Note: Descriptions are shown in the official language in which they were submitted.
CA 02481726 2004-10-12
ARTICLE TRANSFER DEVICE AND METHOD
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to the transfer of articles and more
particularly to carriers therefor.
2. DESCRIPTION OF THE RELATED ART
Manufacturing, assembly, distribution and warehousing facilities usually
involve extensive transfers of
materials and articles from one location to another. This is commonly done by
carriers such as wheeled
carts, which are typically arranged with a pair of caster wheels on one end
and a pair of fixed axle wheels
on the other. Advances in plastics have provided an impressive range of
resilient plastic wheels which are
capable of withstanding the punishing wear and tear that these wheels undergo
when used on these kinds of
carts. However, the use of the resilient plastic wheels can increase the
forces needed to move the carts.
In recent years, there has been an increasing focus on improving the ergonomic
aspects of different
processes used in manufacturing, assembly, distribution and warehousing
facilities. An important facet of
these ergonomic studies is the reduction of injuries such as back injuries.
With this in mind, the transfers of
articles using carriers or carts which involve physical exertion by an
operator are significant sources of
such injuries.
It is therefore an object of the present invention to improve the transfer of
articles.
SUMMARY OF THE INVENTION
In one of its aspects, the present invention provides a cart comprising a
support frame portion, a pair of
swivel wheels and a pair of non swivel wheels, the swivel and non swivel
wheels lying in a common plane
to roll along a common ground surface, lifting means having at least one non
swivel support wheel and
being operable to transfer the support wheel between a first position above
the common plane and a second
position below the common plane, the lifting means further comprising
actuating means to displace the
support wheel between the first and second positions below the common plane,
the support wheel being
operable in the second position to displace either the swivel wheels or the
non-swivel wheels off the ground
surface.
CA 02481726 2004-10-12
Preferably, the common plane is fixed relative to the support frame portion,
but may be adjustable relative
thereto if desired.
In an embodiment, the lifting means is located centrally between the non-
swivel wheels and the swivel
wheels and includes an undercarriage supporting a pair of fixed axle support
wheels. Preferably, the
undercarriage is movable relative to the support frame portion.
In an embodiment, the support frame portion further comprises positioning
means to position the
undercarriage relative to the support frame portion. In this case, the support
frame portion has a pair of
longitudinal central frame members and a pair of frost undercarriage support
flanges oppositely mounted
on, and inwardly extending from, the central frame members. The undercarriage
has a pair of outwardly
extending second undercarriage support flanges, each extending along a
corresponding side of the
undercarriage. The second undercarriage support flanges are positioned for
slidable movement along the
corresponding first undercarriage support flanges. The positioning means
further provides a number of
threaded fasteners, each extending through a corresponding one of a series of
matching passages formed in
the first undercarriage support flange.
In an embodiment, the undercarriage includes displacement means to displace
the undercarriage relative to
the support frame portion. The displacement means includes a threaded rod
which is threadably engaged
between the undercarriage and the support frame portion, by one or more
threaded support flanges.
However, an alternative embodiment is also provided in which displacement
means includes an electrical,
hydraulic or pneumatic motor and/or a gear arrangement which is operable
between the undercarriage and
the support frame portion.
In an embodiment, the actuating means includes an electrical, hydraulic and/or
manual motor portion and a
transmission portion operable in response thereto, for delivering an actuating
force to the support wheels.
In one example, the transmission portion includes a ram portion, but may
include other arrangements, such
as gear assemblies, linkages and the like.
In an embodiment, the support wheels are mounted for rotation on an axle
member. The ram portion
further comprises an hydraulic ram acting between the support frame portion
and the support wheels and
the motor portion includes an hydraulic pump for displacing the hydraulic ram,
the hydraulic ram and the
hydraulic pump being operably joined by a hydraulic fluid circuit. In this
example, the actuating means
further comprises a pair of link members each pivotally mounted to the
undercarriage and supporting a
corresponding support wheel. A cross member extends across the undercarriage
and each of the link
members includes an end plate fixed to a corresponding end of the cross
member. Each support wheel is
thus mounted on a corresponding end region.
2
CA 02481726 2004-10-12
In an embodiment, the actuating means includes a bleed unit for bleeding the
hydraulic ram for
progressively returning the support wheels to the first position. The bleed
unit includes a variable valve in
the hydraulic fluid circuit, the hydraulic ram or the hydraulic pump. A first
foot pedal is provided which is
movable between a first operable position and a second operable position for
pressurizing the hydraulic
fluid circuit for advancing the hydraulic ram. A spring portion biases the
first foot pedal to its first
operable position.
In an embodiment, a releasing means is provided for depressurizing the
hydraulic fluid circuit for retracting
the hydraulic ram. The releasing means is activated by a second foot pedal.
In an embodiment, the actuating means includes return means for returning the
support wheels to the first
position, preferably following activation of the releasing means.
In an embodiment, each support wheel includes a ground engaging portion formed
from a substantially non
resilient material. Preferably, the non resilient material includes one or
more of steel, bronze and
aluminum, but may include other materials as desired.
In an embodiment, each of the swivel and non swivel wheels includes a ground
engaging portion formed
from a resilient material.
In an embodiment, the cart further comprises a hitch portion which is operable
between a first position and
a second position, wherein in the first position the hitch portion is arranged
to connect to an adjacent cart
and/or a tow vehicle. In one example, the hitch portion includes a hitch arm
which is generally horizontal
in the first position and generally upright in the second position.
A further embodiment provides safety means which is responsive to the hitch
portion to cause the actuating
means to displace the support wheels to the first position when the hitch
portion is displaced toward the
first position or when the hitch portion reaches the first position or a
position between the first and second
positions.
1n a further embodiment, the actuating means further comprises a trigger
assembly for triggering the motor
portion for deploying the transmission portion. The cart is provided, in one
example, with a cart handle and
the trigger assembly may, if desired, be mounted on the cart handle, or
another suitable location on the cart,
as desired. The motor portion includes a hydraulic pump which is responsive to
a switch portion operably
coupled to the trigger assembly. The trigger assembly also desirably includes
a trigger latch which is
positioned adjacent the cart handle to be actuated when the cart handle is
gripped by an operator. A power
source supplies a power signal to the hydraulic pump.
3
CA 02481726 2004-10-12
1n another of its aspects, the present invention provides a carrier for
transporting an article comprising a
support frame portion, a first undercarriage including a plurality of first
wheels to roll along a ground
surface and having rolling contact points lying in a common plane, a second
undercarriage located centrally
within the first undercarriage and including one or more second wheels,
actuating means for actuating the
second undercarriage from a position with the one or more second wheels above
the common plane to a
position beyond the common plane which is sufficient to displace one or more
of the first wheels of the first
undercarriage off the ground surface.
In an embodiment, one or more of the first and/or second wheels are swivel
wheels. However, if desired,
one or more of the first and/or second wheels may be non-swivel wheels.
In an embodiment, one or more of the first and/or second wheels are fixed axle
wheels.
In an embodiment, the second undercarriage is inclined relative to the first
undercarriage.
In one embodiment, the support frame portion has a longitudinal axis and the
second undercarriage is
operable to adjust the position of the one or more second fixed axle wheels
relative to the longitudinal axis.
Preferably, the second undercarriage is movable in a direction substantially
parallel with or substantially
perpendicular to the longitudinal axis, or both, though other movements at
other angles relative to the
longitudinal axis are also contemplated.
In still another of its aspects, the present invention provides a method of
transporting an article, comprising
- a step for providing a carrier for supporting the article;
- a step for providing a first undercarriage including a plurality of first
wheels to roll along a
ground surface with rolling contact points of the first wheels lying in a
common plane,
- a step for providing a second undercarriage located centrally within the
first undercarriage and
including a pair of second fixed axle wheels,
- a step for displacing the second undercarriage so that the second fixed axle
wheels are above the
common plane,
- a step for transferring the carrier from an originating location to a
destination location;
- and after the carrier arrives near the destination location, a step for
actuating the second
undercarriage from the position with the second fixed axle wheels above the
common plane to a
4
CA 02481726 2004-10-12
r
position beyond the common plane sufficient to displace one or more first
wheels off the ground
surface; and
- manipulating the carrier for the article to be in a predetermined
orientation at the destination
location.
In yet another of its aspects, the present invention provides a method of
improving the transfer of an article
between an originating location and a destination location, comprising the
steps of:
a) providing a carrier for supporting an article during transfer;
b) providing the carrier with a first wheeled undercarriage having a plurality
of first wheels on
which to displace the carrier between the originating and destination
locations;
c) arranging the first wheels to roll on a ground surface with rolling contact
portions of the first
wheels lying in a common plane;
d) selecting a predetermined characteristic of the first wheels to optimize
the transfer of the
article between the originating location and destination locations;
e) transferring the carrier between the originating and destination locations
on the first wheels,
f) providing a second undercarriage with at least one second fixed axle
support wheel;
g) selecting a predetermined characteristic of the at least one second fixed
axle support wheel to
optimize the manipulation of the carrier at the destination location;
h) and after step e), actuating the at least one second fixed axle support
wheel from a position
above the common plane to a position beyond the common plane, sufficient to
raise at least
one selected first wheel of the first undercarriage off the ground surface;
and
i) manipulating the carrier for the article to be in a predetermined
orientation at the destination
location.
In one embodiment, the step d) includes the step of selecting the first wheels
with a ground engaging
portion formed from a resilient material, while step g) includes the step of
selecting the second fixed axle
wheels with a ground engaging portion formed from a substantially non-
resilient material.
5
CA 02481726 2004-10-12
In still another of its aspects, the present invention provides a kit for
converting a cart of the type having a
support frame portion, a pair of swivel wheels and a pair of non swivel
wheels, the swivel and non swivel
wheels lying in a common plane to roll along a common ground surface, the kit
comprising lifting means
having at least one non swivel support wheel and being mountable on the
support frame portion for
transferring the at least one support wheel between a first position above the
common plane and a second
position below the common plane, the lifting portion further comprising
actuating means mountable
between the support frame portion and the at least one support wheel to
displace the at least one support
wheel between a first position above the common plane and a second position
below the common plane,
the at least one support wheel being operable in the second position to
displace either the swivel wheels or
the non-swivel wheels off the ground surface
In still another of its aspects a cart comprising a support frame portion, a
pair of swivel wheels and a pair of
non swivel wheels, the swivel and non swivel wheels lying in a common plane to
roll along a common
ground surface, a lifting portion having at least one rolling support element
and being operable to transfer
the at least one rolling support element between a first position above the
common plane and a second
position below the common plane, the lifting portion further comprising an
actuating portion to displace
the at least one rolling support element between the first and second
positions, the rolling support element
being operable in the second position to displace either the swivel wheels or
the non-swivel wheels off the
ground surface.
In one embodiment, the at least one rolling support element includes one or
more rollers and/or wheels.
1n one embodiment, the cart has two non swivel wheels and two swivel wheels.
This arrangement is suited
to carts which are towed from one location to another, among other methods of
transport. However, other
wheel an-angements may be used. For instance, all wheels may be of the swivel
or non swivel variety.
Some wheels may be swivel in one operative mode and non swivel in another
operative mode. The rolling
support elements may similarly be provided in a number of possible
combinations. For example, the
rolling support elements may be all swivel wheels, non-swivel wheels, rollers
or be provided in other
arrangements as desired.
In still another of its aspects, the present invention provides a cart
comprising a support frame portion, a
pair of swivel wheels and a pair of non swivel wheels, the swivel and non
swivel wheels lying in a common
plane to roll along a common ground surface, a lifting portion having at least
one rolling support element
and being operable to transfer the at least one rolling support element from a
first position relative to the
common plane and a second position below the common plane, the lifting portion
further comprising an
actuating portion to displace the at least one rolling support element between
the first and second positions,
6
CA 02481726 2004-10-12
the rolling support element being operable in the second position to displace
either the swivel wheels or the
non-swivel wheels off the ground surface.
In an embodiment, the first position is either above the common or in the
common plane.
In an embodiment, the at least one rolling support element is operable in the
first position to contact the
common ground surface together with the swivel and non swivel wheels.
In another embodiment, the at least one rolling support element includes a
suspension arrangement for
permitting the at least one rolling support element, in the first position, to
accommodate changes in the
common ground surface.
BRIEF DESCRIPTION OF THE DRAWINGS
Several preferred embodiments of the present invention will now be described,
by way of example only,
with reference to the appended drawings in which:
Figure 1 is a fragmentary perspective view of a cart;
Figure 2 bottom plan view of the cart of figure 1;
Figure 3 is a side view of the cart of figure 1 in a first operative position;
Figure 4 is a side view of the cart of figure 1 in a second operative
position;
Figure 5 is another side view of the cart;
Figure 6 is a fragmentary perspective view of a portion of the cart of figure
2 in one operative position;
Figure 6a is another fragmentary perspective view of the portion shown in
figure 6;
Figure 6b is another fragmentary perspective view of the portion shown in
figure 6, in this case in another
direction;
Figure 7 is a fragmentary perspective view of a portion of the cart of figure
2 in another operative position;
Figure 8 is a fragmentary perspective view of another portion of the cart of
figure 1;
7
CA 02481726 2004-10-12
Figure 9 is another fragmentary perspective view of the portion shown in
figure 8;
Figure 9a is a fragmentary perspective view of another portion of the cart of
figure 1;
Figure 9b is a fragmentary schematic vie taken on plane 9b-9b of figure 9;
Figure 10 is a fragmentary plan view of an alternative portion to that shown
in figure 9a;
Figure 11 is a fragmentary perspective view of another cart; and
Figure 12 is a partly schematic plan view of the cart of figure I 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, particularly figures 1 and 2 there is provided
a cart shown at 10 having a
support frame portion 12 with a load supporting deck 14, a pair of swivel (or
otherwise known as castered)
wheels 16, 18 on one end and a pair of non swivel (or otherwise known as fixed
axle) wheels 20, 22 on an
opposite end. As can be seen in figure 3, the wheels 18 and 22 have lowermost
points 26 and 30
respectively (as do wheels 16 and 20 though not shown in figure 3) which lie
in a common plane 32 so that
they can roll along a ground surface 34 for the transfer of a load shown in
phantom at 36. The load 36 may
include such things as manufactured articles, materials and the like. In this
case the common plane 32
corresponds with the ground surface 34.
Referring to figures 2 and 3, lifting means is generally shown at 42 with at
least one, in this case two, non
swivel support wheels 38, 40. As can be seen in figures 3 and 4, the lifting
means 42 is operable to transfer
the support wheels 38, 40 between a first position above the common plane 32
(figure 3) and a second
position below the common plane 32 (figure 4). Thus, in figure 4, for the sake
of illustration, the common
plane 32 is now shown as being situated parallel to and above the ground
surface 34. However, in this
particular example, the cart 10 will tend to support the load 36 on the
support wheels 38, 40 and either on
the swivel wheels 16, 18 or non-swivel wheels 20, 22 respectively. Thus, in
the particular arrangement
shown in figure S, the cart 10 is operable to roll on the ground surface 34 on
the support wheels 38, 40 and
the swivel wheels 16, 18.
Referring to figure 2, it can be seen that the support wheels 38, 40 are
located relatively closer to a central
longitudinal axis 'A' of the cart 10 in comparison with the swivel and non-
swivel wheels 16, 18 and 20, 22.
If desired, each of the support wheels 38, 40 can be substantially aligned
with their neighboring swivel and
non swivel wheels along a common corresponding longitudinal edge region of the
cart, the position of the
CA 02481726 2004-10-12
support wheel 38 in this case being shown in phantom generally at 38'. For
that matter, the support wheels
38, 40 may also be positioned beyond the swivel and non-swivel wheels 16, 18
and 20, 22 relative to the
longitudinal axis A, if desired, as shown (for the support wheel 40) in
phantom generally at 40'. Further, it
will be understood that the spacing between the support wheels 38, 40 may be
increased or decreased to
provide a desired level of lateral stability to the cart 10. For instance the
wider the stance of the support
wheels 38, 40, the greater the stability of the cart 10 when the support
wheels 38, 40 are in the second
position against the ground surface 34.
Still further, the support wheels 38, 40 may be replaced by a single rolling
support element, either in the
form of one or more than one wheel or one or more than one roller (as shown in
phantom at 39) whose
lateral dimension is selected to provide the required degree of stabilized for
the cart 10 or some other form
of rolling support as desired.
In this example, the common plane 32 is fixed relative to the support frame
portion 12. However, the
position of the common plane 32 may be adjustable relative to the support
frame portion 12, if desired.
This may be achieved, for example, through the use of height adjustable axle
support structures (not
shown) supporting one or both pairs of swivel or non-swivel wheels 16, 18, or
20, 22 respectively.
Referring now to figure 3, the lifting means 42 provides an actuating means
shown generally at 44 to cause
the support wheels 38, 40 to pass through the common plane 32 for lifting
either pair of swivel or non-
swivel wheels 16, 18 and 20, 22 off the ground surface 34.
1n this example, the lifting means 42 is centrally located with the non-swivel
wheels 20, 22 on one side and
the swivel wheels 16, 18 on the other. In this case, the specific location of
the lifting means 42 may be
adjusted relative to the support fi-ame portion 12 to accommodate variations
in the load 36 and its position
on the deck 14. As shown in figure 2, this may be achieved by way of an
undercarriage 46 which is
mounted on the support frame portion 12 for movement thereof as shown by the
double arrow.
Though not necessary in all examples of the cart 10, the ability provided by
the undercarriage 46 to adjust
the location of the lifting means 42 is particularly beneficial in situations
wherein changes to the load 36 or
its position on the deck 14 alter the location of the centre of gravity of the
cart 10, as shown at 48 in figure
3. A shift in the load's centre of gravity may thus cause a corresponding
shift in the centre of gravity 48 of
the cart 10. Thus, the undercarriage 46 may be adjusted to maintain the centre
of gravity 48 on one side of
the support wheels 38, 40 so that the swivel wheels 16, 18 remain in contact
with the ground surface,
regardless of the orientation, shape or weight of the load 36 on the deck 14.
However, if desired, the centre
of gravity 48 may be centered on the support wheels 38, 40.
9
CA 02481726 2004-10-12
Referring to figure 6, the support frame portion 12 has a pair of longitudinal
central frame members 50 and
a pair of first undercarriage support flanges 52 oppositely mounted on, and
inwardly extending from, the
central frame members 50. The undercarriage 46 has a pair of outwardly
extending second undercarriage
support flanges 54, each being part of a right angled frame member 56
extending along a corresponding
side of the undercarriage 46. The second undercarriage support flanges 54 are
positioned for slidable
movement along the first undercarriage support flanges 52.
As shown in figure 6a, one or more additional first and/or second support
flanges 58, 60 may be provided
adjacent the corresponding first and second support flanges 52, 54, as desired
to enhance the coupling
between the support frame portion 12 and the undercarriage 46.
Referring again to figure 6, the support frame portion 12 has a positioning
means 62 to position the
undercarriage 46 relative to the support frame portion 12. In this case, the
positioning means 62 is
provided in the form of a number of threaded fasteners 64 each extending
through a corresponding one of a
series of matching passages 66 formed in the first undercarriage support
flange 52. The positioning means
may also include such things as clamping members (not shown) and the like to
secure the undercarriage 46
to the support frame portion 12.
As shown in figure 2, the undercarriage 46, may also be provided with
displacement means 68 to displace
the undercarriage 46 relative to the support frame portion 12. The
displacement means 68 may, for
example, take the form of a threaded rod 70 which is threadably engaged
between the undercarriage 42 and
the support frame portion 12, by one or more threaded support flanges 72 or
the like. Alternatively, the
displacement means 68 may include other arrangements such as an electrical,
hydraulic and/or pneumatic
motor (as shown schematically at 74), gear arrangements (not shown) or the
like. In this case, the motor 74
may be responsive to an external controller as will be described. While the
undercarriage 46 allows the
position of the lifting means to be adjusted along the longitudinal axis 'A'
in relation to the support frame
member 12, the lifting means may alternatively be fixed in position relative
to the support portion 12.
The actuating means 44 is best shown in figures 6, 6a, 6b and 7 and includes
an hydraulic ram 76, including
a housing portion 78 and a ram portion 80 extending outwardly therefrom and
acting between the
undercarriage 46 and the support wheels 38, 40. The housing portion 78 has one
end region which presents
the ram portion 80 and an opposite end region which is pivotally mounted by a
first pivot pin 82, to a pair
of first flanges 84 extending from the undercarriage 46. The ram portion 80,
is pivotally mounted at a
remote end region thereof by way of a second pivot pin 86 (figure 6b) to a
pair of second flanges 88
mounted on a cross member 90.
CA 02481726 2004-10-12
Referring to figure 6, the cross member 90 has a central angled portion 92 and
a pair of link members 93 in
the form of end plates 94 welded on corresponding opposite ends thereof. Each
end plate 94 has a first
passage 96 to receive a third pivot pin 98, for pivotally mounting the end
plate 94 to a corresponding frame
member 56. In addition, the corresponding frame member 56 has an adjustable
stopping means 100 to
provide a limit for the cross member 90 to arrive at a predetermined end
location when the support wheels
38, 40 are deployed to the second position. The stopping means 100 includes a
first pair of stop blocks
102, each fixed to a corresponding frame member 56. A threaded fastener, in
this case a bolt 106, is
threaded into each first stop block 102 extending outwardly therefrom. The
bolt 106 has a head which is
positioned to intercept a corresponding second stop block 104 (figure 6) which
itself is fixed to an inner
side of a corresponding end plate 94. Each end plate 94 has a second passage
108 to receive an axle
member 110, itself supporting the support wheels 38, 40 at opposite ends
thereof. Thus, the first and
second stop blocks 102, 104 are operable to limit the travel of the end plate
94 and thus the support wheels
38, 40 beyond the second operating position thereof.
While the cross member 90 provides a secure positioning of the link members 93
(in their preferred form as
end plates 94), the cross member 90 may be replaced by a direct coupling of
the hydraulic ram 76 to the
link members 93. The link members 93 may in turn each be pivotally secured to
the undercarriage 46, in a
manner permitting them to support the axle member 110 without the need of the
cross member 90. If
desired, the axle member 110 may be replaced by axle segments (not shown),
each fixed to a corresponding
link member 93.
Referring to figure 6, a return means 112 is also provided for returning the
support wheels 38, 40 to the first
position above the common plane 32. In this case, the return means 112 is
provided in the form of a double
spring rod arrangement 114 involving a pair of opposed rods 116 extending
through a first support flange
118 on the housing portion 78 and fixed at one end to a second support flange
120 (figure 7) by way of
fasteners 122. The second support flange 120 is in turn fixed to the ram
portion 80 at a location near its end
region. Each rod 116 is provided at its other end with an anchor fastener 124
to cooperate with the first
support flange 118 to position a compression spring 126 therebetween. A
commercial version of the
hydraulic ram 76 is available from NORTHRIDGE METAL FABRICATORS, New Lowell,
Ontario
CANADA.
Referring to figures 8 and 9, the actuating means 44 is further provided with
a motor means 128 in the form
of an hydraulic pump 136 having first and second foot pedals 130 and 132
respectively. The first foot
pedal 130 operates the hydraulic pump 136, while the second foot pedal 132
operates a release means 134,
which is integrally formed with (and operable to release) the hydraulic pump
136 to displace the support
wheels 38, 40 toward their first position above the common plane 32. A
commercial version of the
hydraulic pump 136 is available from STAR HYDRAULIC under model number FP3AC-
PL. Thus, the
11
CA 02481726 2004-10-12
first foot pedal 130 is operable in two reciprocating movements, the first
movement when it is moved from
its first operable position to its second operable position to pressurize the
hydraulic pump 136 and thus the
hydraulic ram 76 by way of a hydraulic fluid circuit 138. The second movement
occurs when the second
foot pedal returns to its first operable position, in this case under the
action of a spring 139. The hydraulic
circuit 138 is provided in the form of first and second hydraulic hoses 140,
142. The release means 134 is
provided, in one example, as a release valve which is responsive either to the
second foot pedal 132 or a
predetermined limit function. The latter is operable to avoid damage when the
fluid pressures in the
hydraulic fluid circuit 138 exceed a predetermined upper pressure limit. The
predetermined limit function
is a built in function of the commercial version of the hydraulic pump 136
described herein, but may be
external to the hydraulic pump 136, if desired.
Refen-ing to figure 9a, the actuating means 44 also provides a bleed unit 144
for bleeding the hydraulic ram
76 from the extended position (figure 6) in which the support wheels 38, 40
are at or near their second
position below the common plane 32 in order to return the support wheels 38,
40 toward the first position.
The bleed unit 144 provides, in this case, the substantial equivalent of an
imperfect hydraulic seal on a high
pressure side of the hydraulic ram 76. This has the effect of causing a
gradual leakage of hydraulic fluid
from the hydraulic chamber (not shown) of the hydraulic ram 76. This is
provided by a variable valve 146,
which is located in the hydraulic fluid circuit between the hydraulic ram 76
and the second hydraulic hose
142. If desired, the bleed unit function may be provided elsewhere, such as in
the hydraulic fluid circuit or
the hydraulic pump 136 itself. The bleed unit 144 is operable to insure that
the actuation means 44 is not
deployed beyond a reasonable dwell time. This allows the operator to deploy
the support wheels 38, 40 to
raise the cart 10 and then, within a predetermined dwell time, to manipulate
the cart with the support
wheels 38, 40 gradually traveling toward their first position, as seen by a
gradual lowering of the cart 10.
For example, the bleed unit 144 may be configured by making an appropriate
adjustment to the variable
valve 146 by way of an adjustment portion 146a to completely retract the
support wheels within about two
minutes for an unloaded cart 10 (which may in one case weigh in the order of
about 250 pounds) and
within about 30 seconds for a loaded cart (which may in one case weigh in the
order of about 1350
pounds).
When fully retracted to their first position, the support wheels 38, 40 may
provide ground clearances in the
order of about 1 inch to about 8 inches. When the support wheels 38, 40 are
fully deployed they may be
about 0.5 inch below the common plane 32, though other specific ground
clearances or deployments may
be used as desired. If desired, the variable valve unit 146 may be responsive
to an electrically,
pneumatically or hydraulically powered actuator shown schematically at 146b
which in turn may be
responsive to a switch 146c located on a control pod 147 (figure I) at a
suitable location on the cart 10 such
as a cart handle 148 shown in figure 1. If desired, the control pod 147 may
also be provided with one or
more other control functions by way of one or more buttons, graphical readouts
and the like, as shown
12
CA 02481726 2004-10-12
schematically at 147a to control other functions of the cart 10. For instance,
the control functions may
include the adjustment of the undercarriage by way of the motor shown at 74 in
figure 2 as described
earlier, and the operation of the hydraulic ram 76 by way of an electric motor
(not shown).
The swivel and non swivel wheels 16, 18 and 20, 22 are conveniently equipped
with ground engaging
portions formed from resilient materials such as urethanes and other plastics,
though other suitable
materials may of course be employed, depending on, for instance, the operating
weight of cart 10 and the
nature of the ground surface 34. The support wheels 38, 40 are preferably
equipped with ground engaging
portions which are of a substantially non resilient wheel material, such as
steel, bronze, aluminum and the
like. This has the benefit of ensuring the forces needed to displace the cart
when the support wheels 38, 40
in their second position are substantially reduced since the rolling friction
of the support wheels 38, 40
should, by consequence, generate lower frictional forces compared with the
higher frictional forces
generated by the resilient material of the swivel and non swivel wheels, 16,
18 and 20, 22.
The support wheels 38, 40 are also desirably provided with a set of bearings
(not shown) which provide an
improved reduction of rolling friction. Examples of suitable bearings for use
on the support wheels 38, 40
are available from CANADIAN BEARINGS.
However, other materials may be used, as desired. Moreover, the same materials
or different material may
be employed for one or more of the wheels, including resilient material for
the support wheels and
substantially non resilient materials for the swivel or non swivel wheels, as
desired. For example, suitable
support wheels, swivel and non swivel wheels are available from COULSON.
As seen in figure 1, the cart handle 148 is configured to assist the operator
in maneuvering the cart 10 and
includes an inverted U-shaped support member fixed to the frame 12 adjacent a
hitch arm 150. The hitch
arm I50 is operable for connecting the cart 10 to an adjacent cart or a tow
vehicle, as shown in fragmented
fashion at 153 in figure 3. In figure 8 and 9, a safety means 152 is operably
coupled to the hitch arm 150
and is responsive to movements thereof to release the hydraulic ram 76 to
return the support wheels 38, 40
to their first position above the common plane 32. The safety means 152
includes a cable assembly 154
having a cable 155 which is coupled to a lower region of the hitch arm 150 by
way of a fastener 154a and at
an opposite end to the second foot pedal 132 by way of anchor member 154b. The
cable assembly 154 has
a pair of cable supports 156, 158 which secure the cable assembly 154 to the
cart frame 12. Of course other
hitch portions may be used in place of the hitch arm 150, such as ball and
socket, or loop and hook
coupling units. Though not specifically illustrated herein, another safety
means may include an "inertia"
switch which activates based on relative movement between a switch and its
associated contacts. In this
case, when a load is pulled, a short movement in the hitch forward will cause
the "inertia" switch to release
the hydraulic pressure.
13
CA 02481726 2004-10-12
Thus, the second foot pedal 132 may be activated to release the hydraulic
pressure in the hydraulic fluid
circuit 138, either by directly depressing the second foot pedal 132 or by
lowering the hitch arm 150. In the
latter case, as the hitch arm 150 is moved from its upright position as shown
in figure 8 to its horizontal
operative position as shown in figure 9. The hitch arm 150 thus draws the
cable 155 outward in the region
of the fastener 154a, as seen by the arrow adjacent thereto causing a
proportional displacement of the
anchor member 154b and thus the second foot pedal 132. Thus, the safety means
152 may be operable
when the hitch arm 150 reaches the first position, or in between the first and
second position and/or when
the hitch arm 150 leaves the second position.
Thus, the cart 10 may be used as follows. The cart 10 is first assembled as
shown and is positioned with
the supporting wheels 38, 40 in their first position above the common plane 32
to receive a load 36 on the
deck 14. The load 36 may, in this case, include a rack or fixture containing a
number of manufactured or
assembled articles or components for later manufacture or assembly into a
finished article, such as a
vehicle.
It is preferable that the load 36 be located so that the centre of gravity 48
of the cart is just to the left of the
support wheels 38, 40 (figure 5) when in their second position, in order to
have the majority of the load
resting on the support wheels 38, 40 for reasons to be described. If desired
at the time of placing the load
36 on the deck 14 (or at a later stage in or following the transfer of the
load 36), the undercarriage 46 may
be adjusted as desired by rotating the threaded rod 70 or by displacing the
motor 74, to bring the centre of
gravity 48 to a desirable location relative to the support wheels 38, 40. For
instance, the load 36 may be
positioned so that about 55 percent of the load is located on the swivel wheel
side of the support wheels 38,
40.
With the load 36 in position, the cart is then transferred from an originating
location to a destination
location. For example, the originating location might be the output of a
vehicle component storage or
manufacturing area and the destination location might be a site on an assembly
line where the vehicle
component is to be installed on a vehicle. The transfer of the cart 10 is
conducted by a tow vehicle 153
which is connected to the hitch arm 150 in its horizontal position as shown in
figure 3. It will be
understood that, with the swivel and non swivel wheels 16, 18 and 20, 22
having a resilient ground surface
engaging portion, the frictional forces generated between the ground surface
34 and the ground wheel
engaging portions requires a relatively high "push pull" force to be exerted
by the tow vehicle 153 on the
hitch arm 150. The term "'push pull" force is intended to mean the minimum
force needed to overcome the
collective static friction generated at the swivel and non swivel wheels 16,
18 and 20, 22. This term can be
considered to include the forces needed to twist the swivel wheels 16, 18 from
a transverse or "sideways"
position to a position in line with the longitudinal axis A. Of course, this
"push pull" force would be
14
CA 02481726 2004-10-12
significant if an operator were to attempt to displace the load bearing cart
10 by exerting forces on the cart
handle 148 and doing so would risk back injury. Of course, these forces would
not pose a problem for the
tow vehicle 153 in most practical cases.
The tow vehicle 153 delivers the cart 10 to a location near the destination
location and the hitch arm 150 is
thus disconnected from the tow vehicle 153 and raised to its upright storage
position as shown in figure 1.
While grasping the cart handle 148 for support, the operator depresses the
first foot pedal 130 in a
reciprocating fashion, first to depress the pedal 130 and then to allow the
force of the spring 139 to return
the first foot pedal 130 to an upper position. With each stroke of the first
foot pedal 130, the hydraulic ram
76 is extended causing the hydraulic ram 76 to displace the cross member 90
which in turn displaces the
support wheels 38, 40 toward, and then beyond, the common plane 32. With the
location of the load 36 on
the swivel wheel side of the support wheels 38, 40, continued displacement of
the support wheels 38, 40
beyond the common plane 32 brings the non swivel wheels 20, 22 off the ground
surface 34 with the vast
majority of the weight of the load being carried by the support wheels 38, 40.
These wheels, in their most
preferred form, are steel and thus have substantially non resilient ground
surface engaging portions, which
means that the forces needed to overcome the rolling friction of the support
wheels 38, 40 are also
significantly reduced. Thus, with the support wheels 38, 40 in their deployed
position as shown in figure 5,
the operator may grasp the cart handle 148 and manipulate the cart 10 to
position the load 36 in its proper
orientation at the destination location.
Meanwhile, the bleed unit 146 slowly reduces the pressure in the hydraulic ram
76 resulting in the support
wheels 38, 40 slowly retracting toward their position above the common plane
32. The speed of this
retraction is, of course, adjustable and is intended to provide the operator
sufficient time to manipulate the
cart 10 to its desired position at the destination location while ensuring
that the cart 10 will not remain with
the support wheels 38, 40 fully deployed. It will be understood that the cart
10 may be used without the
bleed unit 146, if desired.
Should the operator wish to release the pressure in the hydraulic ram 76, the
operator depresses the second
foot pedal 132 which activates the release valve located within the hydraulic
pump 136. Should the
operator opt to connect the hitch arm 150 with a tow vehicle 153, the
corresponding swinging of the hitch
arm 150 from the upright position toward the horizontal position displaces the
cable 155 which in turn
similarly depresses the second foot pedal 132 to release the pressure in the
hydraulic ram 76. Of course,
other variations of the cart 10 are intended without necessarily using the
release means as described herein.
Once the pressure is released from the hydraulic ram 76, the support wheels
38, 40 will travel toward the
common plane 32. In the case where the return means 112 is utilized (figure
6), the support wheels 38, 40
will return to their first position above the common plane 32 under the action
of compression springs 126.
CA 02481726 2004-10-12
Figure 9b shows an alternative safety means wherein a satellite hydraulic
release valve 160 is located
adjacent a lower region of the hitch arm 150. The release valve 160 is
provided with an activator 162 and
is in fluid communication with the hydraulic fluid circuit 138 (figure 9) by
way of satellite fluid circuit
portion 164. In this case, the hinge arm I50 is provided with a cam portion
150a to engage the activator
162 to release the hydraulic pressure in the hydraulic fluid circuit 138 when
the hitch arm I50 is moved
from its upright storage position to its horizontal operative position.
An alternative to the hydraulic ram 76 is shown in figure 10. In this case, a
hydraulic ram 170 and a
tension spring assembly 172 are separately mounted between a cross member 174
(supporting a pair of
support wheels not shown) and a lateral frame member 176 (of an undercarriage
not shown) by way of a
respective set of pivot pins 178, 180, each held by a corresponding pair of
mounting flanges 182, 184
respectively. The hydraulic ram 170 is fluidly coupled to a hydraulic fluid
circuit 186 and is thus operable
to displace the support wheels as described earlier. In this case, the
hydraulic ram 170 is separate from the
tension spring assembly 172 and the latter is operable to return, the support
wheels 38, 40 to their first
position above the common plane 32 as described earlier.
It may be desirable in some cases to provide a cart which does not rely on a
manual pumping of a hydraulic
pump as necessary in one version of the cart 10 as described above. Thus, with
reference to figure I 1 and
12, an alternative cart is shown at 200, having a cart handle 202 which is
mounted on a cart frame 204.
Mounted on the cart handle 202 is a trigger assembly 206, operably coupled
with an hydraulic actuator
assembly 208, by way of a cable 210. The trigger assembly 206 has a trigger
latch 212 which is responsive
to the gripping hand of an operator as when gripping the cart handle 202 to
maneuver the cart 200. The
trigger assembly 206 thus emits an actuating signal to the hydraulic actuator
assembly 208 when the
operator grips the cart handle 202 and displaces the trigger latch 212. In
this case, the hydraulic actuator
assembly 208 includes a switch portion 214 which is operably coupled with the
cable 210 to receive the
actuating signal. A hydraulic pump 216 receives a corresponding actuating
power signal from the switch
portion 214 to pressurize or depressurize a hydraulic fluid circuit shown at
218. The hydraulic fluid circuit
218 includes a hydraulic ram (not shown) which is operably coupled with a pair
of support wheels (not
shown) as described above. The hydraulic pump 216 is powered by a power supply
220 in this case in the
form of a battery pack 222. In this case, then, the cart 200 is operable to
actuate the support wheels when
the operator grips the handle and thus depresses the trigger latch 212. The
cart 200 is also operable to
retract the support wheels when the operator releases his grip on the cart
handle 202 thus releasing the
trigger latch 212, which causes the hydraulic pump 2I6 to depressurize the
hydraulic circuit 218.
Figure 12 shows another variation of the cart 200 in which the hydraulic pump
216 is positioned locally to
the hydraulic ram and receives power from the battery pack 222 by way of a
power cable 224.
16
CA 02481726 2004-10-12
Y
While the present invention has been described for what are presently
considered the preferred
embodiments, the invention is not so limited. To the contrary, the invention
is intended to cover various
modifications and equivalent arrangements included within the spirit and scope
of the appended claims.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such
modifications and equivalent structures and functions.
If desired, the support wheels and the hardware providing the actuating means
may be provided in a kit for
retrofitting existing wheeled carts.
While the cart 10 is provided with an undercarnage 46 which is capable of
adjustments along the
longitudinal axis "A", the undercarriage 46 may, if desired, be arranged to
provide lateral adjustment, that
is, perpendicular to the longitudinal axis "A". This may be necessary or
desired, in some cases, to
accommodate lateral imbalances caused by a misplacing of a toad on the deck
14, for example as shown
schematically in dashed lines at 36' in figure 2. The lateral adjustment may,
if desired, be provided in
addition to the longitudinal adjustment, or as an alternative thereto.
Furthermore, the undercarriage may be inclined relative to the support frame
portion, as shown in chain-
dotted lines at 42' in figure 3. In this case, deployment of the support
wheels between their first and second
positions may be made by displacing the undercarriage 42' along an inclined
axis B (as shown by the chain
dotted arrow) which is at an angle relative to the support frame portion. This
displacement includes a
component, in this case a vertical component as viewed in figure 3, which may
be selected to provide the
necessary displacement of the support wheels without additional displacement
of the support wheels 38, 40
relative to the undercarriage 42'. In other words, in this case, the support
wheels 38, 40 may be fixed
relative to the undercarriage 42, if desired.
While the cart 10 has one or more rolling support elements which are
positioned above the common plane
in the first position, there may be cases where the one or more rolling
support elements need not be above
the common plane. For instance, the one or more rolling support elements may
be in fact located at one of
a number of locations relative to the common plane. For instance, the one or
more rolling support elements
may in fact be located in the common plane in the first position, provided the
one or more rolling support
elements do not unreasonably limit the maneuverability of the cart 10 beyond
its intended use.
Furthermore, though not specifically illustrated herein, the one or more
rolling support elements may be
provided with a suspension arrangement, permitting them to accommodate
variations in the common
ground surface. A suspension arrangement may also be provided for the swivel
and non swivel wheels.
17
CA 02481726 2004-10-12
Furthermore, the hydraulic fluid circuit may be arranged to override the
suspension arrangement when the
one or more rolling support elements are displaced from the first position to
a second position, thus making
the one or more rolling support elements static or "inflexible" or less
flexible to changes in the common
ground surface. Thus, the first position may be above the common or in the
common plane, or for that
matter both if the rolling support elements are movable by way of a suspension
arrangement. The one or
more rolling support elements may thus be operable in the first position to
contact the common ground
surface together with the swivel and non swivel wheels. Thus, the suspension
arrangement may permit the
one or more rolling support elements, in the first position, to accommodate
changes in the common ground
surface. If desired, the undercarriage 46 and/or hydraulic fluid circuit 138
may be configured to provide
the suspension arrangement.
18
