Invalid transfer arrangement

Apparatus used in conjunction with a bed and having rollers and a transfer sheet to transport a patient over the bed and partially onto a horizontal seat of a wheelchair. The patient is then raised to a normal seated position, without requiring any effort on the part of the patient. The patient can also be transported to a sitting position at the end of the bed, or to a standing position on the floor. The apparatus is arranged for installation on existing hospital or home-type beds so that a patient can be comfortably transported to a seated position on a wheelchair, commode, surface, or to a seated or standing position at the end of the bed.

The process of transferring an invalid person from a bed to a wheelchair, 
to a commode, to a toilet, or to a standing position, or assisting such a 
person in such a transfer, often involves more than one person to assist, 
is labor intensive and consequently can be costly. The task frequently 
requires considerable strength and is a common source of injury to the 
person being transferred or to the nurse(s) or attendant(s) doing the 
transfer. These problems often are the major factors that require a person 
to be hospitalized or moved to a nursing home, rather than being cared for 
at home. They also increase the cost of caring for persons in hospitals 
and nursing homes. 
Even when a patient is not seriously disabled and may be capable of 
walking, once he is standing, he may have great difficulty and may require 
assistance in getting in and out of bed and in getting from a bed to a 
wheelchair. The patient may also require assistance in reaching a sitting 
position at the side or end of the bed. The parent application describes 
an arrangement for transferring an invalid person from a bed to a separate 
horizontal surface by means of a sheet which was pulled over the surface 
of the mattress by being rolled up on a roller at the foot of the bed and 
unrolled from a roller at the head of the bed. 
Accordingly, it is the primary object of the present invention to provide 
additional apparatus on a bed equipped with rollers and a transfer sheet, 
and on an associated wheelchair, so that a patient can be comfortably 
transported over the bed and partially onto the horizontal seat of the 
wheelchair and then raised to a normal seated position thereon, with no 
effort on the part of the invalid person. Minimal physical strength or 
skill on the part of an attendant is to be required according to the 
present invention. 
It is another objective of the present invention to provide means for 
comfortably transporting an invalid person in a similar manner to a 
sitting position at the end of the bed or to a standing position on the 
floor, with little or no effort on the part of the person and requiring 
only moderate physical strength or skill from an attendant. 
It is still another object of the present invention to provide apparatus 
which can be installed on existing hospital or home-type beds so that a 
person can be comfortably transported to a seated position on a 
wheelchair, commode, surface, or apparatus, or to a seated or standing 
position at the end of a bed. 
Additional objects and advantages of the present invention will become 
evident from the following description of specific embodiments when read 
in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1a through 1f schematically illustrate the principles used to 
transport a person 1 from a bed 2 to a wheelchair 3. 
The bed 2 consists of a conventional bed 4 as found in a home or 
institution such as a hospital or nursing home with modifications to be 
described. An elevating device 5, either manual or power driven, as is 
found on hospital type and some home beds, is used to raise or lower the 
bed 2 to the proper height to perform the required operations. 
Alternatively, a conventional home bed may be blocked up to the proper 
height and left there for the duration of the patient's use. 
Also attached to the bed 4 is an arrangement for transporting a person 1 
from a postion on the bed to and beyond the edge of the bed. 
This arrangement contains a foot-end roller 6 (shown in FIG. 1a) whose 
length is approximately equal to the width of the bed, and which is 
mounted to the bed frame at the foot-end of the bed. A similar head-end 
roller 7 is positioned at the head-end of the bed. (Head and foot are 
described from the patient's point of view.) A specially designed bed 
sheet 39, approximately equal in width to the width of the bed and 
significantly longer than the bed, is fastened to and partially rolled up 
on the head-end roller 7 while the other end is fastened to the foot-end 
roller 6 at the foot-end of the bed. 
It is generally desirable to keep the length of the modified bed 2 as short 
as possible. For this reason, although not a requirement of this 
invention, the rollers 6 and 7 are shown located under the main bed frame 
members 11. To ease the transport of the sheet 39 over the mattress 32, a 
foot-end corner roller 8 and head-end corner roller 9 are mounted to the 
bed frame 11. These rollers 8 and 9 are preferably constructed with stiff 
cores covered with soft material. The tops of these rollers are 
approximately level with the top surface of the mattress 32. 
Mechanical power for driving the two rollers to wind up the sheet on one 
roller while allowing it to unwind from the other so as to move the sheet 
over the surface of the mattress and to transport a reclining person from 
a position on the bed 2 to and beyond the end of the bed, is provided from 
electric motor drives or hand cranks as described subsequently. 
This particular arrangement of rollers is shown to help illustrate the 
principles of this invention, but the invention is not limited to this 
configuration, and other arrangements for moving a sheet across a bed to 
transport a person over the bed can be used equally well. Some of these 
are described subsequently. 
The wheelchair 3 consists of the elements normally found on a conventional 
wheelchair: a seating area 12, a backrest 13, and a leg rest 14, all 
attached to a frame 15. The whole assembly is supported on wheels 16. The 
wheels 16 are depicted as small and of approximately equal size, but, as 
in conventional chairs in the art, either pair may be castered or fixed, 
or either the front or rear pair may be large with fixed axles and the 
other pair castered. Although not a requirement of this invention, a leg 
rest 14, which can be raised and lowered by conventional means well known 
in the art, can be used. If used, it should preferably have a full leg or 
calf support and adjustable foot plates. 
For the present invention, the top of the wheelchair backrest 13 can be 
moved from the normal position shown in FIG. 1a, to a position flush with 
or below the level of the seat as indicated in FIG. 1b. 
A latch 113 is mounted to bed 2. As chair 3 moves toward bed 2, as shown in 
sequence in FIGS. 1a to 1b, axle rod 116 on chair 3 will strike the front 
face 117 of latch 113 causing it to pivot counter-clockwise about axle rod 
118 in support 114. As the chair 3 moves further, spring 115 between 
support 114 and latch 113 will cause latch 113 to pivot clockwise. This 
locks rod 116 and thereby holds chair 3 in position for transferring a 
person, as shown in FIG. 1b. At the conclusion of the transfer, the latch 
113 may be manually lifted to allow the chair 3 to be moved away from the 
bed 2. Alternatively, other latching or fastening means well-known in the 
art can be used. For simplicity, the latching mechanism is omitted from 
most of the remaining drawings in this disclosure. 
The wheelchair 3 is shown in FIG. 1b locked in position at the foot-end of 
the bed 2 and in line with the person 1. The foot rest 14 has been raised 
by conventional methods and the backrest 13 lowered by means to be shown. 
The height of the bed 2 is adjusted by use of the elevating mechanism 5 or 
other arrangement so as to place the top of the mattress 32 approximately 
level with the height of the chair seat 12. 
When roller 6 is driven in a clockwise direction, in a manner to be 
described, sheet 39 unwinds from roller 7 and moves to the right over the 
surface of mattress 32, carrying person 1 also to the right as depicted in 
FIG. 1c. When the person 1 has reached the position approximately as shown 
in FIG. 1c, the movement of roller 6 halts. At this point, the person 1 is 
resting partly on the wheelchair 3 and partly on the bed 2 and is ready to 
be lifted to a sitting position on the wheelchair 3. 
As shown in FIGS. 1c and 1d, the bed 2 is equipped with two parallel lift 
arms 19, one on each side of the bed, pivoted about a common axis 76. Each 
lift arm 19 is equipped with sheet support means, described subsequently, 
and an optional clamp 75 each of which, if used, is now tightened to 
securely grasp the edge of sheet 39. The lift arms are then driven 
together clockwise, as shown in FIG. 1d, to an essentially vertical 
position by a lift drive mechanism, to be described. The sheet 39, 
supported by the lift arms 19 is stretched between them and so lifts the 
person 1 to a sitting position. The legs 18 of the person 1 may also be 
lowered by releasing the foot support 14. As the lift arms 19 are raised, 
sheet 39 unwinds from roller 7 to provide the required slack. 
In FIG. 1e, the backrest 13 is raised, by means to be shown, between the 
person's back 17 and the sheet 39 which is supported by the lift arms 19, 
and thereby fully completing the transfer of the person 1 to the chair 3. 
The chair 3 may now be unlatched and moved, as required, with the person 1 
thereon as indicated in FIG. 1f. 
FIG. 2 is a simplified partial perspective view of the invalid transfer 
arrangement with a wheelchair 3 in position to receive a person, not 
shown, from bed 2. 
A sheet 39 with thickened edges 39a and 39b is pulled over the mattress 32 
and corner roller 8, by take-up roller 6 to which it is fastened. The 
supporting structure and means for driving these items, described 
subsequently, are omitted from FIG. 2 for clarity. 
To aid in guiding the sheet 39, guidance members 44a and 44b, as also shown 
in FIG. 6, contain large internal grooves 61a and 61b through which the 
thickened edges 39a and 39b of sheet 39 slide freely and in which they are 
confined by the narrow outer portions or slits 62a and 62b. Through these 
slits only the thin body of the sheet 39 can slide, thereby guiding the 
sheet in its motion over the bed. 
The guidance members 44a and 44b are fastened to and extend along lifting 
arms 19a and 19b, to guide the sheet over the bed and to support it when 
the lift arms are raised. Similar, but much shorter fixed guidance members 
(not shown) are mounted to the roller supporting structure near the 
head-end of the bed to guide the sheet over the head-end corner roller 
(not shown). 
Initially, the supine person is transported so that the lower part of his 
body is on the wheelchair 3. Then the lift arms 19a and 19b are rotated 
about the axis of roller 8, as described subsequently, to raise sheet 39 
and thereby the person's upper body resting thereon to an essentially 
vertical position, previously illustrated in FIG. 1d. 
At this point, foot latch 65 may be released and foot rest 66 may be 
lowered. 
To complete the transfer, the chair back rest assembly 67 is raised by 
rotating crank and shaft 68 on which two pinions (not shown) engage and 
drive up rack teeth on each vertical member of back frame 20, slidably 
mounted on wheelchair frame 15. When raised, the back is locked into 
position by means not shown. 
FIG. 3a is a schematic side view showing one design concept of the 
wheelchair back, when in its elevated position, between raised bed sheet 
39 and the person's back 17. As shown in FIG. 2 and in schematic drawing 
FIG. 3a, the surface of back rest 67 comprises an endless belt 22 which 
passes around and is supported by rollers 21a and 21b, which are rotatably 
mounted to the top and bottom of frame 20, respectively. FIG. 3a shows the 
front side of belt 22 firmly attached to the fixed chair frame 15 at point 
71, so that belt 22 cannot slide along the person's back 17. As frame 
member 20 is driven upward, the rear portion of belt 22 progressively 
passes over roller 21a and moves into a position behind and with no 
relative sliding motion along the person's back 17. The wheelchair back is 
locked in its top position by means not shown. 
Another method of achieving the same result is shown schematically in FIG. 
3b, and in perspective in FIG. 4a, where the wheelchair's back is lowered. 
In a partial perspective view, FIG. 4b shows the wheelchair with the back 
raised to a normal position. The upper end of frame member 27 supports 
roller 29, which is analagous to a conventional window shade, in that a 
belt of flexible material 28 attached to the roller, is wound up around it 
by action of a spring or other means (not shown). The other end of belt 28 
is fastened to the chair frame 15 at point 70 (shown only in FIG. 3b). 
Rotating shaft 73, as shown by arrow 74 (FIG. 4b only), rotates pinion 
gears (not shown) engaging racks 77 which are part of frame member 27 to 
drive it up as indicated by arrow 30. As frame member 27 rises, belt 28 
unrolls from roller 29 and moves into position against the person's upper 
back 17 (as seen in FIG. 3b) with no rubbing or relative motion to cause 
discomfort or injury. When the frame 27 has been driven up to its full 
height, the belt 28 will have been unrolled and stretched tautly between 
the roller 29 and chair frame 15 so as to support a sitting person. It is 
then locked, by means not shown. Alternatively, a simple back with a fixed 
surface supported on a raisable frame may be used. 
FIGS. 5, 6 and 7 are partial cross-sectional side elevation, end elevation 
and plan views of the foot-end of the bed, showing the arrangement of the 
transport and lift arm mechanisms. The conventional hospital type bed 
consists of an elevating mechanism 5 supporting a fixed frame 11 to which 
an articulated frame 33 is attached, and on top of which is the mattress 
32. All of this is supported by castered wheels 40. Supporting the lifting 
and transport mechanisms are left and right (as seen from a patient's 
position in bed) side plates 34a and 34b connected by cross member 51 and 
suitably attached through supporting spacer blocks 35a and 35b to bed 
frame member 11. 
Supported between side plates 34a and 34b by bearings, not shown, is takeup 
roller 6. As shown in FIGS. 6 and 7, and in FIG. 5, which is a side 
elevation view of the bed with a partial section taken through the lifting 
and driving mechanism to show details of operation, roller 6 is driven by 
motor drive 37. The latter is a reversible motor with speed reducer and 
optional clutch, through pulley 38a, belt 112, and pulley 38b which is 
firmly attached to take-up roller 6. The motor drive 37 is fastened to 
frame member 11 by adjustable bracke 119. 
Sheet 39, which is wrapped around and fastened to roller 6, passes over 
corner roller 8, through guidance members 44a and 44b, over the mattress 
32 to the other end of the bed, not shown, and to a similar arrangement of 
corner guidance members, corner roller and take-up roller. Corner roller 8 
rotates coaxially about axle 41 in bearings 42. Axle 41 rotates in 
bearings, not shown, in side plates 34a and 34b. Rigidly fastened to axle 
41 are lift arms 19a and 19b. These arms extend along the sides of the bed 
and on them are mounted guidance members 44a and 44b which contain 
internal grooves 61a and 61b to guide and support the thickened sheet 
edges 39a and 39b, and slits 62a and 62b through which the center portion 
of the sheet 39 slides. (For simplicity, the thickened edge 39a of sheet 
39 is not shown in side view FIG. 5, and sheet 39 is indicated by a single 
line.) 
On the arms 19a and 19b and concentric with axle 41, are gear segments 45a 
and 45b. The gear segments 45a and 45b mesh, respectively, with pinions 
46a and 46b. These pinions are on a common shaft 47 supported by bearings 
(not shown) in sideplates 34a and 34b. This shaft 47 has an attached worm 
gear 48 in mesh with worm 49, which is driven by motor drive 50, mounted 
on sideplate 34a, to raise the lift arms. 
To transport a person to the right in FIG. 5, as previously illustrated in 
FIG. 1c, foot-end motor drive 37 rotates roller 6 in a clockwise direction 
to pull sheet 39 across the bed, while the head-end motor/clutch drive 
pays out the sheet or allows it to be drawn out at the head end of the 
bed, not shown in FIGS. 5, 6, and 7. 
As the person reaches the proper location for transfer to a seated or 
standing position the motor drive 37 driving sheet 39 is stopped. At this 
point, optional over-center locks 53a and 53b are rotated as shown by 
arrow 54 to lock the sheet edges 39a and 39b in guidance members 44a and 
44b, respectively. Alternatively, these locking means may be omitted. Lift 
motor 50 is then actuated to rotate worm 49 engaging worm gear 48 on shaft 
47. To this shaft are attached gears 47 meshing with sector gears 45a and 
45b on lift arms 19a and 19b for raising these lift arms and sheet 39, so 
as to move the person to a sitting position as shown previously in FIG. 
1d, with sheet 39 being paid out from the head-end roller. 
To return the person to a supine position, or to lower the lift arms, motor 
50 is actuated to run in the opposite direction, and the motor drive 
head-end transport is actuated to take up the slack in sheet 39. 
FIG. 5a is a front view of the electrical control box 97. It connects to a 
power source through cable 122, and to both transport motor drives (only 
one of which is shown) and lift motor drive 50, through electrical cables 
102, 100 and 101, respectively. Transport controls 98a and 98b are 
spring-centered switches, normally off, which, in conjunction with logic 
and control circuitry well known in the art, actuate the transport drives 
to drive in either direction. Similarly, lift control 99 is also a 
spring-centered switch which actuates the lift drive in either direction. 
If optional electrically actuated clutches are included in the transport 
motor drives, a single such transport control switch is used to actuate 
either transport motor drive to wind up the sheet on its respective roller 
and to dis-engage the opposite-end clutch so as to allow the sheet to be 
drawn off the opposite-end roller. 
FIG. 6a is a front elevation view of parts of the bed showing an alternate 
hand-crank drive for the lift arms in place of motor drive 50 shown in 
FIGS. 5, 6, and 7. For the hand-crank embodiment of the invention, motor 
drive 50 in FIG. 6 is replaced by gear box 95 containing a socket to mate 
with hand crank 96. The latter passes through a hole in side plate 34c, 
which is otherwise identical to side plate 34a of FIG. 6. 
Similarly, hand-crank drives can be used for the transport rollers in place 
of the motor drives shown in FIGS. 5, 6, and 7. 
FIG. 8 is a schematic plan view of the bed showing another embodiment of 
the invention in which a transverse lift sheet 92 passes between transport 
bed sheet 39 and mattress 32, and is fastened to and stretched between 
lift arms 91a and 91b. Lift arms 91a and 91b are similar to lift arms 19a 
and 19b of FIG. 7, except that greatly shortened guidance members 31a and 
31b are used. In FIG. 8, these shortened guidance members 31a and 31b are 
also shown schematically at the opposite end of the bed to guide the sheet 
39 uniformly over corner roller 9. 
When lift arms 91a and 91b are rotated, as illustrated previously in FIGS. 
1d and 1e, transverse lift sheet 92 raises sheet 39 and a supine person 
thereon (not shown). This arrangement is usable with the drive mechanisms 
shown in FIGS. 5, 6, 6a and 7. 
FIG. 9 is a schematic side view of a person being transferred to a 
wheelchair. The person 1 has been raised to a seated position on 
wheelchair 3 as in FIG. 1d, except that if he is leaning forward, he will 
be supported by safety support 86, removably attached to lift arms 19. 
FIG. 10 is a schematic back view of a wheelchair 3 with a detachable back 
88 which fits into sockets with locking thumb screws 90 on frame 89. This 
wheelchair and back arrangement is another embodiment which can be used in 
place of elevating back structures, shown previously. Alternatively, the 
flexible wheelchair back surface 87 is detachable from one of two 
wheelchair back support members 84 by a zipper 85, for example. After a 
person has been transferred to the wheelchair in an upright position, the 
detachable end of the flexible back surface is re-attached to provide back 
support. 
FIG. 10a is a perspective view of the wheelchair 3 showing a further 
embodiment of this invention. The back frame 151 is attached by hinge 152 
to a frame member 153 of wheelchair 3. During transfer of a person to 
wheelchair 3, the back is folded to one side as shown. After the person is 
seated on wheelchair 3, back frame 151 is folded over to its normal 
position and secured there to frame member 153 by latch 154. The handles 
155 are rotatably attached to back frame 151, so that they can be twisted 
from their normal positions in which they extend backwards, to extend 
sidewards, as shown, in order to slide easily between the person's back 
and the support sheet behind him when he is seated as shown in FIG. 1d. 
FIG. 10b is a partial perspective view of a different arrangement of 
wheelchair 3, in which back frame member 158 fits and slides into a groove 
156 in wheelchair frame member 157. It is secured there by the manually 
rotating latch 160 which engages member 159. 
FIG. 11 is a partial schematic end view showing still another embodiment of 
the invention in which a person is raised without lifting the sheet 39. In 
this arrangement, a crossbrace 80 is removably attached to lift arms 83a 
and 83b by fasteners 81, which are shown as removable pins but which can 
have many other forms. The person 1 is attached to the lifting arms by a 
flexible lifting support 82 comprising a band of flexible material slipped 
under the person's shoulders and neck 17a and removably attached, by 
straps 82a to the crossbrace 80. Alternately, it may be attached to the 
lift arms 83a and 83b. Raising lift arms 83a and 83b lifts the person 
comfortably to a seated or a standing position. The crossbrace 80, if 
used, is preferably made stiff in order to greatly reduce the horizontal 
bending forces on the lift arms and thereby their required weight. 
FIGS. 12a through 12c are schematic sequenced views showing the transfer of 
a person to a standing position at a walker 93. 
FIG. 12a shows the person 1 recumbent on the bed 2 ready for transfer. 
FIG. 12b shows the person 1 after he has been moved to the end of the bed 
2, by the motion of the sheet 39 over the bed, as described earlier. At 
this point, with the person's feet 17b on the floor, the drive of the 
foot-end roller 6 is stopped. The invalid walker 93, equipped with knee 
brace 94, is then moved to the end of the bed, with knee brace 94 placed 
as a support for the person's knees. (Alternatively, a wheelchair or other 
device equipped with a knee brace structure can be used.) The lift drive 
mechanism is then activated to rotate the lift arms 19, which raise the 
sheet 39 and the person 1, at the end of the bed 2, to a standing 
position, as shown in FIG. 12c. The knee brace structure 94 supports the 
person's knees 17c so that they straighten instead of buckle as the person 
is moved forward and upward by the lift arms 19 and sheet 39. During this 
process, the walker 93 is preferably held fixed by an attendant or by a 
latch. To use the walker, the knee brace 94 is removed by unfastening it 
or folding it away. Alternatively, the knee brace support can be fastened 
to the front or side edge of the walker and the walker turned around so 
that the knee brace support is close to the end of the bed. After the 
person is in a standing position, the walker can be returned to its normal 
position for use by the person. 
FIG. 13 is a schematic front view of the person 1 and walker 93, showing 
the knee brace 94. 
There are known a number of methods of fabricating a thickened edge on a 
sheet. Front sectional FIGS. 14a, 14b and 14c show an additional method, 
with the associated guidance support. 
FIG. 14a shows a rope 107 or other circular or near circular flexible 
member enveloped by the edge of sheet 106 that has been folded over on 
itself, and fastened together by stitching 108 to form a thickened edge 
with a near-circular cross section 121. A similar edge is formed on the 
opposite side of the sheet 106. 
FIG. 14b shows guidance members 109, similar to members 44a and 44b in FIG. 
2, except that members 109 contain inner grooves 110 of near-circular 
cross section along which the near-circular cross-section edges 121 of 
sheet 106 fit and slide, as shown in FIG. 14c. They contain narrow outer 
slits 111 along which the body of sheet 106 can slide. Since the thickened 
edges 121 are too thick to pass through slits 111, the guidance members 
109 control the position of sheet 106 when it is pulled over the bed. They 
support the sheet when the guidance members 109 are lifted to raise a 
person. 
FIG. 15 is a schematic plan view, and FIGS. 16 and 17 are schematic side 
elevation views showing a different embodiment of the present invention 
wherein the person is raised by raising part of the mattress, which is 
divided into two sections, the head section 113a and foot section 113b. 
The division is made near the lowest joint 120 in the articulated bed 
frame member 33 so as to not interfere with the normal operation of the 
bed. A lifting member 124 consisting of a sheet of flexible material is 
fastened to both lift arms 128a and 128b, and extends between them under 
the foot section of the mattress 113b, with enough slack for the 
articulated foot section of a hospital type bed to be elevated without 
interference, during normal operation of the bed. When raised, mattress 
section 113b is supported by brace 123 attached to lift arms 128a and 
128b. 
FIG. 17 shows lift arms 128a and 128b rotated about pivot axis 76 to raise 
member 125 and mattress section 113b to a near-vertical position in such a 
way, as to raise a person to a seated position in a wheelchair or a 
standing position on the floor, as illustrated previously in FIGS. 1d and 
12c. Alternatively, a conventional mattress can be used in place of the 
divided mattress 113a and 113b. 
The lift arms 128a and 128b of FIG. 16 can be constructed in such a way, 
that they are integrated with, become part of, or replace part of the 
articulated frame 33 of the bed, and they may be driven by a screw jack as 
is commonly used in articulated hospital beds. There is no intent to limit 
the present invention to the types of lift arm and lift arm drives 
described earlier and shown in FIGS. 2, 5, 6, 7, and 8. 
FIGS. 18, 19, and 20 show an alternative transport sheet drive arrangement, 
using drive and pinch rollers, in addition to a corner roller and driven 
wind-up roller. 
To transport a person to the right as illustrated in FIG. 1c, the sheet 39 
must be moved to the right. To do this, the drive system must apply enough 
force to pull the sheet with a person thereon smoothly across the 
mattress. In addition, the sheet 39 must be wrapped or rolled up for 
storage at one end of the bed and paid out, or freely drawn off a roller, 
at the other end of the bed. When the sheet is not being driven, its 
tension should be maintained so that it is not free to unwind and bunch 
under the person, causing discomfort. 
During adjustments, such as raising the head or knee sections of a 
hospital-bed mattress, which are normally carried out, the sheet from the 
appropriate roller must be slackened to allow it to unwind and move with 
the mattress; however, when the bed adjustment has been completed, the 
sheet tension should be restored so as to support a person on the mattress 
without sliding. When the lift arms raise the person to a sitting or 
standing position, the sheet from the appropriate roller must again be 
slackened to accommodate the motion. 
FIG. 18 is a side view of the bed with partial section taken through the 
lifting and driving mechanism to show details of operation. FIG. 19 is a 
partial cross-sectional front elevation view showing the arrangement of 
the transport and lift arm mechanisms mounted on a conventional hospital 
type bed 4. Parts of the drive and lift mechanisms have been deleted from 
FIGS. 18 and 19, for clarity. FIG. 20 is a schematic perspective of the 
sheet drive only, with the rest of the bed omitted for clarity. 
As shown in FIGS. 18 and 19, the conventional hospital type bed 4 consists 
of an elevating mechanism 5 supporting a fixed frame 11 to which an 
articulated frame 33 is attached and on top of which is the mattress 32. 
All of this is supported by castered wheels 40. Supporting the lifting and 
transport mechanisms are left and right (as seen from a patient's position 
in bed) side plates 34d and 34e connected by cross members 51, and 
suitably attached through supporting brackets 35a and 35b to frame member 
11. 
Supported between side plates 34d and 34e by bearings, not shown, is 
take-up roller 6. As shown, roller 6 is driven by drive unit 125 
comprising a reversible motor 126 with speed reducer 127. Drive unit 125 
propels take-up roller 6, through pulley-clutch 129 comprising overrunning 
clutch 129b and pulley 129a, belt 130, pulley 131, and slip clutch 132. 
The drive unit 125 is fastened to frame member 11 by adjustable bracket 
133. 
Also supported between side plates 34d and 34e by bearings, not shown, are 
drive roller 134 and pinch roller 135. Drive roller 134 is also propelled 
by drive unit 125 through pulley-clutch 137 comprising overrunning clutch 
137b and pulley 137a, belt 138 and pulley 139. 
As shown in FIGS. 18, 19 and 20, sheet 39, which is wrapped around and 
fastened to storage roller 6, passes over drive roller 134 and under pinch 
roller 135. The surface layer 144 of drive roller 134 is somewhat flexible 
and has a high coefficient of friction to enable it to propel the sheet 
39, which is compressed betweeen pinch roller 135 and drive roller 134. 
The sheet 39 then passes through guidance member 140, over corner roller 
8, through guidance members 44a and 44b, over the mattress 32, to the 
other end of the bed, and to a similar arrangement of guidance members, 
corner roller, pinch and drive rollers and a take-up roller. (In FIG. 19, 
guidance member 140 is not shown for clarity.) Corner roller 8 rotates 
coaxially about axle 41 in bearings 42. Axle 41 rotates in bearings in 
side plates 34d and 34e. Rigidly fastened to axle 41 are lift arms 19a and 
19b. These arms extend along the sides of the bed 4 and mounted to them 
are guidance members 44a and 44b which contain internal grooves 61a and 
61b to guide and support the thickened sheet edges 39a and 39b, and slits 
62a and 62b through which slides the center portion of the sheet 39. 
As shown in FIGS. 18 and 19, the arms 19a and 19b include gear segments 45a 
and 45b, concentric with their axle 41. The gear segments 45a and 45b 
mesh, respectively, with pinions 46a and 46b, which are on a common shaft 
47 supported by bearings in sideplates 34d and 34e. This shaft 47 has an 
attached worm gear 48 in mesh with worm 49, which is driven by motor drive 
50, mounted on sideplate 34d, to raise or lower said lift arms. 
In FIGS. 19 and 20 are shown pulley-clutch units 129 and 137 which contain, 
respectively, overrunning clutches 129b and 137b. These units are 
commercially available and well known in the art. They may be of the 
wrapped spring, ratchet, or any other type. They are arranged in FIG. 20 
so that when the output shaft 142 from speed reducer 127 rotates 
clockwise, as shown by arrow 141, the clutches 129b and 137b drive the 
pulleys 129a and 137a respectively in a clockwise direction. If the shaft 
142 rotates counterclockwise relative to these pulleys, only negligible 
torque will be transmitted to said pulleys. In addition, the pulleys 129a 
and 137a may rotate freely clockwise relative to the shaft 142 thereby 
transmitting negligible torque to said shaft. In a counter-clockwise 
direction, however, they will be locked to and will transmit torque to 
shaft 142. 
To drive sheet 39 in the direction of arrow 143, motor 126 is actuated to 
rotate shaft 142 clockwise, which drives rollers 134 and 6 clockwise. For 
the sheet to be taken up properly on roller 6, the various drive pulley 
and roller diameters are selected so that in the absence of a sheet 39, 
the surface velocity of wind-up roller 6 exceeds that of drive roller 134. 
As a result, a sheet 39 driven by rollers 134 and 135 puts a retarding 
torque on windup roller 6 and causes clutch 132 to slip. The sheet will 
then be wound up on roller 6 with no slack, and with a tension determined 
by the slip torque setting of clutch 132. 
To lock the sheet 39 in place so that it cannot be drawn through the drive 
and pinch rollers 134 and 135, and thus off roller 6, motor 126 is 
stopped. A gear train which has high frictional resistance to back 
driving, such as a worm gear drive, is used in speed reducer 127, so that 
with the motor 126 stopped, shaft 142 is effectively locked. Then, overrun 
clutch 137b will prevent any counterclockwise rotation of pulley 137a, and 
thereby of roller 134. This will secure the sheet 39 from being drawn from 
roller 6. 
To allow sheet 39 to be drawn off roller 6, motor 126 is driven in the 
reverse direction so that shaft 142 rotates counterclockwise. When driven 
in this direction overrun clutches 137b and 129b will slip and will not 
transmit appreciable torque to rollers 134 and 6. These rollers can then 
rotate freely in either direction, and sheet 39 can be drawn through the 
drive and pinch rollers 134 and 135 and off roller 6. The only limitation 
here is that pulley 137a cannot rotate counterclockwise faster than shaft 
142. To prevent friction torque through overrunning clutch 129b from 
causing roller 6 to unwind, added friction is provided by a small drag 
brake 145 between pulley 131 and slip clutch 132. 
In an alternative embodiment, overrunning clutch 137b is replaced on shaft 
142 by an electrically actuated clutch 137c as shown in FIG. 21, and 
clutch 129b and brake 145 are deleted. To draw the sheet 39 across the bed 
and wind it on roller 6, motor 126 is actuated with clutch 137c engaged, 
driving roller 134 through pulley 137a and roller 6 through pulley 129a, 
as described above. To secure the sheet, motor 126 is stopped, and clutch 
137c is engaged. To allow the sheet 39 to be drawn off roller 6, clutch 
137c is dis-engaged. Clutch 132 then slips and roller 6 unwinds when the 
pulling torque from the sheet exceeds the slip torque of the clutch. 
Clutch 137c is electrically connected by cable 148 to control circuits, 
not shown, but well known in the art, which cause the clutch to be engaged 
or disengaged. 
A supine person presents an uneven weight distribution across the width of 
a bed. As a result, when a sheet is pulled uniformly across its width, 
some portions of the sheet where the load is greatest stretch more than 
others. For this reason, it has been found desirable to pull the central 
portion of the sheet where the load is greatest. It is a specific object 
of the present invention to provide a drive and pinch roller structure as 
described herein to produce the principal pulling force along the central 
portion of the sheet. 
To accomplish this, as shown in FIGS. 19 and 20, the surface 144 of drive 
roller 134 is preferably cut away or relieved toward the ends of roller 
139. This will provide driving friction between sheet 39, the roller 
surface 144, and pinch roller 135 where needed to optimize the tension 
distribution across sheet 39 and minimize sheet bunching and wrinkling. 
Similarly, and for the same reasons, head-end roller 7 and corner roller 9 
shown in FIG. 1a and the foot-end roller 6 and corner roller 8 shown in 
FIGS. 1a and 2 are preferably also cut away to smaller diameters toward 
their ends.