Note: Descriptions are shown in the official language in which they were submitted.
CA 02700907 2012-10-23
MODULAR PATIENT SUPPORT SYSTEM
FIELD
The present invention is generally directed to support platforms and/or carts
that
provide enhanced patient mobility.
BACKGROUND
Current practice for patients in a healthcare facility involves having
multiple unrelated
treatment, maintenance and/or monitoring devices that are attached to the
patient. These
include intravenous fluids and drugs, drainage catheters, suction catheters,
leg compression
stockings and vital sign monitoring devices. Such devices often create a
hazard for the patient
both directly and indirectly. The myriad of devices may become entangled and
inadvertently
removed if not adequately accounted for by the patient or caregiver. This may
require an
invasive intervention, including surgery, in order to replace the removed
device.
The number of devices generally associated with the patient require the
patient to have
the physical and mental ability to manage organizing or carrying the devices
to ambulate even
as far as the bathroom. Since patients are debilitated by the nature of their
illness and
medications, two staff persons are frequently required to help the patient
move even short
distances. One staff member must assist the patient, providing physical
support, while the
other manages the attached devices. The patients thus do not get out of bed
and ambulate as
often since the staff of the typical health facility is not able to provide
this kind of support
readily to all of the patients at all times.
The resulting immobility increases the patient's risk for deep venous
thrombosis,
pulmonary embolus and pneumonia. Additionally, mobility improves gut motility
and
decreases the time a patient must wait before obtaining enteral nutrition and
ultimately
discharge from the healthcare facility. Patients that require prolonged
hospital stays or
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admission to skilled-nursing facilities for non-medical indications related to
mobility and
personnel support may be able to be discharged home sooner with a device that
provides
the same type of care. The cost to the healthcare system may be reduced by
decreasing the
stays in expensive healthcare facilities and decreasing complications that are
costly both in
patient morbidity and monetary value.
The patient-care staff is also at risk for injury, as they must provide
physical
support to the debilitated patient. Back injuries are frequent in healthcare
staff as a result
of the physical nature of assistance provided. Allowing the patient to rely on
an
ambulatory assist device will help the patient-care staff as well by keeping
them out of
harm's way.
Current poles that provide an intravenous ("IV") fluid and/or liquid
medication
delivery source are often times taken with patients when the patient moves
around, such as
when a patient walks in a hospital hallway. The patient typically places at
least one hand
on the IV pole to move the IV pole while walking. However, typical IV poles
are
approximately 6 to 7 feet tall, and are often unstable for providing weight
support to a
patient, particularly when one or more substantially full IV bags are
positioned near the
top of the pole. As a result, a patient is at risk of further injury by
falling if the IV pole
tips and/or falls over. In addition, in order to prevent tipping, conventional
IV poles have
widely spread wheels, which require a large amount of floor space. IV poles
are
completely unable to manage uneven terrain as is found outside the confines of
the patient
care facility, and as may be found at home or in the field for disasters or
military
operations.
In addition to being relatively unstable, current IV poles do not provide for
the
additional needs of a patient that is moving about. For example, IV poles do
not include
an oxygen source for assisting the patient with breathing. Current IV poles
also do not
include various pumps or suction devices that may be necessary for continuous
operation
to provide proper medical treatment to the patient. In addition, vitals
monitoring
equipment and communication devices are typically not present on a standard IV
pole.
Furthermore, even if an IV pole is adapted to include a monitoring device or
pump, the IV
pole tends to become even more unstable because the resulting added weight of
the device
typically is positioned relatively high along the pole.
In connection with patients that require assistance walking, various "walker"
devices are available. A typical walker includes handrails interconnected to a
stable base.
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However, because use of a walker usually requires both hands of the patient, a
patient is
typically unable to take an IV pole with them when using a walker.
Patient care devices and services such as suction and oxygen are not built in
to the
facilities of several countries and regions. This is also true in field
situations of military
conflict or civilian disaster. Patients may be far from a medical facility or
in the hallway
of a medical facility not equipped with patient support equipment/services.
Yet a further
difficulty exists in maintaining electrical power to electronic devices such
as monitoring
equipment, suction pumps and/or injection pumps while the patient is walking
with an IV
pole or walker, or while the patient is being moved in their bed or while the
patient is not
located next to an electrical outlet. This may occur in: 1) the operating room
while
needing to adjust the bed height or keep the pumps charged during a long
procedure, 2)
during a disaster when patients may be stationed in hallways or temporary
areas, 3) during
military conflict or civilian situations that require creation of field
hospitals with limited
generator availability, and 4) in countries or regions that do not have
consistent access to
power. Accordingly, an apparatus that maintains electrical power to these
devices would
be advantageous, as would an apparatus that provides power in case of an
electrical outage
or blackout.
In order to move patient support equipment, carts supported by castors are in
wide
use. Castors may be found in such applications as shopping carts, chairs,
hospital beds,
and mobile carts. Castors may be fixed or may be capable of swiveling.
Typically,
remotely operable braking mechanisms used in connection with castors are
deployed only
on fixed castors. Currently, there is a need for remotely operable braking
mechanisms that
can be deployed on swiveling castors. More particularly, there is a need for
braking
mechanisms that can be applied in any rotational position of the castor, and
that can be
used with castors capable of supporting relatively heavy loads. Additionally,
there is a
need for control mechanisms that can be used to control a number of castor
brakes as well
as other cart components.
SUMMARY
The present invention is directed to solving these and other problems and
disadvantages or the prior art. Embodiments of the present invention provide a
mobile
support cart or platform that is structurally stable and can thereby provide
weight bearing
assistance to a patient without being predisposed to tipping over. A mobile
support cart in
accordance with embodiments of the present invention includes upper and lower
platforms
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interconnected by first and second support members. The first and second
support
members and the upper and lower platforms may define a plurality of storage
spaces
operable to store one or more medical devices that may be needed by a user of
the mobile
support cart. In addition, the first and second support members and the upper
and lower
platform may provide a plurality of attachment points. The upper platform may
include an
ergonomic handle for safe and comfortable user by a patient or other user of
the cart.
In accordance with embodiments of the present invention, mobility of the cart
is
provided by a number of wheels that are disposed on the underside of the lower
cart
platform. The wheels may include a plurality of castors or castor wheels and a
tracking
wheel. A braking system may be provided in connection with the castors to
brake the cart
and/or maintain the cart in a stationary position. Alternatively or in
addition, the tracking
wheel may be associated with a brake. The tracking wheel may be operable to be
lowered
and raised between an engaged and a disengaged position. In the engaged
position, the
tracking wheel is in contact with the underlying support surface (e.g., the
floor) on which
the mobile support cart moves.
In accordance with embodiments of the present invention, a transmission system
is
provided that controls the operation of the braking mechanism associated with
the castors
and the tracking wheel. The transmission system may define a number of modes
that
establish various degrees of mobility for the cart. In accordance with
embodiments of the
present invention, three specific modes are defined. In particular, "stop",
"walk" and
"roll" modes are defined. In the "stop" mode, the castor brakes or braking
mechanisms
are engaged. In the "walk" mode, the castor brakes are released and the
tracking wheel is
lowered to its engaged position. In the "roll" mode, the castor brakes are
released and the
tracking wheel is raised to its disengaged position. In the "stop" mode, the
mobile support
cart is maintained in a stationary position. In the "walk" mode, the tracking
wheel
provides guidance or tracking to the movement of the cart. In the "roll" mode,
the mobile
support cart has its greatest range of motion. In particular, the wheels can
rotate or swivel
through the 360 degree movement of the castor's bracket or fork.
In accordance with embodiments of the present invention, the control mechanism
includes a control arm provided on the underside of the top platform. The arm
may
include first and second handles that are disposed on the front and rear
portions of the top
platform. The control arm may include a tracking wheel provided in association
with a
curved guidance member having a plurality of detents. In particular, pivoting
the control
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arm about a pivot point moves the tracking wheel along an edge of the curved
guidance
member. Each detent defines a set position for the control arm. These set
positions may
control the castor wheel brakes and tracking wheel to establish the above
described "stop",
"walk" and "roll" modes.
In accordance with embodiments of the present invention, the top platform may
include recessed portions that provide a means for mounting an oxygen bottle
or cylinder
onto the cart. Alternatively or in addition, IV receiver pole holes may be
associated with
the top platform to provide a mounting for IV poles.
Further embodiments of the present invention provide a braking mechanism.
Generally, the braking mechanism includes a cable and an associated brake arm,
wherein
the cable is positioned to allow braking at any point in the castor wheel's
360-degree
rotation or swivel. The braking mechanism is associated with a control
mechanism that
includes a single actuator that operates to separately engage two Bowden
cables or two
groups of Bowden cables.
In accordance with embodiments of the present invention, a mobile support cart
is
provided that includes:
an upper platform;
a lower platform;
a vertical member interconnecting the lower platform and the upper platform;
a plurality of castor wheels interconnected to the lower platform, the castor
wheels
comprising assemblies, each castor wheel assembly including:
a mounting plate, wherein the mounting plate is secured to the lower
platform;
a bracket, wherein the bracket is rotatably mounted to the mounting plate
such that the bracket is free to swivel relative to the mounting plate;
a wheel mounted to the bracket;
a plurality of braking mechanisms, wherein one of the plurality of braking
mechanisms is associated with each castor wheel assembly included in the
plurality of
castor wheel assemblies;
a tracking wheel assembly, including:
a tracking wheel arm, pivotally mounted to the lower platform at a first
end;
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a tracking wheel rotatably mounted to a second end of the tracking wheel
arm, wherein the tracking wheel can be placed in either of a lowered position
to
engage a support surface or a raised position such that the tracking wheel
does not
engage the support surface;
a transmission system operable to control the plurality of bracking mechanisms
and
a position of the tracking wheel, wherein the transmission system can be
placed in a
selected mode, including:
a walk mode, in which the wheels of the castor wheel assemblies are free to
rotate and in which the tracking wheel is in the lowered position to engage
the support
surface;
a roll mode, in which the wheels of the castor wheel assemblies are free to
rotate and in which the tracking wheel is in the raised position;
a stop mode, in which the braking mechanisms are engaged such that the
wheels of the castor wheel assemblies are inhibited from rotating and in which
the
tracking wheel is in the lowered position.
In accordance with other embodiments of the present invention, a castor with a
braking mechanism is provided that includes:
a mounting plate having a central hole formed therein, wherein the central
hole is
along an axis R;
a bearing having an open area formed in an area corresponding to an axis of
rotation of the bearing;
a bracket, wherein the bracket is interconnected to the mounting plate by the
bearing having an open area formed in an area corresponding to an axis of
rotation of the
bearing, wherein the axis of rotation of the bearing is parallel to the axis
R, and wherein
the bracket is capable of swiveling with respect to the mounting plate about
the axis of
rotation of the bearing;
a wheel interconnected to the bracket;
a brake arm mounted to the bracket by a pivot, the brake arm including:
a first end including a control member attachment point, the first end
having a location adjacent the open area formed in an area corresponding to an
axis of
rotation of the bearing;
a biasing member operable to bias the brake arm in a first direction;
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a contact area, wherein the control member one of: 1) allows the biasing
member to pivot the brake arm in the first direction such that the contact
area engages the
wheel, or 2) acts against the biasing member to pivot the brake arm in a
second direction
opposition the first direction such that the contact area is disengaged from
the wheel.
These and other features and advantages of embodiments of the present
invention
will become more readily apparent from the following description, particularly
when taken
together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is perspective view of an exemplary mobile cart in accordance with
embodiments of the present invention;
Fig. 2 is a side elevation view of the mobile cart shown in Fig. 1;
Fig. 3 is an underside view of the mobile cart shown in Fig. 1;
Fig. 4 is a perspective view of a portion of the mobile cart shown in Fig. 1;
Fig. 5 is a plan view of an underside portion of the mobile cart shown in Fig.
1,
showing a transmission system in accordance with embodiments of the present
invention
in a first position;
Fig. 6 is another plan view of an underside portion of the mobile cart shown
in Fig.
1, showing a transmission system in accordance with embodiments of the present
invention in a second position;
Fig. 7 is still another plan view of an underside portion of the mobile cart
shown in
Fig. 1, showing a transmission system in accordance with embodiments of the
present
invention in a third position.
Fig. 8 is a front elevation view of a castor, which includes a braking
mechanism, in
accordance with embodiments of the present invention;
Fig. 9 is a side elevation view of the castor shown in Fig. 8;
Fig. 10 is a perspective view of the castor shown in Fig. 8;
Fig. 11 is an enlarged view of a braking mechanism, in accordance with
embodiments of the present invention;
Fig. 12 is a flow chart showing a method of braking a castor in accordance
with
embodiments of the present invention; and
Fig. 13 is a state diagram depicting the various states of a mobile support
cart in
accordance with embodiments of the present invention.
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DETAILED DESCRIPTION
The present invention is generally directed to a mobile support cart or
platform for
use in increasing the mobility of a patient. The present invention is suited
for use in a
hospital, clinic or other patient care facility. In addition to these
environments, the present
invention may also be used in other settings such as, for example, a disaster
recovery area.
A mobile support cart or platform in accordance with embodiments of the
present
invention provides structure for accommodating a number of medical devices
which may
be associated with a patient. A mobile support cart, in accordance with
embodiments of
the present invention, may include a number of selectable modes that define
various
degrees of mobility for the mobile support cart. In a first mode, an onboard
braking
system may be engaged that places the mobile support cart in a stopped or
braked position
by preventing rotation of the castor wheels. In a second mode, the braking
system may be
disengaged and a tracking wheel may be lowered. In the second mode, the mobile
support
cart may be guided by the tracking wheel along a user defined path. In a third
mode, the
braking system is disengaged and the tracking wheel is raised. In this third
mode, the
patient support platform has its greatest range of motion. More particularly,
the castor
wheels provided on the base of the mobile support cart are allowed to freely
rotate and
swivel, thereby providing forward, backward and lateral motion for the mobile
support
cart.
Referring now to Fig. 1, a mobile support cart in accordance with embodiments
of
the present invention is generally identified by reference numeral 100. As can
be seen in
Fig. 1, a mobile support cart 100 in accordance with embodiments of the
present invention
includes an upper platform 104 and a lower platform 108. The upper platform
104 and the
lower platform 108 are interconnected by one or more vertical members,
including at least
a first support member 112. The upper platform 104 and the lower platform 108
may
additionally be interconnected by a second support member 116. The first 112
and second
116 support members may generally include flat, planer surfaces disposed in a
substantially vertical orientation. As shown, the second support member 116
may be
slightly less wide than the first support member 112. As also shown, the first
support
member 112 may be split into two separate vertical members or may feature an
open area
adjacent the lower platform 108. A cover 114 may be associated with one of the
vertical
members, such as the second support member 116, to assist in the routing of
control
cables.
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As can be seen in the side view of the mobile support cart 100 shown in Fig.
2, the
second support member 116 is separated from the first support member 112 by a
predetermined distance. The mobile support cart 100 may include a number of
storage
areas. As seen in Fig. 2, a first storage area 204 is provided between the
first 112 and
second 116 support members. A second storage area 208 is provided forward of
the
second support member 116. (As used herein, forward refers to the forward
direction of
motion of the cart when the cart is pushed or otherwise used for mobility
support by a
patient.) A third storage area 212 is provided by the top surface of the upper
platform 104.
A fourth storage area 214 is provided by the top surface of the lower platform
108. These
storage areas provide a means for mounting or otherwise carrying medical or
other devices
that may be needed by the patient. In addition, mounting points may be
provided for
receiving and/or interconnecting devices to the mobile support cart 100,
either directly or
through an adapter or container. For example, threaded holes 218 may be
provided by the
support members 112, 116. A further example are the IV pole receiver holes
128. Such
devices may include without limitation IVs and IV poles, IV and entreal pumps,
oxygen
cylinders, suction wound vacuums, portable ventilators, chest tubes, catheters
and drains,
ventricular assistant devices, cardiac monitors and defibulators, blood
pressure monitors,
pulse oxymeters, transesophageal cardiac monitors, tissue oxygenation
monitors, invasive
cardiac monitors and/or odometers. Plug and play computational devices may be
mounted
in, for example, the first storage area 204. A wireless communication
interface may be
provided in connection with the onboard plug and play devices to facilitate
transfer of
medical data.
An onboard power supply system may be provided for delivering power to one or
more of the onboard medical devices. As can be seen in Figs. 1-2, a mobile
support cart
100 in accordance with embodiments of the present invention includes a power
outlet box
120 disposed on a rear portion of the mobile support car 100. More
particularly, the
power outlet box 120 may be mounted underneath the upper platform 104 and on a
rear
facing side of the first support member 112. (As used herein, rear or rearward
refers to the
reverse direction of motion of the cart when the cart is pulled by a patient.)
Electrical
power may supplied from a wall outlet or other source through a power cord
216. The
power cord 216 may be extendable and retractable with respect to the power
outlet box
120. Alternatively or in combination, the power outlet box 120 may be provided
in
association with an onboard power source or universal power supply 220. As
shown in
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Fig. 2, the universal power supply 220 may be mounted or otherwise located on
the lower
platform 108. The universal power supply 220 is mounted in this position to
provide
added stability to the mobile support cart 100. In particular, as the
universal power supply
220 provides substantial weight to the cart, the universal power supply 220 is
provided
close to the base of the cart, thereby lowering the center of gravity of the
cart. Examples
of a universal power supply 220 include an isolation transformer, a battery,
and/or a fuel
cell.
Referring again to Fig. 1, a number of features are illustrated herein that
facilitate
attachment of onboard equipment. As can be seen in Fig. 1, the mobile support
cart 100
includes an attached IV pole 124. The attached IV pole 124 is mounted to the
mobile
support cart 100 through an IV pole receiver hole 128, which is disposed on
the surface of
the upper platform 104. The mobile support cart 100 shown in Fig. 1 includes
two IV pole
receivers 128. It should be understood however, that a number of IV pole
receiver holes
may be associated with a particular mobile support cart 100.
The upper platform 104 may additionally include two recessed side cut portions
132. The recessed side cut portions 132 are adapted to receive a cylindrical
object such as
an oxygen taffl( or bottle. In particular, the oxygen taffl( or bottle may be
placed on the
surface of the lower platform 108, in a position where the upper end of the
cylinder or
bottle is cradled at its upper end by the recessed side cut portion 132 of the
upper platform
104. The cylinder or bottle may then be secured in place by a fastener member,
which
attaches to one or both of the support members 112 and 116 to thereby
immobilize the
cylinder or bottle.
As can be seen in Figs. 1 and 2, a mobile support cart 100 in accordance with
embodiments of the present invention includes a platform handle 136. The
platform
handle 136 may be of an ergonomic design adapted specifically for patient
comfort and
safety. The platform handle 136 is disposed approximately at lower to mid
chest level and
includes two raised hand gripping portions 140. The platform handle 136
provides for a
symmetric axial loading of the patient's arms. In this regard, the platform
handle 136
transfers the force associated with moving the mobile support cart 100 to the
scapula
and/or to the back and not to the sternum of the patient or user. The platform
handle 136
also allows the quadriceps to participate in the pushing of the mobile support
cart. In
using the platform handle 136, the patient's joints are at a midpoint in their
range of
motion. Generally, the design of the mobile support cart 100, including the
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handle 136, is adapted to resist rotational movement, thereby preventing
excessive strain
on the patient and the patient's limbs. The above described advantages are in
contrast
with the standard mobile IV pole known in the art. In moving a standard IV
pole, a patient
must rely exclusively on the pectoralis and smaller muscle groups to move the
pole. This
creates leverage on the sternum and a twisting strain on the torso. Moreover,
the patient's
joints are extended beyond the midpoints of their ranges of motion, thereby
increasing
strain on the joints. Moreover still, prior art mobile IV poles are prone to
twisting and
catching on surfaces, thereby exposing the patient to greater risk of injury.
As can be seen in Figs. 1 and 2, a number of castors 304 provide mobility for
the
mobile support cart 100. The castors 304 are better seen in Fig. 3, which
shows an
underside of the mobile support cart 100. In accordance with embodiments of
the present
invention, the mobile support cart 100 includes a plurality of castors 304 or
means for
traversing an underlying or supporting surface. Additionally, the mobile
support cart 100
includes a tracking wheel 308 or means for providing tracked movement. As can
be seen
in Fig. 3, two castors 304 are mounted on a front or forward portion of the
lower platform
108. Two of the castors 304 are mounted on a rearward portion of the lower
platform 108.
The tracking wheel 308 is mounted in or near the center of the lower platform
108. Fig. 2
shows a profile of the mobile support cart, including components associated
with the
tracking wheel 308. As shown therein, the tracking wheel 308 is part of an
assembly that
includes a tracking wheel arm 224. The tracking wheel arm 224 is mounted at an
attachment point 228 that is disposed at the forward end of the lower platform
108. The
tracking wheel arm 224 is additionally associated with a biasing spring 232.
The biasing
spring 232 operates to bias the lever arm 224 in a downward position, wherein
the tracking
wheel 308 is engaged with the underlying surface.
The mobile support cart 100 may include a transmission or transmission system
having a lift cable that is operable to lift the tracking wheel 308 and
tracking wheel arm
224 against the action of the biasing spring 238. In the raised position, the
tracking wheel
308 is disengaged from the underlying surface. Fig. 4 provides an illustration
of
components that may be included in a transmission system 404 in accordance
with
embodiments of the present invention. Fig. 4 shows an underside of the top
platform 104
including connections to other cart components. Particular portions of the
mobile support
cart 100 are omitted from Fig. 4 to simplify the illustration. The
transmission system 404
includes a control arm 408 that can be moved into at least two and preferably
three
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positions to select from two or three modes of operation. The control arm 408
is
operatively associated with a first or short lever 412 and a second or long
lever 416. The
short lever 412 is interconnected to one or more brake cables 420. The long
lever 416 is
interconnected to a lift cable 424 or means for raising and lowering the
tracking wheel
308. The brake cables 420 and/or the lift cable 424 may comprise Bowden cables
or the
like and are operatively associated with the castors 304 and the tracking
wheel 308,
respectively. The lift cable 424 that is associated with the long lever 416,
is used to lift or
otherwise control a different cart component than those controlled by the
brake cable(s)
420. For example, the lift cable 424 may be used to control whether the
tracking wheel
308 is in a retracted position in which the tracking wheel 308 is disengaged
from the floor
or support surface, or is in a lowered position in which the tracking wheel is
engaged with
the floor or support surface. Alternatively, the lift cable 424 may be used to
actuate other
cart components such as a transmission, a gear system, or additional braking
mechanisms.
In moving the short lever 412 and the long lever 416, the control arm 408
includes
an attachment point that provides a rotatable connection to the upper platform
104. In
particular, a pivot type connection 428 is provided at or near the center of
the underside of
the upper platform 104. The control arm 408 is adapted to move or pivot about
the
attachment point 428. The control arm 408 may include a first 432 and second
436 handle
that may be gripped by a user to rotate the arm 408. The first or rear handle
432 may be
provided at the rear of the control arm 408. The rear handle 432 is typically
operated by a
patient who is using the mobile support cart 100 to enhance his or her
mobility. The
second or forward control handle 436 may be provided at the forward end of the
control
arm 408. Typically, this forward control handle 436 is used by doctors, nurses
or other
hospital staff in moving or controlling the mobile support cart 100 or in
demonstrating the
various modes of the cart to a patient who is typically located at the rear of
the mobile
support cart 100.
In accordance with embodiments of the present invention, the control arm 408
includes a guide wheel 440 provided in association with a curved guidance
member 444.
The guide wheel 440 is biased by a guidance wheel spring 448 that maintains
the guide
wheel 440 in operative contact with the curved guidance member 444. The guide
wheel
440 is mounted to the control arm 408. For example, the guide wheel 440 may be
mounted within a slot 452 formed in the control arm 408. The curved guidance
member
444 is disposed so that it is in contact with the guide wheel 440. For
instance, the curved
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guidance member 444 may be disposed in the slot 452 in the control arm and may
be
mounted on the underside of the upper platform 104. As the control arm 408 is
rotated
about the attachment point 428, the guidance wheel 440 moves along an edge 442
of the
curved guidance member 444. A number of discrete set positions are defined for
the
rotatable arm 408 by a number of detents 504 (see Figs. 5-7) associated with
the forward
edge 442 of the curved guidance member 444. In particular, as the control arm
404 is
moved such that the guide wheel 440 reaches a defined control position, the
guide wheel
440 is drawn into the particular detent 504 to provide a set point for the
control arm 408.
More particularly, the guide wheel 440 is biased by a guide wheel spring 448.
As a result,
a force is required to dislodge the guide wheel 440 from a detent 504 in the
curved guide
member edge 444. In this way, a number of tangible set positions is
established for the
control arm 408. Moreover, because any one of these operating modes provided
by the
mobile supply cart can be selected using the control arm 408, the control arm
408 is part
of a single selection mechanism that can also include the guidance wheel 440,
guidance
member 444, the short lever 412, the long lever 416, The Bowden cables 420,
424 and
other associated components.
In embodiments of the present invention that include a tracking wheel 308, the
mobile support cart 100 may include three modes. In a "stop" mode, the mobile
support
cart 100 is prevented from moving freely. In a "walk" mode, the mobile support
cart 100
is allowed to move, but the tracking wheel 308 prevents or inhibits lateral
movement, to
provide guided or tracked movement. In a "roll" mode, the mobile support cart
100 is
allowed to move freely. As shown in Figs. 5-7, first, second and third detents
504a-c may
be associated with the curved guidance member 444 to provide three set points
for the
control arm 408 that set the mobile support cart 100 in the three modes. These
three
modes are described in connection with Figs. 5-7, which each show one of the
three
positions of the transmission system 404.
In Fig. 5, the control arm 408 has been moved into a position that engages the
short lever 412 such that the short lever 412 has been moved from the short
lever's first
position to the short lever's second position and leaves the long lever 416 in
the long
lever's first position. Here, the cart is in a "stop" mode. In particular, as
the short lever
412 rotates, it retracts and applies a tensile force to the inner cable of the
brake cables 420.
This causes a braking mechanism associated with each castor 304 to engage.
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Additionally, in the "stop" mode the tracking wheel 308 is not retracted. In
the "stop"
mode the guidance wheel 440 is located in the first detent 504a.
In Fig. 6, the control arm 408 is moved into a neutral position that leaves
both the
short lever 412 and the long lever 416 unaffected such that they are in the
first or vertical
positions to which they are normally biased. Here, the cart is in a "walk"
mode. In
particular, the braking mechanisms associated with the castors 304 are not
engaged and
the tracking wheel 308 is not retracted. Accordingly, the tracking wheel 308
is engaged
with the floor or underlying surface under the action of the spring 232. In
this position,
the tracking wheel 308 operates to provide tracked movement of the mobile
support cart
100. In the "walk" mode the guidance wheel 440 is located in the second detent
504b.
In Fig. 7, the control arm 408 is moved into a position that engages the long
lever
416 such that the long lever is moved to a second position of that lever and
leaves the
short lever 412 in the first position of that lever. Here, the cart is in a
"roll" mode. In
particular, as the long lever 416 rotates, it applies tension to and retracts
the lift cable 424.
This causes the tracking wheel 308 to be retracted against the action of the
spring 232 such
that the tracking wheel is lifted and is disengaged from the support surface
or floor. With
the tracking wheel 308 disengaged from the floor, the mobile support cart 100
is allowed
to roll freely. In the "roll" mode the guidance wheel 440 is located in the
third detent
504c.
Figs. 8-10 illustrate an exemplary castor wheel 304 assembly 812 that includes
a
braking mechanism 804 in accordance with embodiments of the present invention.
The
braking mechanism 804 is used to brake an associated castor wheel 812 in such
a way that
the castor 812 maintains the freedom to swivel 360 degrees. The castor wheel
assembly
812 includes a wheel 306 mounted to a bracket or fork 816. The wheel 304
together with
the bracket 816 is interconnected to a mounting plate 820 by a swivel or
bearing to allow
the wheel 304 and bracket 316 to swivel. The braking mechanism 804 features a
brake
cable 420 operatively associated with a brake arm 824. The brake cable 420 may
comprise a Bowden cable having a flexible inner cable within a hollow outer
housing.
The brake cable 420 passes through a central hole located in the mounting
plate 820 and
through an open area formed in an area corresponding to and encompassing an
axis of
rotation of the bearing. The mounting plate 820 may include a plurality of
mounting
points 822 (see Fig. 10), and an area generally between at least some of the
plurality of
mounting points 822 defines an area through which the axis of rotation R
passes. In
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accordance with embodiments of the present invention, the mounting points 822
comprise
holes through which fasteners may be received or passed through the mounting
plate 820.
The brake arm 824 is pivotally mounted to the bracket 816. A biasing member
such as a
spring 828 normally biases the brake arm 824 to a position disengaged from the
castor
wheel 304. A user may engage the braking mechanism 804 by actuating an
associated
control mechanism, such as the transmission system 404, which is disclosed
herein.
Alternatively, the braking mechanism 804 may be controlled by other control
mechanisms
or actuators, such as a handgrip lever brake. An actuation of the associated
control
mechanism places the inner cable of the brake cable in tension and causes the
inner cable
of the brake cable 420 to retract such that the end of the brake arm 824 to
which the inner
cable is attached is drawn towards the mounting plate 820. The inner cable
acts against
the bias of the spring 828 causing the end of the brake arm 824 opposite the
end attached
to the inner cable to pivot into engagement with the wheel 306. The inner
cable of the
brake cable 420 passes through the mounting plate 820 along an axis R, about
which the
wheel 306 and bracket 816 swivels. This orientation of the brake cable 420
allows the
braking mechanism 804 to engage at any point in the 360-degree swivel motion
of the
wheel 306 and bracket 816 around the axis R. In addition, the freedom of the
wheel 308
and the bracket 816 to swivel relative to the mounting plate 820 is not
inhibited or limited
by the braking mechanism 804.
Fig. 11 is an enlarged view of a braking mechanism 804, in accordance with
embodiments of the present invention. The braking mechanism 804, shown in Fig.
11
includes an insert member or ferrule 1100 that operates to maintain the
alignment of the
brake cable 420. In particular, the portion of the brake cable 420 that passes
through the
mounting plate 820 is maintained in alignment with the axis of rotation R of
the castor
wheel 304 and bracket 816. More particularly, the location of the end of the
brake cable
420 housing remains fixed with respect to the plate 824, as the castor wheel
304 and
bracket 816 rotates with respect to the mounting plate 820. The brake arm 824
is
interconnected to the inner cable 1102 of the brake cable 420 through a swivel
1104 that
allows the brake arm 824 to rotate with respect to the brake cable 420. Both
the insert
member 1100 and the swivel 1104 may include a thrust bearing 1108 that
facilitates the
interconnection of the brake cable 420 to the castor 812. The insert member
1100 may be
held in place by a retention nut 1112. A contact area or brake pad 1116 may be
disposed
on the end of the brake arm 824 for engagement with the castor wheel 304. In
accordance
CA 02700907 2010-03-25
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with embodiments of the present invention, the brake pad 1116 comprises a
rubber stop.
A castor wheel assembly 812 may be manufactured with the various parts
described in
connection with Fig. 11, including the insert member 1100, the swivel 1104 and
the brake
arm 1108. Alternatively, one or more of these parts may be machined for
incorporation
with an existing plate castor.
Fig. 12 is a flow chart showing the steps in a method of braking a castor, in
accordance with embodiments of the present invention. Initially, at step 1200
a first
portion of a brake cable 420 is disposed in a substantial coaxial alignment
with an axis R
about which a wheel mount or bracket 820 swivels. At step 1204, the brake
cable 420 is
tensioned. At step 1208, as a result of the tensioning the brake cable 420, a
brake arm 824
is rotated about a pivoted attachment point. At step 1212, as a result of the
rotation of the
brake arm 824, an end of the brake arm 824 is brought into engagement with the
wheel
306, to thereby brake to wheel 306.
Fig. 13 is a state diagram depicting the different states in which a mobile
support
cart 100 having a transmission system 404 in accordance with embodiments of
the present
invention can be placed. When the transmission system 404 is placed in a
"stop" position
1304, the mobile support cart 100 is in the "stop" mode 1308, with the castor
brake
mechanisms or braking mechanisms 804 applied, and with the support surface or
floor
engaged by the tracking wheel 308. In accordance with embodiments of the
present
invention, the transmission system 404 is placed in the "stop" position by
moving a handle
432 or 436 of the control arm 408 into a position marked on the upper surface
of the upper
platform 104 as corresponding to the stop mode.
In accordance with embodiments of the present invention, the transmission
system
404 can be moved from the "stop" mode 1308 to a "walk" mode 1316 by moving the
control arm 408 from the "stop" position to the "walk" position. In the "walk"
mode
1316, the castor brake mechanisms 804 are released, and the support surface or
floor is
engaged by the tracking wheel 306.
From the "walk" mode 1316, the transmission system 404 can be placed in a roll
position 1320. Placing the transmission system 404 in the "roll" position 1320
can include
moving a handle 432 or 436 of the control arm 408 to a position marked on the
top surface
of the upper platform 104 as corresponding to the "roll" mode 1324. In the
"roll" mode
1324, the braking mechanisms 804 are released, and the tracking wheel 306 is
disengaged
from the support surface.
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In accordance with embodiments of the present invention, from the "roll" mode
1324, the transmission system 404 can be placed back into the "walk" position
1312b, to
place the mobile support cart 100 in the "walk" mode 1316. Therefore, it can
be
appreciated that at least some embodiments of a mobile support cart 100 in
accordance
with the present invention require that the "walk" mode 1316 be entered, at
least
momentarily, when switching from any of the other modes 1308 or 1324. However,
other
embodiments of the present invention are not limited in this way.
Although particular examples and embodiments of a mobile support cart 100 in
accordance with embodiments of the present invention have been described
herein,
variations of the mobile support cart 100 are possible, and are within the
scope of the
present invention. For example, the transmission system 404 is not necessarily
limited to
an arrangement comprising short and long arms 412, 416 and cable actuated
control of the
braking mechanisms 804 and of the tracking wheel 308. For example, push rods
and/or
screw type members may be used to transfer control inputs from a control arm
408 to the
braking mechanisms 804 and/or the tracking wheel 308. In addition, although
certain
exemplary embodiments have featured braking assemblies 804 that are biased
towards a
disengaged position, other embodiments of the present invention may
incorporate braking
mechanisms 804 that are biased towards an engaged position. According to such
embodiments, in a "walk" 1316 or "roll" 1324 mode, the transmission system 404
would
be operated to act against the bias, while in the "stop" mode 1308 the
transmission system
404 would be operated to release the braking mechanisms 804 such that the
biasing
member was free to place the contact area or brake pad into contact with the
castor wheels
304. The position of the tracking wheel 308 may, according to embodiments of
the
present invention, be biased towards a raised position, although biasing the
tracking wheel
308 towards a lowered or engaged position can be advantageous where the
support surface
is uneven. As yet another variation, embodiments of the present invention may
feature a
control arm 408 that is turned or rotated by a user to select the desired mode
1308, 1316 or
1324. According to such embodiments, the control arm 408 may be associated
with cams
or lifters to control the positions of the braking mechanisms 804 and the
tracking wheel
306.
The foregoing discussion of the invention has been presented for purposes of
illustration and description. Further, the description is not intended to
limit the invention
to the form disclosed herein. Consequently, variations and modifications
commensurate
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CA 02700907 2012-10-23
with the above teachings within the skill or knowledge of the relevant art are
within the scope
of the present invention. The embodiments described herein above are further
intended to
explain the best mode presently known of practicing the invention and to
enable others skilled
in the art to utilize the invention in such or in other embodiments and with
various
modifications required by the particular application or use of the invention.
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