Abstrict A castor control assembly for an adjustable bed includes a linkage
mechanism having rigid link elements, and a single pedal actuator.
The pedal may be actuated from the control station to shift the
linkage mechanism and operate individual castors for selection of
swivel, locking and steering modes, as desired.
Claims What is claimed is:
1. In an adjustable hospital bed having head, foot and side members,
a plurality of cam-operated castors supporting said members, and
an assembly for controlling operation of said castors; the improvement
wherein said assembly comprises an actuator movable selectively
to swivel, locking and steering positions, said actuator being a
pedal pivotably supported adjacent said foot member, whereby the
castors may be selectively actuated from a control station at the
foot of the bed, a linkage mechanism having rigid elements operatively
engaged with said actuator and at least two of said castors and
including a series of links, connecting rods and rotatable shafts,
at least one of said castors including a first cam for operation
thereof selectively by a first rotatable shaft to swivel, locking
and steering modes in response to movement of said actuator to its
swivel, locking and steering positions, and at least one other of
said castors including a second cam for operation thereof selectively
by a second rotatable shaft to swivel and locking modes in response
to movement of said actuator to its swivel and locking positions
and retention thereof in said swivel mode in response to movement
of said actuator to its steering position, said one castor supporting
a corner of the bed formed by said foot member and a side member,
and said other castor supporting a corner of the bed formed by said
head member and a side member, said corners being diagonally opposed.
2. In an adjustable bed having head, foot and side members, a plurality
of camoperated castors supporting said members, and an assembly
for controlling operation of said castors; the improvement wherein
said assembly comprises an actuator movable selectively to swivel,
locking and steering positions, said actuator being a pedal pivotably
supported adjacent said foot member, whereby the castors may be
selectively actuated from a control station at the foot of the bed,
a linkage mechanism having rigid elements operatively engaged with
said actuator and two of said castors positioned at diagonally opposed
corners of said bed, one of said castors including a first cam for
operation thereof selectively to swivel, locking and steering modes
in response to movement of said actuator to its swivel, locking
and steering positions, and the other of said castors including
a second cam for operation thereof selectively to swivel and locking
modes in response to movement of said actuator to its swivel and
locking positions and retention thereof in said swivel mode in response
to movement of said actuator to its steering position, said linkage
mechanism including first and second shafts, said first and second
shafts respectively engaged with said first and second cams for
operation thereof, first and second link elements respectively engaged
with said first and second shafts for operation thereof, a connecting
rod engaged with said link elements, said shafts extending in opposite
directions from said connecting rod and a tie rod engaged with said
connecting rod and said pedal, whereby actuation of said pedal moves
said connecting rod and thereby rotates the shafts through the link
elements to select the modes of said castors.
3. The invention of claim 2 said one side member, first and second
links and connecting rod forming parallelogram linkage pivotable
about the axes of said first and second shafts for rotation thereof,
said parallelogram linkage being pivotable by said tie rod in response
to pivoting of said pedal to thereby select said modes of said castors.
Description BACKGROUND OF THE INVENTION
This invention relates generally to controlling the movement of
adjustable beds. More particularly, it relates to an improved assembly
for controlling the castors associated with a hospital bed.
In a hospital enviornment, it is necessary for a bed to be provided
with multiple functional capabilities. Such a bed must be free to
swivel so as to be readily positionable; must be lockable so as
to prevent movement thereof, and must be steerable for effective
patient transport. Suitable castors are available for providing
these functions. The control of such castors, however, is in need
of improvement.
In the past, a typical assembly for controlling the castors associated
with a hospital bed incorporated separate operators for each individual
castor, which operators included pedals located at the sides of
the bed. This required that an attendant leave the control station,
which generally is at the foot of the bed, in order to use the assembly.
Such an assembly also incorporated cables associated with the pedals.
These cables could come out of adjustment, resulting in improper
function.
There remains a need in the art to provide a simple, inexpensive,
efficient, long-wearing assembly for controlling the castors associated
with a hospital bed. The assembly preferably should be located at
or adjacent the control station at the foot of the bed, and should
not be capable of easily coming out of adjustment.
SUMMARY OF THE INVENTION
The primary object of this invention is to meet the needs noted
above. To that end, there is provided a pedal-actuated linkage mechanism
which constitutes a control assembly for establishing the various
functional modes necessary for a hospital bed. The pedal is located
at the control station so that an attendant may easily select the
mode desired. The linkage mechanism incorporates rigid link elements
associated with selected cam actuators for associated castors.
The pedal is selectively movable to swivel, locking and steering
positions. Pedal movement shifts the linkage mechanism, and selected
cams are rotated thereby in such a manner that the castors establish
the desired functional modes. The linkage mechanism incorporates
rigid link elements to ensure that the assembly cannot come out
of adjustment and cause improper functional selection.
The result is a simple, inexpensive, efficient, long-wearing assembly
for controlling the castors associated with a hospital bed.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and advantages of this invention will become apparent
to those skilled in the art upon careful consideration of the specification
herein, including the drawings, wherein:
FIG. 1 is an elevational view of the lower frame of a hospital
bed showing the arrangement of the castors and control assembly;
FIG. 2 is a plan view of the frame, castors and control assembly
shown in FIG. 1;
FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2
showing details of the pedal and linkage mechanism;
FIG. 4 is a sectional view taken along the line 4--4 of FIG. 3
showing additional details of the pedal and linkage mechanism;
FIG. 5 is a sectional view taken along the line 5--5 of FIG. 2
showing additional details of the linkage mechanism;
FIG. 6 is a sectional view taken along the line 6--6 of FIG. 2
showing additional details of the linkage mechanism;
FIG. 7 is a detail view showing one of the castor and cam arrangements;
and
FIG. 8 is a detail view showing another of the castor and cam arrangements.
While this invention is susceptible of embodiment in many different
forms, there is shown in the drawings and herein will be described
in detail a preferred embodiment. It should be understood that the
present disclosure is considered to be an exemplification of the
principles of the invention, and is not intended to limit the invention
to this embodiment.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawings in greater detail, there is shown
generally a portion of a typical hospital bed 10. Bed 10 includes
a lower frame 12 having a head member 14 a foot member 16 and first
and second side members 18 and 20 joining members 14 and 16.
Castors 22 24 26 and 28 are mounted at the corners of lower frame
12 with each castor supporting one end of a side member 18 or 20
adjacaent an associated head member 14 or foot member 16. Each castor
includes a wheel 30.
In a preferred form of the invention, foot castor 22 includes a
movable plunger 32 and a first cam 34. Plunger 32 is movable from
a first, intermediate swivel position to a second, lower locking
position in which wheel 30 is locked, and to a third, upper steering
position in which wheel 30 can roll but castor 22 cannot swivel.
Cam 34 has three lobes. With a three-lobed cam, rotation thereof
moves plunger 32 selectively to its first, second and third positions
to establish respectively the swivel, locking and steering modes.
Similarly, head castor 28 includes a movable plunger 36 and a second
cam 38. Plunger 36 is movable as is plunger 32. However, cam 38
has two lobes. With a two-lobed cam, rotation thereof moves plunger
36 selectively to its first and second positions to establish respectively
the swivel and locking modes. Rotation of the two-lobed cam to what
normally would be the third position has no effect on plunger 36.
Rather, the cam configuration is such that plunger 36 remains in
its first position and castor 28 remains in the swivel mode.
Castors of this type and their associated cams are commercially
available, and need not be described further in detail.
A control assembly 40 is provided for rotating cams 34 and 38 so
as to place castors 22 and 28 in the swivel, locking and steering
modes, as desired.
Assembly 40 includes a bracket 42 secured to foot member 16 and
extending inwardly in a direction generally parallel to side member
18. Similarly, a bracket 44 is secured to foot member 16 and extends
outwardly therefrom at the control station. In a preferred form
of the invention, bracket 44 is located adjacent side member 18
and extends generally parallel thereto.
An actuator in the form of a foot pedal 46 or the like is pivoted
to bracket 44. Pedal 46 includes a heel portion 48 and a toe portion
50. Pedal 46 may be pivoted clockwise, as shown in FIG. 3 by the
application of pressure to heel portion 48. Similarly, pedal 46
may be pivoted counterclockwise by the application of pressure to
toe portion 50. This may be accomplished by an attendant without
leaving the control station.
A tie rod element 52 is pivoted to toe portion 50 of pedal 46.
Tie rod 52 extends through a convenient opening in foot member 16.
A first link element 54 is pivoted at one end to tie rod 52. The
other end of link 54 is rigidly secured to a first shaft element
56 which in turn is suitably journalled at 58 for rotation relative
to bracket 42. In a preferred form of the invention, shaft 56 is
of polygonal configuration, and is engaged in a corresponding polygonal
opening in cam 34.
Thus, it will be seen that pivotal movement of pedal 46 shifts
tie rod 52 and link 54 which in turn rotates shaft 56 such that
cam 34 is rotated. Pedal 46 may be pivoted selectively to swivel,
locking and steering positions corresponding to the swivel, locking
and steering modes of castor 22.
A connecting rod element 60 extends generally parallel to side
member 18 and is pivoted at one end to tie rod 52. The other end
of connecting rod 60 is pivoted to a second link element 62. In
turn, link 62 is rigidly secured to a second shaft element 64 which
is journalled by a suitable bearing 66 in a bracket 68. Bracket
68 is secured to head member 14 and extends inwardly generally parallel
to side member 18.
Side member 18 connecting rod 60 and links 54 and 62 form parallelogram
linkage pivotable about the axes of shafts 56 and 64 to thereby
rotate the shafts.
Shaft 64 extends generally parallel to head member 14 into engagement
with cam 38. Actuation of castor 28 is the same as that of castor
22 described above. Shaft 64 preferably is of polygonal configuration
so as to conform to the polygonal opening in cam 38.
In a preferred form of the invention, castor 22 is provided with
a cam 34 having three lobes, and thus is shiftable to swivel, locking
and steering modes. Castor 28 is provided with a cam 38 having two
lobes, and thus is shiftable with castor 22 to swivel and locking
modes. Castor 28 remains in the swivel mode when assembly 40 is
actuated to shift castor 22 to the steering mode.
As shown in FIG. 3 pedal 46 is in the swivel position. Assembly
40 is oriented such that cams 34 and 38 place castors 22 and 28
in the swivel mode. In this mode, bed 10 may be moved easily in
any direction.
Clockwise pivoting of pedal 46 shifts assembly 40 such that cams
34 and 38 place castors 22 and 28 in the locking mode. They may
not swivel, nor may wheels 30 roll. In this mode, bed 10 may not
be moved.
Pivoting of pedal 46 counterclockwise shifts assembly 40 in the
opposite direction such that castor 22 is placed in the steering
mode, wherein it may not swivel but wheel 30 is free to roll. At
the same time, castor 28 remains in the swivel mode. In this mode,
an attendant may move bed 10 while steering it, so as to transport
a patient. In this regard, an attendant typically pushes bed 10
from head member 14.
In a preferred form of the invention, diagonally opposed casters
22 and 28 are subject to control by assembly 40. Similarly, the
opposite diagonally opposed casters 24 and 26 are free and remain
in the swivel mode. It should be understood, however, that the number
and orientation of castors subject to control by assembly 40 is
a matter of choice.
It should be apparent to those skilled in the art that there is
disclosed herein an improved assembly for controlling the castors
associated with a hospital bed, which assembly may be actuated easily
by an attendant at the control station. The assembly is comprised
of rigid linkage, and thus may not come out of adjustment. It is
simple, inexpensive, efficient and long-wearing, and may be serviced
easily in the field.
It is not intended that the present invention be restricted in
its application to the hospital bed shown herein by way of example.
It is contemplated that the invention will be utilized in a wide
variety of applications in which it is desirable to control castors
associated with a frame.
It should be understood that while a preferred embodiment of the
invention has been shown and described, this is to be considered
as illustrative and may be modified by those skilled in the art.
It is intended that the claims herein cover all such modifications
as may fall within the spirit and scope of the invention. |