U.S. patent number 3,642,301 [Application Number 05/029,028] was granted by the patent office on 1972-02-15 for handtruck with means for shifting center of gravity of load.
Invention is credited to Burdette B. Crawford.
United States Patent |
3,642,301 |
Crawford |
February 15, 1972 |
HANDTRUCK WITH MEANS FOR SHIFTING CENTER OF GRAVITY OF LOAD
Abstract
A two-wheel, tilt-type handtruck incorporates a spring-loaded,
vertically shiftable axle and is adapted to handle a loaded pallet
from a floor position, shift the load center of gravity for
transport of the load and return the load to its original position
for removal of the loaded pallet.
Inventors: |
Crawford; Burdette B.
(Chadbourn, NC) |
Family
ID: |
21846839 |
Appl.
No.: |
05/029,028 |
Filed: |
April 16, 1970 |
Current U.S.
Class: |
280/47.12;
280/47.27; 254/2R; 280/47.22; 414/444 |
Current CPC
Class: |
B62B
1/12 (20130101); B62B 2301/20 (20130101) |
Current International
Class: |
B62B
1/12 (20060101); B62B 1/00 (20060101); B62b
001/02 () |
Field of
Search: |
;280/47.12,47.21,47.22,47.27,47.28,47.29 ;214/370 ;254/2R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
731,968 |
|
Jun 1932 |
|
FR |
|
209,198 |
|
May 1960 |
|
OE |
|
1,098,077 |
|
Mar 1955 |
|
FR |
|
418,288 |
|
Jul 1933 |
|
GB |
|
731,644 |
|
Jun 1955 |
|
GB |
|
Primary Examiner: Friaglia; Leo
Assistant Examiner: Paperner; Leslie J.
Claims
What is claimed is:
1. A handtruck comprising in combination:
a. a rigid frame providing a vertically positionable rectangular
front loading plane, load-receiving means adjacent the base of and
extending outwardly from said loading plane, handle means adjacent
the top of and extending rearwardly of said loading plane, and
behind and extending lengthwise of and substantially parallel to
said loading plane an axle slide;
b. toe pivot means adapted with the truck in a vertical loading
position to be releaseably engaged with the floor at a location
substantially immediately below said loading plane and when so
engaged causing said load-receiving means to move upwardly to
engage said load and adapted to provide pivotal support for the
truck and its load in forward tilted positions;
c. a floating axle-wheel arrangement having a pair of wheels
journaled to the ends of an axle and the axle slidably mounted on
said axle slide for movement between extreme upper and lower axle
positions in a plane substantially parallel to said loading
plane;
d. tension spring means extending between said frame and axle-wheel
arrangement and adapted to constantly urge said axle-wheel
arrangement towards said lower axle position; and
e. adjustable stop means positioned to engage and stop the upward
movement of said axle-wheel arrangement on said axle slide at any
one of a plurality of selectable axle positions including said
upper and lower positions,
said wheels thereby being allowed to engage the floor for vertical
positioning and loading of said truck and for transport of the
tilted load said axle being allowed to slide in said parallel plane
and to engage said stop means whereby said wheels are brought to a
selected position corresponding to selected said axle position and
the center of gravity of said truck is brought to a predetermined
position corresponding to the weight of the specific load.
2. A handtruck as claimed in claim 1 including toe pivot means
adapted with the truck in a vertical loading position to be
releaseably engaged with the floor at a location substantially
immediately below said loading plane and such that the distance
between the front loading plane and the parallel center of gravity
load plane is greater than the distance between the toe pivot means
and the same load center of gravity plane and when so engaged
causing said load-receiving means to move upwardly to engage said
load and adapted to provide pivotal support for the truck and its
load in forward tilted positions.
3. A handtruck as claimed in claim 1 including hand lever and
linkage means mounted on said frame and connected to said toe pivot
means and being adapted to move and releaseably lock said toe pivot
means in any of a plurality of downward positions dependent on the
nature of the load being engaged by said load-receiving means.
4. A handtruck as claimed in claim 3 including intermediate pivot
means formed integral and movable with said toe pivot means, said
intermediate pivot means being adapted to provide pivotal support
for said truck and load in rearwardly tilted positions between that
rearward position where the wheels entirely support the load and
that forward position where said toe pivot means entirely support
the load.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to handtrucks and more particularly to
manually operable, two-wheel handtrucks having shiftable and
spring-mounted axle supports.
2. Description of the Prior Art
The prior art handtrucks most commonly in use for handling bags of
fertilizer, cement, feed, etc., are those having tongs which are
adapted to grip or support arms to be slid under the load to be
transported. Pallets are normally but not necessarily used. Two
people are usually required to load and unload these trucks. In
loading, once the handtruck is ready to be tilted backward, a
second person must steady the load especially with high-stacked and
heavy loads, so that the load isn't tilted forward and cast off.
Also, once the load has been moved and the operator is ready to set
the load down, the second person must again steady the load so that
it will not be thrown forward. Some handtrucks have applied devices
which secure the vertical stacked loads to the truck before moving
so the load will not fall forward, however, even these handtrucks
allow the load weight to suddenly be shifted and placed upon the
operator's arms.
Some prior art patents teach improved handtrucks having movable
axles, however, even these patents leave much to be desired. U.S.
Pat. Nos. 729,931; 2,292,605; 2,485,545; 2,574,825; 2,607,606 and
2,650,834 as examples all provide movable wheels and axles.
However, these handtrucks provide no means of adjustment for
regulating the amount of travel of the wheels and axle to the load.
Their axle travel would be the same for extremely heavy loads as
well as for lighter loads. Thus, it would be desirable to provide
adjustment for wheel and axle travel dependent upon the load weight
but none of the prior patents teach such a desirable feature.
Moreover, none of the prior patents teach advantageous, movable
initial and intermediate pivot points.
It is evident that the handtruck of the prior art may be improved
upon to a significant degree and it is to this end that this
invention as shown and described herein is directed.
SUMMARY OF THE INVENTION
The handtruck of the invention slidably mounts the axle on a pair
of side frames extending behind the front loading frame. A pair of
springs constantly urge the axle and its wheels downwardly. The
handtruck has a pair of rearwardly disposed handles for the
operator and a generally conventional pair of load support members,
sometimes called shoes or tongs, which are moved in under the
pallet or load when the handtruck is positioned vertically during
loading. Before tilting the truck rearwardly with the load the load
support members are pressed up against the bottom of the pallet by
means of a pair of vertically movable toe members which are
operated through a hand lever and linkage. These toe members when
moved down engage the floor below the front loading plane and with
the distance shown as X in FIG. 4 between the front loading plane
and the parallel center of gravity load plane being greater than
the distance shown as Y in FIG. 4 between the toe members and the
same load center of gravity plane and once locked in a lower
position provide a pair of pivotal supports for tilting the load
rearwardly. Integral with the toe members there is also provided a
pair of intermediate pivot members which are at a slightly higher
elevation than the toe members but which move and are locked in
place with the toe members. As the handtruck is tilted back with a
loaded pallet the truck first pivots on the toe members and then on
the intermediate pivot members and finally on the wheels. The
wheels however do not immediately assume the full load since as the
truck is tilted rearwardly the axle slides vertically upwardly on
the side frames until the axle engages adjustable stops. These
stops are in turn positionable according to the weight of the load.
The load center of gravity, relative to the axle, during transport
can thus be regulated according to the amount of load weight, and
the load balanced for ease of tilting and transport. For light
loads the axle stops are located for very short vertical axle
movement on the side frames whereas for heavy loads the stops are
positioned for relatively long axle movement so as to shift the
load center of gravity toward the top of the loading frame. When
the truck reaches the tire at which the loaded pallet is to be
left, the operator reverses the tilting procedure. As the truck is
tilted forward the axle is urged down by the springs and moves
toward its bottommost position. As the truck tilts forward, the
load is first substantially relieved from the wheels, is next
returned to the intermediate pivots and, as tilting continues, is
then transferred to the toe members when the truck reaches its
vertical position and the loaded pallet is again resting on the
floor. The toe members are finally disengaged from the floor by
being moved vertically and the truck is free to be moved to another
loaded pallet. In none of these operations is there any tendency to
lose the load as in the prior art trucks.
Therefore, an object of the invention is to provide a handtruck
adapted for use in connection with moving heavy, bulky and normally
difficult to handle loads.
Another object is to provide a new and improved handtruck of the
type having a shifting center of gravity of the load with respect
to the wheels and axle whereby heavy and bulky loads are handled
with greater ease then heretofore.
These and other objects of the invention will become apparent when
the following detailed description is read in conjunction with the
accompanying drawings, in which:
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of the handtruck of this
invention.
FIG. 2 is a front elevation view of the handtruck of FIG. 1.
FIG. 3 is a side elevation section view taken along line 3--3 of
FIG. 2 and showing in solid lines the handtruck loaded with a
pallet holding four bags of fertilizer, a relatively light load,
and illustrating in dashed lines the handtruck tilted forward and
being slid beneath the pallet prior to engagement of the hand lever
controlling the toe members.
FIG. 4 is an enlarged, fragmentary, elevation section view
illustrating one of the toe members in a raised position and also
showing one intermediate pivot and one of the sliding axles and
frame structure, the dashed lines indicating a lowered
position.
FIG. 5 is an enlarged, fragmentary, elevation section view with the
toe member and linkage removed and illustrating in solid lines the
sliding member set for receiving four bags of fertilizer and in
dashed lines the pin is set for eight bags, a relatively heavy
load.
FIG. 6 illustrates in an enlarged fragmentary view the solid line
arrangement of FIG. 5 with the pallet and four bags tilted
backward.
FIG. 7 illustrates in an enlarged fragmentary view the dashed line
arrangement of FIG. 5 with the pallet and eight bags tilted
backward.
FIG. 8 is a fragmentary side elevation view with the loaded
handtruck tilted backward into a position where the load is
balanced and rests entirely on the wheels and the intermediate
pivots.
FIG. 9 is a view similar to FIG. 8 except that the handtruck has
been tilted backward beyond the FIG. 8 position and the load is
supported by the truck wheels and the operator.
FIGS. 10 and 11 are fragmentary perspective views which illustrates
more clearly the roller members which ride up and down on the side
frame.
FIG. 12 is a fragmentary perspective view showing the hand lever
which actuates the toe members when the handtruck is in place
beneath the load.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the drawings, the reference character 10 indicates generally the
handtruck of this invention which is shown as being formed with a
front frame 11 and a pair of side frames 12 and 13. Frames 11, 12
and 13 are shown as being formed of bent tubing and made integral
by welding frames 11, 12 and 13 together.
Front frame 11 is comprised of vertical tubes 15 and 16, vertical
extensions 17, 18 in the form of hand holds and horizontal tube 19
extending laterally between extensions 17, 18. A pair of
substantially U-shaped tubes 20a, 20b are made integral, by
welding, with vertical tubes 15 and 16. U-shaped tubes 20a and 20b
are welded to the base of handtruck 10 and the free end extends
upward and backward away from front frame 11. Also welded to frame
11 are a pair of wheel guards 21 which prevent any portion of the
load from coming into sliding contact with rotation of wheels 22,
23. Extending downward in a plane parallel to tubes 15 and 16 is
flat metal member 24. Flat member 24 is welded at its upper end to
crossmember 19 and is welded at its base to U-shaped member 20.
Member 24 is designed to add support to front frame 11 and to
support extremely heavy loads during tilting. Load-bearing members
14a, 14b extend outward from load-bearing surface 11 and are
integral with the base of handtruck.
Approximately midway the length of vertical tubes 15 and 16, tubes
25, 26 are made integral with tubes 15 and 16 and extend outward at
right angles thereto. Tubes 25, 26 are bent at curves 27, 28 and
continue from curvatures 27, 28 to extend downward at a
predetermined angle until they form curvatures 29, 30. At this
point, tubes 31, 32 extend beyond curvatures 29, 30 and are
generally parallel with tubes 25, 26. The free ends of tubes 31, 32
are welded to vertical tubes 15, 16 respectively. Tube 33 extends
between frames 12, 13 and supports the operator's foot when he
tilts the load back. A pair of vertical bars 35, 36 extend upward
at right angles from horizontal tubes 21, 32 respectively and are
welded to tubes 25, 26 respectively at their upper ends. Bars 35,
36 are vertically aligned and are parallel to vertical tubes 15 and
16. Bars 35, 36 have beginning at a predetermined point several
longitudinally spaced holes drilled therein through which heavy
cotter pins or the like may be placed and which will be described
later in the description.
The description will now shift to the sliding axle and wheel
assembly and for ease in describing the assembly, only one side
will be described since both wheels are mounted on the same axle
and the assemblies are identical. Vertical bar 36 is integrally
mounted on tube 32 by means of welding. Prior to welding bar 36 to
tube 32, a sleeve member 40 is slid onto bar 36. Once bar 36 is
welded to tube 32 at its base and welded to tube 26 at its
uppermost end, sleeve 40 is slideable on bar 36 but is not
removable therefrom. Plates 41a, 41b are welded to sleeve 40
adjacent its base. Plates 41a, 41b have a pair of holes 42, 43
respectively therein. Holes 42, 43 receive a small shaft 44 which
shaft in turn receives a roller 45. Roller 45 extends through a
slot (not shown) in sleeve 40 and rolls against bar 36 when in use.
Axle 50 passes through plates 41a, 41b and mounts on one end a
wheel 23. An angle member 49 is welded to sleeve 40 so as sleeve 40
rides up and down on bar 36, angle member 49 moves therewith. The
upper end of angle member 49 is closed by plate 51. Plate 51 has a
central hole through which a rod 52 passes. Rod 52 receives a nut
53 on its outer end and rod 52 terminates in a rounded hook 54
which extends downward. A coil spring 55 is secured to hook 54 and
extends downward. A small plate 56 is welded to tube 32. Plate 56
receives the free end of spring 55. Spring 55 now acts to hold a
sleeve 40 down adjacent tube 32. As sleeve 40 rides up and down on
bar 36 spring 55 expands and contracts with this movement. A cotter
pin, or the like, 57 is designed to fit into one of several holes
58 in bar 36. Cotter pin 57 limits and determines the upward limits
of travel of sleeve 40. Thus, the upward movement of axle 50 and
consequently the disposition of the load center of gravity relative
to axle 50 can be controlled by the positioning of pin 57.
Previously mentioned U-shaped tubes 20a, 20b are integrally welded
to tubes 15 and 16 respectively and the free-end extends upward and
backward at an angle from front plane 11. U-shaped tube 20b will be
described in detail and it should be understood that U-shaped tube
20a is identical to tube 20b and will therefore not be described. A
V-shaped member or toe member 60 has one long leg 61 and one short
leg 62. Legs 61 and 62 terminate at 63. Long leg 61 passes through
tube 20b and has a small plate 64 rigidly secured at a
predetermined point. Rectangular bar 65 is rigidly secured to plate
64 and extends downward substantially parallel to front load plane
11. Bar 65 has integrally secured to its lower end a plate 66 which
has an angled base 67. Plate 66 is made integral with short leg
member 62 of toe member 60. Leg 61 can slide within tube 20b
without being withdrawn therefrom. The extreme uppermost end of leg
61 has a connecting bar 70 pivotally mounted therewith at 71. It is
to be understood that all of this mechanism is repeated for the
other side of the handtruck.
Referring now to FIGS. 1, 2, 3 and 12, a pair of sleeves 75, 76
extend outward from tubes 25, 26 respectively and are welded to
these tubes. Another sleeve 77 has a half-moon-shaped disc 78 made
integral therewith and which has notches 79 cut along its outer
periphery. Sleeve 77 and disc 78 are fixedly secured to a tube 90
by means of bar 91 which is welded at one end to sleeve 77 and at
the other end to tube 90 which extends crossways between side
frames 12 and 13. Tube 90 is made integral with side frames 12 and
13 adjacent curvatures 27 and 28 by welding, therefore, side frames
12 and 13, bar 91, sleeve 77 and disc 78 are integrally connected,
nonmovable members. A shaft 77a is rotatably mounted through
sleeves 75, 76, 77 and is held in a confined lateral position by
these sleeves. A handle bar 80 is integrally secured to shaft 77a
immediately adjacent and in sliding relation against disc 78. A
second bar 92 of shorter length, is fixedly secured to handle bar
80 by screws 93.
Bar 92 is mounted so that it slides with handle bar 80 against disc
78 on the side opposite handle bar 80. A release handle 81 is
pivotally mounted, by pin 94, on handle bar 80. Handle 81 has a
spring 82 attached thereto at 95 which extends down to a release
member 83 and is secured thereto at 96. A connecting member 84
secured to handle 81 and running down to release member 83 causes
release member 83 to disengage from notches 79 when release handle
81 is mashed back towards handle bar 80 by the operator's hand.
Spring 82 causes release member 83 to engage notches 79 when handle
81 is released.
Connecting bar 70 extends from leg 61 upward and is pivotally
secured to shaft 77a. A second connecting bar 85 extends upward
from the other side of handtruck 10 where it is connected to a leg
identical in construction to leg 61 but located on that side of the
handtruck not described since it is identical to the side
described. Bars 70, 85 are pivotally connected with shaft 77a
through link 100 and pin 101, therefore, when shaft 77a and
integral handle bar 80 is rotated by disengaging release member 83,
bars 70, 85 are caused to be lifted or forced downward dependent on
the direction of rotation of shaft 77a and integral handle bar 80.
The movement of bars 70 and 85 in turn causes toe member 60 and the
identical toe member on the opposite side of truck 10 to be raised
or lowered.
Having described the construction of handtruck 10, the description
will now be directed to the use and operation of handtruck 10.
Handtruck 10 is useful for various jobs, however, for illustration,
it will be described as being used for moving fertilizer in bags of
100 lb. sizes. Referring to FIGS. 1, 3 and 5, handtruck 10 is
prepared for use, see FIG. 5, by placing cotter pin 57, the axle
stop, in the desired hold 58. In this example the hole spacings are
related to 100 lb. bag weights and use of the fourth hole from the
bottom corresponds to moving four bags at once. FIG. 3, dashed line
position, shows the handtruck being pushed up against a pallet
which is loaded with four bags of fertilizer. Once load plane 11 is
as close to the pallet and fertilizer bags as is possible, handle
81 is gripped and in turn releases release member 83. Bar 80 and
integral shaft 77a are rotated towards the load as far as is
possible and then handle 81 is released thereby allowing release
member 83 to drop into the nearest notch 79 and maintain handle 81
in its position. Rotation of bar 80 and integral shaft 77a having
forced bars 70, 85 downward and this in turn forces toe member 60
and the identical toe member for the opposite side down onto
engagement with the floor which causes handtruck 10 to assume a
vertical position and raises load-bearing members 14a, 14b so that
they are snugly held against the base of the loaded pallet.
Handtruck 10 is now tilted backward, using toes members 60 for
pivots, to its free standing position as seen in FIG. 8 with the
load being supported by angled based 67 of plate 66 and by the
wheels 22, 23. At this point, handtruck 10 will sit by itself fully
loaded. By tilting truck 10 further back, see FIG. 9, the load
weight first pivots on the angled base members 67 and then rests
almost entirely on the wheels which have be now moved back further
beneath the load. Once the load has been moved to its new location,
truck 10 is tilted forward to the FIG. 8 position once again. In
moving forward the truck tilts on the intermediate pivots provided
by baseplates 67 and then on the pivots provided by toe members 60.
Next, the load is set upright, handle 81 is released which through
bars 70, 85 allows the toe members to retract and slide back within
their respective tubes. Truck 10 can now be moved away from the
pallet and load.
The same operation is performed for all loads except that the axle
stop, i.e., cotter pin 57, is placed in the correct holes 58
depending upon the number of bags desired to be moved and where the
truck center of gravity is best located. FIGS. 3, 5 and 6 show
truck 10 set up for movement of four bags and FIGS. 5 (dashed-line
cotter pin position), 8 and 9 show an eight-bag operation. In all
positions for bags from one through 10 bags, the wheels and axle
are allowed, when truck 10 is tilted back into carrying position,
to move further back beneath the load so that the wheels can be
made to bear a major portion of the weight of the load. Of special
importance is the fact that by means of the adjustable axle stops
the amount of axle travel and consequently the position of the
center of gravity can be regulated according to load. Furthermore,
with the toe and intermediate pivot members shown the vertical axle
shifting is gradual and all tendency to lose the load is
eliminated. It will also be noted that the handle mechanism by
being positionable in any of several positions allows the
load-bearing members to accommodate to both relatively low and
relatively high pallets.
* * * * *