US3835847A

US3835847A - Portable intermittent orthopedic traction device

Info

Publication number: US3835847A
Application number: US00268565A
Authority: US
Inventors: F Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-07-03
Filing date: 1972-07-03
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17

Abstract

A portable intermittent orthopedic traction device for applying vertical or horizontal cervical traction and horizontal pelvic traction. The device utilizes a reversible motor assembly to apply traction controllable in amount by a simple lever control for a short time period. Thereafter, the motor reverses, relieving the traction for a second short time period whereupon the cycle is again initiated and traction reapplied. A time delay relay provides the timing for the system and a quick release is provided so as to allow the rapid extension or withdrawal of the tension line to a desired position. The device is adapted to connect to a door or bed in a simple and convenient manner.

Description

United States Patent Smith Sept. 17, 1974 [76] Inventor: Fenter Willie Smith, 1133 Coronada Ave., West Covina, Calif. 91790 [22] Filed: July 3, 1972 [21] Appl. No.: 268,565

[52] U.S. Cl. 128/75 [51] Int. Cl A61h 1/02 [58] Field of Search..... 128/75, 84; 242/107, 129.1, 242/1292, 129.3

[56] References Cited UNITED STATES PATENTS 2,658,698 11/1953 Leroy 242/107 R 2,776,804 l/1957 Prout ct al.... 242/1293 2,811,965 11/1957 Richards 128/75 2,940,442 6/1960 Wilhelm 128/75 3,117,572 l/1964 Wright 128/75 3,168,094 2/1965 Siltamaki 128/75 3,314,623 4/1967 Blandino 242/1293 3,710,787 l/l973 Rabjohn 128/75 Primary Examiner-Richard A. Gaudet Assistant Examiner.l. Yasko Attorney, Agent, or Firm-Boniard 1. Brown [57] ABSTRACT A portable intermittent orthopedic traction device for applying vertical or horizontal cervical traction and horizontal pelvic traction. The device utilizes a reversible motor assembly to apply traction controllable in amount by a simple lever control for a short time period. Thereafter, the motor reverses, relieving the traction for a second short time period whereupon the cycle is again initiated and traction reapplied. A time delay relay provides the timing for the system and a quick release is provided so as to allow the rapid extension or withdrawal of the tension line to a desired position. The device is adapted to connect to a door or bed in a simple and convenient manner.

2 Claims, 9 Drawing Figures PORTABLE INTERMITTENT ORTHOPEDIC TRACTION DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of orthopedic devices, and in particular to orthopedic devices for applying traction to a patient.

2. Prior Art In certain types of injuries and ailments, beneficial treatment may include applying traction to the body or various parts thereof, of the patient. Thus, in the prior art, various forms and mechanisms for applying such traction are well-known. By way of example, weights and pulley systems have been used to apply a steady and continuous traction as desired. However, it has been found that greater benefit may be achieved if the tractive forces applied are intermittent and cyclical, and preferably selected in amplitude based on the patient and the nature of the ailment.

In light of the foregoing, certain devices for applying traction in a repetitive and controlled manner are currently in use. These machines, however, are not adapted for purchase and use by a patient in his own home. In particular, these devices are expensive and heavy, and generally mechanically complicated in design, unreliable and expensive to repair. Thus, such machines as are now known are generally limited to purchase and use by doctors, hospitals, clinics and physical therapists.

There is, therefore, a need for a light weight, reliable and easily controlled portable intermittent orthopedic traction device suitable for use in the home, preferably adapted so as to be mounted and used with ease and readily removed for storage thereafter.

BRIEF SUMMARY OF THE INVENTION A portable intermittent orthopedic traction device for applying vertical and horizontal cervical traction and horizontal pelvic traction. The device utilizes a reversible motor assembly comprising a pair of shaded pole motors on a common shaft adapted to drive the shaft in opposite directions. The cord through which the traction force is applied passes over a first pulley on an arm-like member and downward past a second pulley, the axis of which further serves as a pivot axis for the arm. The arm is spring restrained in a region of the first pulley so as to deflect against the spring restraint in response to tension in the cord. A switch is mounted on the arm and is actuated in a first direction by the deflection of the arm against the restraining spring in an amount readily selectable by the user of the device. Actuation of the switch terminates the drive to the cord take up system and shortly thereafter, as determined by a time delay relay, the motor reverses, relieving the traction and resulting in the operation of the switch in a reverse direction upon return of the arm-like member to its original position, so that the time delay relay will reinitiate the operating cycle of the device. A quick release capability is provided so as to allow the rapid extension and withdrawal of the tension line to a desired position. A clamping means is provided for readily attaching the device to a door, a bed member or other similar restraining structures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the traction device of the present invention illustrating one manner of using the device.

FIG. 2 is a side view of the traction device of FIG. I with the outer enclosure removed therefrom.

FIG. 3 is a top view of the apparatus of FIG. 2.

FIG. 4 is a partial cross sectional view of the apparatus of FIG. 2 taken along lines 4-4 of FIG. 3.

FIG. 5 is a partial cross sectional view of the drum drive means taken along lines 5-5 of FIG. 2.

FIG. 6 is a partial cross sectional view taken along lines 6-6 of FIG. 5.

FIG. 7 is the second side view of the apparatus of FIG. 2 illustrating the location of various electrical components and the manner of operation of the device.

FIG. 8 is a partial cross sectional view of the motor assembly of the present invention.

FIG. 9 is a schematic diagram of the electrical interconnection of the electrical components of the present invention.

DETAILED DESCRIPTION OF THE INVENTION First referring to FIG. 1, a view of the present invention portable intermittent orthopedic traction device generally indicated by the numeral 20, as it might be used by a patient in the patients own home, may be seen. The traction device has a generally flat rear surface adapted to lie flat against the surface of the door, with a clamp, generally indicated by the numeral 22, extending over the top of the door and being adjustable so as to clamp the device to the door by a knob 24. An outer enclosure 26 encloses the mechanical apparatus of the device, with a main power cord 28 being adapted to plug into an ordinary volt 6O cycle power supply. A second power cord 30 is coupled in series with one line of the power cord 28 so that electrical power delivered to the traction device 20 may be controlled by a switch 32 at the end of the power cord 30 conveniently accessible to the patient.

A nylon cord 34 extends downward from the outer.

end of the traction device 20, and has attached to the lower end thereof a hook 36 which may be used to connect to an appliance for engaging a body member, such as the combination of member 38 and a traction harness or strap assembly 40 shown in FIG. 1 for engaging the patients head. In addition to knob 24 for clamping the traction device 20 to the door (or a bed member or other member depending on the nature of the use of the system) and switch 32 for turning on and turning off the traction device, there is also provided a lever 42 for adjusting the extent of tractive force applied through cord 34, and a knob 44 for controlling a quick take-up and release mechanism, to be subsequently described in greater detail.

FIG. 2 is a side view of the traction device 20 of FIG. 1 with the outer enclosure 26 removed therefrom. FIG. 3 is a top view of the traction device of FIG. 2, and FIG. 4 is a partial cross-section of the device taken along lines 4-4 of FIG. 3. The general frame arrangement for the traction device may be best seen in FIG. 3. A flat member 46 has fastened thereto by screws 48 a normally vertical member 50 which provides the basic spacing and support for side plates 52 through screws 54. The side plates 52 are maintained in substantially parallel relationship by additional spacing members as shall subsequently become obvious as more fully described herein.

Now referring specifically to FIG. 2, the major components of the traction device may be generally seen. The device has a motorized drive means including a reversible motor and a reduction gear assembly 56 supported by a support plate 58 attached to the reduction gear assembly (of ordinary construction) by a. plurality of screws 60, and attached to one of side members 52 by a plurality of screws 62. The reduction gear 56 drives a sprocket 64, which in turn drives a larger sprocket 66 through a chain 68, generally similar to a small bicycle chain. Socket 66 drives a drum, generally indicated by the numeral 70, located between side plates 52 on which cord 34 is wound. The cord 34 extends over a first pulley 72 and from there downward past a second pulley 74. The axis of pulley 74, as shall be subsequently more fully described, provides a pivot point for an arm 76 supporting pulley 72, so that tension in the cord 34 may cause rotation of the arm about the axis of pulley 74, which is resisted by a spring return comprised, at least in part, of coil spring 78.

The adjustment lever 42 extending outward from the case 26 of the unit is frictionally pivotally supported at point 80 so as to provide an adjustment in the position of lobe 82 integral with the lever 42. Adjacent lobe 82 is a switch actuating member 84 attached to a switch 86 supported from arm 76 by a support plate 88. Similarly, an assembly generally indicated by the numeral 90 supported by one of the side plates 52 is disposed so as to actuate switch 86 in a reverse manner as the switch moves in a direction away from lobe 82. Thus, as tension in cord 34 increases, the upper portion of arm 76 moves to the left, pivoting about the axis of pulley 74 against the force of coil spring 78, resulting in the actuation of switch 86 by lobe 82 at a selected tension in line 34 determined by the adjustment of lever 42 to determine the relative position of lobe 82. When the motor reverses, as shall be more fully described herein, tension in line 34 is reduced, allowing arm 72 to return to the position shown in FIG. 2 and to actuate the switch 86 in the opposite manner by contact with the assembly 90.

Now referring specifically to FIGS. 3 and 4, further details of the components described with respect to FIG. 2 may be seen. The device may be mounted to a door 92 by a clamp member 94 adapted to project over the top of the door and to be adjustable so as to clamp against the door. Thus, clamp 94 is adapted to slide in the slots, generally indicated by the numeral 96, in

members

46 and 50 and to be forced in a horizontal direction by a member 98 attached to the clamp member 94 by screws 100. Member 98 threadedly engages a screw member 102 rotationally supported at each end by

members

50 and 104 respectively, with an extension of the screw member 102 extending through member 104 to receive an adjustment knob 24 attached to the screw member by a set screw 106. Thus, by rotation of the knob 24, the desired clamping and releasing action may be obtained, and clamp member 94, being supported both by screws 102 and slots 96 in

members

46 and 50, provides strong clamping action as well as adequate vertical support to support the maximum tension allowable in line 34. Member 104 also acts as a separator for the side plates 52 and is rigidly attached therebetween by screws 108.

Arm 76 is basically in the form of a channel member and is adapted to receive an axle bolt through the upper end thereof, and a pivot axle 112 at the lower end thereof. Within the channel of member 76, pulley 72 is supported by the axle bolt 110, and also pivotally supported by the axle bolt is a forked member 114 supported to each side of member 76 by the axle bolt, with cap nuts 116 retaining the axle bolt 110 in place. The relative position of the axle bolt 110, as well as the axle bolt 112, is chosen in relation to the depth of the channel of member 76 so that the

pulleys

72 and 74, which have a concave periphery to matingly accept the cord 34, is chosen so that the bottom of the channel generally retains the cord 34 in proper disposition with respect to pulleys.

Attached to member 1 14 by means of a set screw 116 and a nut 118 is a rod 120 slidably projecting through a spring restraining member 122. The rod 120 is maintained in member 122 in part by a nut 124 which prevents theinadvertent withdrawal of rod 120 from member 122. Member 122 in turn is rotationally supported by slide plate 52 by means of screws 126. The lower end of member 76 is rotationally supported by axle 112, comprising a flat head screw retained in position between the two slide plates 52 by a nut 130, with cylindrical spacers 132 on each side of the member 76. (A metal axle bearing 134 is provided for each of

pulleys

72 and 74 so as to prevent the nylon pulleys from being scored by the axle.)

Thus, it may be seen that member 76 is pivotally supported by axle 112 and the top thereof is limited in its travel to the right (FIG. 4) by the engagement of nut 124 on rod 120 with member 122. On the other hand, as the line 34 is wound up on drum 70 and the tension in line 34 increases, the forces of the line on pulley 72 cause a horizontal component of force on the top of arm 76, forcing the top of the arm to the left against the yieldable and steadily increasing resistance of coil spring 78. (Fixed guide members 69 are fastened by screws to and between each side plate 52 and provide a guide for, the entry of line 34. Also, pulley 74 guides the line in this region irrespective of the rotation of member 76.)

Member 42 is supported by one of the side plates 52 and is spaced therefrom by a nylon spacer 140, with a screw 142 having a nut 144 thereon, and a washer 146 to prevent the scoring of member 42 by the screw is used to reasonably firmly encourage member 42 into abutment with the nylon spacer and the nylon spacer in turn into abutment with side plate 52. Thus, substantial frictional resistance prohibits the free rotation of member 42 about the screw 142 but allows the manual manipulation of member 42 to a new position as desired. Switch 86 is supported by a screw 146 to a mounting plate 88 which in turn is fastened to member 76 by screws (not shown), and in particular is mounted to member 76 at a position substantially above the pivotal axis for that member. Thus, as the top of member 76 is forced to move to the left (FIG. 4) as a result of tension in line 34, switch 86 will similarly move to the left until the switch actuating member 148 engages lobe 82 on member 42. Thus, member 42 provides a readily controllable selection of the peak tension in cord 34 before the switch 86 is switched by controlling the maximum compression of coil spring 78 before the switch is actuated.

Mounted to one of side plates 52 is a member which supports an adjustment screw 152 locked at a predetermined position by a lock nut 154. The purpose of this assembly is to provide for the resetting of switch 86 by the engagement of the end of screw 152 with the switch actuating member 156 on the switch. Thus, switch 86 in the preferred embodiment is a single pole, double throw switch having a first actuating member 148 to cause it to switch in a first direction and a second actuating member 156 on the other side of the switch to cause it to switch to the reverse position.

Now referring to FIGS. 5 and 6, details of the drum 70 and the drive therefor may be seen. FIG. 5 is a crosssection taken along lines 55 of FIG. 2, and FIG. 6 is a cross-section taken along lines 6-6 of FIG. 5. Drum 70 is a nylon drum and is attached to shaft 160 by a key 162 as may be best seen in FIG. 4. The drum has a first hole 164 angularly drilled through the periphery thereof, and a second hole 166 larger than the first hole drilled parallel to the axis of the drum to intercept the first hole. Thus, the end of cord 34 is attached to the drum by passing it through the first and second holes and enlarging the end thereof by a knot (or otherwise) so as to allow the withdrawal of the end of the cord into the larger hole 166 but to prevent its further withdrawal through the smaller hole 164. The shaft is supported by side plates 52 through a pair of metal bushings 168 and is retained in position by a collar 170 having a set screw 172 therein, and by member 174 which, as may be seen in FIG. 6, is retained to the shaft by a set screw 178.

Member 176 has a plurality of holes 180 therethrough equally spaced about a circular arc having its center at the center of shaft 160. Sprocket 66 similarly has a mating hole therethrough. The sprocket is generally freely supported by shaft 160 and is retained in a disposition immediately adjacent member 174 by a collar 182 locked in position by a set screw 184. A member 186 has an inward projecting flange 188 thereon, with a pin 190 pressed into a mating hole on the flange 188 at the same radius from the center of shaft 160 as the holes 180 in member 176 and the mating hole in sprocket 66. Thus, with member 186 in the position shown in FIG. 5, pin 190 projects through the hole in sprocket 190 into one of holes 180 in member 174 so as to rotationally lock the sprocket to member 174, which in turn is rotationally locked to the shaft so as to provide a drive means between the sprocket and the shaft. Member 186 is internally threaded at the end thereof to receive a threaded member 192 which has knob 44 (FIG. 1) on the end thereof, so that member 186 may be withdrawn in a horizontal position to withdraw pin 190 from the hole 188 in member 174 to allow the free rotation of drum 70 with respect to the sprocket. It is apparent that the structure just described and operable by the knob 44 constitutes a radially releasable clutch means for selectively connecting and disconnecting the drum 70 to and from its motorized drive means. The knob 44 provides a readily accessible clutch operating member for releasing and engaging the clutch means.

A coil spring, retained between flange 188 on member 186 and in an inwardly directed flange 196 on member 198 yieldably encourages member 186 into the locked position, but allows withdrawal of the pin as hereabove described by an outwardly directed force on knob 44. (Member 198 is retained to the sprocket 66 by a plurality of screws 200.) Thus, it may be seen that drum 70 may be driven in rotation by the chain drive on sprocket 66 (a relatively slow drive), or may be allowed to freely and rapidly rotate by the withdrawal of knob 44 to disengage the sprocket from the drum. In order to provide a quick windup capability, that is to provide for the quick takeup of excess line 34, a multiple turn spring 202 is provided having one end 204 projecting through a cotter pin 206 (see also FIG. 7) to provide a torsional drive for the shaft, with the other end of 208 of the spring extending upward and disposed over the top edge of one of side members 52 to provide a fixed attachment point for that end.

Now referring to FIG. 8, a cross-section of the motor assembly used in the present invention may be seen. Already described herein is the gear box 56, and sprocket 64 which is attached to the output shaft 250 of the reduction gear. The motor itself is comprised of a pair of motors of the conventional AC shaded pole type using a common shaft, with a main forward drive motor having a rotor 252 and a stater 254 containing the shaded pole, with a single winding 256 on the stater having a pair of

connections

258 and 260 thereto. A second smaller motor is comprised of a rotor 262 within a stater 264 having a winding 266 with a pair of leads thereto, one of which is connected in common with lead 260 of the larger motor and the other of which is identified as lead 268. Thus, lead 260 is the common connection for the two motors.

A bearing cap 270 supports the shaft at one end, with the shaft being supported at the other end on bearings located within the gear box 56. The entire assembly is fastened together by screws 272 extending through the various components and terminating in the housing of gear box 56, with spacers 274 appropriately spacing the staters so as to provide clearance for the windings thereon. The construction of shaded pole motors is well-known in the prior art, and by use of the two shaded pole motors as shown in FIG. 8 on a single common assembly, a reversing capability is achieved, that is, the poles on one motor are shaded so as to cause rotation of the shaft in a first direction and the poles on the other motor are shaded so as to cause rotation of the shaft in the reverse direction. In this particular invention, the larger motor is used to drive drum 70 to apply tension to cord 34, with the smaller motor driving in the reverse direction so as to unwind the cord 34 from the drum 70.

The remaining electrical components and the interconnection thereof may be seen in FIGS. 7 and 9. Aside from the electrical components heretofore described, there is mounted on one side plate 52 a relay 280 and various additional circuitry including capacitor 282. The specific elements in the circuit and their interconnection is shown in FIG. 9. Standard 1 15 volt 60 cycle AC power is applied through the main power cord 28. (A third lead for purposes of grounding the metal chassis or frame of the traction device is also used in accordance with standard practice, but for purposes of clarity is not included in FIG. 9.) One of the leads of the power cord 28, specifically lead 300, forms one of the twin leads in line 30 and is connected to switch 32 at the end thereof. Thus, switch 32 is a means for providing an on/off switch capability, with power being applied thereby to the traction device, and more specifically initially to the moving contact 320 of switch 86. As indicated with respect to FIG. 8, there are two separate motor windings which are connected so as to have a common lead, specifically line 260. This line forms the second lead in the power cable 28 as shown in FIG. 9. The second lead of the motor winding 256, specifically lead 258, is coupled to a moveable switch contact 308 of relay 280, and the second motor lead of motor winding 266 is coupled through line 268 to moving contact 310 of relay 280. The

stationary contacts

312 and 314 of relay 280 are coupled through

lines

316 and 318 respectively to the stationary contacts 304 and 306 of switch 86 respectively. Coil 330 of the solenoid 280 has one lead thereof coupled to one side of the power cord, namely lead 260, through a diode 332, with the other end of the coil 330 being coupled to line 318 through resistor 334, with capacitor 282 coupled between the two leads of the coil.

When switch 32 is closed with switch 86 and relay 280 in the positions shown in FIG. 9, power is not applied to either of the

motor windings

256 and 266. However, AC power is coupled through switch 86 and line 318 to the circuit comprised of the diode, the capacitor, the relay coil and the resistor. The resistor 334 acts as a current limiting resistor preventing the passage of sufficient current on each cycle of the AC power to cause a sufticient voltage across capacitor 282 to cause actuation of the relay. However, diode 332 rectifies the voltage applied to resistor 334 so as to cause the gradual build up in voltage (DC voltage) across capacitor 282 until after a time delay of approximately five seconds, a sufficient DC voltage exists across the capacitor to actuate the relay through coil 330. When this occurs, the moving contacts 308 and 310 of the relay move to the positions shown in phantom, with power then being applied through line 318 to the motor winding 256, causing the drum 70 to slowly wind up the cord 34. While the motor is running, capacitor 282 will continue to be charged and, therefore, the relay will stay locked in for so long as the motor continues to operate.

As tension in cord 34 increases, member 76 starts to deflect, as previously described, against the resistance of coil spring 78 until finally lobe 82 strikes the switch actuating member 148 (see also FIGS. 4 and 7). This causes the actuation of switch 86 interrupting power to the motor winding 256 and simultaneously applying power to line 316 through moving contact 320. However, the charge previously stored on capacitor 282 prevents the moving contacts in relay 280 from returning to the upper position until the capacitor discharges, through the resistance of winding 330 in the relay, to a level allowing the return of the relay to the unactuated position. Typically, in the preferred embodiment, the various parameters are chosen so that a time delay of 3 to seconds is achieved. Thus, when the relay returns to the unactuated position, power is applied through line 316 to winding 266 of the reversing motor, resulting in the counter rotation of drum 70, thereby relieving the tension in line 34. When tension has been reduced to a level ranging from between zero and, typically, approximately 5 pounds, member 76 returns to the position shown in FIG. 4, with the result that switch actuating member 156 of switch 86 contacts the end of screw 152 so as to actuate switch 86 from the position shown in phantom in FIG. 9 to the initial position shown in FIG. 9, whereupon capacitor 282 again starts to charge. (it is to be noted that at least part of the time delay in the actuation of the relay 280 is achieved by the fact that the magnetic circuit in the relay is more efficient when in the actuated position that when in the unactuated position, so that higher solenoid coil current is required to actuate the relay than is required to maintain the relay in the actuated position, thereby effectively giving an electrical hysteresis to the relay.)

As a result of the circuit hereabove described, it may be seen that the traction device of the present invention provides for automatic cyclic application and removal of a tractive force in cord 34, with the traction force being applied for a period of approximately 5 seconds and then removed for a period of approximately 5 seconds (the periods of course being readily controllable and alterable by appropriate selection of the component time delay determining components. Further, it will be noted that in the event there is substantial slack in cord 34, the take up motor will continue to run until the slack is taken up and the tension has reached the selected level determined by the position of lever 42. Of course, as herebefore described, a quick wind up and release mechanism controllable through knob 44 is also provided to quickly take up excessive slack or let out the cord 34 as may be required prior to operation of the device. Thus, there has been described herein a portable intermittent orthopedic traction device of rugged yet simple construction which may be quickly and securely mounted, either in vertical, horizontal or slanted positions, to provide a readily controllable intermittent tractive force as desired. While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

1 claim:

1. An orthopedic traction device comprising:

a frame,

means for attaching said frame to a support,

a drum rotatable on said frame,

a cord having one end for attachment to a traction harness and its opposite end attached to said drum,

drive means including reversible motor means for driving said drum in either direction of rotation to wind said cord on and unwind the cord from the drum,

readily releasable clutch means including a readily accessible clutch operating member for effecting disengagement and engagement of the clutch means, whereby said drum may be selectively released for free rotation independent of said drive means,

means responsive to the tension in said cord for controlling said motor means to effect driving of said drum in one direction to wind the cord on the drum when the cord tension is less than a preset maximum tension and in the opposite direction to unwind the cord from the drum when the cord exceeds said maximum tension, and

said motor controlling means comprises a supporting arm pivoted at one end of said frame, a pulley on the opposite end of said arm around which said cord passes in a manner such that tension in said cord urges said arm in one direction about its pivot, a spring acting between said arm and frame for urging the arm in the opposite direction about its pivot, a switch mounted on said arm including an actuating member, a lever pivoted on said frame having a portion spaced from the pivot axis of the lever and located in the path of movement of said switch actuating member with said arm for engagement with said actuating member to actuate said switch upon pivoting of said arm in said one direction, and said lever having a readily accessible end for adjusting the lever on its pivot to adjust the position ofsaid lever portion along said path, and means for conditioning said motor means to drive said drum in its said opposite direction in response to actuation of said switch by said lever.

2. An orthopedic traction device comprising:

a frame,

means for attaching said frame to a support,

a drum rotatable on said frame,

a spring connected between said drum and frame for rotating said drum in said one direction when said clutch means is disengaged,

means responsive to the tension in said cord for controlling said motor means to effect driving of said drum in one direction to wind the cord on the drum when the cord tension is less than a preset maximum tension and in the opposite direction to unwind the cord from the drum when the cord exceeds said maximum tension,

said motor means comprising relay means including contact means operable between a first position wherein said motor means is conditioned to drive said drum in its said one direction and a second position wherein said motor means is conditioned to drive said drum in the opposite direction and coil means adapted to be selectively energized to effect movement of said contact means between their said positions, switch means in circuit with said coil means, means for actuating said switch means in response to said cord tension, capacitor means connected in electrical parallel with said coil means for delaying energizing and de-energizing of said coil means following actuation of said switch means,

a supporting arm pivoted at one end of said frame, a pulley on the opposite end of said arm around which said cord passes in a manner such that tension in said cord urges said arm in one direction about its pivot, a spring acting between said arm and frame for urging the arm in the opposite direction about its pivot, a switch mounted on said arm including an actuating member, a lever pivoted on said arm having a portion spaced from the pivot axis of the lever and located in the path of movement of said switch actuating member with said arm for engagement with said actuating member to actuate said switch upon pivoting of said arm in said one direction, and said lever having a readily accessible end for adjusting the lever on its pivot to adjust the position of said lever portion along said path, and means for conditioning said motor means to drive said drum in its said opposite direction in response to actuation of said switch by said lever.

Claims

1. An orthopedic traction device comprising: a frame, means for attaching said frame to a support, a drum rotatable on said frame, a cord having one end for attachment to a traction harness and its opposite end attached to said drum, drive means including reversible motor means for driving said drum in either direction of rotation to wind said cord on and unwind the cord from the drum, readily releasable clutch means including a readily accessible clutch operating member for effecting disengagement and engagement of the clutch means, whereby said drum may be selectively released for free rotation independent of said drive means, means responsive to the tension in said cord for controlling said motor means to effect dRiving of said drum in one direction to wind the cord on the drum when the cord tension is less than a preset maximum tension and in the opposite direction to unwind the cord from the drum when the cord exceeds said maximum tension, and said motor controlling means comprises a supporting arm pivoted at one end of said frame, a pulley on the opposite end of said arm around which said cord passes in a manner such that tension in said cord urges said arm in one direction about its pivot, a spring acting between said arm and frame for urging the arm in the opposite direction about its pivot, a switch mounted on said arm including an actuating member, a lever pivoted on said frame having a portion spaced from the pivot axis of the lever and located in the path of movement of said switch actuating member with said arm for engagement with said actuating member to actuate said switch upon pivoting of said arm in said one direction, and said lever having a readily accessible end for adjusting the lever on its pivot to adjust the position of said lever portion along said path, and means for conditioning said motor means to drive said drum in its said opposite direction in response to actuation of said switch by said lever.

2. An orthopedic traction device comprising: a frame, means for attaching said frame to a support, a drum rotatable on said frame, a cord having one end for attachment to a traction harness and its opposite end attached to said drum, drive means including reversible motor means for driving said drum in either direction of rotation to wind said cord on and unwind the cord from the drum, readily releasable clutch means including a readily accessible clutch operating member for effecting disengagement and engagement of the clutch means, whereby said drum may be selectively released for free rotation independent of said drive means, a spring connected between said drum and frame for rotating said drum in said one direction when said clutch means is disengaged, means responsive to the tension in said cord for controlling said motor means to effect driving of said drum in one direction to wind the cord on the drum when the cord tension is less than a preset maximum tension and in the opposite direction to unwind the cord from the drum when the cord exceeds said maximum tension, said motor means comprising relay means including contact means operable between a first position wherein said motor means is conditioned to drive said drum in its said one direction and a second position wherein said motor means is conditioned to drive said drum in the opposite direction and coil means adapted to be selectively energized to effect movement of said contact means between their said positions, switch means in circuit with said coil means, means for actuating said switch means in response to said cord tension, capacitor means connected in electrical parallel with said coil means for delaying energizing and de-energizing of said coil means following actuation of said switch means, a supporting arm pivoted at one end of said frame, a pulley on the opposite end of said arm around which said cord passes in a manner such that tension in said cord urges said arm in one direction about its pivot, a spring acting between said arm and frame for urging the arm in the opposite direction about its pivot, a switch mounted on said arm including an actuating member, a lever pivoted on said arm having a portion spaced from the pivot axis of the lever and located in the path of movement of said switch actuating member with said arm for engagement with said actuating member to actuate said switch upon pivoting of said arm in said one direction, and said lever having a readily accessible end for adjusting the lever on its pivot to adjust the position of said lever portion along said path, and means for conditioning said motor means to drive said drum in its said opposite direction in response to actuation of said switch by said lever.