Drive unit and clutch assembly for an adjustable bed

The present invention is a drive unit for an adjustable bed, comprising motor means and a clutch assembly comprising a toothed gear jack drive coupling, a toothed gear drive coupling and means for engaging and disengaging the jack drive coupling and the drive coupling, wherein the drive coupling is driven by the motor means and wherein the jack drive coupling, when engaged with the drive coupling by the clutch assembly, drives a controller shaft of the adjustable bed to raise or lower a section of the bed.

BACKGROUND OF THE INVENTION 
The present invention relates generally to adjustable beds, and more 
particularly to a single motor drive unit for an adjustable bed. The drive 
unit includes a toothed gear clutch assembly. 
Adjustable beds are well known in the art and are used extensively in 
hospitals, nursing homes, and private homes by people who must spend 
extensive periods of time in bed for reasons of health, injury, or 
physical handicap. More recently, adjustable beds have gained in 
popularity for general home use by people who simply want to be more 
comfortable when sleeping, reading, watching television, etc. 
In general, adjustable beds are categorized as either manual or powered. 
Manual beds utilize hand cranks to move the adjustable sections of the bed 
to the desired attitude and height, whereas powered beds use electric 
motors or hydraulic actuators to perform the same result. 
Typically, both manual and powered beds have three, four, or even five 
articulated sections which may be separately adjusted. A common 
arrangement, for example, includes a head adjustment, a leg adjustment, 
and a bed height adjustment (which raises or lowers the entire bed). 
Usually, each adjustable section of the bed has a separate actuator, 
including a rotatable shaft, which turns in one direction to raise the 
section and in the opposite direction to lower the section. 
There are advantages and disadvantages associated with both manual beds and 
powered beds. Manual beds are less expensive than powered beds and are 
usually simpler in construction, which makes them easier to repair. The 
disadvantages of a manual bed are the requirement that another person must 
be available to operate the bed (assuming the person in bed is bedridden), 
as well as the extra effort and awkwardness of turning the handcranks, 
etc. Powered beds are, of course, much easier to use and may even be 
controlled by the bedridden person himself. Motor-powered beds are 
substantially more expensive than manual beds, however, and are generally 
more difficult to repair as well. 
Due to the high cost of powered beds, many people who require an adjustable 
bed in their home purchase or rent a manual bed. If, at a later time, the 
user wishes to upgrade to a powered bed, the general trend has been for 
the user to sell the manual bed and purchase a powered bed, or to trade in 
the manual bed and pay extra for the powered bed. This has generally 
necessitated that adjustable bed dealers carry inventories of both manual 
and powered beds. Another problem typically encountered with powered beds 
is that of repair. In very early models, a motor failure required a 
service call by a repairman and sometimes resulted in temporary loss of 
bed function until the motor problem was resolved. Improved beds provided 
an emergency handcrank which could be used to power the bed manually until 
the motor was repaired. A further improvement is disclosed in U.S. Pat. 
No. 4,545,084 (Peterson) which describes a modular drive arrangement for 
adjustable beds. The Peterson invention provides individually 
interchangeable motor and manual drive units which allegedly may be 
interchanged without disturbing the patient. Unfortunately, assuming a 
person is in the bed, it is necessary to crawl under the bed to 
interchange one of the Peterson drive units. To ensure sufficient 
clearance for the serviceman to be able to crawl under the bed, it is 
necessary that the bed have adjustable legs so that the entire bed can be 
raised off the floor (presumably the patient must be removed from the bed 
before this can be accomplished). Another problem with the Peterson bed is 
that the service person must troubleshoot a defective bed to determine 
which drive unit is in need of repair. To diagnose a defective bed, it is 
again necessary to crawl under the Peterson bed to determine which drive 
unit is defective, or else remove the mattress and bedding (and the 
patient) to enable a visual inspection of the moving parts. 
A variety of drive units are known for powered beds. Some beds utilize 
hydraulic or pneumatic actuators, while others use electric motors. Among 
those powered by electric motors, some use multiple motors per bed, 
usually one motor for each drive shaft. An advancement over this scheme is 
a bed which uses a single motor and appropriate coupling mechanisms to 
activate particular drive shafts. 
One example of a single-motor drive unit for an adjustable bed is disclosed 
by Houlberg et al. in U.S. Pat. No. 4,324,010. Houlberg et al. use a 
unidirectional motor which necessitates a more complex clutch assembly 
comprising eight solenoids and two gears per drive shaft. 
U.S. Pat. No. 4,472,846 (Volk, Jr. et al.) discloses a coupling system for 
an adjustable bed which utilizes a single reversible motor which drives 
one or more adjusting mechanisms through individual clutches. According to 
the patent, a salient feature of the invention is the use of a relatively 
light (i.e., weak) restoring spring to disengage the clutch and 
corresponding less powerful solenoids to overcome the spring when engaging 
the clutch. Unfortunately, it is necessary to unload each clutch prior to 
disengagement to prevent the clutch mating surfaces from locking or 
binding after the solenoid has been de-energized. This unloading is 
accomplished by momentarily reversing the direction of the bidirectional 
motor which jogs the gear train sufficiently to take the forces off of the 
clutch so that it can release. This requires complex control circuitry as 
shown in FIGS. 18 and 19. 
What is needed, then, is a coupling mechanism for a bi-directional 
single-motor drive unit which comprises a clutch which will not bind up 
upon disengagement and does not require reversing the motor to accomplish 
disengagement. 
Finally, adjustable beds are, of course, usually more complicated in 
construction than conventional beds. Due to this more complex 
construction, it is generally more difficult to disassemble, transport and 
reassemble adjustable beds. This is especially troublesome in that there 
is usually a much greater need to transport adjustable beds than 
conventional beds. 
SUMMARY OF THE INVENTION 
The present invention is a drive unit for an adjustable bed, comprising 
motor means and a clutch assembly comprising a toothed gear jack drive 
coupling, a toothed gear drive coupling and means for engaging and 
disengaging the jack drive coupling and the drive coupling, wherein the 
drive coupling is driven by the motor means and wherein the jack drive 
coupling, when engaged with the drive coupling by the clutch assembly, 
drives a controller shaft of the adjustable bed to raise or lower a 
section of the bed. The invention also includes an adjustable bed and 
drive unit therefor, comprising a bed frame, a plurality of separately 
adjustable bed sections pivotally secured to the frame, a corresponding 
plurality of controller shafts wherein each shaft controls one of the 
adjustable sections, a drive unit operatively arranged for controlling and 
driving the controller shafts, wherein the drive unit comprises motor 
means, a separate clutch assembly for each controller shaft which clutch 
assembly comprises a toothed gear jack drive coupling, a toothed gear 
drive coupling and means for engaging and disengaging the jack drive 
coupling and the drive coupling, and, means for coupling the motor means 
to the clutch assembly, wherein the drive coupling is driven by the motor 
means and wherein the jack drive coupling, when engaged with the drive 
coupling by the clutch assembly, drives a controller shaft of the 
adjustable bed to raise or lower a section of the bed. 
A primary object of the invention is to provide a drive unit for an 
adjustable bed which uses a single electric motor to drive a plurality of 
drive shafts of the bed and includes a toothed gear clutch assembly which 
does not bind up when disengaging. 
These and other features, advantages and objects of the present invention 
will be appreciated by those having ordinary skill in the art in view of 
the following specification, claims and appended drawings.

DETAILED DESCRIPTION OF THE INVENTION 
For purposes of the description which follows, the terms flupperill 
"lower", "left", "right", "front", "rear", "vertical", "horizontal", and 
derivatives thereof, refer to the invention as illustrated in the drawings 
from the perspective of a normal observer facing the drawings. The terms 
"foot" and "foot-end" refer to the end of the bed where the drive unit is 
secured, and where the user's feet would usually be, whereas the terms 
"head" and "head-end" refer to the opposite end of the bed, where the 
user's head would normally be. "Bind-up" refers to a failure of a clutch 
to disengage when its driving solenoid is de-energized. Identical drawing 
reference numbers on different drawing FIGURES refer to identical 
elements. 
What follows is a description of a preferred embodiment of the invention, 
illustrating the best mode of the invention known to the patentee. The 
claims are not intended to be limited in scope to the preferred embodiment 
described herein, but rather are intended to encompass variations thereof 
which are readily apparent to those having ordinary skill in the art. For 
example, an important point of novelty of the invention is the 
interchangeability of manual and powered drive units, where each unit 
controls a plurality of bed drive shafts and associated bed positions. In 
the preferred embodiment depicted, three separate drive shafts are shown 
for controlling the head, foot and general elevation of the bed, 
respectively. It is not intended that the claims of the invention be 
limited in scope to a bed with three drive shafts, however. The present 
invention is intended for adjustable beds with two, three, four, five or 
even more separately adjustable sections. The essence of the invention is 
that it permits the quick and easy interchangeability of the drive unit 
for the entire bed, regardless of how many separately adjustable sections 
the bed may have. 
Similarly, the preferred embodiment shown includes a first powered drive 
unit with three electric motors, and a second powered drive unit with a 
single electric motor. However, the claims are not intended to be limited 
to a particular number of electric motors in the powered drive unit, nor 
is it necessary that the powered drive unit include electric motors at 
all; for example, hydraulic or pneumatic actuators could be employed as 
well. 
Adverting now to the drawings, FIG. 1 is a top plan elevation of the 
adjustable bed 10 of the invention with manual drive unit 11 installed, 
and FIG. 2 is a side elevation of the bed shown in FIG. 1. It is to be 
noted that FIG. 2 illustrates the left side of the bed as viewed from the 
perspective of one facing the foot end of the bed. Although not completely 
shown in the drawings, the right side of the bed is identical to the left 
side, and so a detailed description thereof has been generally omitted for 
simplicity. 
Bed 10 is generally of conventional construction, but with several 
important modifications to accommodate the interchangeability of the drive 
units and to facilitate nesting of the bed frame for easier storage and 
transport. The bed comprises frame 12 which is supported by dual head-end 
legs 15 which rest on casters 18, and dual foot-end legs 16 which rest on 
casters 19, and is sometimes also supported by head-end vertical support 
20 and foot-end vertical support 21 (when the bed frame is not in an 
elevated position). (For convenience, reference numbers 15 & 16, 18 & 19, 
and 20 and 21 denote pairs of legs, casters and vertical supports, 
respectively, half of which pairs are shown in FIG. 2) . A conventional 
spring-wire mattress support 120 covers the head, center and foot sections 
of the bed. 
Frame 12 comprises head-end support section 54 and foot-end support section 
55. Head-end support section 54 comprises side rails 49 and 50, transverse 
member 99, and head rail 51, all of which may, for example, be 
individually constructed of tempered steel and then welded together or 
otherwise secured. Similarly, foot-end support section 55 comprises side 
rails 56 and 59, transverse members 101 and 102, and coupling mounting 
bracket 58 which extends transversely across the side rails. Once again, 
the side rails may, for example, be constructed of tempered steel and 
welded or otherwise secured to the mounting bracket. 
The respective side rails of the two U-shaped support sections 54 and 55 
telescopingly engage one another and are joined together by locking pins 
61 and 62 which pass through aligned bores in the side rails. For added 
stability and ease in alignment side rails 56 and 59 include inwardly 
protruding pins 63 and 64, respectively, which engage corresponding slots 
in the ends of side rails 50 and 49, respectively. Pins 61 and 62 may be 
easily removed to disassemble the bed. 
Bed 10 includes a pivoting head section 66, pivoting foot and center 
sections 68 and 69, respectively, as well as a general elevation 
adjustment of frame 12 (as best shown in FIG. 4). Head section 66 pivots 
about pivot pins 70 and 71; and foot and center sections 68 and 69 pivot 
about stationary pivot pins 72, 73, 74 and 75, and moving pivot pins 76, 
781 79 and 80. 
As best illustrated in FIG. 1, conventional screw jacks 81 and 82 are used 
to control the attitude of head section 66 and foot and center sections 68 
and 69, respectively. Conventional screw jack 83 controls the general 
elevation of frame 12. Hand crank 84 turns controller shaft 81' which in 
turn drives jack 81; hand crank 85 turns controller shaft 83' which in 
turn drives jack 83; and hand crank 86 turns controller shaft 82' which in 
turn drives jack 82. Drive jack 81 is pivotally secured at pivot pin 88 to 
bracket 91 which is fixedly secured to transverse member 94 of head 
section 66. Drive jack 82 is pivotally secured at pivot pin 90 to bracket 
93 which is fixedly secured to transverse member 98 of foot and center 
sections 68 and 69. Drive jack 83 is pivotally secured at pivot pin 89 to 
bracket 92 which is fixedly secured to transverse frame members 95 and 96. 
As shown in FIG. 21 transverse members 95 and 96 are fixedly secured to 
pivoting cross member 106 which, in turn, is pivotally secured to leg 15 
at pivot pin 113 and to vertical support 20 at pivot pin 111. Pivoting 
cross member 105 is also pivotally secured to leg 15 at pivot pin 112 and 
to vertical support 20 at pivot pin 110. Drive jack 83 is pivotally 
secured at pivot pin 051 to bracket 119 which is fixedly secured to 
transverse frame members 103 and 104. Also as shown in FIG. 2, transverse 
members 103 and 104 are fixedly secured to pivoting cross member 09 which, 
in turn, is pivotally secured to leg 16 at pivot pin 18 and to vertical 
support 21 at pivot pin 115. Pivoting cross member 108 is also pivotally 
secured to leg 16 at pivot pin 116 and to vertical support 21 at pivot pin 
114. 
The bed's various functions are best illustrated by reference to FIGS. 
3--5. FIG. 3 is a vertical cross-section of the bed with sections cut 
away, taken generally at line 3-3 of FIG. 11 with adjustable foot section 
68 and center section 69 in an elevated position. To elevate foot section 
68 and center section 69 as shown, hand crank 86 is rotated in a clockwise 
direction (from a perspective facing the foot-end of the bed). Hand crank 
86 drives shaft 821 into the hollow tube of jack 82. Shaft 821 engages nut 
122 which is secured inside the hollow tube of jack 82. As controller 
shaft 821 rotates in a clockwise direction, jack 82 travels rightwardly, 
causing bracket 93 through its mounting on center section 69 to pivot in a 
counterclockwise direction about hinge pivots 72 and 73, thereby rotating 
transverse member 98 and center section 69 about pivots 72 and 73 which 
are secured to center section 69. As center section 69 pivots in a 
counterclockwise direction, it raises the leftward end of foot section 68, 
which is pivotally secured to section 69 at pivot pin 79. As foot section 
68 moves generally leftward, it causes member 121 to pivot in a 
counterclockwise direction about pivot pin 74 which is secured to frame 
12. Turning hand crank 86 in the opposite direction lowers sections 68 and 
69. It is important to note that when sections 68 and 69 are fully 
lowered, the left end of section 68 rests on stop 57 (as shown in FIGS. 21 
4 and 5) which is welded to the frame. Stop 57 serves two functions; it 
absorbs the force exerted by one sitting on the foot end of the bed and, 
as shown in FIG. 13, it helps to align the bed halves when nesting the 
halves together. Head rest 167 (shown in FIGS. 2-5), which is also welded 
to the frame, similarly functions to support head section 66. 
FIG. 4 is a view similar to FIG. 31 except taken generally at line 4-4 of 
FIG. 1, and illustrates how hand crank 85 controls the general elevation 
of frame 12. To elevate frame 12 as shown, hand crank 85 is rotated in a 
clockwise direction (from a perspective facing the foot-end of the bed) 
.It should be noted that the handle of hand crank 85 pivots about pin 124 
to enable its handle to clear the other handles when cranking (the other 
two handles also include this pivoting feature) Hand crank 85 drives shaft 
83' into the hollow tube of jack 83 (which includes head section 83a and 
foot section 83b). Shaft 83' engages nut 123 which is secured inside the 
hollow tube of jack 83. As controller shaft 83' rotates in a clockwise 
direction, jack 83 travels rightwardly, causing upward forces along legs 
20 and 21, and downward forces along legs 15 and 16, which results in the 
left ends of brackets 119 and 92 raising the bed off the floor. Since 
transverse members 103 and 104 are secured to bracket 1191, and transverse 
members 95 and 96 are secured to bracket 92, these transverse members are 
also elevated relative to the floor. Finally, transverse members 95 and 96 
are secured to member 106 (see FIG. 2), and transverse members 103 and 104 
are secured to member 109 (see FIG. 2), and members 106 and 109 are 
pivotally secured to legs 20 and 21 which are rigidly secured to frame 12. 
Thus it is seen that turning the handcrank in a clockwise direction 
results in elevating frame 12 whereas turning hand crank 85 in the 
opposite direction lowers frame 12. 
FIG. 5 is a view similar to FIGS. 3 and 4, except taken generally at line 
5-5 of FIG. 1. To elevate head section 66 as shown, hand crank 84 is 
rotated in a clockwise direction (from a perspective facing the foot-end 
of the bed). Hand crank 84 drives shaft 81' into the hollow tube of jack 
81. Shaft 811 engages nut 124 which is secured inside the hollow tube of 
jack 81. As controller shaft 81' rotates in a clockwise direction, jack 81 
travels rightwardly, causing bracket 91 to pivot in a clockwise direction 
about pivot pin 88, thereby raising transverse member 94 which is secured 
to bead section 66. Turning hand crank 84 in the opposite direction lowers 
section 66. 
Thus it is seen in FIGS. 3-5 that turning the appropriate crank in a 
clockwise direction elevates its associated bed section, whereas turning 
the crank in a counterclockwise direction lowers the particular section. 
FIG. 6 is a foot-end elevation of the bed of FIG. 1. showing manual drive 
unit 11 installed. Also shown in FIG. 6 are quick connect/disconnect 
latches 125 and 126 which are pivotally secured to drive unit 11 at pivot 
pins 128 and 129, respectively. Secured to the housing of drive unit 11 
are mounting brackets 131 and 132 which slidingly engage square-shaped 
side rails 59 and 55., respectively. Once the drive units are slid into 
position, the latches interlock the drive unit with the side rails as 
shown in more detail in FIG. 9. 
FIG. 7 is a fragmentary horizontal cross-section of the bed taken generally 
at line 7-7 of FIG. 6 which illustrates how the manual drive unit 
slidingly engages the foot-end of the bed frame. Note slots 133 and 134 in 
side rails 59 and 55, respectively. 
FIG. 9 is a fragmentary section taken generally at line 99 of FIG. 6 which 
illustrates how the drive unit latches onto the bed frame. Side rail 59 
includes slot 133 which receives straight portion 135 of latch 125 to lock 
drive unit 11 into place. Thus it is seen that replacing or interchanging 
the manual drive unit with another drive unit (either manual or powered) 
is quickly and easily accomplished by turning latches 125 and 126 and 
sliding out the drive unit and then reversing the process with the 
replacement unit. Indeed, the entire interchange can be accomplished in 
less than 30 seconds. 
Both the manual and powered drive units include identical coupling 
assemblies (three assemblies in each unit) for coupling the drive to the 
appropriate screw jacks. FIG. 8 is a vertical cross-section of the manual 
drive unit and coupling assembly taken generally at line 8--8 of FIG. 7. 
Since all three coupling assemblies are identical within the manual drive 
unit, only coupling assembly 140 is described herein. Handcrank 84 
generally comprises handle 142 secured to crank arm 141 which is pivotally 
secured to shaft extension 138 at pivot pin 124. The crank arm may be 
rotated in a counterclockwise direction about pin 124 to provide clearance 
and avoid interference with the center hand crank. Drive unit shaft 143 
and its shaft extension 138 extend through a bore in wall 158 of drive 
unit 11 and are secured by bearing 148. Drive unit shaft 143 also extends 
through a bore in bracket 145 where it is further secured by bushing 144. 
Mounted on the distal end of shaft 143 is pin 149. Coupling 150, which 
includes slot 151, slidingly engages shaft 143. Spring 146 extends between 
bushing 144 and coupling 150, biasing the coupling leftwardly until pin 
149 abuts the rightward end of slot 151. Drive shaft 81' extends through 
bushing 152 (which includes internal bearings not shown) which is mounted 
to mounting clevis 154. Drive shaft extension 153 of shaft 81' includes 
pin 156 which engages an open-ended slot (shown more clearly in FIG. 12A) 
in the leftward end of coupling 150. Thus, it is seen how rotating 
handcrank 84 drives shaft 81' to cause jack 81 to operate. 
The motor drive unit 160 mounts in exactly the same manner as the manual 
drive unit, as shown in FIGS. 10, lit 12 and 12A. The obvious difference 
between the two units is that the handcranks of the manual unit are 
replaced by electric motors in the powered drive unit. FIG. 10 is a view 
similar to FIG. 6, except illustrating the motor drive unit installed in 
the bed, and FIG. 11 is a view similar to FIG. 7. 
FIG. 12 illustrates a vertical cross-section of the motor drive unit and 
coupling assembly taken generally at line 12--12 of FIG. 11. Motor 161 is 
mounted to the drive unit housing and drives motor shaft 165 through gear 
reducer 162. The motor is controlled by motor control 163, also mounted to 
the housing. Motor leads 171 are shown disconnected but would of course be 
connected to control circuit 163. Not shown in the drawings is a clutch 
which engages the gear reducer when activated by control circuit 163. 
(Note that the clutch is optional and may not be necessary depending upon 
the gear ratio of the gear reducer.) In the event of motor failure or 
electrical failure the clutch is disconnected which permits the jack to be 
driven by an emergency handcrank which may be secured to shaft extension 
164. 
Mounted on motor shaft 165 are pins 168 and 173. Coupling 169, which 
includes slot 170, slidingly engages shaft 165. Spring 166 extends between 
washer 172 which abuts pin 173 and coupling 169, biasing the coupling 
leftwardly until pin 168 abuts the rightward end of slot 170. Drive shaft 
81' extends through bushing 152 (which includes internal bearings not 
shown) which is mounted to mounting clevis 152. Drive shaft extension 153 
of shaft 81' includes pin 156 which engages an open-ended slot (shown more 
clearly in FIG. 12A) in the leftward end of coupling 150. Thus, it is seen 
how the motor rotates shaft 81' to cause jack 81 to operate. 
FIG. 12A is a partially exploded horizontal cross-section taken along line 
12A-12A of FIG. 12, illustrating the coupling of the drive unit to the 
drive jack. Clevis 154 is pivotally mounted to angle brackets 175 and 176 
at pivot bolts 178 and 179, respectively. Angle brackets 175 and 176 are 
fixedly secured to mounting bracket 58 by nut/bolt 180 and 181, 
respectively. 
The pivoting action of controller shaft 81', and jack 81, is a subtle but 
important part of the present invention. This feature is perhaps best 
appreciated with respect to FIG. 5, which shows head section 66 in an 
elevated position. Since bracket 91 is rigidly secured to transverse 
member 94 (which in turn is part of head section 66) and pivotally secured 
to jack 81 at pin 88, it necessarily follows that jack 81 must be capable 
of vertical "play" as it operates. As shown in FIG. 5, jack 81 pivots 
through an angle theta as head section 66 is raised or lowered. This 
movement is made possible by the unique mounting of clevis 154 to bracket 
58. It should be noted that all three jacks are mounted in the same way, 
and each pivots somewhat during operation, as shown in FIGS. 3-5. 
FIG. 12A also illustrates the manner in which coupling 169 engages shaft 
153. Cylindrical pin 156 is rigidly secured to, and extends outwardly on 
two sides from shaft 153. In operation, pin 156 engages slot 182 (shown in 
FIGS. 11 and 12A) of coupling 169 engages slot 182 (shown in FIGS. 11 and 
12A) of coupling 169. When installing the drive unit, it is obviously 
unlikely that all three of the slotted couplings will align with their 
respective shaft pins (in fact, usually none of the couplings are 
aligned). With reference to FIG. 12A, for example, it is seen that as 
coupling 169 is moved leftwardly towards shaft 153 that pin 156 will come 
into contact with annular surface 183 of coupling 169. As the drive unit 
moves further leftward, spring 166 compresses, and continues to compress 
until the drive unit is latched into place by latches 125 and 126. Thus it 
is seen that the drive unit can be completely installed into the bed, and 
yet one or more of the couplings may not be engaged with its respective 
shaft. However, as the drive unit shaft is rotated relative to the jack 
drive shaft (which remains stationary due to its relatively large inertia) 
eventually slot 182 will become aligned with pin 156 and spring 166 will 
bias the coupling into mating engagement with the controller shaft. In 
other words, all three couplings will eventually spring into engagement 
with their respective controller shafts, as the controller shaft pins will 
"pop" into the slots of the coupling. This same mechanism operates with 
both the manual and powered drive units, and permits quick and simple 
interchangeability thereof. 
It is sometimes desired to transport an adjustable bed from room to room or 
even from one building to another. In fact, it is much more likely that a 
need will arise to move an adjustable bed from place to place as compared 
to a conventional bed. To solve this problem, the bed of the present 
invention may be easily disassembled into two parts which then nest one 
within the other for compact storage and convenient transport. Adverting 
to FIG. 1, it is seen that the bed may be quickly disassembled by removing 
pins 61 and 62 which hold the frame side rails together, and by removing 
pins 88, 90, 105' and 184. Pins 184 and 105' hold head section 83a and 
foot section 83b of jack 83 together; pin 90 pivotally secures jack 82 to 
bracket 93; and pin 88 pivotally secures jack 81 to bracket 91. Thus, the 
bed may be easily disassembled by removing six pins. 
FIG. 13 is a side elevation of the adjustable bed of the invention, 
illustrating how the bed may be separated into two pieces which nest 
together which makes the bed easier to transport or store and FIG. 14 is a 
top plan elevation of the bed shown in FIG. 13. It should be noted that 
jacks 81, 82 and 83 are offset in position in such a way to accommodate 
nesting, i.e., the jacks do not interfere with one another when the bed 
halves are stacked as shown in FIGS. 13 and 14. This spacing and 
orientation of the jacks is best seen with respect to FIG. 1. Although the 
distance between jacks 82 and 83 is equal to the distance between jacks 81 
and 83, jack 81 is closer to the bottom rails than jack 82 is to the top 
rails. 
FIG. 15A is a top plan elevation of an alternative single-motor drive unit 
having a single motor and three toothed-gear clutch assemblies. Drive unit 
300 comprises motor 301 which drives belt drives 303 and 304 through gear 
reducer 302. Belt drive 303 comprises drive sheave 314 which is mounted on 
gear reducer shaft 311, sheave 313 of head section drive 350 which is 
mounted on drive unit shaft 310, and belt 319 which loops about sheaves 
313 and 314. Belt drive 304 comprises drive sheave 315 which is mounted on 
gear reducer shaft 311, sheave 316 of foot section drive 330 which is 
mounted on drive unit shaft 312, and belt 320 which loops about sheaves 
315 and 316. Gear reducer shaft 311 drives bed elevation drive 340 
directly. It is important to note that the placement and coupling of motor 
301 and gear reducer 302 to center drive 340 (the bed elevation drive) 
enables all three drives to be driven using only two belts, which is an 
improvement over the embodiment disclosed and illustrated in the parent 
patent. 
Each individual drive unit shaft may be coupled to its respective jack 
drive shaft by engagement of its toothed-gear clutch assembly. Electronic 
control circuitry (not shown) permits only one solenoid to be engaged at 
any one time. This is because, with a single motor drive, it is not 
possible to lower one section of the bed while raising another section, 
since each of these operations requires a different motor direction. 
Moreover, performing only one function at a time permits use of a lower 
horsepower motor, thereby reducing the cost of the drive unit. 
Clutch assembly 323 is associated with drive unit shaft 310, clutch 
assembly 324 is associated with drive unit shaft 311 and clutch assembly 
325 is associated with drive unit shaft 312. Since all three clutch 
assemblies are identical, only clutch assembly 325 will be described in 
detail, although the description is intended to describe the two remaining 
clutch assemblies. Moreover, since the clutch assemblies are identical, 
identical elements of the assemblies are labeled with the same reference 
numbers. 
Clutch assembly 325 comprises toothed gear drive coupling 326, toothed gear 
jack drive coupling 327, solenoid 328, solenoid pivot spring 329, pivot 
post 348, first retaining spring 331, second retaining spring 332 (shown 
in FIG. 16A), and manual override pullchain 333. Solenoid 328 includes 
solenoid plunger 334 which travels into the solenoid body when the 
solenoid is energized. Solenoid pivot spring 329 is wrapped about pivot 
post 348 and a first end of the spring is fixedly secured to plunger 334 
by Cotter pin 335 (shown in dotted lines in FIG. 16B). Pivot spring 329 is 
free to rotate about the pivot post. A second end of the spring is in 
contact with washer 336 which is secured about a shoulder of drive 
coupling 326. The drive coupling is biased toward the pulley sheave by 
spring 332 (shown in FIG. 16A), thereby maintaining contact between the 
second end of the pivot spring and the washer. 
Drive coupling 326 is shown in an enlarged view in Figure 18, which 
illustrates tooth gear 344. Jack gear coupling 327 is also illustrated in 
FIG. 18, having teeth 341. FIG. 18 shows the two gears 326 and 327 
disengaged or uncoupled, whereas Figure 17 shows the two gears engaged. 
Obviously, when the gears are engaged, the respective jack shaft rotates 
to raise or lower the particular bed section. 
Referring again to FIG. 15A, couplings 323 and 325 are shown disengaged 
while coupling 324 is shown engaged. To engage coupling 325, solenoid 328 
is energized which pulls plunger 334 into the solenoid housing. This 
causes pivot spring 329 to pivot about pivot post 348 in a clockwise 
direction, and urges washer 336 and coupling 326 toward coupling 327. It 
is important to note that use of the pivot spring enables use of a less 
powerful solenoid than would be required if the solenoid was linked to the 
coupler with a straight linkage. When the solenoid is de-energized, 
restoring spring 332 (shown in FIG. 16) causes the two coupling halves to 
disengage. Clutch assemblies 323 and 324 operate in exactly the same 
fashion, except the direction of rotation of the respective pivot springs 
is counterclockwise instead of clockwise when the solenoids are energized. 
In the event of a solenoid failure or complete power failure, it may be 
necessary to engage one or more of the clutch assemblies manually. In FIG. 
15A, drive 340 is shown as manually engaged. To manually engage drive 340, 
pullchain 333 is pulled through a keyhole slot of the front wall of the 
drive unit (shown in FIG. 15B) by ring 347. Below slot portion 346 is a 
narrower slot portion 346' which is smaller in diameter than individual 
bead 351 of pullchain 333. As the pullchain is pulled, the pivot spring 
pivots about the pivot post and urges the coupling halves into engagement. 
Once engaged, the pullchain is locked by sliding bead 351 downward such 
that the bead of the pullchain is precluded by the smaller slot from 
passing back into the housing of the drive unit. Once the clutch is 
engaged, a manual crank handle can be secured to shaft extension 348 which 
extends out the front of the drive unit. The manual crank operates as 
described supra. For simplicity, only one shaft extension 348 is shown in 
FIG. 15A, although each drive has such an extension. 
FIGS. 15C and 16B illustrate how pivot spring 329 is secured to solenoid 
plunger 334 by Cotter pin 335. Rubber pad 365 is secured to the inner 
surface of drive unit housing wall 362 to cushion the plunger and prevent 
it from striking the wall when the clutch is disengaged. Pivot post 348 is 
secured to the housing wall by screws 361 and 363, respectively. As shown 
in both FIGS. 15C and 16B, spring 329 wraps about and is free to rotate 
about the vertical section of post 348. An arcuate end of spring 329 is in 
contact with washer 336 which rides on a shoulder of coupling 326. 
FIG. 16A is a partial cross-sectional view of drive 330 taken generally 
along line 16A--16A of FIG. 15A. As shown in the drawing, shaft 312 is 
supported by bearing 370 which is secured to drive unit housing wall 362. 
The shaft is further supported by bearing 312. Sheave 316 is fixedly 
secured to shaft 312 by a set screw 371. Drive coupling 326 is secured to 
the shaft in a manner such that it rotates with the shaft but is free to 
slide a short distance axially along the shaft. In the embodiment shown, 
pin 373 is secured within a radial through-bore of the shaft and extends 
through slot 374 of coupling 326. Thus it is seen that the coupling must 
rotate with the shaft but is free to travel a short distance defined by 
the length of slot 374. Jack gear coupling 327 includes a through-bore 
which is larger in diameter than the outer diameter of shaft 312, such 
that coupling 327 is free to rotate about the shaft. Shaft 312 includes a 
circumferential groove at one end where a U-shaped retaining clamp 372 is 
mounted to secure coupling 327 to the shaft. Spring 332 surrounds shaft 
312 between couplings 327 and 326 and functions to prevent the couplings 
from inadvertently engaging. As shown in the drawing, spring 332 abuts 
circular grooves in both couplings, which grooves are located underneath 
the teeth of the couplings (closer to the centerline of the shaft). Spring 
331 surrounds shaft 312 between bearing 321 and coupling 326 and functions 
to maintain slight tension on spring 332, thereby maintaining the relative 
positions of the couplings on the shaft. Washer 336 is fixedly secured 
about a shoulder of coupling 326, and pivot spring 329 contacts the washer 
as shown in both FIGS. 16A and 16B. When solenoid 328 is energized, pivot 
spring 329 urges coupling 326 leftward, (as shown in Figure 16A) 
overcoming the force of spring 332 and forcing the teeth of coupling 326 
to engage the teeth of coupling 327, thus forcing coupling 327 to rotate 
with the shaft. Springs 329 and 331 together push coupling 327 towards the 
bed drive shaft and the slotted end of the coupling engages the pin on the 
bed drive shaft as described infra with respect to FIG. 12A. When the 
solenoid is de-energized, spring 332 separates the couplings, thereby 
disengaging the clutch. 
FIG. 16C is a cross-sectional view taken along line 16C--16C in FIG. 16A, 
and shows a face view of the teeth 344 of coupling 326. 
FIG. 19 is a diagrammatic view of intermeshing teeth 341 and 344 showing a 
clearance 360 maintained to prevent wedging of the teeth 344 into and 
between the teeth 341. As shown in the drawing, in a preferred embodiment 
the tooth faces have a pitch of approximately 20 degrees as measured from 
a bisecting line between adjacent teeth to a face of the tooth. 
Experiments indicate that other angles are also suitable and an 
approximate range of 20 to 30 degrees affords suitable results. The larger 
the angle, the less likely are the gears to bind up when disengaging, but 
the more torque is required to drive the jack screw. Thus, the object is 
to find the minimum angle at which bind-up will not occur. It should also 
be noted in FIGS. 17, 18 and 19 that all of the teeth have flattened tips 
and that the spaces between teeth are flattened as well. This flattening 
of the teeth also functions to prevent the gears from binding up when 
disengaging. Finally, when the teeth are engaged and driving the jack 
screw, only one tooth face engages a corresponding tooth face when driving 
in one direction, while the remaining tooth face is separated by its 
corresponding tooth face by a clearance, indicated generally as 360 in 
FIG. 19. Obviously, when the motor reverses the formerly non-contacting 
tooth faces would engage and the clearance would exist between the 
formerly contacting faces. This clearance is of course necessary for the 
teeth to properly mesh, and also helps to prevent bind-up when 
disengaging. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently obtained. Since 
certain changes may be made in carrying out the above-described invention 
and in the construction set forth without departing from the scope of the 
invention, it is intended that all matter contained in the above 
description or shown in the accompanying drawings be interpreted as 
illustrative and not in a limiting sense. It is also to be understood that 
the following claims are intended to cover all of the generic and specific 
features of the invention herein described, and all statements of the 
scope of the invention, which, as a matter of language, might be said to 
fall therebetween.