Single chair muscle exercise and rehabilitation apparatus

A muscle exercise and rehabilitation apparatus including a patient chair having a first side and a second side is disclosed. Structure is provided for the rehabilitation and exercise of a patient seated in the patient chair. Structure is provided to move the rehabilitation and exercise structure between a first position adjacent the first side of the patient chair and a second position adjacent the second side of the patient chair in a first linear path. Structure is provided to support the patient chair for movement along a second linear path toward and away from the exercise and rehabilitation structure.

BACKGROUND OF THE INVENTION 
This invention generally relates to a muscle exercise and rehabilitation 
apparatus and more particularly to a muscle exercise and rehabilitation 
apparatus that utilizes a single patient chair where the patient chair and 
the apparatus powerhead can each be independently moved to a desired 
position and orientation so that the patient chair can be placed in a 
large number of locations and orientations relative to the powerhead. 
In U.S. Pat. No. 4,628,910 a muscle exercise and rehabilitation apparatus 
is disclosed in which a person's knee can be rehabilitated but no other 
limbs. The muscle exercise and rehabilitation apparatus of U.S. Pat. No. 
4,628,910 discloses a chair upon which a patient sits while his leg is 
strapped to a handle. The muscle exercise and rehabilitation apparatus of 
U.S. Pat. No. 4,628,910 was distributed in 1985 by Biodex Corporation, the 
assignee of the instant application, and known as the B-1000. While the 
B-1000 had certain additional circuit features in it not disclosed in U.S. 
Pat. No. 4,628,910, it generally conformed to the description contained in 
this patent. 
In U.S. Pat. No. 4,691,694, also owned by Biodex Corporation, an improved 
muscle exercise and rehabilitation apparatus is disclosed. In the muscle 
exercise and rehabilitation apparatus of U.S. Pat. No. 4,691,694, a dual 
chair arrangement is shown for an apparatus that is capable of 
rehabilitating and exercising a plurality of joints and limbs. The 
apparatus of U.S. Pat. No. 4,691,694 was known as the B-2000 and first 
distributed in 1986. While the apparatus of U.S. Pat. No. 4,691,694 has 
been widely sold throughout the United States and is suitable for its 
intended purpose of rehabilitating and exercising different joints of a 
person, it has two chairs and requires that a patient, who is exercising 
and rehabilitating one leg and wishes to exercise and rehabilitate the 
other leg, must first dismount from the chair he is sitting on and mount 
the other chair before exercise and rehabilitation of the other leg can 
commence. While this sounds simple enough, it can be a difficult procedure 
for a person who is injured and not fully ambulatory. 
Muscle exercise and rehabilitation apparatus of the kind disclosed in U.S. 
Pat. No. 4,691,694 is used by hospitals, physical therapists, sports 
clinics, etc. Frequently, space is at a premium in these establishments 
and while the muscle exercise and rehabilitation apparatus of this patent 
satisfactorily rehabilitates and exercises various joints and limbs of a 
person, nevertheless because of its dual chair arrangement it occupies a 
significant amount of space. 
It is also desirable that there be an infinite number of positions and 
orientations of the muscle exercise and rehabilitation apparatus chair 
relative to the powerhead so that a physical therapist will have a wide 
variety of such relative positions and orientations to choose from when 
providing physical therapy for an individual. 
There is presently on the market a muscle exercise and rehabilitation 
machine known as the OSCER, which is an acronym for OPTIMUM SYSTEM FOR 
CONTROLLED EXERCISE AND REHABILITATION. The OSCER is manufactured and sold 
by Chattecx Corporation, which is a part of the Chattanooga Group located 
in Chattanooga, Tenn. With the OSCER, a chair is provided which can be 
raised and lowered as required. A powerhead unit to which an exercise arm 
is attached is fixed on a support structure so that it can swivel relative 
to the chair. However, the powerhead cannot be moved linearly toward or 
away from the chair. 
A further muscle exercise and rehabilitation apparatus on the market is 
manufactured by Loredan Biomedical, Inc. and is known as the LIDO Active. 
The LIDO Active includes a bench system having a flat bench that "breaks" 
in the middle. However, the LIDO Active does not allow rotation of the 
bench relative to the powerhead. 
It is an object of the present invention to provide a muscle exercise and 
rehabilitation apparatus having a single chair wherein the chair can 
assume a large number of positions and orientations relative to the 
powerhead. 
Another object of the present invention is to provide a muscle exercise and 
rehabilitation apparatus having a single chair wherein the apparatus 
utilizes a minimum amount of floor space. 
A further object of the present invention is to provide an improved muscle 
exercise and rehabilitation apparatus wherein, during the course of 
physical therapy for a patient, a physical therapist will have a great 
number of positions in which to place the chair relative to the apparatus. 
Other objects of the invention will be apparent to those of ordinary skill 
in the art. 
In accordance with the present invention, a powerhead and controller are 
utilized which are identical to those described in U.S. Pat. No. 
4,691,694, the specification of which is incorporated herein by reference. 
The powerhead is mounted on a powerhead support stand and can be 
selectively elevated, lowered or rotated as required. The base of the 
powerhead support stand is mounted for linear movement on a powerhead 
support guide. Means is provided to allow the powerhead support stand to 
move along the length of the powerhead support guide in opposite 
directions and to a desired location. 
Perpendicular and affixed to the powerhead support guide is a chair support 
guide and slidable thereon is a chair support. Mounted at the top of the 
chair support is a single chair. The chair support allows the height of 
the chair to be raised or lowered as desired and also allows the chair to 
be rotated. 
In use, a patient is strapped onto the chair and if the patient is 
exercising and rehabilitating his right leg, the right leg will be 
strapped to the exercise arm which is driven by the powerhead. The 
physical therapist will select the appropriate height of the chair, the 
appropriate rotation of the chair and the distance from the powerhead to 
the chair. The position of the powerhead on the powerhead support guide, 
the powerhead height and degree of rotation of the powerhead on the 
powerhead support stand will also be selected by the physical therapist, 
all so that the person's right leg can be properly exercised and 
rehabilitated. 
After the person has completed exercising and rehabilitating his right leg, 
the powerhead and powerhead support stand will be moved along the 
powerhead support guide so as to be located outside the person's left leg. 
The person's left leg will then be strapped to the exercise arm and he 
will exercise and rehabilitate his left leg, all of this occurring without 
the patient having to leave the chair. 
By having the powerhead capable of moving along the powerhead support guide 
and the chair capable of moving along the chair support guide, a large 
number of positions and orientations of the chair relative to the 
powerhead can be obtained so that the optimal position for any patient can 
be utilized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1 of the drawings, a muscle exercise and rehabilitation apparatus 
10 is disclosed and is of the type shown in U.S. Pat. No. 4,691,694 
insofar as the electro and electromechanical servo systems. However, the 
chair arrangement is entirely different, as will hereinafter be described. 
Muscle exercise and rehabilitation apparatus 10 includes a powerhead 12 
and a gearbox output shaft (control element) 14. The gearbox output shaft 
14 of powerhead 12 projects outwardly from the right side of the 
powerhead, as shown in FIG. 1, and an identical shaft (as shown in FIG. 7) 
projects outwardly from the left side of powerhead 12. Rotatable with 
shaft 14 is a fixture 16 which has a handle 18 at the free end thereof. 
Affixed to handle 18 in FIG. 1 is a leg cuff 20 but it is to be 
appreciated that other exercise and rehabilitation implements could 
likewise be affixed thereto or to gearbox output shaft 14. 
Inasmuch as the powerhead 12 and associated control apparatus are described 
in U.S. Pat. No. 4,691,694, the entire disclosure of which is incorporated 
herein by reference, there is no need to describe the functions and manner 
of operation of the powerhead other than to note, as will hereinafter be 
described with more particularly, that the powerhead can yaw upon its 
yoke-shaped support. 
A cart 22 is positioned next to powerhead 12 and has shelves 24, 26 and 28. 
Located on cart 22 are the controls and data acquisition computer 
associated with the muscle exercise and rehabilitation apparatus 10. More 
particularly, located on shelf 24 is a computer 30, on shelf 26 a printer 
32 and on shelf 28 the controller 36 for powerhead 12. Details of the 
controller are provided in U.S. Pat. No. 4,691,694. Affixed to the cart 
and located above controller 36 is a display screen 38. Keyboard 34 is 
supported by a shelf (not shown in the drawings) affixed to the bottom of 
shelf 28 of cart 22 or by some other conventional manner. 
A cord 40 extends from controller 36 to powerhead 12 and serves to control 
the operation of powerhead 12 and the muscle exercise and rehabilitation 
apparatus 10 as disclosed in U.S. Pat. No. 4,691,694. 
Powerhead 12 is mounted on a powerhead support stand 42 which can raise or 
lower the powerhead, as will hereinafter be described. Attached to a shaft 
46 (FIG. 6) which extends from the top of powerhead stand support 42 is a 
bracket 44 having a bearing mounting which has leg 45 and base 47. 
Powerhead 12 has a bearing shaft which is rotatable in leg 45 and allows 
the powerhead to rotate as shown by arrow 49. Shaft 46 can rotate in yaw, 
as illustrated by the arrow 51 (FIG. 6), which rotation is controlled by a 
lever arm and clamp arrangement 48. A further lever arm and clamp 
arrangement 50 controls the extension of shaft 46 from powerhead support 
stand 42 and hence the elevation of the powerhead above ground. 
An additional lever arm and clamp arrangement 52 is provided which controls 
the tilt of powerhead 12 in bracket 44. 
Powerhead support stand 42 is movable along the length of powerhead support 
guide 54 in a manner that will hereinafter be discussed. 
A patient chair 56 is provided and includes a back 58 and a base 60, as 
well as straps 62 and 64 for strapping a person's torso to the chair. 
Strap 65 is for strapping a person's leg to the chair. Chair 56 is mounted 
on a chair support stand 66 which can raise or lower the chair relative to 
the ground. 
As best seen in FIG. 4, chair support stand 66 includes a plurality of 
telescoping sections 68, 70 and 72 which can, under the control of an 
electric motor 74, telescope relative to each other to either raise or 
lower chair 56. Chair 56 and its operation will be described in greater 
detail hereinafter but it is to be noted that the back 58 of chair 56 can 
be reclined in any one of a large number of positions, as shown in FIG. 4, 
inasmuch as there is no detent structure for limiting the number of 
positions. The chair can rotate 360 degrees relative to chair support 
stand 66 to a finite number of positions by reason of a detent mechanism 
being utilized. Chair support stand 66 moves linearly along a chair 
support guide 76 in a manner that will hereinafter be described. 
Referring now to the powerhead support guide 54 and particularly FIGS. 1, 2 
and 3, said powerhead support guide includes a base 80 which sits on the 
floor. Located at the opposite ends of base 80 are end plates 81. The 
front face 82 of base 80 includes a scale 83 on it with numerical 
notations so that the position of powerhead 12 along the position of 
powerhead support guide 54 can be visually preset and/or recorded. 
Extending upwardly from base 80 are parallel support rails 85 and 87. The 
upper surfaces of rails 85 and 87 are concave. 
Defining the uppermost portion of the powerhead support guide 54 is a cover 
plate 84 which is releasably attached to base 80. Extending transversely 
through the length of powerhead support guide 54 are a pair of bearing 
rods 86 and 86. A portion of bearing rod 86 contacts the upper concave 
surface of rail 85 (FIG. 3), while a portion of bearing rod 88 contacts 
the upper concave surface of rail 87. Bolts secure the bearing rods to the 
rails and to base 80. 
Attached to and forming a part of the bottom of powerhead support stand 42 
is a powerhead support plate 43 which is bolted to slide plate 57, slide 
plate 57 being affixed to a slide 90. Movable with slide 90 are bearing 
sleeves 92 and 94. The bearing sleeves only encircle a portion of the 
bearing rods, as can be seen in FIG. 3, with the unencircled portion of 
each bearing rod in contact with a rail. Sleeve 92 is in bearing 
relationship with bearing rod 86 and sleeve 94 is in bearing relationship 
with bearing rod 88. Sleeves 92 and 94 slide respectively along bearing 
rods 86 and 88 and by so doing move slide 90 and powerhead support stand 
42 along the length of powerhead support guide 54. 
A gear rack 98 which has its teeth in a downward direction extends 
substantially along the length of powerhead support guide 54 and is 
affixed to a lever 100. Lever 100 rotates about a rod 102 which is affixed 
to base 80. A compression spring 104 has one end abutting against a fixed 
spring rest 106 and the other end against the top surface of gear rack 98. 
Spring rest 106 is fixed relative to base 80. 
The bottom surface of lever 100 abuts a pin 107 which slides relative to 
boss 110 with the boss being welded or otherwise affixed to shelf 111 of 
base 80. Pin 107 has a bottom section 112 which is of a larger diameter 
than the top section of the pin and can slide through shelf 111. Extending 
from the bottom of pin 107 is a rod 113. Movable with slide 90 is a shelf 
with a segmented gear rack 114 located atop said shelf. 
A pedal 108 is affixed to a pedal lever 108a which is rotatable about a pin 
115. Pin 115 is supported by U-shaped bracket 115a that is affixed to base 
80. The portion of lever 108a furthest from pedal 108 includes a yoke 108b 
and the base 112 of pin 107 abuts the top of said yoke with rod 113 
extending therethrough. Lever 108a extends through an opening 80a in base 
80. Gear rack segment 114 is a narrow segment, has its teeth facing 
upwardly and engages with gear rack 98 whose teeth face downwardly in a 
manner that will hereinafter be described. 
A second pedal 119 is provided on the opposite side of chair support guide 
76 as is pedal 108 and has structure associated therewith (not shown in 
the drawings in detail) for controlling the position of slide 90 along the 
length of powerhead support guide 54 in the same manner that pedal 108 
controls the position thereof. 
In FIGS. 4 and 5 of the drawings, chair support stand 66 is shown having a 
base plate 66a which is affixed to a slide plate 123. Slide plate 123 is 
affixed to a slide 120 which slides along the length of chair support 
guide 76. Chair support guide 76 extends perpendicularly away from the 
center of powerhead support guide 54 while being affixed thereto. 
Chair support guide 76 includes a base 132 and extending along the length 
of base 132 are bearing rods 125 and 127 which are supported in the same 
fashion as are bearing rods 86 and 88, as shown in FIG. 2. 
Movable with slide 120 are bearing sleeves 124 and 126. Bearing sleeve 124 
partially surrounds and is in slidable relation to bearing rod 125 and 
bearing sleeve 126 partially surrounds and is in slidable relationship 
with bearing rod 127. Support rails 129 and 131 extend upwardly from base 
132 and each includes a concave surface that is in contact with the 
portions of bearing rods 125 and 127 not encircled by bearing sleeves for 
support purposes. A cover plate for base 132 is provided and identified by 
reference numeral 128 and can best be seen in FIGS. 1 and 5. 
A gear rack 146, which has its teeth in a downward direction, extends 
substantially along the length of chair support guide 76 and is affixed to 
a lever 138. Lever 138 rotates about a rod 144 which is affixed to base 
132. A compression spring 133 has one end abutting against a fixed spring 
rest 135 and the other end against the top surface of gear rack 146. 
Spring rest 135 is fixed relative to base 132. 
The bottom surface of lever 138 abuts a pin 137 which slides relative to a 
boss 139, with the boss being welded or otherwise affixed to a shelf 141 
of base 132. Pin 137 has a bottom section 143 which is of a larger 
diameter than the top section of the pin and can slide through shelf 141. 
Extending from the bottom of pin 137 is a rod 145. Movable with slide 132 
is a shelf 147 with a segmented gear rack 149 located atop said shelf. 
A pedal 134 is affixed to a pedal lever 134a which is rotatable about a pin 
151. Pin 151 is supported by U-shaped bracket 151a that is affixed to base 
132. The portion of lever 134a furthest from pedal 134 includes a yoke 
134b and the base 143 of pin 137 abuts the top of said yoke with rod 145 
extending therethrough. Lever 134a extends through an opening 132a in base 
132. 
Gear rack segment 149 is a narrow segment, has its teeth facing upwardly 
and engages with gear rack 146 whose teeth face downwardly in a manner 
that will hereinafter be described. 
While two pedals are disclosed for controlling the position of powerhead 12 
along the length of powerhead support guide 54, only one such pedal is 
used to control the position of chair 56 along the length of chair support 
guide 76. 
It is to be appreciated that scale markings 150 are located on opposed 
surfaces of chair support guide base 132, as can partially be seen in FIG. 
1, and provide a visual indication of the location of the chair support 
stand on chair support guide 76. 
The muscle exercise and rehabilitation apparatus 10 as encompassed by 
powerhead 12 and controller 36 operates in the manner described in U.S. 
Pat. No. 4,691,694. Computer 30 and keyboard 34 are for data acquisition 
purposes. 
If we assume for purposes of illustration that the patient is to have his 
right leg and, more specifically, the right knee rehabilitated and 
exercised he will sit in the chair and straps 64 and 62 will be placed 
around his torso while strap 65 is utilized to strap the person's right 
leg to the chair. 
The physical therapist, based on his knowledge of the patient's physiology, 
will raise or lower the chair to a desired height and, in addition, move 
the chair back to a desired position and rotate the chair to the desired 
orientation. The therapist will depress pedal 134, causing pin 137 to 
elevate so that lever 138, which rotates in a clockwise direction, 
compresses spring 133 disengaging rack 146 from gear rack 149. As a 
consequence thereof, slide 120 will be able to slide under a force applied 
by a physical therapist along rods 125 and 127 until a desired position is 
reached. The rails associated with bearing rods 125 and 127 will support 
the rods to prevent the rods from deflecting. When it is desired to cease 
any further movement of slide 120, pedal 134 will no longer be depressed 
so that rack section 144 will engage gear rack 149 under the bias of 
compression spring 133. 
If the therapist knows the desired position for the patient, he/she can 
move slide 120 to that position by stopping the slide at the appropriate 
scale marking 150. Alternatively, the therapist can use his/her 
professional judgment to move slide 120 to the preferred position. 
In a similar fashion, the therapist will depress either of pedals 119 or 
108 compressing spring 104 (FIG. 3) and elevating rack 98 which is affixed 
to lever 100 so that the rack 98 is no longer engaged with gear segment 
114. The therapist will then move slide 90 along rods 86 and 88 until they 
are in the appropriate position adjacent the outside portion of the right 
leg of the patient. The pedal will then be released, causing the lever 100 
under the bias of spring 104 to rotate in a counterclockwise direction so 
that gear rack 98 engages the teeth of gear rack 114 thereby preventing 
lateral movement of slide 90. 
The height of powerhead 12 will be adjusted to the desired position by use 
of lever arm and clamp 50 and, in a similar fashion, the rotational 
orientation of the powerhead will be controlled by use of lever arm and 
clamp 48. Finally, the tilt of the powerhead will be adjusted by means of 
lever arm and clamp 52. 
The goal of the therapist is to align the axis of the powerhead with the 
axis of rotation of the patient's limb which is being rehabilitated while 
at the same time making sure that the patient is comfortable and safe. 
Of course, the position and orientation of the chair can be fixed prior to 
fixing the position and orientation of the powerhead or a combination 
thereof. The patient will then exercise and rehabilitate his right leg and 
after the exercise is completed, if it is desired to then exercise the 
left leg, strap 65 will be released and placed about the thigh of the 
person's left leg. It is to be appreciated that the means for securing 
straps 64, 62 and 65 are conventional and can include conventional VELCRO, 
hooks and loops or any other appropriate fastening means. 
Fixture 16 and cuff 20 will be removed from gearbox output shaft 14 shown 
in FIG. 1 and attached to the gearbox output shaft on the other side of 
powerhead 12 of FIG. 1. Pedal 119 or 108 will be depressed causing gear 
rack 98 to move out of engagement with gear rack 114, at which time the 
therapist will move slide 90 such that the powerhead is positioned outside 
the person's left leg (or, from the position partially shown in dotted 
lines in FIG. 7, to the position shown in solid lines). Pressure on the 
depressed pedal will be released locking slide 90 in place. If desired and 
necessary, the orientation and location of the chair can be further 
adjusted. The cuff will be attached to the patient's left ankle, allowing 
him to exercise and rehabilitate his left leg without having to first 
dismount from the chair after having completed his exercise and 
rehabilitation on his right leg. 
As can be seen in FIG. 7, there are a plurality of positions of chair 56 
relative to the powerhead such that an optimal position for each patient 
can be obtained. 
It is important to note that chair 56 is ergonomically designed and 
incorporates lumbar and lateral support for the patient as well as 
providing 360 degrees of rotation. By enabling the chair to be rotated for 
a full 360 degrees of seat rotation, the physical therapist can position 
the patient at numerous angles to the powerhead. 
By having scale notations on powerhead support guide 54 and scale settings 
on chair support guide 76, after a patient has utilized the muscle 
exercise and rehabilitation apparatus, the therapist can input into the 
computer the scale settings for a particular patient so that when the 
patient returns for further exercise and rehabilitation, the powerhead and 
chair can be set to the correct positions along their respective support 
guides. 
It is, of course, to be appreciated that, while reference has been made 
herein to a muscle exercise and rehabilitation apparatus utilizing a 
powerhead and controller, as illustrated in U.S. Pat. No. 4,691,694, this 
is for purpose of illustration and not limitation. The present invention 
can be used with other types of muscle exercise and rehabilitation units 
which regulate exercise and rehabilitation of a patient when seated in a 
patient chair. 
In the embodiment of the invention shown in FIGS. 8, 9 and 10, an electric 
motor 200 is affixed to base 80 and has an output shaft 202 which extends 
in a bearing relation through a mounting plate 204 which is affixed to 
base 80. Mounting plate 204 includes an opening through which shaft 202 
extends and located on the distal end of shaft 202 is a gear 206. In 
engagement with gear 206 is a timing chain 208. A rotatable lead screw 210 
is provided and the right end, as viewed in FIG. 8, is journaled in a 
bearing block 212 which is affixed to base 80. The left end of lead screw 
210 is journaled through mounting plate 204 and extends therethrough and 
terminates in a non-threaded portion 213. Rotatable with non-threaded 
portion 213 is a gear 214, and timing chain 208 is in engagement 
therewith. A pulley bracket 216 is affixed to base 80 and rotatably 
supports a pulley 218. As can be seen in FIG. 10, pulley 218 includes on 
its periphery serrations 219 which are parallel to each other and parallel 
to the axis of rotation of the pulley. A timing chain 220 includes spaced 
apart locking elements 221 which can fit into serrations 219 to prevent 
relative motion between the portion of the timing chain encircling the 
pulley and the pulley. Timing chain 220 is wrapped around pulley 218 so 
that the locking elements on the timing chain which are in contact with 
the pulley are each received within a serration. 
Timing chain 220 is affixed to clamp 222 so that when the clamp moves, as 
shown by the arrow in FIG. 10, the timing chain likewise moves. Clamp 222 
is secured to a securing member 223 which is affixed to a sleeve 224 which 
sleeve has internal threads and is in threaded engagement with external 
threads of lead screw 210. Threaded sleeve 224 is affixed to guide 90 such 
that when the threaded sleeve moves in a longitudinal direction along the 
length of lead screw 210, the guide similarly moves in a longitudinal 
direction along the length thereof. Because timing chain 220 is affixed to 
clamp 222, when the clamp moves along with sleeve 224 the timing chain 
likewise is pulled in the direction of such movement. 
Located at the right end of powerhead support guide 54 is a further pulley 
support 226 which supports a pulley 228 for rotation. Pulley 228 is 
identical to pulley 218. Rotatable with pulley 228 is a lock nut 230 
having an internal opening through which a post 234 of a potentiometer 236 
extends. Post 234 of potentiometer 236 rotates with lock nut 230 and 
pulley 228. 
Limit switch 240 having an actuator post 242 is located adjacent the left 
end of base 80 and a further limit switch 244 having an actuator post 246 
is located adjacent the opposite end of base 80. 
As a safety precaution, if slide 90 moves too far toward either end of 
powerhead support guide 54, one of the limit switches' actuator posts will 
be depressed, terminating energy to the motor so that all further movement 
of slide 90 will cease. It is to be appreciated that in the embodiment of 
the invention shown in FIG. 8, gear locking means is not provided as this 
is not necessary since, when the motor is de-energized, the longitudinal 
movement of slide 90 is prevented by reason of lead screw 210 not 
rotating. 
In FIG. 9 of the drawings, the identical structure which is used to move 
the slide 90 along the length of powerhead guide 54 is depicted for 
controlling the position of the chair along the length of chair guide 76 
and, accordingly, the reference numerals used in FIG. 9 are the same for 
identical elements that appear in FIG. 8. 
The cable and pulley structure shown in FIG. 10, while discussed in 
conjunction with positioning the powerhead support stand, is identical to 
the structure for positioning the chair support. 
It is to be noted that electric motor 200 is a reversible direction 
electric motor and controls are provided to control the actuation and 
direction of rotation thereof. When it is desired to move slide 90 to a 
particular location, motor 200 is energized, rotating shaft 202, gear 206, 
timing chain 208, gear 214 and lead screw 210. This causes threaded sleeve 
224, which is constrained from rotation, to move along the length of lead 
screw 210 together with slide 90, powerhead support stand 42 and powerhead 
12 until it reaches the desired location. As the powerhead support stand 
is moved, timing chain 220 is likewise moved, causing pulley 228 to rotate 
and causing rotation of post 234 of potentiometer 236, changing the 
resistance of the potentiometer. Knowing the change in the resistance of 
the potentiometer and how it corresponds to the location of slide 90 along 
the length of the powerhead support guide 54, it is relatively simple to 
move the powerhead support stand to a selected and desired position and to 
determine the position of the powerhead guide at any moment. In a similar 
fashion, the position of the chair support stand is controlled and 
regulated. 
It is, of course, to be appreciated that one can pre-position the location 
of the powerhead support stand and chair support stand by actuation of the 
respective electric motors before the patient is seated on the chair, 
provided, of course, this pre-positioning does not interfere with the 
patient's access to the chair. The correct position of the powerhead and 
chair for a particular patient can be stored in the computer and when the 
patient presents himself for a physical therapy session, the therapist 
will know the correct position for that particular patient by merely 
bringing up the patient's historical file on the computer screen. This 
information can then be used to move the powerhead and chair to the 
desired position. 
Having described specific preferred embodiments of the invention with 
reference to the accompanying drawings, it will be appreciated that the 
present invention is not limited to those precise embodiments and that 
various changes and modifications can be effected therein by one of 
ordinary skill in the art without departing from the spirit or scope of 
the invention as defined in the appended claims.