. 6 is a fragmentary end view of the groove in which the strip spring is secured,
FIG. 7 is a sectional view on line 7-7 of FIG. 8 showing another modification,
FIG. 8 is a plan view of the outer end of the latch, and
FIG. 9 is a plan view of the inner end of the latch.
In FIG. 1 there is shown a stack of a plurality of pallets l of generally rectangular shape having peripheral side and end walls 2 each provided with a pair of fork entry openings 4 to provide the usual four-way entry. Each pallet has upper and lower load carrying surfaces 6 and 7. The particular pallet shown is constructed in accordance with US. Pat. No. 3,307,504, incorporated by reference. As described in greater detail in that patent, the load carrying surfaces 6 and 7 of each pallet is associated with the lattice of intersecting ribs presented edgewise to the surfaces and providing a rigid construction which is adapted to molding from impact resistant plastic such as polyethylene. This is merely one of the pallets to which the present invention is applicable.
In order to hold the empty pallets in stacked relation as shown in FIG. 1, at several (e.g. four) points around the periphery of the pallet there are provided sockets 8 which extend between the surfaces 6, 7. As shown in FIGS. 1 and 2, the sockets are spaced inward from the outer walls 2 of the pallet. Each socket comprises walls 9, l0, l1 and 12, each extending in the thickness direction between the surfaces 6, 7 and each integral with the adjoining sections of the pallet.
At the center of one end of each of the sockets 8 is a latch member 13 supported by one of the walls of the socket, for example the wall 11. The latch member has rectangular sides 14 and ends 15 at the center of which is a rounded projection 16. When the pallets are stacked one on top of the other, the latches 13 enter the sockets 8 in the adjoining pallet. The rectangular sides 14, 15 provide abrupt shoulders for holding the pallets in alignment. The rounded projection 16 acts as a cam surface which allows the pallets to slide into position as they are stacked. Once the latches have entered the sockets 8, the stack of pallets is interlocked by the latches so that they will remain in stacked relation.
The manner of making the latch members 13 is shown in FIG. 3. As molded, the latch member 13 is integral with the lower ends of arms 17, 18 of width substantially equal to the length of the latch. When viewed in section, the arms 17, 18 and the associated latch 13 form a U with the latch at the base of the U and with the amrs offset laterally from the walls of the socket. The arm 18 is joined to the socket wall 11 by a curved section 20. There is a similar curved section 19 at the upper end of the arm 17 which has a cut or interruption 19a so that after removal from the mold the latch member 13 and the arms 17, 18 assume the position generally indicated by dotted lines 13a, 17a and 18a. The arm 18 with the associated. section 20 forms a yieldable support for the latch member 13 which permits the latch member 13 to be moved laterally and in and out of the socket so as to prevent damage to the latch members while the pallets are being used. For example, when the pallet is supported by its lower surface 7, the latch members 13 are free to retract within the socket. While the pallets are being stacked, the latch members 13 are free to move either laterally or inwardly. When the latch members 13 come into alignment with a socket 8 in an adjoining pallet, the latch members spring into engagement with the adjoining socket and provide a mechanical interlock which holds the pallets in stacked relation but: which yields to permit removal from the stack without injury to the latch members or the associated parts of the pallet.
' The arms 17, 18 and the section 20 are substantially wholly within the sockets 8 and are well protected. The latch construction is adapted to molded plastic pallets. The integral construction provides reliability at minimal cost.
In order to increase the speed of operation of the latch member 13, a supplemental strip spring 21 may be used. One end of the spring has an angular section 22 seatedon the inner surface 23 of the latch member. The other end of the spring has a head 23 received in a T-slot 24 molded integral with the wall 1. The head is provided with inclined barbs 25 which dig into the bottom walls 26 of the T-slot and resist movement out of the slot. The spring may be easily installed by pushing the head 23 downward into the T-slot until the lower end 22 seats on the surface 23 of the latch member 13. Once pushed into place, the barbs 25 resist outward movement and hold the spring in assembled relation. The spring supplements the inherent resilience of the arm 18 of the latch member and in addition overcomes any tendency of the arm 18 to take a set if held in its retracted position for a long period of time.
The T-slot 24 which may be molded integral with the pallet provides a simple construction for fixing one end of the supplemental spring to the pallet with minimal material and assembly cost.
In the modification of FIGS. 7-9, where corresponding parts of the pallet are indicated by the samev reference numerals, the stationary part 27 of the latch comprises a cross wall or partition integral with the socket walls 9, 10, 11 and 12 and having at its center an integral tubular guide 28, preferably of square or other non circular cross section. The movable part 29 of the latch is slidable in the socket 8 and has outwardly projecting ribs 30 slidably engaging the socket walls 9, 10, 11 and 12. On its under side the latch member has a hollow post 31 slidable in the guide member 28. At the inner end of the post 31 are a plurality of resilient fingers 32 having outwardly projecting hook or locking projections 33 cooperating with the inner end of the guide 28 to limit the outward movement of the latch member. Spring means such as a coil spring 34 arranged between the latch member 29 and a suitable part of the stationary member 27 urges the latch member outward so that in the extended position shown in FIG. 7 the hook members 33 stop against the inner end of the guide 28. When the latch member 29 projects downward, as shown, gravity would provide equivalent spring action. The coil spring 34 permits operation with the latch member 29 extending upward. The latch member 29 and the spring 34 are separately manufactured parts. In the assembly, the spring 34 is assembled on the post 31 and the assembly is pushed into the guide 28 until the hook members or projections 33 move past the inner end of the guide 28. Upon reaching this position, the hook members 33 spring outwardly and hold the latch member 29 in assembled relation to the stationary latch part 27.
The latch member 29 has abrupt surfaces 35 which when received in the open end of one of the sockets 8 of an adjacent pallet cooperate with the walls 9, 10, l1 and 12 of that socket and hold the pallets in aligned relation. Because the locking surfaces 35 resist relative movement in all directions, only two latches per pallet are needed to provide positive alignment in the stack. The latch members 29 also have four inclined surfaces 36 which act as cam surfaces to assist in leading the I latch members into the sockets so as to assist in bringing a pallet being stacked into alignment with the other pallets in the stack. The cam surfaces 36 also assist in camming the latch members inward.
The reference to upper and lower load carrying surfaces of the pallet refers to the position of the surfaces in the particular stack. The stack could be inverted without changing the operation. The terms upper and lower are, accordingly, interchangeable and not words of limitation.
What is claimed is:
1. In a molded plastic pallet having vertically spaced load carrying surfaces and means providing sockets extending in the thickness direction between said surfaces with open ends presented to said surfaces and registering with the open ends of sockets of adjoining pallets in a stack of pallets of like construction, said sockets having plastic walls extending in the thickness direction inward from said surfaces, latch means having a stationary part comprising a cross wall molded integral with one of said walls inward of said surfaces and connected by resilient means to a movable part outward of one of said surfaces in position to enter the open end of a socket of an adjoining pallet of like construction, said resilient means yielding to permit retration of the movable part of the latch means into the associated socket.
2. The pallet of claim 1 in which the movable part of the latch has a post guided in the stationary part.
3. The pallet of claim 1 in which the resilient means is a coil spring surrounding the post and biasing the movable part outward of the socket.