Note: Descriptions are shown in the official language in which they were submitted.
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21 97831
This invention relates to load handling apparatus;
and more particularly relates to a novel and improved
attachment for pallet jacks to facilitate loading and
unloading of slip sheet- supported loads.
It has been customary practice in the past to place
containerized loads on pallets so that a pallet jack or
forklift truck of the type having narrow tines or forks can be
employed for lifting, transporting and otherwise handling such
0 loads. More recently, plastic slip sheets have been employed
in place of pallets but have necessitated the use of
~A~ specialized lifting and transporting devices.
It has been proposed in the past to equip the
standard pallet jack or fork lift unit with a handling
attachment and which is generally characterized by having a
; flatbed support surface or platen mounted on the tines or
forks and a powered gripping -~h~nis~ which is able to grip
a free edge of the slip sheet in order to draw the slip sheet
and load onto the platen. Representative slip sheet handling
devices are set forth and described in U.S. Letters Patent
, : .
~ Nos. 4,828,450 to D. F. A~re~i et al, 4,890,973 to E. C.
-: :-
Frison et al, 5,316,433 to D. F. Chase and 3,640,414 to Brudi.
--In accordance with the present invention, it is
-~~ proposed to greatly simplify the handling attachment unit and
the manner of attachment to a standard pull jack or fork lift
truck and to greatly enhance its utility and efficiency in
lifting, transporting and unloading slip sheet-supported
loads. As employed herein, the term "lift jack" is understood
to refer to and include any type of standard pull jack or
forklift truck unit having spaced tines.
It is an object of the present invention to provide
for a novel and improved slip sheet handling unit which is
21 97831
specifically adaptable for use as a retrofit unit to be
attached to existing lift jack units.
Another ob;ect of the present invention is to
provide for a slip sheet handling unit including a gripping
assembly which can be clo~ely controlled for advAncs--nt along
a flatbed support surface for a load to be transported, and
further wherein the unit is movable beyond the ~u~po~L surface
into ground-engaging relation to a slip sheet to be grasped
and is capable of automatically applying increased pressure to
0 the edge of the slip sheet once grasped.
It is a further object of the present invention to
provide in a slip sheet handling attachment for a flatbed
support surface which is automatically tiltable to facilitate
alignment with a load to be engaged and further tiltable
upwardly from a ground-engaging position so that the load can
be transported from one site to another.
A further object of the present invention is to
provide in a slip sheet hAn~l;ng unit for a novel and i _~ved
gripper assembly inco.p~Lating a drive system for smoothly
- 20 advancing and retracting the gripper assembly with respect to
. ,
a flatbed support surface.
A still further object of the present invention is
to provide in a slip sheet handling unit for a novel and
improved remote control which will permit the operator to
closely follow advancement and retraction of a gripper
assembly in picking up and depositing a load.
~ " . ~. :
~ In accordance with the present invention,
a slip sheet handling apparatus has been devised for lift jack
of the type provided with spaced, horizontally ext~n~ing
tines, the apparatus being made up of a platen having means
mounting the platen on the tines for tilting mov~ment of the
platen about a transverse horizontal axis beneath the platen
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2 1 9783 1
whereby a forward end of the platen is movable between a
raised position and a lowered ground-engaging position, and a
gripper assembly mounted for horizontal advancement above the
platen between a rearward and forward end of the platen, the
-~ gripper assembly including upper and lower jaws and control
means for advancing the jaws between an open position to
receive an edge of the slip sheet and a closed, slip sheet-
engaging position.
In the preferred form of gripper assembly, the upper
and lower ~aws are defined by a pressure pad which is movable
downwardly under the control of a linear actuator cooperating
with a spanner to equalize the pressure across the pad in
driving the pad downwardly into engagement with the lower jaw,
and the lower jaw preferably takes the form of a flange which
is fixed with respect to the pressure pad and has an upper
-- shelf portion adapted to receive an edge of the sllp sheet so
that downward pressure of the pressure pad will firmly wedge
~- ~ the edge of the slip sheet between the pad and flange. The
gripping pressure is further Pnh~nced by mounting the pressure
pad for suspension from swivel joints o that the pad is free
to undergo limited rocking or pivotal ~1 -nt along the shelf
portion. Further, the gripper assembly is floatingly mounted
with respect to a carriage which is slidably secured to the
platen so that the assembly can ride along the upper surface
'"~ of the platen and automatically drop below the platen when the
gripper assembly is advanced beyond the leading edge of the
platen.
The above and other objects of the present invention
will become more readily appreciated and understood from a
consideration of the following detailed description of
preferred and modified forms of the present invLention when
taken together with the accompanying drawings in which:
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21 9783 1
Figure 1 is a side view in elevation of a preferred
form of slip sheet handling attachment in accordance with the
present invention in assembled relation to a standard pallet
jack unit and illustrating a load s~poLLed on the attachment;
Figure 2 is a top plan view of the preferred
embodiment shown in Figure 1;
Figure 3 is an enlarged rear view in elevation of
the gripper assembly forming a part of the slip sheet handling
attachment of the present invention;
: 10Figure 4 is an enlarged side view of the gripper
assembly shown in Figure 3;
Figure 5 is an enlarged front view in elevation of
the gripper assembly shown in Figures 3 and 4;
Figure 6 is a somewhat schematic side view of the
handling attachment of the present invention with the gripping
assembly engaging a slip sheet beneath a load;
Figure 7 is another somewhat schematic side view of
~: the handling attachment of the present invention shown
depositing a load upon a pallet; and
20Figure 8 is another schematic side view illustrating
the completion of the unloading procedure onto a pallet.
Referring in more detail to the drawings there is
shown by way of illustrative example in Figures 1 to 8 a
preferred form of slip sheet handling attachment 10 mounted on
a conventional jack unit J. The unit J is merely
~ representative of various types of pallet ~acks and forklift
: ~ trucks employed in lifting and transporting loads and
especially large, containerized loads. Thus, for the purpose
of illustration but not limitation, the unit J is made up of
30a wheelbase B having ground-engaging wheels W, handle H,
closely spaced horizontally extending tines T w~hich may be
appropriately equipped with front rollers R, a pump P with
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2 1 97831
foot control lever L, and a motor drive M to control
advanc -nt of the jack unit J. The spacing between tines T
is such that the tines are capable of being advanced into the
opening in one side or end of a pallet in a conventional
manner so that the pallet and load rest upon the tines T and
can be easily lifted and transported. Further, the unit J is
= typically provided with a control panel, not shown,
conveniently located on or near the handle H for operator
co~trol of the motor drive M. One commercial version of the
- 10 unit as described is manufactured and sold by Warn Industries,
Inc. of Milwaukie, Oregon.
The slip sheet handling attachment 10 of the present
invention is characterized by its ability to be retrofit to
the unit J for ease of interchangeable use of the unit J
either as a standard pallet jack or as a jack for handling
slip sheets. A slip sheet as represented at S is customarily
- ~ placed beneath a containerized load K directly on a floor
surface or on a pallet Y, for example, as illustrated in
Figures 7 and 8. The typical slip sheet S is a rectangular,
high strength plastic sheet which is oversized with respect to
the load K so that an edge E of the slip sheet S projects
beyond the load and can be grasped by the attachment 10 in a
manner to be described. Accordingly, the attachment 10 i8
broadly comprised of a flatbed support surface or platen 12
; which is dimensioned for extension over and beyond the tines
T, and lower fulcrum-like support members 13 depend downwardly
from the platen 12 so as to straddle the tines T and are
pivotally connected for tiltable r-v. -nt of the platen 12
about aligned transverse horizontal axes through the forward
ends of the tines T. A gripper assembly 14 is mounted on a
carriage 15 for horizontal adv~nz -nt between a ~earward end
of the platen 12 adjacent to the wheel base B and a forward or
: ~ ~ .
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21 9783l
free end of the platen 12 beyond the free ends of the tines T.
This advancement is controlled by a chain drive 16 traversing
the substantial length of the platen 12 between the rearward
and forward ends and including a power transmission drive 18
on the gripper assembly 14.
As best seen from Figures 3 and 5, a pair of
fulcrum-like support members or stringers 13 flank opposite
sides of each tine T, and the stringers 13 are pivotally
connected to each tine T by a pivot pin 20 ext~n~ing
0 transversely through forward ends of the tines T. Each of the
:: stringers 13 diverges forwardly or increases in depth toward
~: ~ a fulcrum point 22 and then taper forwardly as at 24 to
terminate at the forward or leading edge 25 of the platen 12.
For heavier loads, pivot pins can be inserted into op~nings
~: 20' that are closer to the forward ends of the tines T than
the pins 20 to better.distribute the load on the platen. In
: this way, forward adv~nc~ -nt of the gripper assembly 14 along
~ the platen and beyond the fulcrum points 22 will cause the
platen to automatically tilt about the pivot pins 20 to cause
the leading edge 25 to advance into a ground-engaging
; position, for example, as illustrated in Figures 6 and 8.
Another important feature of the present invention
resides in the gripper assembly 14 and the construction and
arrangement of upper and lower ~aws 26 and 28 at the forward
end of the gripper assembly. The upper ~aw 26 is preferably
in the form of an elongated pressure pad having a metal bar 27
~- tow hich is affixed a strip 27' of rubber or rubber-like
composition which traverses the entire width of the platen and
is suspended from a pair of upper swivel joints 29 beneath a
vertical push plate or frame 30. The lower jaw 28 is in the
: : form of a rigid flange which is coextensive with ~the pressure
: pad 26 and includes an upper horizontal support 32 which i6
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2 1 9783 1
- ~ attached to the lower end of the frame 30. The jaw 28 extends
downwardly from the ~ppo~ 32 behind the pressure pad 26 and
curves forwardly into a lower beveled end 34, the beveled end
having an upper horizontal shelf or notched portion 35 for a
purpose to be described. A pair of laterally spaced brackets
36 are affixed to the rear vertical surface of the lower jaw
28 and are provided with vertically extending, closed slots 37
' to receive pins 38 on spaced support arms 39 on the carriage
15.
10The carriage 15 includes a horizontal base or skid
40 with diagonally extending link arms 42 inclining upwardly
and forwardly from pivotal connection to support arms 43 at
the rearward end of the skid 40 and pivotally connected at the
upper end of the frame 30. Thus, the entire assembly 14 is
free to undergo limited vertical floating movement by virtue
of the slidable movement of the support pins 38 with respect
to the slots 37. For instance, the weight of the lower jaw 28
is normally supported by the platen 12, but the lower jaw 28
along with the rest of the carriage assembly 14 will be free
to slide downwardly when it is advanced beyond the leading
edge 25 into ground-engaging disposition, as shown in Figures
6 and 8.
The upper jaw or pressure pad 26 is movable upwardly
and downwardly with respect to.the beveled end 34 of the lower
jaw i8 under the control of a linear actuator 44 mounted
behind the frame 30. The actuator 44 includes a motor-driven
worm drive 46 having a lower end 47 pivotally connected as at
48 to the midpoint of a spanner arm 50 which extends
horizontally across an open intermediate portion of the frame
30. A connecting rod 52 extends downwardly from pivotal
connection to each of the opposite-ends of spanner 50 through
a hollow slotted guide 53 on the frame 30, the lower end of
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21 q7831
each connecting rod 52 being connected to one of the spaced
swivel joints 29 for the pressure pad 26. The pressùre pad 26
i~ normally suspended and spaced above the lower jaw 28 by the
connecting rods 52 and is caused to move downwardly into
engagement with the lower end 34 of the lower jaw 28 when the
- . linear actuator 44 is activated to drive the spann~r 50
. downwardly; however, the pivotal mounting of the spanner will
equalize the pressure of the pressure pad 26 against the lower
jaw 28 so as to impart ùniform pressure along the length of
the lower jaw 28.
: In order to advance the gripper assembly 14 and its
carriage 15 along the platen 12, the chain 16 is disposed in
an intermediate slot 60 traversing the substantial length of
the platen 12, the chain being anchored at opposite ends 61
; and 62. The rearward end of the chain 16 extends forwardly
and is trained about an idler 64, looped over a sprocket drive
: 65 on a motor-driven winch and passed over a lower idler
sprocket 66 and then into the slot 60. One suitable form of
sprocket drive is the utility wedge manufactured by Warn
Industries, Inc. of Milwaukie, Oregon, and which can be
emplayed either as a chain drive or cable drive. The sprocket
drive 65 together with the idler 64 and 66 make up the power
transmission drive 18 for the chain and are mounted on a
pedestal 68 above the base 40. The base 40 also supports a
battery 69 which serves as a power source for the sprocket
drive 65.
In order to center the gripper assembly 14 with
respect to the platen 12, the base 40 is guided along the
platen 12 by centering pins 70 ext~n~ng downwardly through
the slot 60 into staggered or offset guide wheels 72 which are
journaled with respect to the drive pins beneath,the slot 60
~ and advance along a guide track 73 on the.underside of the
21 97831
: platen 12 as shown in Figures 2 and 3. The offset guide
wheels 72 in cooperation with the guide track 73.not only
serve to guide or center the carriage 15 with respect to the
platen 12 but to prevent any t~ndency of the.carriage 15 to
tilt or fishtail when the gripper assembly 14 engages a slip
sheet and a load is being drawn- onto the platen. one
commercial version of the guide means as described is the
: DUALVEE manufactured and sold by 8ishop-Wisecarver Corporation
of Pittsburg, California.
0 The frame 30 is of generally rectangular
configuration, of rigid metal construction and comprised of
: upper and lower frame members 74 and 75 ,traversing the width
~ of the platen and rigidly interconnected by horizontally
spaced vertical braces 76 and an intermediate gusset plate 77
between a pair of the intermediate braces 76.
In use, Figures 1 and 6 to 8 illustrate the
~: operation of the slip sheet handler attachment 10 in drawing
a containeri~ed-load K resting on a slip sheet S onto the
platen 12, as illustrated in Figures 1 and 6; Figures 7 and
. . 20 8 illustrate transportation of the load into alignment with a
pallet Y and removal of the load K from the platen 12 onto the
pallet Y. More specifically, as shown in Figure 6, the
gripper assembly 14 is advanced by the power transmission
drive 18 through a remote hand control represented at 80 which
-~ is hard-wired via line 82 which is electrically connected to
the linear actuator 46 and to the sprocket drive 65. As
illustrated, the remote control 80 includes two sets of
buttons, one pair of buttons 83 and 84 being "open" and
"closè" buttons, respectively, to control vertical -Vt --t of
~ 30 the pressure pad 26 away from and into engagement with the
lower jaw 28. Another set of "push" and "pull" buttons 85 and
86 control the forward and reverse movement of the carriage 15
.. ' . 9 ~.
. 219783~
along the platen 12. The remote hand control as described
permits the operator to position himself alongside the
; apparatus in order to closely view the loading and unloading
'~ operations.
The pallet jack J is manually controlled to advance
the platen 12 into confronting relation to the load K to be
transported. The carriage 15 is then advanced forwardly along
the platen 12 by depres6ing of the button 85 and, as the
carriage 15 passes beyond the fulcrum point 22 will cause the
0 platen 12 to automatically tilt downwardly at ieS leading edge
25 into the attitude shown in Figure 6. As the gripper
assembly 14 passes beyond the leading edge 25, it will be free
to slide downwardly into engagement with the floor surface.
The lower jaw 28 is then advanced forwardly either by
depression of the button 85 or advancement of the pallet jack
until the lower jaw 28 slides under the edge of the slip sheet
25. The pressure pad 26 is then driven downwardly by the
llnear actuator 46 when the operator depresses the Close
Button 84 to tightly grip the slip sheet S between the
pressure pad 26 and jaw 28. Depression of the pull button 86
will cause the carriage 15 to be retracted by the sprocket
drive 65 and draw the load K along with the slip sheet S
upwardly onto the platen, as shown in Figure 1. As the
carriage is retracted, the swivel mounts 29 will permit the
pressure pad 26 to rotate or pivot slightly in a direction
toward the upper crest of the shelf portion 35 thereby
increasing the pressure against the slip sheet s and resist
any tendency of the slip sheet S to separate from the jaws 26
and 28. Again, when the center of gravity of the carriage
15, load K and sprocket drive 65 advances beyond the fulcrum
point 22, the platen 12 will automatically return to its
horizontal transport pasition as shown in Figure 1 with the
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21 q7831 -
platen 12 and tines T restin,g on the rollers R. ' As more
clearly seen from Figures 7 and 8, the standard pallet jack J
typically includes linkage arms A for the roller4 which will
permit the operator to lower the rollers R as the tines T are
lifted by the pump P under the control of the lift lever L,
for example, in aligning the leading edge of the platen 12
with the pallet Y. The carriage lS is once again advanced
forwardly along the platen with the frame 30 pushing the load
K forwardly off of the platen 12 and onto the pallet Y as
shown in Figure 8. The pressure pad 26 is then r,eleased by
reversing the linear actuator 46 with the open button 83, and
the reverse button 86 is depressed to withdraw the lower ~aw
28 from beneath the slip sheet S.
From the foregoing, in order to install the
attachment 10 onto the jack unit J the pivot pins 20 are
removed from the tines T and the tines T passed through the
stringers 13 until the openings in the tines T are aligned
with those in the stringers 13 for re-insertion of the pivot
-~ pins. The process is reversed when it is desired to use the
~, 20 jack for other loading and unloading operations. It will be
appreciated that the attachment 10 is readily conformable for
, use with forklift trucks as well as pallet jacks of the type
described and basically can be installed and removed in the
same manner as described.
It is therefore to be understood that while a
preferred form of invention has been herein set forth and
described, various modifications and changes may be made in
the construction and arrangement of parts as well as its
adaptability for use with different types of lift jack units
without departing from the spirit and scope of the present
invention as defined by the appended claims a~d reasonable
' equivalents thereof.
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