Note: Descriptions are shown in the official language in which they were submitted.
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ERGONOMICALLY DESIGNED WHEELED LUGGAGE
FIELD OF THE INVENTION
The invention relates in general to luggage. More particularly, the
present invention relates to an ergonomically designed wheeled luggage.
BACKGROUND OF THE INVENTION
A great many types and styles of wheeled luggage, to include suitcases
and carry-on bags, are known. The most popular style of wheeled upright
luggage has a fixed axis provided as a part thereof and extending along a
lengthwise edge of a lower base portion of the case, with a pair of spaced
wheels rotatably mounted to the case and along the axis. The wheels are
typically oriented so that the case can be rolled broadside. The upper face of
the case is provided with a telescopic handle with which the user balances the
case on its two wheels. Using the handle, the case can therefore be pulled
with relative ease.
The wheeled luggage, to include cases and bags, collectively referred to
hereinafter as "cases," commercially available today have handles for pulling
or
pushing the case and which are positioned parallel to the axis of the wheels.
Such an arrangement forces the user to adopt an unnatural posture or stance
in which the user's arm is extended back from the body and rotated about plus
or minus 90° from the normal position of the arm, in which the arm
extends
along the side of the body and the palm faces the leg, while walking and
carrying the case such that the user's palm instead faces up or down to grasp
the handle.
This rotation of the arm and hand is achieved by a combination of
shoulder and forearm rotation. In pulling the handle forward, the arm is
extended from about 10° to about 40° toward the rear of the
body. Due to the
required position of the hand, shoulder abduction is thus from about
10° to
about 30°, and the arm is positioned straight with the elbow joint
fully extended.
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The wrist is deviated in the ulnar direction, generally from about 15°
to about
25°, in order to align the user's hand with the luggage handle.
Depending on
the required pulling force, therefore, the wrist may also be subjected to
flexion,
generally from about 0° to about 15°. The positioning of the arm
required to
pull the wheeled case may therefore result in fatigue and/or a repetitive
movement type injury to the user, especially those types of injuries
associated
with wrist movement. For individuals already suffering from repetitive
movement injuries associated with other activities, for example keyboard
associated wrist injuries, the hand and arm positions required by the
currently
available wheeled cases can result in significant pain to the user, and/or
further
injury thereto.
Moreover, the currently available types of wheeled cases generally
come in a "one size fits all" design. The length of the extendable handle when
extended is fixed, and is designed for a person of "average height" so that
the
weight of the luggage should be balanced over the wheels and thus require a
minimal amount of force to maintain the luggage in an equilibrium or balanced
position during usage. Taller persons, however, generally have to exert a
downward force on the handle in order to keep the luggage from tipping
backwards, whereas shorter persons have to exert an upward force to keep the
luggage from falling toward the floor. Even persons of the "average height"
for
which the luggage is designed may have similar difficulties if additional
items of
luggage are attached to, or carried on, the wheeled case due to a shift in the
center of gravity over the wheels.
What is needed, therefore, but currently unavailable among the known
types of wheeled cases or luggage, is an improved ergonomically designed
piece of wheeled luggage which will allow for a more natural user posture or
stance during usage of the luggage. It would also be desirable to provide such
a wheeled case with an ergonomic handle that may be easily adjusted for users
of different height.
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SUMMARY OF THE INVENTION
The present invention provides an ergonomically designed piece of
wheeled luggage including, but not limited to, suitcases, bags, and other
forms
of luggage, which overcomes some of the design deficiencies of the art. The
present invention thus provides luggage that is more comfortable and less
tiring
to use and which permits the user to adopt a more natural stance when
carrying or otherwise moving or transporting the luggage across a floor
surface,
and which also permits the user to adjust the handle length to fit their
respective body height, carrying preferences, and/or load conditions, thereby
increasing user comfort while otherwise reducing fatigue and minimizing the
risk of injury to the user, including injuries commonly associated with
repetitive
movement of the arm and wrist. Additionally, the ergonomically designed
wheeled luggage of the present invention reduces the risk of repetitive or
constant movement injuries to the luggage user.
More specifically, the present invention provides a wheeled case having
a handle which when deployed is positioned to be essentially perpendicular to
the axis of the wheels, and which can be adjusted to the height of the
operator.
Moreover, the present invention allows the user to adjust the length of the
handle based on the user's height. The present invention thus provides
ergonomically designed wheeled luggage which includes a four sided luggage
or suitcase body adapted for holding articles, the luggage body having a
bottom
surface, a back surface, and a top surface, with the back surface thereof
intersecting both of the bottom and top surfaces, respectively.
The luggage also has at least two wheels rotatably attached to the
bottom surface of the luggage body adjacent the intersection of the back
surface to the bottom surface thereof, such that a longitudinal axis passing
through the wheels is parallel to the intersection of the back surface and the
bottom surface of the luggage. A handle assembly is also provided, the handle
being mounted on or adjacent the back surface of the luggage body, the handle
assembly having a handle grip for being gasped by a user and used to roll or
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transport the wheeled luggage across a floor surface. The handle, when not in
use, is essentially flush with the top surface of the luggage body.
In use, the handle extends for an adjustable distance above the top
surface of the luggage body and can be locked in place at the selected
distance or height. When extended, the handle grip is grasped by the user so
that the handle is essentially perpendicular to the axis of the wheels, and
wherein the adjustable distance or height of the handle can be selectively
varied depending on the height of the user. In a preferred embodiment, the
grip portion of the handle is essentially parallel to the surface when the
wheeled
luggage is being rolled across a floor surface by the user. The handle, when
not in use, is essentially flush with both the top surface and the back
surface of
the luggage body.
The wheeled luggage of the present invention is also provided with
guides or markings by which the user can easily and repeatedly adjust the
length of the handle to the user's height and body proportions. For example,
the handle may have height or other markings which the user will use as a
reference or gauge to adjust the length of the handle. The wheeled luggage
may also be provided with a "bubble" indicator which would be used to adjust
the appropriate handle length. The length of the handle would be adjusted
such that when the grip portion of the of the handle is essentially parallel
to the
ground, the center of gravity of the luggage would be over, or very nearly
over,
the wheels, as indicated by the bubble indicator. This would allow the handle
length to be adjusted so that the optimum inclination angle, which occurs
where
the center of gravity is directly, or nearly directly, over the wheels, is
achieved
when the luggage is either pulled or pushed. Once the optimal handle length
has been established for a particular user, the user can then easily adjust
the
length of the handle using the markings or other indicators on the handle to
the
desired, and predetermined, handle length.
An object of the present invention, therefore, is to provide improved
ergonomically designed wheeled luggage. It is to these objects, as well as the
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other objects, features, and advantages of the present invention, which will
become apparent upon reading the specification when taken in conjunction with
the accompanying drawings, to which the invention is directed.
5 BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates the pulling positions employed by persons of varying
height using the known types of wheeled luggage.
Fig. 2 illustrates the pulling position of a person using the wheeled
luggage of the present invention.
Fig. 3 illustrates a free body diagram of wheeled luggage used to
develop the wheeled luggage of the present invention.
Fig. 4 is a graph showing the effect of body height and acceleration on
the lifting force with the conventional wheeled luggage of Fig. 1, having a
handle length of about 1 meter.
Fig. 5 is a graph showing the effect of body height on the lifting force for
varying handle lengths with the conventional wheeled luggage of Fig. 1.
Fig. 6A illustrates a first embodiment of the wheeled luggage of the
present invention having a handle assembly.
Fig. 6B is a side elevational view of a first embodiment of the handle
assembly of the wheeled luggage of Fig. 6A.
Fig. 6C is a side elevational view of a second embodiment of the handle
assembly of the wheeled luggage of Fig. 6A.
Fig. 7A illustrates a second embodiment of the wheeled luggage of the
present invention having a handle assembly.
Fig. 7B is a side elevational view of the handle assembly of Fig. 7A as
the handle is deployed in its transport position.
Fig. 7C is a side elevational view of the handle assembly of the wheeled
luggage of Fig. 7A as it is first withdrawn from the wheeled luggage.
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DETAILED DESCRIPTION
Referring now in detail to the drawings, an illustrative embodiment of the
known types of conventional wheeled luggage is illustrated in Fig. 1. The
known wheeled luggage has a handle spaced from and extending parallel to
the axis of the wheels. In order to hold the handle of the case, the palm of
the
user's hand must either face forward or backward, as shown, which requires a
rotation of the arm and wrist through approximately 90° in either
direction,
achieved by a combination of shoulder and forearm rotation. In pulling the
handle forward the shoulder is extended in a rearward direction in the range
of
from about 10° to about 40°, thereby placing the hand behind the
user's body.
The extension of the arm to the rear, and the rotation of the user's palm
results
in a shoulder abduction of from about 10° to about 30°, and a
wrist deviation in
the ulnar direction of from about 15° to about 25°.
Additionally, the user's arm
is held straight with the elbow joint fully extended. Depending on the
required
pulling force, therefore, the user's wrist may also be subjected to flexion,
generally in the range of from about 0° to about 15°. Most users
will find the
carrying or transporting positions illustrated in Fig. 1 uncomfortable,
especially
during prolonged periods of use, and/or while carrying heavy, unbalanced
loads.
Moreover, conventional wheeled luggage generally has a fixed handle
length. Thus, the user's height will significantly affect the angle of
inclination
between the luggage body and the ground. In Fig. 1, the woman on the right is
at a disadvantage because she must exert a greater force to pull the same size
and weight of the wheeled luggage compared to the man on the left side of Fig.
1 due to the differing angle the handle makes with the ground. For
conventional wheeled luggage as shown in Fig. 1, and defining the x and y
axes as forming the plane of the paper, as illustrated in Fig. 3, the axis of
the
gripping portion of the handle is parallel to the axis of the shaft joining
the two
wheels together, with both axes extending along the z axis and out of the
page.
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The luggage of the present invention is illustrated in use, generally, in
Fig. 2. As shown in Fig. 2 the user can adopt a more natural stance or posture
when grasping the handle of the wheeled luggage. Once again representing
the x and y axes as forming the plane of the paper, the gripping portion of
the
handle of the wheeled luggage of the present invention is within the x, y
plane
and is also perpendicular to the axis extending between the wheels rather than
extending along the z axis. Thus, the user is not required to extend their arm
to
the rear, and/or rotate their arm so that their palm is either facing forward
or
backwards. As illustrated, the user can now pull the wheeled luggage of the
present invention without extending their arm in a rearward direction, and
without significant rotation of the wrist.
A free body diagram, illustrated in Fig. 3, of a piece of conventional
wheeled luggage was used to develop the wheeled luggage of the present
invention. To simplify the analysis, the following assumptions were made.
First, the mass of the wheels is negligible relative to the mass of the
luggage
and its contents. Secondly, that the radius of the wheels is small relative to
the
overall geometry of the luggage. Third, that all motion of the wheeled luggage
is due to the rolling of the wheels across a floor surface, and fourth, that
the
rolling of the wheels is frictionless. The required force to move the luggage
case has been divided into a horizontal component FP representing a pulling
force, and a vertical component F~ representing a lifting force.
The nomenclature listed below is used in Fig. 3, as well as in the several
equations which follow, in which the presence of an asterisk (*) is used to
denote the performance of a multiplication step therein:
L is the length from the wheel center to the end of the extended handle;
8 is the angle of inclination with respect to the ground;
~ is the angle between the luggage edge and the line OC, where O is the
center of the wheel and C is the center of gravity of the luggage (in the
plane);
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W is the weight of the luggage;
m is the mass of the luggage;
a and b represent the height and width of the luggage, respectively;
F~ is the lifting force;
FP is the pulling force;
FN is the normal force;
FF is the friction force (FF = m* FN);
N is the coefficient of kinetic friction between the wheel and the
ground; and
acc is the horizontal acceleration vector.
Summing the forces in the x direction, therefore, the following equation
is obtained:
EF=FP-FF=m*acc, (1)
which for pure rolling motion becomes
Fp = m * acc. (2)
The sum of the forces in the y direction is zero, thus
F~ = W - FN. (3)
Assuming that the center of gravity coincides with the center of geometry C of
the case, the sum of the moments around the center of the wheel is zero and is
described by the equation:
-F~ * L * cos(0) + FP * L * sin(0) + W * a/2 * cos(0) - W * b/2 * sin(0)
-m * acc *'~2 (a2 + b2)v2 * cos(0 + ~) = 0 (4)
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For a static system, or a system moving at a constant speed where acc = 0,
equation 4 becomes:
W * (a/2 * cos(0) - b/2 * sin(6) = FI * L * cos(0). (5)
The inclination angle 8 of the case is a function of the length L of the
extended
handle, and the height H of the operator's grip such that:
8 = arcsin(H/L). (6)
Since the grip height, which is the approximate distance from the floor to
the hand with the arm held at the side, of an individual is approximately 45
percent of the total height H, the effect of height can be determined using
the
above equations. Using typical values for the size and weight of the luggage,
for example W = 180 Newtons, a = 58 cm, b = 23 cm, and L = 100cm, the
variation in lifting force as a function of body height is shown in Fig. 4 for
an
acceleration of zero, representing an at rest or steady movement state, and
for
a typical acceleration of 0.8 m/s2. The mechanical advantage of rolling
luggage
can clearly be seen from Fig. 4.
The force required to steadily pull a 180 Newton wheeled case of known
construction thus varies from about 26 Newtons for a tall person to about 36
Newtons for the short person. The shorter person is therefore at a significant
disadvantage and would have to exert approximately 50 percent more lifting
force than the taller person, with an even higher lifting force required
during
acceleration. Although the relative advantage of the taller individual is
reduced,
the shorter individual must still exert a higher lifting force as compared
with the
taller individual. As the horizontal pulling force is increased due to
acceleration,
a moment around the axis of the wheels is created which tends to push the
handle toward the floor. The vertical lifting force has to create a moment in
the
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opposite direction in order to keep the case stable, and thus a higher lifting
force is needed.
Fig. 5 shows the effect of the handle length L on the required lifting force
for persons of different height. At a handle length of one meter, shorter
5 individuals are again at a disadvantage and have to exert a greater lifting
force.
As the handle length is increased, the lifting force for shorter users is
decreased. As the handle length is further increased, the force curve
approaches vertical. Thus, a shorter person would benefit from a somewhat
longer handler. Of course, simply extending the length of the handle is not a
10 practical approach since this would become unwieldy and increase the
overall
weight of the luggage.
When the center of gravity of the wheeled luggage is directly above the
axis of the wheels, the required lifting force to balance the case is
essentially
zero. From Fig. 3, the center of gravity is directly above the wheel axis when
0+~=90.
For typical luggage dimensions, where a=58cm and b=23cm, ~ would be about
22°. Thus, the optimum inclination of the luggage during pulling would
be at a 8
of about 68°. Using equation 6 and setting H equal to about 45 percent
of the
total body height, the optimum handle length would be about 0.485 of the total
body height. This value is roughly equal to the location of the hand from the
floor when standing with the arm and the hand fully extended along the side of
the body.
In order to achieve an ergonomic hand-handle gripping interface, the
shape, size, surface, and orientation of the handle can be adjusted consistent
with these calculations. Preferably, the surface of the handle grip 32 (Figs.
6A-
7C) will be coated with a non-slippery and a compressible material, and is
otherwise free of sharp edges. If desired, the handle may have finger grooves
or other means to assist the user in gripping the handle. The cross-section of
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the handle is preferably circular, oval, or rectangular with rounded corners,
and
will provide a good fit between the user's hand, will prevent unwanted
rotation
of the handle therein, and will give the user a sense of the orientation of
the
handle. Preferably, the length of the grip portion 32 of the handle is
sufficient to
allow the largest user to use a closed fist grip that is formed with all
fingers and
thumb; normally a four inch or longer grip area length is sufficient. The
handle
axis should be essentially perpendicular to the axis of the wheels when the
handle is being used to carry/transport the luggage. The orientation of the
handle should allow the use of the luggage without excessive deviation of the
wrist. The handle may be provided with a flange or other means at the end of
the grip to eliminate or significantly reduce slippage, as desired.
Alternatively,
the grip portion of the handle may form a closed opening such that the fingers
fit within the opening during operation.
The present invention discloses two ergonomic design features to
improve the design of a wheeled luggage case. The first is the ability to
control
the length of the telescopic handle whereby the length of the handle can be
set
to a suitable and desired length depending on the user's height and/or body
proportions, for example the length of the user's arm relative to their
height. In
contrast, when the handle length of the known types of wheeled luggage is
adjusted, this does not significantly effect the center of gravity of the
wheeled
luggage. The optimum handle length for a given user will generally be a length
such that the handle can easily be grasped by the user when standing up with
their arm and hand fully extended along their side, and will vary for any
given
individual based on their unique physical characteristics.
The second design feature is the orientation of the handle. The
ergonomically designed handle for use with wheeled luggage of this invention
enables a user to pull the luggage using a more comfortable and natural
posture. For every joint in the human body there is an ergonomically preferred
position at which the human body is the strongest and most comfortable. Thus,
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in designing for the comfort of the user, the present invention allows the
user to
assume, or at least approximate, the preferred or more natural posture.
The following Table lists the body segments and joints normally used
when pulling wheeled luggage and provides a comparison between convention
wheeled luggage and the present invention.
Body Segment Preferred PositionConventional The Inventive
or
Joint Luggage Luggage
Shoulder 0 10 - 30 0
Abduction
Shoulder 0 10 - 40 0 - 20
j
Extension
Shoulder Lateral0
Rotation
Combination 0
movement of
45
Shoulder Medial0
Rotation
Forearm 0
Supination
Forearm 0
Pronation
Elbow Flexion 90 0 0
Wrist Ulnar 0 15 - 25 +5
Deviation
Wrist Flexion 0 0 -15 0
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As demonstrated, the wheeled luggage of the present invention allows
the user to assume a more natural posture, especially with regard to the
position of their wrist, shoulder, and forearm. Use of the inventive wheeled
luggage should therefore increase user comfort and reduce user fatigue, as
well as the risk of repetitive movement type injuries.
Figs. 6A-7C illustrates several embodiments of the wheeled luggage of
the invention. Accordingly, the wheeled luggage of the present invention
includes a luggage body or case 10 provided with a handle assembly 12. The
case is~provided with a pair of spaced and parallel wheels 14 which are
rotatably mounted thereto and have a common elongate longitudinal axis
extending therethrough.
The luggage body or case 10 is formed by a back surface 16, a bottom
surface 18, two opposed side surfaces 22, a top surface 24, and a front
surface
23, all joined to one another along their common side edges, in known fashion.
Although shown as a rigid body or case, it is anticipated that the body may
instead be a semi-rigid or soft body case or bag formed for carrying and
enclosing the user's personal effects (not illustrated) therein. The
intersection
of the back surface and the bottom surface of the case is parallel to the axis
of the two wheels 14.
20 The handle assembly 12, when folded, fits into a well 34 defined within
or formed by the case. Preferably when the handle assembly 12 is in its
stowed position, the handle is essentially flush with the luggage body, namely
the top surface 24 and the back surface 16 thereof, as shown in Fig. 6A. The
handle assembly 12 is constructed such that it will lock when in its stowed
position within the well of the case. Although not shown, the well 34 can also
be closed or sealed over with a zippered or Velcro-type of hook and loop
fastener covering when the handle assembly is not being used in order to
prevent the handle assembly from opening and/or being damaged during
baggage handling. The case 10 will also be equipped with a conventional carry
handle 26 mounted on the top surface of the case body.
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The handle assembly, when deployed, will provide an elongate handle
grip 32 that will be positioned essentially perpendicular to the axis of the
wheels
14 of the case, and is also perpendicular with respect to the intersection 20
of
the back surface 16 and the bottom surface 18 of the case. The handle
assembly as constructed thus allows for the adjustment of the overall handle
length to accommodate different users. Preferably, the handle grip 32 is
deployed so that it is generally parallel to the floor or other surface over
which
the wheeled luggage is to be transported. Of course, other configurations of
the handle assembly 12 shown in Figs. 6A-7C could be used so long as the
handle, when in its operating position, is perpendicular to the wheel axis and
where the length of the handle can be adjusted to the height of the user
without
significantly affecting the center of gravity of the luggage.
The handle assembly 12 is shown in its stowed position in Fig. 6A. A
lock or release button 28 is provided on the handle assembly to lock the
handle
assembly in place, as illustrated. By engaging the lock button 28, the user
can
move the handle assembly into its open operating position as illustrated in
Figs.
6B and 6C. In its operating position the handle grip 32 is positioned such
that it
is perpendicular to the axis of the wheels 14.
The handle assembly includes the handle grip 32 for being grasped
within the hand of the user, a handle shaft 36, a slidably moveable inner tube
38, and a stationary outer tube 40. The handle shaft 36 is attached to the
inner
tube 38 by a hinge 30 formed about a center point or pivot pin 51. In the
stored
position of the handle assembly (Fig. 6A), the handle shaft 36 is essentially
parallel to the inner and outer tubes 38 and 40. When the handle is extended,
as shown in Figs. 6B and C, the handle shaft 36 is rotated about the pivot pin
into the operating position of the handle, as indicated by arrow 44. In
deploying
the handle assembly, the inner tube 38 is slidably moved upwardly within the
outer tube 40 to provide the desired handle length. The gripping surface of
the
handle 32 may have a flared end 33 to allow a better grasp thereof by the
user,
or to minimize hand slippage when being grasped by the user. If desired, the
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handle may also define an opening 33' through which the user can insert their
fingers in order to permit the user to obtain a better grip.
Once the handle assembly is properly positioned and adjusted to the
desired length in its extended position (Fig. 6C), the inner tube of the
handle
5 assembly will then be locked in position with respect to the outer tube by
using
any one of the several known types of locking devices and mechanisms. For
example, the outer tube could be provided with a fitting which selectively
compresses the inner tube so as to tightly grip the inner tube. Alternately,
the
inner tube may have a series of spaced openings defined therein and through
10 which a pin (not illustrated) can be inserted to lock the two tubes 38 and
40
together so as to provide a handle of the desired length. Additionally, the
markings 42 can be used to gauge the extended position of the inner tube 38
relative to the outer tube 40 and, thus, the length of the extended handle.
The length of the extended handle is determined based upon the
15 ergonomic principles described above. Once such a length is determined for
a
particular user, the length that the inner tube 38 must be extended within the
outer tube 40 to attain that desired length can be marked or otherwise
indicated
on the inner tube 38 by the gauge markings to permit the user to easily set
the
handle assembly at the desired length in the future.
A bubble indicator 46 (Fig. 6A) may also be provided, and used if
desired, to assist the user in adjusting the length of the handle to the
correct
ergonomic position for that user so that the bubble is centered within the
level
and the extended handle shaft and handle grip are positioned parallel to the
floor surface across which the wheeled luggage will be rolled during
transport.
Of course, for a particular individual, the desired handle length will be
determined empirically, or through an initial trial and error process. It is a
feature of the present invention, however, that the inclination angle, i.e.,
the
angle 0 formed by the lower portion of the handle relative to the ground, is
not
significantly modified by changing or adjusting the handle length.
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Although the weight distribution of the load within the luggage body is
not expected to significantly alter the desired handle length, the addition of
other luggage, either placed on the top surface 24, or hung from the top
surface
24 and extending over the front surface 23 of the body/case 10 may modify the
case's center of gravity to the extent that it may be desirable to further
adjust
the handle length. Since the handle length can be adjusted as needed, and as
described above, the present wheeled luggage is ideally suited for use in
situations where the load distribution may change or where more than one user
may use and/or pull the luggage.
Figs. 7A-C illustrate a second embodiment of the present invention, and
uses like reference characters to identify like components of the two pieces
of
luggage. The handle assembly 12 is housed once again within the back
surface 16 of the luggage body, and comprises a handle grip 32, a handle shaft
36, an inner tube 38, and an outer tube 40. In its stored position (Fig. 7A),
the
handle shaft 36 and the inner tube 38 are aligned with and received within the
outer tube 40 of the handle assembly, with a flared end 33 of the handle grip
fitted within the recess or well 34 of the case.
A locking button 28 is once again provided for locking the handle
assembly into, and releasing the handle assembly from, its stored position
within the body of the case. To move the handle assembly into its operating
position, the handle grip 32 is released by depressing the locking button 28
and
pulling the handle grip 32 upwardly until the desired overall extension
thereof is
obtained, as shown in Fig. 7C. The handle grip 32 is then rotated about a
pivot
50 and a center pin 51 as indicated by the arrow 44', such that the handle
grip
is positioned to be essentially parallel to the ground (during use) and
perpendicular to the axis of the wheels 14, as illustrated in Fig. 7B.
The inner tube 38 may be provided with actual height indicators 52 (Fig.
7B), or with arbitrary indicators 52' (Fig. 7B) used to indicate or gauge the
desired distance the inner tube 38 must be extended within the outer tube 40
to
attain the desired handle length. In Fig. 7C, the inner tube 38 has been
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extended or adjusted for a person having a height in the range of from 5' 5"
to
5' 7".
This embodiment of the wheeled luggage may also be provided with a
"bubble" indicator, as discussed above, which will be used to adjust the
appropriate handle length. The length of the handle is adjusted such that when
the grip portion of the of the handle is held essentially parallel to the
ground,
the center of gravity of the luggage will be over, or very nearly over, the
wheels,
as indicated by the centered bubble within the bubble indicator. This allows
the
handle length to be adjusted so that the optimum inclination angle, which
occurs where the center of gravity is directly, or nearly directly, over the
wheels,
is achieved when the luggage is either pulled or pushed. Once the optimal
handle length has been established for a particular user, the user can then
easily adjust the length of the handle using the markings or other indicators
on
the handle to the desired, and predetermined, handle length.
Although several embodiments of the invention have been disclosed in
the foregoing specification, it is understood by those skilled in the art that
many
' modifications and other embodiments of the invention will come to mind to
which the invention pertains, having the benefit of the teaching presented in
the
foregoing description and associated drawings. It is thus understood that the
invention is not limited to the specific embodiments disclosed hereinabove,
and
that many modifications and other embodiments are intended to be included
within the scope of the appended claims. Moreover, although specific terms
are employed herein, as well as in the claims which follow, they are used only
in a generic and descriptive sense, and not for the purposes of limiting the
described invention, nor the claims which follow.
