Exercise Apparatus

Abstract

An exercise apparatus comprising a pair of relatively rotatable friction members, one of which is driven from a rotatable spool through a ratchet and pawl assembly. A rope wound on the spool drives the members when the rope is pulled and a centrifugal brake clamps the members to increase the friction force responsive to the speed at which the rope is pulled. In one form, the frame is rockable against springs. A follower moves along a helical groove in the spool and carries a marker for indicating the relative force exerted on the rope during each pull. A spring windup mechanism returns the rope for repeated pulling operation.

Description

This invention relates to exercising apparatus, and more particularly, to apparatus wherein a rope is pulled against a yieldable resistive force during the exercise operation.

Various devices have been utilized for permitting repetitive exercise. These have generally involved structures in which a rope is wrapped around a member for resisting the pull on the rope by the friction generated between the member and the rope. While these devices have met with general acceptance and some may be quite helpful in permitting isotonic and isometric repetitive exercises, they have certain limitations for use in a well rounded, body and endurance conditioning, program.

It has generally become recognized that such a program should provide for the working of the various muscles under loads which are tailored for the various exercises carried out and for the ability of the muscles to perform throughout all of the various body positions assumed during the exercise. Isometric exercises are adequate for strengthening a muscle at a given position but it has been learned that this type of exercise has very little effect toward strengthening the muscle throughout the entire range of muscle contraction. Similarly, isotonic exercises work the muscle under load throughout its contracting range but the load is uniform throughout the range and must accordingly be sufficiently small that it can be overcome even when the muscle and body are in positions of least ability.

Ideally, an exercising device should provide a resistance to the muscle which matches the user's specific muscular capacity throughout the entire range of movement. This means that the load must be variable and must automatically work the muscle at its maximum ability at every position throughout the entire range of motion if maximum conditioning is to be achieved. Exercise which involves maximum effort through a complete range of motion has been termed isokinetic exercise.

Apparatuses have heretofore been suggested for accomplishing isokinetic exercise. These have involved complicated motor driven machinery wherein a particular movement is preprogrammed in the machine and the exerciser serves as a pacer to permit the user to carry out the exercise at the speed set up in the program. Such machines have been complicated, are extremely expensive and do not lend themselves to ready portability and home use.

Accordingly, it is the primary object of this invention to provide an exercise apparatus which automatically accommodates the resistance afforded by the apparatus to the user's immediate and specific muscular capacity throughout the entire range of motion during the exercise.

It is another important object of the invention to provide apparatus which provides automatic braking action responsive to the pull of the rope so that the harder the rope is pulled, the greater the resisting force, thereby insuring maximum effort through the entire exercise range.

Still another object of this invention is to provide an apparatus to permit isokinetic exercising which utilizes a relatively simple braking device responsive to centrifugal force generated in the apparatus during the use thereof so that the apparatus may be relatively economically fabricated and maintained.

A yet further object of the present invention is to provide an exercising apparatus utilizing a novel rope rewinding device so that the apparatus is automatically readied for continued repetitive exercise programs.

Another object of this invention is to provide an optional, timed lock to permit initial isometric exercising upon the initiation of an isokinetic exercise repetition.

Still another object of this invention is to provide novel means for insuring level, uniform winding of the rope upon the rewind spool.

A further object of one form of the present invention is to provide simple, easily fabricated, yet highly reliable means for recording the relative force exerted by pulling on the rope throughout the entire range of motion so that a user may accurately observe progress from the conditioning program.

A very important object of this invention is to present a relatively lightweight and highly portable exercise apparatus which is suitable for home as well as institutional use and which lends itself to virtually every conceivable pulling, lifting and pushing exercise which may form a part of a beneficial body conditioning program.

These and other objects of this invention will be further explained or will become apparent from the specification, claims and drawings.

In the drawings:

FIG. 1 is a front, top perspective view on a reduced scale illustrating an exercise apparatus embodying the principles of this invention;

FIG. 2 is a fragmentary, front elevational view thereof with the cover removed, parts being broken away to reveal details of construction;

FIG. 3 is a fragmentary top plan view thereof with the cover removed;

FIG. 4 is a side elevational view thereof with the cover removed, parts being broken away to reveal details of construction;

FIG. 5 is a detailed cross-sectional view through the spool shaft illustrating the ratchet and pawl assembly;

FIG. 6 is a fragmentary side elevational view of the rotating member and lock assembly, one side of the frame having been removed to reveal details of construction;

FIG. 7 is a fragmentary vertical cross-sectional view through the spool assembly;

FIG. 8 is a fragmentary side elevational view of the brake structure illustrating the components thereof in their clamped positions;

FIG. 9 is a fragmentary, vertical cross-sectional view through a modified form of exercising apparatus having components for recording the relative force exerted during pulling of the rope; and

FIG. 10 is a fragmentary, top plan view of the apparatus of FIG. 9, parts being broken away to reveal details of construction.

Referring initially to FIGS. 1-8, apparatus embodying the principles of this invention is broadly designated with the reference numeral 20 and includes a support 22. The latter may comprise a casting including an upwardly extending base portion 24 having an uppermost substantially flat surface 26. Support 22 is thus configured in a generally inverted dish shape to present a compartment 28 beneath surface 26 as is illustrated best in FIG. 6. A pair of outwardly extending wings 30 (FIGS. 1 and 6) are integral with portion 24 and present surfaces upon which the user of apparatus 20 may place his feet during exercising procedures as will be subsequently explained.

A pair of spaced apart upwardly extending rigid frame members 32 and 34 are secured to respective opposite sides of the upwardly extending portion 24 and are interconnected adjacent the uppermost ends of members 32 and 34 by a transversely extending rod 36. A transversely circular shaft 38 extends between members 32 and 34 and is journaled therein by suitable bearings in each frame member.

A relatively large gear 40 is pinned to shaft 38 so that the gear 40 rotates with shaft 38. The innermost surface of gear 40 facing frame member 34 is suitably configured to carry thereon a plurality of dogs 44 illustrated in FIGS. 5 and 7. To this end, a stub shaft 46 for each dog 44 is carried by gear 40 and projects outwardly therefrom for pivotally coupling the corresponding dog 44 thereto for swinging movement about its respective shaft 46. Each shaft 46 has mounted thereon a torsion spring 48 (FIG. 5) engaging the gear 40 and the corresponding dog 44 for biasing the latter in a counterclockwise direction as illustrated in FIG. 5. The outermost ends of the dogs 44 are bevelled as shown in FIG. 5 for cooperating with a series of spaced apart integral projections 50 extending radially inwardly from an annular dish shaped enlargement 42 formed at one end of a rope windup spool 54. The latter is journaled over shaft 38 and is provided with an axially extending enlarged bore 56. A torsion spring 58 is wound on shaft 38 and is contained within bore 56 as illustrated in FIG. 7. One end of spring 58 is secured to frame member 34 and the opposite end thereof is secured to enlargement 42 for exerting a biasing force tending to rotate spool 54 about shaft 38 in one direction.

It should be pointed out at this juncture that dogs 44 are disposed with respect to the stub shafts 46 and projections 50 so that rotation of spool 54 in one direction causes a corresponding rotation of gear 40 by virtue of the engagement of the end of one of the dogs 44 between a pair of projections 50. This rotation of spool 54 with respect to the frame winds spring 58 which subsequently, upon the release of the rotational forces from spool 54, causes the latter to be turned in an opposite direction about shaft 38. The turning of spool 54 in such opposite direction does not, however, turn gear 40 since the projections 50 merely swing the dogs 44 against the bias of force 48 and the orientation of the dogs 44 is such that no driving force may be imparted through the latter to gear 40.

The outer intermediate surface 60 of spool 54 is provided with an elongated continuous radially outwardly extending ridge 62. Ridge 62 is disposed in a helical fashion throughout a substantial portion of the length of surface 60 thereby presenting an elongated helically extending groove 64 in surface 60. It is to be noted that groove 64 is arcuate to substantially complementally embrace the outer arcuate surface of an elongated flexible element in the nature of a rope 66 having one end thereof secured to spool 54 proximal portion 52. The groove 64 serves as a guide to insure uniform winding of rope 66 on the spool as will be subsequently more fully explained.

A transversely circular shaft 68 extends between frame members 32 and 34 in horizontally spaced relationship from shaft 38 and the ends of shaft 68 are journaled for rotation in the respective members 32 and 34 by suitable bearings. A sprocket 70 is rigidly secured to shaft 68 and is operably engaged with gear 40. Friction resistive means broadly designated by the reference numeral 72 is carried by shaft 68 and includes a first member in the form of a disc 74 carried on the outer ends of a pair of spaced apart elongated rods 76 and 78 extending parallel to shaft 68. The rods 76 and 78 each respectively extends through a corresponding outwardly projecting leg 80 of a pair of L-shaped brackets 82 rigidly secured to shaft 68 on opposite sides thereof (one of which is removed in FIG. 8 for clarity) and rotatable with the latter. The rods 76 and 78 are threadably received in suitable apertures through frustoconical disc 84 also received over shaft 68. A second frustoconical disc 86 is positioned opposite disc 84 so that the surfaces of the discs at the smaller ends of the conical frustums are in mutual engagement. Disc 86 is also received over shaft 68 and rods 76 and 78 as illustrated best in FIG. 2. Springs 88 are interposed on each of the rods 76 and 78 intermediate bracket legs 80 and corresponding nuts 90 threaded on the outermost ends of the respective rods 76 and 78.

By virtue of the construction of the discs 84 and 86 together with their association with guide rods 76 and 78, a force exerted parallel to shaft 68 against the largest planar surface of disc 84 causes the latter to move to the left as viewed in FIG. 2. Since disc 84 threadably receives the rods 76 and 78, such movement may occur only against the yieldable bias of the springs 88 as the latter are compressed between nuts 90 and bracket legs 80. Movement of disc 84 to the left causes the latter to push against disc 86 to force disc 86 to slide on rods 76 and 78 in the same direction. This, in turn, moves the smaller disc 74 to the left.

The movement of disc 74 clamps the same against an elongated stationary friction member 92 in the nature of a block of frictionable fabric material. Preferably, member 92 may be constructed from fiber impregnated with a zinc wire mesh and is of the same material having advantageous friction characteristics such as is used in brake linings for automobiles or the like.

Member 92 is provided with a pair of suitably positioned spaced-apart apertures receiving shaft 68 and rod 36 respectively so that member 92 is held stationary at all times irrespective of the rotation of shaft 68. It is to be pointed out, however, that the apertures extending transversely through member 92 are sufficiently large to permit limited axial shifting of member 92 longitudinally with respect to shaft 68.

This shifting of member 92 toward the left as shown in FIG. 2 is limited by a member in the form of a disc 94 rigidly secured to shaft 68 on the opposite side of member 92 from disc 74. Another disc 96 of substantially greater diameter than disc 94 is disposed adjacent the latter and is rigidly secured to shaft 68 by a pin 43. Disc 96 has a notch 98 in the outermost periphery thereof as illustrated best in FIG. 4.

Referring now particularly to FIG. 8, a collar 100 is rigidly secured to shaft 68 and is also rigidly secured to the brackets 82 (only one of which appears in FIG. 8). A pair of opposed L-shaped levers 102 are pivotally secured between brackets 82 on pins 104 with the short legs 106 of the respective levers 102 lying generally parallel with the proximal planar surface of disc 84. Weights 108 are secured at the outermost ends of the longer legs 110 of each lever respectively. The pins 104 extend substantially perpendicular to the longitudinal axis of shaft 68 to permit the outward swing of the legs 110 of the levers at an angle with respect to the axis of shaft 68 under the influence of centrifugal force when the shaft is rotated. To this end, the weights 108 increase the effect of the centrifugal force in swinging the levers generally to the positions illustrated in FIG. 8. It is to be noted that such outward swinging of levers 102 result in the legs 106 pressing against the proximal surface of disc 84 for pushing the latter longitudinally along shaft 68. This also results in the shifting to the left as viewed in FIG. 8 of disc 86 and member 74 thereby clamping member 92 between disc members 74 and 94. Manifestly, the clamping of member 92 between the members 74 and 94 results in the generation of frictional forces from the sliding of the corresponding surfaces of members 74 and 94 against member 92 as shaft 68 rotates. The friction force thus generated resists the rotation of shaft 68. The frustoconical configuration of disc members 84 and 86 insures that the force resulting from levers 102 for moving the disc members along a path of travel toward the stationary member 92 will be applied substantially centrally of member 74 so that the resistive force of the frictional engagement between members 74 and 92 will be substantially uniform throughout the entire path of rotary travel of member 74.

In the embodiment of the invention chosen for illustration in FIGS. 1-8, lock means is provided for holding the rotatable disc members from rotating for a predetermined time interval. Such lock means is broadly designated by the reference numeral 112 and comprises a U-shaped element 114 having opposite ends pivotally received over rod 36. Torsion springs 116 for each end of member 114 engage the corresponding frame members 32 and 34 to bias the member 114 in a counterclockwise direction as illustrated in FIG. 4. A bracket 118 is secured to the upper surface of portion 24 of support 22 and extends upwardly therefrom. A lever 120 is pivotally secured intermediate its ends to the upper end of bracket 118. An inturned leg 122 (FIGS. 2 and 3) at one end of lever 120 is disposed to engage notch 98 in disc 96. The opposite end of lever 120 receives an elongated bent rod 124 which is, in turn, hooked into member 114 as shown most clearly in FIGS. 2 and 3. Springs 126 and 128 are interposed on either side of lever 120 and are secured to the lowermost end of rod 124 between washers 130 to permit limited relative movement of lever 120 with respect to rod 124 either upwardly or downwardly against the bias of springs 128 and 126 respectively.

To this point, it will be clear that when member 114 is swung to the position thereof illustrated in FIG. 6. Lever 120 is rotated to a position which results in engagement of leg 122 in notch 98. This prevents rotation of disc 96 and shaft 68. By the same token, when member 114 is moved to the position illustrated in FIG. 4, lever 120 is disengaged from notch 98 and shaft disc 96 and, consequently, 68 are free to rotate. Means for holding member 114 in the locking position for a limited interval of time and for automatically releasing the locking mechanism is broadly designated by the reference numeral 132 and includes an L-shaped rod 136 received through an aperture in the bight of member 114. Rod 136 extends downwardly and is rigidly secured in the top of a bulb 138 of resilient material such as rubber or the like, having a lowermost annular rim 140 adapted to sealingly engage a smooth surface 142 formed in upwardly projecting relationship from surface 26 of support 22. A bracket 144 secured to support 22 extends upwardly therefrom and pivotally mounts a lever 146 which is loosely received over rod 136 for maintaining bulb 138 in general alignment over surface 142 at all times. A handle or knob 148 is secured to the outermost end of L-shaped rod 136 and projects outwardly from a cover 150 which may be placed over the operating mechanism of apparatus 20.

Accordingly, when it is desired to lock the resistive components of apparatus 20 so that the device may be used for isometric exercising at the beginning of an isokinetic exercise, the user may push knob 148 downwardly. A slot 152 in cover 150 permits downward movement of rod 136 which also results in the swinging of member 114 to the position illustrated in FIG. 6. Bulb 138 is squeezed by this action whereupon a vacuum is created within the bulb by the sealing action of rim 140 on surface 142. The position of member 114 moves lever 120 to a position where leg 122 engages the outer rim of disc 96. When notch 98 is rotated to the location of leg 122, the latter enters the notch to lock disc 96 and shaft 68 from further rotation. The vacuum holds member 114 in the position for locking shaft 68 against rotation only until the restoring characteristics (an inherent function of the material and its form) of the material from which bulb 138 is constructed slowly expand the bulb to its original condition whereupon the vacuum is lost. Manifestly, springs 116 assist in restoring bulb 138 to the vacuum losing position and they continue to swing member 114 to its original position removing leg 122 of lever 120 from notch 98. This releases shaft 68 for rotation.

In operation, the user may stand upon the wings 30 and grasp a T-shaped handle 154 which is attached to the end of rope 66 remote from spool 54 by a releasable fastener 156. The cover 150 may be molded for convenient storing of handle 154 in the position illustrated in FIG. 1.

Upward pulling on the handle unwinds rope 66 and results in the turning of spool 54 about shaft 38. The ratchet means which couples spool 54 with the remaining drive components, namely gear 40 and sprocket 70 produces a resultant rotation of shaft 68. The clamping of members 74 and 94 against the fixed member 92 resists rotation of shaft 68 and therefore resists the unwinding of rope 66 to create the load necessary for conducting the exercise. The greater the force exerted on rope 66 by the user, the further levers 102 swing outwardly in response to centrifugal force. Consequently, the swinging of levers 102 increase the clamping force on the movable members with respect to the fixed member 92 thereby increasing the frictional resistance along the path of travel of the movable members. Consequently, the load throughout the entire range of motion during an exercise is automatically adjusted to the ability of the user to move the load at any particular position throughout the exercise. This insures that the muscles are conditioned by maximum work at all positions throughout the entire range of motion.

As soon as rope 66 has been pulled to the extent desired for one repetition of the exercise, the user may release his pull on the rope whereupon spring 58 automatically rewinds the rope upon spool 54. Apparatus 20 is thereby returned to a ready position for the next successive repetition. Obviously, apparatus 20 is designed to permit continued successive repetitions of the exercise as may be desired by the user for carrying out his conditioning program.

As previously explained, the user may preset the locking mechanism to permit isometric exercising prior to isokinetic exercises. The lock will automatically release after a predetermined interval of time (such interval being, of course, governed by the restoring characteristics of bulb 138) to permit movement of the rope following the isometric exercise.

From the foregoing, it is apparent that rope 66 is a component of a drive means adapted to be operated by the user of the apparatus and the drive means is responsive to the amount of force applied by the user. The drive means is operably coupled through mechanism including gear 40 and sprocket 70 to a movable member 74. Means including shaft 68 journaled in frame members 32 and 34 mounts member 74 for 360.degree. rotation relative to a stationary, friction member 92, and for shifting movement toward and away from the friction member. Centrifugal force responsive structure which includes the weighted, pivoted levers 102 are mounted on shaft 68 for rotation therewith and, acting through the frustoconical discs 84 and 86, serve to move member 74 toward or away from the stationary friction member 92 responsive to the speed of rotation of the shaft and, hence, the rotatable member 74. The latter is, of course, shifted toward member 92 to increase the frictional resistance to rotation from the mutually engageable surfaces of members 92 and 74 when the force on rope 66 increases and away from member 92 to decrease the resistance force when the pull on rope 66 is lessened. Thus, the resistance to the force exerted by the user is correlated to the amount of such force. The rotatable member engageable with the fixed friction member 92 is, in the preferred embodiment, augmented by the rotatable backing disc or member 94 which permits a clamping of the friction member 92 between the members 74 and 94 under the control of the centrifugally responsive levers 102.

A carrying handle 158 is preferably provided at the top of cover 150 for permitting ready portability of apparatus 20. Further, the compartment 28 may, if desired, be provided with a releasable bottom member (not shown) to permit storage of accessory items useful in the conditioning program and a spare rope or the like.

The modified form of apparatus illustrated in FIGS. 9 and 10 is broadly designated by the reference numeral 220 and is constructed generally similar to apparatus 20. In this case, frame members 232 and 234 are interconnected by a cross member 235 which is rigidly secured to and may be integral with members 232 and 234. The members 232 and 234 are each provided with an arcuate corner 237 to permit tilting of the frame about pivot means 239. It is to be understood that there is a pivot means 239 for members 232 and 234 respectively, each pivot means 239 securing each respective frame member to a corresponding one of a pair of upwardly extending brackets 241 which are secured to support 222. A pair of springs 243 extend between the respective frame members and support 222 to hold the frame members in the positions illustrated in FIG. 9. A pedestal 245 may be provided integral with each member 232 and 234. Pedestals 245 provide a rest limiting the clockwise swinging about the respective side pivots 239 as illustrated in FIG. 9. Spool 254 is mounted for rotation on shaft 238 which is journaled in members 232 and 234. It is to be noted that the longitudinal axis of shaft 238 is spaced horizontally and vertically from the horizontal axis of swinging of members 232 and 234 about pivot means 239. As a result of such spacing, the upward pull on rope 266 produces a moment in the frame tilting the latter in a counterclockwise direction as viewed in FIG. 9 and against the bias of springs 243.

An elongated rigid helical rod 247 is bent to complementally ride in the helical groove 264 of spool 254 and to project forwardly from the frame. A socket 249 carried at the outermost end of rod 247 receives one end of a marker 251 and a spring 253 in socket 249 yieldably urges marker 251 outwardly so that the point of the latter engages an indicator card 255. The latter may be removably positioned on the inner face of a swingable door 257 by means of a holder 259. Toggle means 261 releasably maintains door 257 in the position illustrated in FIG. 9 yet permits the same to swing about hinge means 263 to an open position whereupon the indicator card 255 may be removed or replaced. Door 257 may include a panel constructed of transparent material, if desired, and card 255 may comprise a sheet of tracing or otherwise partially translucent paper or the like so that any markings made on the paper are immediately visible externally of apparatus 220.

A rod 265 extends transversely of apparatus 220 between members 232 and 234 and is received in a bend 267 in rod 247. Means such as a cover 269 secure rod 247 to rod 265 yet permit the sliding of rod 247 longitudinally along rod 265. Rod 247 is configured to shift longitudinally of spool 254 when the latter is rotated. Such shifting carries the marker 251 therealong.

The remaining components of apparatus 220 are substantially similar to those previously described with respect to apparatus 20 and need not be further described at this point. When the user pulls on rope 266 during the exercise operation, the moment imparted to the frame comprising members 232, 234 and 235 tilts the frame about pivot means 239. The extent of tilting will, of course, be in direct relation to the amount of force exerted on rope 266.

Further, the pulling on rope 266 will result in the rotation of spool 254 which also shifts rod 247 and marking means 251 longitudinally of spool 254 during the exercise operation. This will result in a trace being marked on indicator card 255 which trace will reveal to the user the relative force exerted in pulling the rope throughout the exercise operation. The indicator card, so marked, serves to record for the user the magnitude of his exertions during the exercise and may thus serve to tell the user of progress which he makes throughout the conditioning program.

A rope guide in the nature of a rigid ring 271 is welded to rod 247 and projects laterally from the trailing side of the latter in alignment with groove 264. The rope 266 is threaded through ring 271 as illustrated in FIG. 10. Inasmuch as rod 247 travels in groove 264, ring 271 holds the rope 266 in alignment with the groove to positively insure that the rope is wound within the groove without any possibility for one turn of the rope overlapping another turn. This cooperates with the nature of the groove itself in positively insuring level winding of the rope during repeated operations of apparatus 220.

Claims

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. Exercising apparatus comprising:

a first movable member;

a second member;

means mounting said first member in juxtaposition with the second member for 360.degree. rotation relative to the second member and for shifting movement toward and away from said second member, said members having mutually engageable surfaces for generating frictional resistance when the first member is rotated relative to the second member with said surfaces in mutual engagement;

force responsive drive means;

mechanism operably coupling the drive means with the first member, said drive means being adapted to be acted upon by the user to rotate the first member at speeds corresponding to the amount of force exerted by the user on said drive means; and

centrifugal force responsive structure operably coupled with said first member and responsive to the speed of rotation of the latter for urging said first member toward the second member to increase said frictional resistance as said speed of rotation of the first member increases and to withdraw the first member from the second member to decrease said resistance as said speed of rotation decreases, whereby the resistance to the force exerted by said user is correlated to the amount of said force.

2. The invention of claim 1, wherein said first member includes a pair of spaced apart discs, said second member being received between the discs, said mounting means including an elongated rotatable shaft, said discs being mounted on said shaft with one disc being movable longitudinally of the shaft and the other disc being fixed against said longitudinal movement, and wherein said centrifugal force responsive means includes a pair of elongated levers pivotally secured to the shaft for rotation therewith and having ends operably engageable with said one disc in disposition to shift the latter longitudinally of the shaft toward said other disc upon outward pivoting of the levers, and weight means carried by each lever respectively in position to effect outward pivoting of the levers responsive to centrifugal force during rotation of the shaft, said drive means being operably coupled by said mechanism with the shaft for rotating the shaft, whereby the levers clamp the discs upon the second member responsive to the speed of rotation of the shaft.

3. The invention of claim 2, wherein is provided spring means operably associated with said discs for normally holding the latter apart to prevent clamping of said other member until said centrifugal force is sufficiently great to overcome the force of said spring means.

4. The invention of claim 2, wherein said drive means includes a flexible element and a windup spool for said element.

5. The invention of claim 4, wherein said drive means includes a ratchet wheel coupled with said spool, a dog coupled with said shaft and engageable with said wheel upon rotation of the spool in one direction for rotating the shaft, and spring means secured to the spool for rotating the latter in the opposite direction to wind said element thereon, whereby said spool may be rotated to drive the member through the ratchet means by pulling on the element.

6. The invention of claim 1, wherein said second member is constructed of frictionable fiber material.

7. The invention of claim 1, wherein is included lock means engageable with said one member for holding the latter against rotational movement relative to the other member, said lock means including time delay means operable to automatically release the lock means to permit said movement upon the expiration of a predetermined interval of time.