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Patent Abstract
Disclosed herein is a hand truck with an electrically operated lifting
platform. The hand truck includes a frame on both sides of which
two guide rails are formed. The frame is provided with a screw shaft
vertically supported on the frame to be vertically moved, one or
more stabilizing bars forwardly extended from the frame, and two
wheels rotatably attached to the rear portion of the frame. A lifting
platform is guided by the guide rails and engaged with the screw
shaft. A platform moving unit is comprised of a first drive motor
for providing rotating force. The platform is situated in the lifting
platform to allow the lifting platform to be moved selectively upward
and downward along the screw shaft by the operation of the first
drive motor. A control unit is electrically and controllably connected
to the first drive motor and a power source.
Patent Claims
What is claimed is:
1. A hand truck with an electrically operated lifting platform,
comprising: a frame on both sides of which two guide rails are formed,
said frame being provided with a screw shaft vertically supported
on the frame to be vertically moved, one or more stabilizing bars
forwardly extended from the frame and two wheels rotatably attached
to the rear portion of the frame; a lifting platform guided by said
guide rails and engaged with said screw shaft; a platform moving
unit comprised of a first drive motor for providing rotating force,
said platform being situated in said lifting platform to allow said
lifting platform to be moved selectively upward and downward along
the screw shaft by the operation of said first drive motor; and
a control unit electrically and controllably connected to said first
drive motor and a power source.
2. The hand truck according to claim 1, further comprising an auxiliary
support pole unit, said auxiliary support pole unit being provided
at its lower end with an auxiliary wheel and restricted to a certain
angle of rotation.
3. The according to claim 1, wherein said stabilizing bars are
bent forwardly to form beads.
4. The hand truck according to claim 1, further comprising one
or more springs, said springs each connecting the upper end of said
frame and the rear portion of said lifting platform.
5. The hand truck according to claim 1, wherein a drive shaft is
coupled at its both ends to said wheels, and a second drive motor
supported on the rear portion of said frame is connected to said
drive shaft to be rotated in one direction.
6. The hand truck according to claim 1, further comprising two
support rods attached at their first ends to both sides of the rear
surface of said frame to be rearwardly rotated at a predetermined
angle, and two auxiliary wheels rotatably attached to the second
ends of said support rods by rotating shafts.
7. The hand truck according to claim 1, wherein said moving unit
include a hollow cylindrical body and is rotatably supported by
a bracket secured to the platform body at its upper and lower ends,
a gear portion being formed on the outer surface of the moving unit
body, the inner surface of the moving unit body being formed to
have a ball screw structure, balls contained in the moving unit
body being positioned to be moved along a screw groove formed on
the screw shaft.
8. The hand truck according to claim 5 or 6, further comprising
one or more conjunctive sprockets fitted around both end portions
of said drive shaft and one or more auxiliary sprockets fitted around
said rotating shafts, said conjunctive sprockets being connected
to said auxiliary sprockets by conjunctive chains.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to hand trucks for
facilitating the conveying, loading and unloading of cargo, and
more particularly to a hand truck with an electrically operated
lifting platform, which is capable of lowering the costs of manufacture
and maintenance and improving convenience in handling and safety.
[0003] 2. Description of the Prior Art
[0004] In general, in order to convey, load and unload massive
cargo, a plurality of pillars and rails are arranged in a factory
and a hoist is mounted so as to be moved along the rails.
[0005] However, this kind of arrangement necessitates high installation
costs, has lower rapidity and inconvenient working procedure to
convey relatively small cargo, and requires to use separate conveying
means and lifting means in an area outside of the area over which
rails are extended.
[0006] On the meantime, a hydraulic pallet truck is proposed so
as to convey, load or unload cargo to which the hoist cannot be
applied or is not easily applied. In the hydraulic pallet truck,
two wheels are rotatably attached to both sides of the lower end
of the frame, a stabilizing plate is forwardly extended from the
lower end of the frame, a handle is formed at the upper end of the
frame, and a lifting mechanism is mounted to the frame.
[0007] The lifting mechanism is comprised of two forks attached
to the frame to selectively lift up and lower down cargo while supporting
the cargo, a hydraulic drive unit to drive the forks, and a control
unit to control the operation of the lifting mechanism. In the lifting
mechanism, the forks are moved upward and downward along the frame
by the action of the hydraulic drive unit through the control of
the control unit, and, accordingly, cargo placed on the forks is
lifted up and lowered down with the movement of the forks.
[0008] However, the conventional hydraulic pallet truck is expensive
and relatively heavy because its hydraulic drive unit and control
unit should be provided, and causes inconvenience to a user because
its forks cannot be brought into contact with the ground owing to
the large mounting space of hydraulic drive unit and should be supported
by a support.
[0009] Additionally there is proposed another hand truck with a
lifting fork unit, in which a square screw shaft is rotatably and
vertically supported by a frame, a drive motor is mounted on the
lower portion of the frame and connected to the screw shaft, and
a lifting fork unit is engaged with the screw shaft to be vertically
moved along the screw shaft. Accordingly, the screw shaft is rotated
by the operation of the drive motor, the lifting fork unit is selectively
lifted up and lowered down by the rotation of the screw shaft, and
cargo is selectively lifted up and lowered down by the movement
of the lifting fork unit.
[0010] However, the conventional hand truck has inferior safety
because their screw shafts are exposed to the outside, and is costly
because its rapid ascent control unit and drive unit are expensive.
SUMMARY OF THE INVENTION
[0011] Accordingly, the present invention has been made keeping
in mind the above problems occurring in the prior art, and an object
of the present invention is to provide a hand truck with an electrically
operated lifting platform, in which a lifting platform is attached
to a frame provided at its lower ends with wheels to be moved selectively
upward and downward, and a platform moving unit is situated in the
lifting platform to be controlled by a drive control unit, thereby
having a simple structure, being manufactured at lower costs and
obtaining the same output as that of a conventional hand truck.
[0012] In order to accomplish the above object, the present invention
provides a hand truck with an electrically operated lifting platform,
comprising; a frame on both sides of which two guide rails are formed,
the frame being provided with a screw shaft vertically supported
on the frame to be vertically moved, one or more stabilizing bars
forwardly extended from the frame and two wheels rotatably attached
to the rear portion of the frame; a lifting platform guided by the
guide rails and engaged with the screw shaft; a platform moving
unit comprised of a first drive motor for providing rotating force,
said platform being situated in the lifting platform to allow the
lifting platform to be moved selectively upward and downward along
the screw shaft by the operation of the first drive motor; and a
control unit electrically and controllably connected to the first
drive motor and a power source.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the accompanying
drawings, in which:
[0014] FIG. 1 is a perspective view of a hand truck with an electrically
operated lifting platform in accordance with an embodiment of the
present invention;
[0015] FIG. 2 is a rear view of the hand truck with its cover removed
from its frame;
[0016] FIG. 3 is a side view showing the hand truck that is provided
with two hooks;
[0017] FIG. 4 is a side view showing the hand truck that is provided
with an auxiliary support pole unit;
[0018] FIG. 5 is a partial sectional view showing a roller used
in the hand truck of the present invention;
[0019] FIG. 6 is a rear view of the hand truck to which its cover
and its corrugated tube are attached;
[0020] FIG. 7 is a cross section showing a stabilizing bar;
[0021] FIG. 8 is a rear view showing a hand truck with an electrically
operated lifting platform in accordance with another embodiment
of the present invention;
[0022] FIG. 9 is a perspective view showing an auxiliary member
of the lifting platform;
[0023] FIG. 10 is a side view showing the hand truck of FIG. 9;
[0024] FIG. 11 is a side view showing the hand truck of FIG. 9,
the hand truck being used on the level ground; and
[0025] FIG. 12 is a side view showing the hand truck of FIG. 9,
the hand truck being used on steps.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Reference now should be made to the drawings, in which the
same reference numerals are used throughout the different drawings
to designate the same or similar components.
[0027] As shown in FIGS. 1 and 2, a lifting platform 20 is attached
to a frame 10, which is provided at both sides of the frame 10 with
two wheels 11 and has a form of a carrier. A platform moving unit
is situated in the lifting platform 20 and controlled by a control
unit.
[0028] When a switch is manipulated, the application of electricity
to the platform moving unit is controlled by the control unit, and
the lifting platform 20 is lifted up and lowered down along both
sides of the frame 10 in accordance with the control of the control
unit, thereby moving cargo selectively upward and downward.
[0029] The frame 10, as depicted in FIGS. 1 to 3, is constructed
in such a way that two spaced vertical rods 10a having an equal
height are connected by two crosspieces, respectively, at upper
and lower ends, two stabilizing bars 12 are forwardly extended from
the lower ends of the vertical rods 10a to form an obtuse angle
of about 95.degree. with the vertical rods 10a, and two handles
13 are rearwardly extended from the upper ends of the vertical rods
10a. Additionally, two guide rails 14 are formed on the inner sides
of the vertical rods 10a, and the side ends of the lifting platform
20 are movably supported by the guide rails 14. A screw shaft 31
is supported at its upper and lower ends by the center portions
of the upper and lower crosspieces 10b, and serves to support the
lifting platform 20. A battery tray 15 is mounted on the lower portion
of the frame 10, and a battery is place on the battery tray 15 to
supply electricity to the truck.
[0030] While the frame 10 is upright, the stabilizing bars 12 are
brought into contact with the ground. When the handles 13 are pulled
rearward to tilt the frame 10, the stabilizing bars 12 are removed
from the ground and the truck of the present invention can be moved
to other locations. Accordingly, the frame 10 should be kept upright
while cargo is loaded or unloaded, and the frame 10 should be kept
tilted and the platform plate 21 is removed from the ground by the
rearward pulling of the handles 13 while cargo is being conveyed.
[0031] As depicted in FIGS. 1 to 3, the lifting platform 20 is
comprised of a body 23 shaped in the form of a box open on its rear
portion and supported by the guide rails 14 of the frame 10 and
the rollers 22 of the body 23, a platform plate 21 attached to the
lower end of the body 23, a first cover 24 detachably attached to
the rear portion of the body 23, and a cargo support frame 25 attached
to both ends of the upper portion of the body 23 and extended upward
to support the rear side of loaded cargo.
[0032] In the lifting platform 20, the platform plate 21 attached
to the front surface of the body 23 is loaded with cargo, loaded
cargo is supported by the cargo support frame 25, thereby allowing
the lifting platform 20 to be moved upward and downward along the
guide rails 14 with the aid of rollers 22.
[0033] Additionally, the platform plate 21 is bent forward to form
a support portion, reinforcing ribs (not shown) are formed along
the circumferential portion of the platform plate 21 and the lower
surface of the support portion of the platform plate 21, and the
vertical portion of the platform plate 21 is secured to the platform
body 23.
[0034] Referring to FIG. 5, in the rollers 22, a clutch bearing
22a, which is rotatable in a direction, is mounted in the body of
each roller 22, and the clutch bearing 22a is secured to the platform
body 23. Accordingly, while the platform body 23 is moved upward,
the clutch bearing 22a is rotated; while the platform 23 is moved
downward, the clutch bearing 22a is not rotated and causes friction
with the sides of the guide rails 14. As a result, the rollers 22
serve as brakes while the platform body 23 is downwardly moved,
and retard the downward moving of the platform body 23, so the rollers
22 are capable of preventing the first drive motor 33 and drive-related
parts from being damaged.
[0035] The cargo support frame 25 is constructed by bending a pipe
so as to form an upper arcuate portion and two side portions. The
side portions are extended downwardly and secured to the upper end
of the platform body 23, and two rings 25a are formed on the side
portions of the cargo support frame 25. The strings for tying cargo
to the frame 10 are fixed to the rings 25a.
[0036] FIGS. 9 and 10 are views showing different embodiments of
the lifting platform 20. In this lifting platform 20, the lower
half of a platform plate 21 is forwardly bent to form a support
portion, a pair of slide slits are formed on both sides of the platform
plate 21, and an auxiliary support frame 21a is situated to be moved
forward and rearward through the slits.
[0037] As shown in FIG. 8, two springs 28 are each positioned to
connect the upper portion of the frame 10 and the platform plate
21 of the lifting platform 20. Accordingly, while cargo is moved
upward, the load exerted on the first drive motor 33 is reduced
by the action of the restoring force of the springs 28. As indicated
in FIG. 10, a second cover 29 is detachably attached to the rear
portion of the frame 10, so the second cover 29 can conceal the
screw shaft 31 and the lifting platform 20, thereby improving the
safety and appearance of the truck.
[0038] Referring to FIG. 3, two hooks 27 are detachably attached
to the rear surface of the first cover 24, and can be moved together
with the first cover 24.
[0039] When a downward switch button 42 is manipulated while the
lower ends of the downwardly projected portions of the hooks 27
are supported on the loading platform of an automobile, the lifting
platform 20 cannot be moved. Therefore, the frame 10 and the wheels
11 are moved upward, so the truck of the present invention can be
easily loaded on the loading platform of an automobile.
[0040] The platform moving unit, as shown in FIGS. 2 and 3, is
comprised of the first drive motor 33 fixedly attached to a bracket
32 secured to the rear surface of the platform body 23 to be situated
between the platform body 23 and the first cover 24, a moving unit
30 engaged with the screw shaft 31 to be rotatable along the screw
shaft 31 and supported on one side of the bracket 32, and an idle
gear 35 for connecting the pinion gear 34 of the first drive motor
33 and the moving unit 30.
[0041] The moving unit 30 includes a hollow cylindrical body, and
is rotatably supported by a bracket 32 secured to the platform body
23 at its upper and lower ends. In the moving unit 30, a gear portion
30a is formed on the outer surface of the moving unit body, the
inner surface of the moving unit body is formed to have a ball screw
structure, and balls contained in the moving unit body are positioned
to be moved along a screw groove formed on the screw shaft 31. The
gear portion 30a of the moving unit 30 is operationally connected
to the first drive motor 33 through the idle gear 35.
[0042] The gear portion 30a is operationally connected to the first
drive motor 33 through the idle gear 35 supported by the bracket
32.
[0043] In accordance with the platform moving unit, when electricity
is applied to the first drive motor 33, the idle gear 35 is rotated
by the pinion gear 34 of the first drive motor 33 and the moving
unit 30 is rotated and moved upward or downward by the idle gear
35 engaged with the gear portion 30a formed on the outer surface
of the moving unit 30. As a result, the platform body 23 is rectilinearly
moved along the screw shaft 31 together with the moving unit 30
and the bracket 32, thereby moving upwardly and downwardly cargo
loaded on the platform plate 21 of the lifting platform 20.
[0044] In the control unit, the battery is placed on the battery
tray 15 attached to the frame 10, the first drive motor 33 is electrically
connected to the battery, and a control switch box 40 attached to
the rear surface of the platform body 23 is electrically and controllably
connected to the battery and the first drive motor 33. Additionally,
an upward switch button 41 is mounted on one side of the upper portion
of the frame 10 to move the lifting platform 20 upwardly, an upward
switch button 41 is mounted on the other side of the upper portion
of the frame 10 to move the lifting platform 20 downwardly, limit
switches 43 are mounted on the upper and lower portions of the platform
body 23, and the upward switch button 41, the downward switch button
42 and the limit switches 43 are controllably connected to a control
switch box 40. On the meantime, the control switch box 40 is capable
of controlling the first drive motor 33 through a reversible relay
circuit, and the vertical stroke of the platform body 23 can be
controlled by the upper and lower limit switch 43.
[0045] In the control unit, when the upward switch button 41 is
pushed, the control switch box 40 allows electricity to be applied
from the battery to the first drive motor 33, thereby rotating the
first drive motor 33 in a normal direction. When the downward switch
button 42 is pushed, the control switch box 40 allows reverse directional
electricity to be applied to the first drive motor 33, thereby rotating
the first drive motor 33 in the reverse direction. When the upward
and downward switch buttons 41 and 42 are released, the control
switch box 40 interrupts the flow of electricity and stops the first
drive motor 33 that is being rotated. Additionally, when the limit
switch 43 is brought into contact with the upper or lower portion
of the frame 10 or an obstacle while the platform body 23 is moved
upward or downward, the control switch box 40 interrupts the flow
of electricity to the first drive motor 33 and stops the first drive
motor 33.
[0046] That is, in the control unit, the platform body 23 and the
platform plate 21 loaded with the cargo are lifted up along the
guide rails 14 of the frame 10 and the screw shaft 31 when the upward
switch button 41 is pushed, whereas the platform plate 21 is stopped
when the upward switch button 41 is released. The platform body
23 and the platform plate 21 loaded with the cargo are lowered down
along the guide rails 14 of the frame 10 and the screw shaft 31
when the downward switch button 41 is pushed, whereas the platform
plate 21 is stopped when the downward switch button 41 is released.
In addition, the platform body 23 and the platform plate 21 are
stopped when the limit switch 43 is brought into contact with the
upper or lower end of the frame 43.
[0047] As shown in FIG. 6, the side portions of a corrugated tube
44 are secured to the first cover 44 by eye bolts 26 secured to
the first cover 24 of the platform body 23, the upper portion of
the corrugated tube 44 is held to be connected to the platform body
23 while being elastically bent, and electric wires connected to
the platform moving unit are arranged through the interior of the
corrugated tube 44.
[0048] In accordance with the present invention, when the platform
body 23 is moved upward or downward, the upper portion of the corrugated
tube 44 and the eye bolts 26 are moved upward or downward together
with the platform body 23. When the positions of bents are changed,
the bent portions of the corrugated tube 44 are guided by the holes
of the eye bolts 26.
[0049] In addition, electric wires used for the control unit are
arranged in the interior of the frame 10 because the frame 10 is
fabricated of hollow pipes, and the electric wires used for the
platform moving unit, as described above, are arranged in the interior
of the corrugated tube 44. As a result, the appearance of the truck
is improved and electric accidents can be prevented.
[0050] In addition, a connector, which is capable of being connected
to the battery of an automobile, is mounted on one side of the battery
tray 15, so the hand truck of the present invention can be operated
for a long time everywhere an automobile is provided.
[0051] As shown in FIGS. 1 to 4 and 6, an auxiliary support pole
unit 50, to which an auxiliary wheel 51 is rotatably attached to
the lower end of the auxiliary support pole unit 50, is rotatably
attached to the rear surface of the frame 10. Accordingly, when
the hand truck of the present invention is loaded and carries relatively
massive cargo, the auxiliary support pole unit 50 can be supported
on the ground through the auxiliary wheel 51 while forming a certain
angle with the frame 10.
[0052] In the auxiliary support pole unit 50, a cross bar 53 provided
with a stopper 52 at its central portion is fixedly attached to
the rear surface of the frame 10, a support pole 54 is attached
at its one end to the cross bar 53 to be rotated at a certain angle
with the aide of a restricting projection 55, and the auxiliary
wheel 51 is rotatably attached to the other end of the support pole
54.
[0053] In a normal state, the support pole 54 is held on the rear
surface of the frame 10 by a holding ring 56. When the hand truck
of the present invention is loaded with massive cargo and the support
pole 54 is released from the holding ring 56, the support pole 54
is capable of being rotated around the cross bar 53. When the support
pole 54 is rotated at a predetermined angle, the restricting projection
55 is brought into contact with the stopper 52, thereby restricting
the rotation of the support pole 54. The auxiliary wheels 51 come
into contact with the ground while forming a predetermine angle
with the frame 10, so the frame 10 is stably supported by the wheels
11 and 51 on the ground. When the handle 13 is pushed forward, the
auxiliary wheels 51 are rolled on the ground, together with the
main wheels 11 attached to the lower portion of the frame 10.
[0054] As illustrated in FIGS. 8 and 10 to 12, in a hand truck
in accordance with another embodiment of the present invention,
a drive shaft 60 connected at its both ends to two spaced wheels
11 and a second drive motor 70 are supported by a bracket in the
lower rear portion of a frame 10, two auxiliary wheels 51 are supported
on both sides of the surface of the frame 10 to be rotated rearward,
a second drive motor 70 is connected to the drive shaft 60 to be
rotated in one direction, and both ends of the drive shaft 60 are
connected to the auxiliary wheels 51 to be moved in conjunction
with the auxiliary wheels 51.
[0055] In accordance with the above embodiment, the wheels 11 and
the drive shaft 60 are moved together and the wheels 11 are rolled
according to the direction of force exerted to the frame 10. When
electricity is applied to the second drive motor 70, the driving
force of the second drive motor 70 causes the drive shaft 60 to
be forcibly rotated. Accordingly, the wheels 11 are integrally rotated
and the auxiliary wheels 51 are moved in conjunction with the drive
shaft 60, so the hand truck of the present invention can be moved
without the pulling of the handles 13 of the frame 10.
[0056] In this case, the drive shaft 60 is supported in such a
way that the drive shaft 60 is rotatably inserted into the interior
of the hollow pipe 66 to be supported by a bracket 65 secured to
the rear surface of the frame 10. Two slave sprockets 62 are fitted
over both end portions of the drive shaft 60 to be rotated in one
direction. Two conjunctive sprockets 63 are each fitted over the
drive shaft 60 at a position inwardly spaced apart from each slave
sprocket 62.
[0057] When the slave sprockets 62 are operationally connected
to the second drive motor 70 and receive driving force from the
second drive motor 70, the drive shaft 60 is rotated in the driving
direction of the second drive motor 70 by the slave sprockets 62
forcibly rotated. On the other hand, when driving force is not transmitted,
the slave sprockets 62 serve as clutches and allow no-load operation.
[0058] The second drive motor 70 is attached to the rear portion
of the frame 10 and the outer surface of the hollow pipe 66, two
drive sprockets 71 are rotatably attached to the ends of the armature
rotating shaft of the second drive motors 70, and the drive sprockets
are connected to the slave sprockets fitted over the drive shaft
60. Additionally, a manipulating switch 73 is provided on one side
of the handle 13 attached to the side of the frame 10, and controls
the application of electricity from power source to the second drive
motors 70.
[0059] When the switch is manipulated, electricity is applied to
the second drive motor 70 and the drive sprocket 71 is rotated.
Rotating force is transmitted from the drive sprocket 71 to the
slave sprocket 62 through a drive chain 72, so the slave sprocket
62 is rotated, thereby allowing the drive shaft 60 to be rotated
in a direction.
[0060] The drive chain 72 is preferably supported tightly by an
idle sprocket operated without load so that the drive chain 72 is
prevented from sagging.
[0061] Two support rods 81 are rotatably attached at their first
ends to the rear portion of the frame 10 or the outer surface of
the hollow pipe 66, two auxiliary wheels 51 are rotatably attached
to the second ends of the support rods 81 by rotating shafts, two
auxiliary sprockets 83 are fitted around the rotating shafts, and
the rotating shafts are connected to the conjunctive sprockets 63
by the conjunctive chains 83 to be moved together.
[0062] The auxiliary wheels 51 are spaced apart from and situated
below the main wheels 11. Accordingly, when the hand truck is loaded
with cargo and the handle 13 is pulled rearward, the auxiliary wheels
51 are brought into contact with the level ground or stairs. As
the main wheels 61 are rotated, the auxiliary sprockets 82 moved
in conjunction with the conjunctive sprockets 63 fitted over the
drive shaft 60 are moved together, thereby allowing the hand truck
of the present invention to be easily moved.
[0063] Two fitting holes are formed on the second ends of the support
rods 81, and the rotating shafts are detachably fitted into the
fitting holes. In this case, the conjunctive chains 83 can be kept
tight by the adjustment of the positions of the rotating shafts.
[0064] The handle 13 is comprised of a single piece bent at its
both ends.
[0065] As shown in FIGS. 11 and 12, in accordance with this embodiment
of the present invention, the wheels 11 and the auxiliary wheels
51 are spaced apart from each other and are situated at different
vertical positions, so the wheels 11 and 51 are smoothly rolled
on the level ground, thereby allowing cargo to be conveyed easily.
When the second drive motor 70 is operated while the truck is tilted
by handling the handle 13 attached to the upper portion of the frame
10, the second drive motor 70 forcibly rotates the wheels 11 and
the auxiliary wheels 51 to be smoothly rolled on an upward slope
and stairs, thereby facilitating the conveyance of cargo.
[0066] As described above, the present invention provides a hand
truck with an electrically operated lifting platform, in which the
lifting platform is rotatably and vertically supported by a frame
and a platform moving unit moves the lifting platform by the conversion
of rotary motion into rectilinear motion, thereby simplifying its
entire structure in comparison with other conventional hand platforms
and allowing the hand truck to be easily moved on an upward slope
and stairs by the provision of auxiliary wheels spaced apart from
main wheels and the forcible operation of these wheels.
[0067] Although the preferred embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in
the art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying claims.
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