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Patent Abstract
A hand truck convertible between forward and sideways displacement
has wheels individually disengageable from the hand truck frame
for mounting to the frame in either a mutually parallel wheel position
or a mutually in-line wheel position transverse to the parallel
wheel position. An optional wheel base extension can be installed
for in-line mounting of more than two wheels. Other options include
a retractable stand for supporting the loaded hand truck in upright
position and an auxiliary load carrying shelf. The hand truck and
one or more of the optional accessories may be sold as a kit of
parts.
Patent Claims
What is claimed is:
1. A hand truck comprising a hand truck frame including a plurality
of vertical members interconnected by a second plurality of cross
members, said frame having an upper end, a lower end, a front side
and a rear side, a handle at said upper end, and a forwardly extending
horizontal load plate at said lower end, two or more wheels mounted
for rotation to said frame, each of said wheels being individually
disengageable from said frame for mounting to the frame in either
a mutually parallel wheel position or a mutually in-line wheel position
transverse to said parallel wheel position, such that the hand truck
is convertible between forward and sideways displacement.
2. The hand truck of claim 1 wherein each of said wheels is retained
to said frame by a manually disengageable fastener such that the
hand truck is so convertible without use of tools.
3. The hand truck of claim 1 wherein each said wheel is retained
to said frame by a manually releaseable Cotter pin.
4. The hand truck of claim 1 wherein said frame has a pair of axially
aligned wheel shafts for rotatably supporting said wheels in said
mutually parallel position and a first plurality of axially parallel
wheel shafts for rotatably supporting said wheels in said mutually
in-line wheel position.
5. The hand truck of claim 1 wherein each of said wheels has an
axle hole sized for receiving any of said wheel shafts.
6. The hand truck of claim 5 wherein each of said wheel shafts
is diametrically perforated for passing a wheel retaining pin.
7. The hand truck of claim 6 wherein said wheel retaining pin is
a Cotter pin.
8. The hand truck of claim 4 further comprising a frame width extension
having a second plurality of wheel shafts more widely spaced than
said first plurality of wheel shafts thereby to extend the wheelbase
of the hand truck in said in-line wheel condition.
9. The hand truck of claim 4 wherein said frame defines a vertical
frame plane and said load plate lies in a horizontal plane perpendicular
to said frame plane, and said first plurality of axially parallel
wheel shafts are angled to said horizontal plane such that said
wheels mounted on said first plurality of axially parallel wheel
shafts are inclined relative to an underlying ground surface in
a self-supporting standing position of said frame with said load
plate resting on the ground surface, said first plurality of axially
parallel wheel shafts being arranged on said frame such that said
wheels mounted on first plurality of axially parallel wheel shafts
are brought into a generally vertical load bearing position in a
reclined load carrying condition of said frame with said load plate
lifted from the ground surface.
10. The hand truck of claim 4 wherein said frame comprises shaft
support brackets, said axially aligned wheel shafts being end portions
of an axle supported between and extending through said brackets,
and each said axially parallel wheel shaft being affixed to one
of said brackets transversely to said axle.
11. The hand truck of claim 10 wherein each said axially parallel
wheel shaft is welded to a corresponding one of said brackets.
12. The hand truck of claim 10 wherein said axle is welded to said
brackets.
13. The hand truck of claim 10 wherein said shaft support brackets
are mutually parallel plates each bracket having a rear edge perpendicular
to a said axially parallel wheel shaft affixed to said bracket.
14. The hand truck of claim 10 further comprising a width extension
plate having a second plurality of axially parallel wheel shafts
affixed to said plate, said plate being adapted for removable attachment
to said shaft support brackets.
15. The hand truck of claim 14 wherein said plate is a substantially
flat plate and said second plurality of axially parallel wheel shafts
are perpendicular to said plate.
16. The hand truck of claim 14 wherein said plate has attachment
brackets for fastening to said shaft support brackets.
17. The hand truck of claim 16 wherein said attachment brackets
are fastened to said shaft support brackets with screws passing
through aligned holes in said brackets.
18. The hand truck of claim 14 wherein said width extension plate
is perforated with holes aligned for receiving said first plurality
of wheel shafts in an installed condition of said plate on said
shaft support brackets.
19. The hand truck of claim 14 wherein said second plurality of
axially parallel wheel shafts comprises three shafts including a
center shaft and two end shafts equally spaced from said center
shaft such that three wheels can be mounted on said three shafts
in said in-line position.
20. The hand truck of claim 19 wherein said center shaft is slightly
lower than said end shafts on said plate in said installed condition
such that said frame can be turned on one wheel mounted on said
center shaft as a pivot wheel for said frame.
21. The hand truck of claim 19 wherein said width extension plate
is perforated with holes aligned for receiving said first plurality
of wheel shafts in an installed condition of said plate on said
shaft support brackets, said holes being intermediate said center
shaft and each of said end shafts.
22. The hand truck of claim 21 wherein said plate is mounted to
said frame with said second plurality of shafts parallel to said
first plurality of shafts.
23. The hand truck of claim 10 wherein said shaft support brackets
are affixed to said vertical members of said frame above said load
plate.
24. The hand truck of claim 1 further comprising a leg spring loaded
to a normally folded condition against said frame, said leg being
movable to a deployed condition away from said frame for supporting
said frame on an underlying ground surface in a rearwardly tilted
position of the frame.
25. The hand truck of claim 1 further comprising a load carrier
removably mounted to said frame at a location intermediate to said
handle and said load plate.
26. The hand truck of claim 25 wherein said load carrier has fasteners
engageable to said vertical elements.
27. The hand truck of claim 26 wherein said fasteners are retained
to said vertical elements by spring force alone.
28. A hand truck comprising a hand truck frame comprising including
parallel side members connected by one or more cross members and
having lower ends fixed to a forwardly extending load plate, a pair
of side wheel shafts and a pair of rearwardly extending rear wheel
shafts on said frame, and wheels engageable for rotation interchangeably
between said side wheel shafts in a mutually parallel wheel position
and said rear wheel shafts in a mutually in-line wheel position
transverse to said parallel wheel position, such that the hand truck
is convertible between forward and sideways displacement.
29. The hand truck of claim 28 wherein said frame defines a vertical
frame plane and said rear wheel shafts are angled on said frame
relative to a plane of said load plate such that said wheels turn
in a plane inclined to said vertical when the wheels are mounted
on said rear wheel shafts in said in-line wheel position such that
said wheels are at least partly lifted away from contact with a
ground surface in an upright standing position of said frame with
said load plate resting on the ground surface, and said wheels are
brought into generally vertical ground contact in a reclined load
carrying condition of said frame with said load plate lifted away
from the ground surface for carrying the weight of said truck frame
and a load on said frame.
30. The hand truck of claim 28 further comprising a wheelbase extension
substantially longer than a spacing between said side members and
having additional rear wheel shafts thereon more widely spaced apart
than said rear wheel shafts on said frame thereby to provide an
extended wheelbase of the hand truck in said in-line wheel position.
31. The hand truck of claim 28 further comprising a leg spring
loaded to a normally folded condition against said frame, said leg
being movable to a deployed condition away from said frame for supporting
said frame on an underlying ground surface in a rearwardly tilted
position of the frame.
32. The hand truck of claim 28 further comprising a load carrier
removably mounted to said frame at a location intermediate to said
handle and said load plate.
33. A hand truck comprising a hand truck frame including a pair
of vertical members interconnected by cross members, said frame
having an upper end and a lower end, a forwardly extending horizontal
load plate at said lower end, a pair of shaft support brackets affixed
to said vertical members, an axle supported on said brackets and
terminating in opposite end shafts, a rear shaft on each of said
brackets, said shaft extending away from said frame and transversely
to said axle, and truck wheels interchangeably mounted for rotation
on said opposite end shafts or said rear shafts, such that the hand
truck is convertible between forward and sideways displacement on
said wheels.
34. The hand truck of claim 33 wherein each of said wheels is retained
to a corresponding one of said shafts by a manually disengageable
fastener such that the hand truck is so convertible without use
of tools.
35. The hand truck of claim 33 further comprising a Cotter pin
inserted diametrically through a pin hole in any of said shafts
for retaining thereon one of said wheels between said Cotter pin
and one of said brackets.
36. The hand truck of claim 33 further comprising a spacer on any
of said shafts between one of said wheels and one of said brackets.
37. The hand truck of claim 33 wherein said rear shafts are angled
on said frame such that said wheels mounted on said rear shafts
are lifted away from contact with a ground surface in a self-supporting
standing position of said frame with said load plate resting on
the ground surface and such that said wheels are brought into approximately
vertical ground contacting relationship in a reclined load carrying
condition of said frame with said load plate lifted from the ground
surface.
37. The hand truck of claim 33 further comprising a wheel base
extension having at least two wheel mounting shafts affixed thereon
and fasteners for securing said extension to said brackets, said
least two wheel mounting shafts being more widely spaced apart from
each other than a mutual spacing between said rear shafts.
38. The hand truck of claim 37 wherein said wheel base extension
is a plate and said least two wheel mounting shafts are perpendicular
to said plate, and said plate is fastened to said brackets such
that said least two wheel mounting shafts are parallel to said rear
shafts
39. The hand truck of claim 33 wherein said brackets are mutually
parallel plates, each of said brackets is affixed to one of said
vertical members and each of said rear shafts is affixed to an inside
surface of a corresponding one of said brackets
40. The hand truck of claim 39 wherein each of said brackets has
a rear edge perpendicular to a said rear shaft affixed to said bracket.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to hand trucks of the type having
an upright truck frame supported on a pair of wheels and a load
carrying plate projecting forwardly from the frame. Tilting of the
truck frame lifts a load on the plate away from the ground surface
allowing the hand truck to be rolled on its wheels for transporting
the load.
[0003] 2. State of the Prior Art
[0004] Conventional hand trucks typically have an upright frame
of welded tubing, a flat load plate projecting forwardly from the
frame and a pair of wheels mounted at the bottom of the frame on
either side and just behind the plate. One common truck frame arrangement
has a continuous tube bent into an inverted U-shape. The closed
end of the U defines a handle at the top of the frame. The U-shaped
tube has two parallel side arms which extend downwardly and have
bottom ends fixed to the load plate. The parallel arms are interconnected
by one or more cross-members for rigidity and strength.
[0005] In an upright standing position of the hand truck the load
plate rests on an underlying ground surface and the truck frame
stands erect in a generally vertical position. The parallel side
arms of the frame define a vertical plane of the frame and the load
plate is usually horizontal on the ground surface and perpendicular
to that vertical plane. In typical use, a load is placed on the
load plate while the plate is resting flat on the ground surface.
The upper end of the truck frame is then pulled back so as to tilt
the frame and shift the truck load onto the wheels while lifting
the load plate and the load away from the ground surface. The hand
truck can then be wheeled either forwards or backwards to move the
load to a desired location.
[0006] Conventional hand trucks of this type are not well suited
for transporting wide loads which extend substantially from each
side of the truck frame when laid across the load plate. This difficulty
stems from the fact that the wide load lies transversely to the
direction of travel of the truck wheels. Examples of such wide loads
are 4 foot by 8 foot sheets of plywood or drywall, large plates
of glass, and long pipes or tubing. Such wide loads cannot be wheeled
through standard sized doorways and hallways, and may be too awkward
to maneuver through cluttered or crowded work areas.
[0007] A continuing need exists for an improved hand truck which
retains the advantages of simplicity and low cost of conventional
hand trucks yet addresses the aforementioned shortcomings.
SUMMARY OF THE INVENTION
[0008] The convertible hand truck of this invention addresses these
and other shortcomings of the prior art by providing a hand truck
which is convertible between forward and sideways rolling displacement.
The conversion is made by dismounting and reinstalling the truck
wheels between a parallel wheel configuration and an in-line wheel
configuration. Tool free removal and installation of the wheels
facilitates conversion of the hand truck configuration.
[0009] The convertible hand truck has a hand truck frame which
preferably has left and right vertical side members interconnected
by one or more cross members. The frame may have a handle at its
upper end and a forwardly extending horizontal load plate at its
lower end.
[0010] Two or more truck wheels are individually engageable and
disengageable to the frame for rotation in either a mutually parallel
wheel configuration or a mutually in-line wheel configuration transverse
to the parallel wheel configuration, such that the hand truck is
convertible between forward and sideways displacement.
[0011] The frame has wheel mounting shafts including a pair of
axially aligned side shafts and a pair of axially parallel rear
shafts. Each of the truck wheels has a shaft hole sized for receiving
any of the wheel mounting shafts. In the preferred form of the invention
each of the wheels is retained for rotation on the frame by a manually
disengageable fastener so that the conversion can be made without
use of tools. The fastener may be a manually releasable pin such
as a Cotter pin inserted in a pin hole diametrically through the
wheel mounting shaft.
[0012] In one form of the invention the hand truck frame defines
a vertical frame plane and the load plate defines a horizontal plane
perpendicular to the vertical frame plane, and the axially parallel
wheel mounting rear shafts are angled to said horizontal plane such
that truck wheels mounted in-line on the axially parallel wheel
shafts are partly or fully lifted away from contact with a ground
surface in a self-supporting standing position of the truck frame
with the load plate resting on the ground surface. The truck wheels
mounted on the rear shafts are brought into generally vertical load
bearing contact with the ground in a reclined load carrying condition
of the frame with the load plate lifted from the ground surface,
such that the weight of the hand truck and its load are carried
by the in-line mounted wheels.
[0013] The hand truck frame may have shaft support brackets, such
as a pair of mutually parallel plates welded to the vertical side
members of the frame near the load plate. The axially aligned wheel
shafts or side shafts may be end portions of an axle supported between
and extending through the shaft support brackets, and each axially
parallel wheel shaft or rear shaft may be affixed to one of the
shaft support brackets transversely to the axle. Both the rear shafts
and the axle and side shafts may be welded to the shaft support
brackets.
[0014] A first optional element of the improved hand truck is a
wheel base extension such as a plate which is removably fastened
transversely to the hand truck frame, for example, to the rear edges
of the wheel mounting brackets of the truck frame. The extension
is substantially longer than the spacing between the wheel mounting
brackets and has a second set of wheel mounting rear shafts more
widely spaced apart from each other than the first set of rear shafts
provided on the frame so as to extend the in-line wheelbase of the
hand truck. The wheel base extension may be in the form of a plate,
such as a substantially flat plate and the second set of axially
parallel rear wheel shafts are perpendicular to the plate. Attachment
brackets may be also provided for fastening the wheel base extension
to the shaft support brackets of the truck frame. In one form of
the invention the attachment brackets are fastened to the shaft
support brackets with screws passing through aligned holes in the
brackets.
[0015] Each shaft support bracket on the truck frame may have a
rear edge angled to the vertical plane of the truck frame and perpendicular
to the axially parallel wheel shaft or rear shaft affixed to that
bracket. The wheel base extension may be installed by fastening
the same against the angled rear edges of the shaft support brackets,
such that the rear wheel shafts of the extension are angled similarly
to the first set of rear wheel shafts of the truck frame in relation
to the truck frame. The wheel base extension may be perforated with
holes aligned for receiving the first set of rear wheel shafts of
the truck frame in an installed condition of the wheel base extension
such that the first and second sets of rear shafts are parallel
to each other. The second set of axially parallel rear wheel shafts
may have three rear shafts including a center shaft and two end
shafts equally spaced from said center shaft such that three truck
wheels can be mounted on the three rear shafts of the extension
in an in-line configuration. The center shaft may be slightly lower
than the end shafts in an installed condition of the extension thereby
providing a pivot about which the truck frame may turn.
[0016] A second optional feature is a foldable support leg pivoted
to the hand truck frame and spring loaded to a normally folded condition
against the frame. The support leg is extendable to a deployed condition
with a lower end of the leg away from the frame for supporting the
truck frame in a rearwardly tilted or reclined position. The support
leg permits the hand truck to be left standing with the load leaning
against the frame.
[0017] A third optional feature is a load carrier shelf removably
mounted to the frame at an elevated location on the truck frame,
for example, vertically intermediate between the handle and the
load plate. The removable load carrier may have fasteners or retainers
engageable to the vertical side members of the frame. For convenience,
these fasteners may be spring clip fasteners adapted to clip onto
the side members of the frame by spring force alone. Supplementary
fasteners may be provided for securing the load carrier shelf more
securely than might be possible with spring clips alone, if needed.
[0018] This invention also contemplates a hand truck kit of parts
including a hand truck frame adapted to receive truck wheels mounted
to the truck frame for rotation in either a mutually parallel configuration
or an in-line configuration, a set of at least two wheels individually
engageable for rotation to the frame in either configuration, and
wheel fasteners for releaseably retaining the truck wheels to the
frame, preferably without use of tools. The kit may also include
a wheel base extension for extending the in-line wheel base of the
hand truck. Optionally the kit may further include one or more load
carrying shelves for attachment at one or more elevated locations
of the frame.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view of the convertible hand truck
of this invention with the truck wheels in parallel configuration
for forward displacement of the hand truck;
[0020] FIG. 2 is a view of the hand truck of FIG. 1 but with the
wheels in in-line configuration for sideways displacement of the
hand truck;
[0021] FIG. 3 is a fragmentary view of the hand truck illustrating
the side and rear mounting positions of the truck wheels on the
side shafts and rear shafts of the hand truck frame, with a truck
wheel shown in exploded relationship to each of the shafts for purposes
of illustration;
[0022] FIG. 4 is a detail view showing the angling of the rear
shaft relative to the vertical side member of the truck frame and
the resulting inclined in-line mounting of a truck wheel on the
rear shaft as well as the angled rear edge of the corresponding
shaft support bracket for accommodating the angled position of the
wheel;
[0023] FIG. 5 is an exploded detail perspective view showing the
spacer washer and Cotter pin used in the installation of a truck
wheel on the right side wheel shaft of the hand truck;
[0024] FIG. 6 is a detail view in vertical cross-section of the
wheel base extension of FIG. 8 installed on the hand truck frame
and showing a truck wheel mounted on the center shaft of the wheel
base extension plate;
[0025] FIG. 7 is a vertical section of the wheel base extension
of FIG. 8 showing one attachment bracket of the extension fastened
to a shaft support bracket of the truck frame and also illustrating
how the rear shaft of the shaft support bracket passes through a
shaft hole in the extension when the extension is installed against
the inclined rear edge of the bracket;
[0026] FIG. 8 is an exploded perspective showing a wheel base extension
fastened to the shaft support brackets to achieve an extended in-line
wheel base, and truck wheels shown in exploded relationship to each
of the two side shafts of the frame and three rear shafts of the
extension;
[0027] FIG. 9 is a perspective view of the convertible hand truck
of FIG. 1 equipped with the wheel base extension of FIG. 8 and an
optional swing leg and removable load shelf; and
[0028] FIG. 10 is a side view of the hand truck of FIG. 9 with
the load shelf removed and supported with a load in a reclined position
by deployment of the swing leg.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] With reference to the drawings wherein like elements are
designated by like numerals, FIG. 1 shows a convertible hand truck
according to this invention which is generally designated by numeral
10. The convertible hand truck 10 has an upright frame 12 including
a pair of parallel right and left vertical side members 14 interconnected
by two cross members 16. Frame 12 has a handle 18 at its upper end
and a forwardly extending horizontal load plate 20 fixed to the
lower ends of the side members 14. The truck frame may be of welded
tubular construction, with a single continuous length of tubing
bent to an inverted U-shape form providing the two side members
14 joined at their upper ends by the handle 18, and the lower ends
of the inverted U-shape welded to the load plate 20. The parallel
side members 14 of truck frame 12 define a vertical frame plane
and the load plate 20 lies in a horizontal plane perpendicular to
the frame plane.
[0030] Two or more truck wheels 22 are individually engageable
to and disengageable from the frame 12 for rotation in either a
mutually parallel wheel configuration illustrated in FIG. 1, or
a mutually in-line wheel configuration, depicted in FIG. 2, which
is transverse to the parallel wheel configuration. The hand truck
10 is convertible between forward rolling displacement in the configuration
of FIG. 1 and sideways rolling displacement in the configuration
of FIG. 2. In the convertible hand truck of this invention the wheels
22 have only one of these two configurations, without any intermediate
positions. In parallel configuration, the axes of rotation of the
two wheels 22 mounted on opposite left and right sides of the frame
12 are aligned with each other. In the in-line configuration of
the wheels 22, the wheels are mounted to the frame 12 on mutually
parallel, spaced apart axes for rotation in a common plane on the
rear side of the frame, behind the load plate 20.
[0031] The hand truck frame 12 has a pair of axially aligned side
wheel shafts 24 for rotatably supporting the truck wheels 22 in
the mutually parallel position of FIG. 1 and a first set of axially
parallel rear wheel shafts 26 for rotatably supporting the truck
wheels 22 in the in-line wheel position of FIG. 2. Each truck wheel
22 has a shaft hole 25 passing axially through the center of the
wheel, as best seen in FIG. 6, for receiving any of the wheel shafts
24 and 26 of the frame 12.
[0032] Turning now to FIG. 3, the hand truck frame 12 includes
wheel shaft support brackets 28 in the form of mutually parallel
plates. Each bracket has a front edge 32 which is fixed as by welding
longitudinally to one of the side members 14 above the load plate
20. An axle 34 is supported between the two brackets 28 transversely
to the planes of the brackets and extends through axle holes 36
in the brackets 28 such that opposite end portions of the axle provide
the pair of axially aligned side shafts 24 on either side of the
truck frame 12. The axle 34 with side wheel shafts 24 may be welded
to each bracket as at 38 to lock the axle and side wheel shafts
against rotation relative to the frame 12. The first set of axially
parallel rear shafts 26 are fixed as by welding 42 to the support
brackets 28.
[0033] Any one of the truck wheels 22 can be mounted to any of
the wheel shafts 24, 26 by inserting the free end of the shaft through
the shaft hole 25 of the wheel and retaining the wheel on the shaft
with a suitable fastener. The preferred fastener is manually disengageable
such that the hand truck is convertible between forward and sideways
rolling displacement without use of tools. A presently preferred
manually releaseable fastener for this purpose is a Cotter pin 40
inserted in a pin hole 44 passing diametrically through the wheel
shaft, as best illustrated in FIGS. 6 and 7. It is preferred to
also provide a spacer or washer 46 axially supported on the shaft
between the wheel 22 and the support bracket 28 in order to space
the wheel away from contact with the bracket.
[0034] As best seen in FIG. 4 the rear shafts 26 are angled to
the horizontal plane of the load plate 20 at an angle .phi.. When
the truck wheels 22 are mounted on the first set of axially parallel
rear wheel shafts 26 the plane of the wheels 22 also lies at the
same angle .phi. away from the vertical plane of the truck frame
12, with the top 22a of the wheel inclined towards the truck frame
12. The bottom 22b of the wheel preferably rests on an inside edge
22c on underlying ground surface G, or is raised slightly above
the ground surface G, when the truck frame 12 is in a standing position
with load plate 20 resting on the ground surface. By pulling back
the truck frame 12 to a reclined load bearing position, such as
suggested in FIG. 10, the in-line mounted wheels 22 can be brought
to a load bearing generally vertical rolling position on the ground
surface G and the load plate 20 is lifted away from the ground surface,
thereby shifting the load onto the wheels. In this condition the
in-line mounted truck wheels 22 can roll on the ground surface G
in a generally vertical plane while the load plate 20 is upwardly
inclined and a load L supported on the load plate tends to lie against
the parallel side members 14 and cross members 16, and the weight
of the hand truck 10 and its load is carried by the in-line mounted
truck wheels 22. In the in-line configuration of the truck wheels
the hand truck 10 is useful as a panel cart for carrying a load
L of plywood, drywall or other paneling and relatively large sheet
materials.
[0035] An optional accessory of the hand truck 10 is a wheel base
extension in the form of wheel base extension 50 best seen in FIGS.
8 and 9. The extension may be a generally flat plate 50 supported
on brackets 28 but having a plate length substantially greater than
the spacing between the brackets 28. The extension 50 supports a
second set of axially parallel rear shafts 52a, 52b, 52c fixed in
perpendicular relationship to a rear facing surface 54 of the plate
50. Each shaft 52a,b,c may be set in a corresponding mounting hole
53a and welded in place as at 53b in the cross section of FIG. 6.
Preferably the second set of rear shafts consists of three rear
shafts including a center shaft 52b and two end shafts 52a, 52c
equally spaced apart from the center shaft. The end shafts 52a,
52c on the extension plate 50 are more widely spaced apart from
each other in a horizontal direction along extension plate 50 than
the spacing between the first set of rear shafts 26 on brackets
28. Consequently, truck wheels 22 mounted on the end shafts provide
a longer in-line wheelbase than wheels 22 mounted on the two rear
shafts 26.
[0036] The extension plate 50 is adapted for removable attachment
to the wheel shaft support brackets 28 by means of attachment brackets
56 fixed to the extension plate as with rivets 58 and fastened to
shaft support brackets with screws 62 passing through aligned holes
in the attachment and support brackets, as seen in FIGS. 7 and 8.
The extension plate 50 is perforated with shaft holes 64 aligned
for receiving the first set of rear wheel shafts 26 in an installed
condition of the plate 50 on the shaft support brackets 28, as shown
in FIGS. 7 and 8. As seen in FIG. 8 one shaft hole 64 is provided
intermediate the center shaft 52b and each of the end shafts 52a,
52c. The extension plate 50 may have an underlip 55 which may run
the length of extension plate 50 and fits under the support brackets
28 to help support the weight of the truck 10 in the in-line configuration
of the truck 10 and to partially relieve the load on the attachment
brackets 56.
[0037] Up to three wheels 22 can be mounted in in-line position
on the three shafts of the extension plate 50. In one form of the
invention, the center shaft 52b is slightly lower than the two end
shafts 52a, 52b on the extension plate 50 such that a wheel 22 mounted
on the center shaft 52b can serve as a pivot with a pivot axis generally
along the middle of the truck frame 12. By balancing the truck frame
12 on the center mounted wheel 22 and with the end wheels 22 raised
slightly above the ground surface G the hand truck 10 can be turned
generally in place so as to change the direction of sideways displacement
of the hand truck.
[0038] Each support bracket 58 has a rear edge 66 which forms an
angle .phi. with the vertical similar to the same angle .phi. of
the in-line mounted wheels 22 in FIGS. 4 and 6. In its installed
condition depicted in FIGS. 6-8, the extension plate 50 lies against
the rear edges 66 at this same angle .phi.. As a result, the rear
shafts 52a,b,c, which are perpendicular to the plate 50 are parallel
to the first set of rear shafts 26 and are angled relative to the
load plate 20 and the truck frame 12 at angles similar to those
of rear shafts 26 on support brackets 28. Truck wheels 22 mounted
on the second set of rear shafts 52a,b,c are consequently inclined
to the vertical at the same angle .phi.. In a resting condition
of the load plate 20 upon ground surface G as shown in FIG. 6, the
wheel edge 22c nearest to the truck frame 12 preferably contacts
the ground G and serves as a pivot upon which the weight of the
hand truck 10 and any load thereon is transferred entirely onto
the wheels 22 when the truck frame 12 is pulled back to a reclined
condition for lifting the load plate 20 away from the ground surface
and the wheels 22 are brought to a generally vertical position with
wheel bottoms 22b in contact with the ground surface G.
[0039] A second optional feature of the convertible hand truck
10 is a foldable, swing-out support leg 70 which is supported by
sleeve 72 on the upper cross member 16 of the truck frame 12. The
sleeve 72 turns about cross member 16, and a coil spring 74 captive
between the support leg 70 and the cross member 16 applies torsional
force normally urging the lower end 76 of the support leg to a folded
or retracted condition against the frame 12 of the hand truck, as
depicted in FIGS. 1 and 9. The leg 70 can be swung away from the
truck frame 12 against the force of spring 74 to a deployed position
illustrated in FIG. 10 for supporting the hand truck 10 on a ground
surface G in a reclined position conducive to supporting a load
L in stable position against the hand truck frame 12 and load platform
20. It will be noted in FIG. 10 that wheel 22 rests on ground surface
G in a generally upright vertical condition brought about by the
reclined position of the hand truck frame 12.
[0040] A third optional feature depicted in FIG. 9 is the provision
of a load carrying shelf 80 removably mounted to the truck frame
12 at a location vertically intermediate to the handle 18 and the
load plate 20. In FIG. 7, the load carrying shelf 80 is shown supported
on the side members 14 at a height between the upper and lower cross
members 16. The removable load carrier 80 has fasteners 82 each
of which engages a corresponding vertical side member 14 of the
truck frame. Each fastener 82 is a spring clip fastener, generally
U-shaped, with the base of the U secured to the load carrier 80
and the open end of the U configuration resiliently spread apart
to receive the vertical member 14 of the frame. For greater security,
where heavy loads are to be carried on the shelf 80, a supplemental
fastener 84 may be provided to hold the open end of the U-shaped
fastener 82 from spreading open. The supplemental fasteners 84 may
take the form of bolts inserted across the open end of each fastener
84, along with a nut threaded on the end of the bolt for holding
the arms of the fastener tightly against the vertical member 14.
[0041] This invention also contemplates a hand truck kit of parts
which includes a combination of some or all of the elements and
optional features identified above. For example, the kit in one
embodiment may include the hand truck frame 12 with the load plate
20 and a set of at least two wheels 22 including a sufficient number
of wheel fasteners such as fasteners 40. In a more complete embodiment
of the kit, the hand truck kit of parts may further include a wheel
base extension 50 such as shown in FIG. 9 for extending the in-line
wheel base of the hand truck 10 and a set of at least three wheels
22 with corresponding wheel fasteners. In a still more complete
form of the hand truck kit of parts, one or more load carrying shelves
80, shown in FIG. 9, are also included in the kit.
[0042] Preferred and alternate embodiments of the invention have
been described and illustrated for purposes of clarity and example
only. It should be understood that still other changes, modifications
and substitutions to the described embodiments will be apparent
to those having only ordinary skill in the art without thereby departing
from the scope of the invention, which is defined by the following
claims. |