refer now in detail to fig2 a and b and 3a b which show corresponding pictorial and side views of the corresponding straight leg and bent leg configurations of the disclosed invention . in general , the frames of both configurations of the invention are constructed primarily of steel tubing which is welded together at the junctions where the tubes meet . welded to these tubular steel frames are steel flanges for journaling the bearings for the moving parts and steel tabs for attaching padded body - machine contact surfaces . as can be seen in the figures , both configurations of this invention are simple , symmetrical , straightforward designs . the primary frame of both configurations of this invention ( assembly 1 . 0 ) consist of three round steel tubing loops . the first of these ( 1 . 1 ), which lies in the machine &# 39 ; s plane of symmetry , differs in shape depending on the configuration , as shown in fig2 and 3 . the other two ( 1 . 2 ), which lie in a plane which is both perpendicular to the machine &# 39 ; s plane of symmetry and oriented at about a 45 ° angle to the ground plane , are symmetrical to each other about the machine &# 39 ; s plane of symmetry and have the same shape in both configurations , as shown in fig2 and 3 . these three loops are welded together to form a simple , stable frame for the respective configurations . in both configurations , these three loops join at their lower rearward ends in a &# 34 ; t &# 34 ; junction at the back of the machine on the ground plane . in the straight leg configuration ( fig2 a and 3a ), these three loops join at their upper ends into a rectangular tube ( 1 . 3 ) which lies in the machine &# 39 ; s plane of symmetry . the central loop ( 1 . 1 ) joins into the rectangular tube ( 1 . 3 ) on its top side just in front of the seat pad , as shown , and two side loops ( 1 . 2 ) join into the rectangular tube ( 1 . 3 ) on its sides just below the seat of the machine , as shown . in the bent leg configuration of the machine ( fig2 b and 3b ), these three loops join into a &# 34 ; cross &# 34 ; junction at their upper ends just below the seat of the machine , where the two loops to the sides ( 1 . 2 ) butt into the central loop ( 1 . 1 ), which extends rearward past the junction and bends up into a back pad support , as shown . in the straight leg configuration ( fig2 a and 3a ), a seat support pad ( 5 . 1 ) is centered about the machine &# 39 ; s plane of symmetry and mounted to frame - attached steel tabs ( 1 . 6 ) generally over the junction of the two side loops ( 1 . 2 ) and the rectangular tube ( 1 . 3 ). in the bent leg configuration ( fig2 b and 3b ), the seat support pad ( 5 . 1 ) is centered about the machine &# 39 ; s plane of symmetry and mounted to frame - attached steel tabs ( 1 . 6 ) generally over the junction of the two side loops ( 1 . 2 ) and the central loop ( 1 . 1 ). in the straight leg configuration ( fig2 a and 3a ), a back support pad ( 5 . 2 ) is centered about the machine &# 39 ; s plane of symmetry and mounted to steel tabs ( 1 . 6 ), which are attached to the &# 34 ; upright &# 34 ; leg of a 70 ° &# 34 ; l &# 34 ; shaped back support assembly ( 1 . 4 ), which is composed of two rectangular tubes joining at a 70 ° angle . the &# 34 ; base &# 34 ; leg of this &# 34 ; l &# 34 ; shaped back support assembly ( 1 . 4 ) telescopes inside of the stationary frame - mounted rectangular tube ( 1 . 3 ), as shown . in the bent leg configuration of the machine ( fig2 b and 3b ), the back support pad ( 5 . 2 ) is centered about the machine &# 39 ; s plane of symmetry and mounted in a fixed position to frame - attached steel tabs ( 1 . 6 ) on the generally upright portion at the top of the frame &# 39 ; s central loop ( 1 . 1 ). the back support assembly ( 1 . 4 ) used in the straight leg configuration of this machine is actuated to move back and forth along the axis of the engaging telescoping rectangular tubes ( 1 . 3 and 1 . 4 ) by an engaging pair of internal and external threads , as shown in detail in fig4 a . as shown in fig4 a , the rearward end of the internal thread ( 101 ) is axially and radially anchored to the &# 34 ; l &# 34 ; shaped back support assembly ( 1 . 4 ) at a position approximately where the legs meet by a transverse pin ( 102 ). the forward end of the internal thread ( 101 ) engages the rearward end of the external thread ( 103 ). the forward end of the external thread ( 103 ) is axially but not radially anchored to a steel plate ( 104 ) which s welded to the front of the external ( frame - mounted ) rectangular tube ( 1 . 3 ). attached to the front of the external thread ( 103 ) is a hand - actuated knob ( 105 ) which is used in operating the adjusting mechanism . the bent leg configuration of this machine ( shown in fig2 b and 3b ) also contains a pair of telescoping rectangular tubes . the outer frame - mounted rectangular tube ( 1 . 3 ) lies vertically in the machine &# 39 ; s plane of symmetry in a position generally directly above and extending radially away from the axis of rotation of the machine &# 39 ; s foot - engaging force - transmitting assembly ( axis a ). this rectangular steel tube ( 1 . 3 ) joins , at its bottom end , into the upper forward end of the central loop of the machine ( 1 . 1 ). also lying in the machine &# 39 ; s plane of symmetry and extending diagonally rearward from the upper end of the vertical rectangular steel tube ( 1 . 3 ) down to the central loop ( 1 . 1 ) is a rectangular tube brace ( 1 . 5 ). telescoping inside of the vertical rectangular tube ( 1 . 3 ) is a &# 34 ; t &# 34 ; shaped leg holddown assembly ( 1 . 4 ) which is composed of a vertical telescoping tube which joins into a transverse flat steel bar at its top end . leg holddown pads ( 5 . 5 ) are attached to the underside of the transverse bar on this &# 34 ; t &# 34 ; shaped leg holddown assembly ( 1 . 4 ), one on each side , in positions where they will engage the operator &# 39 ; s lower frontal thigh / knee regions while performing the exercise with legs in generally parallel planes . the leg holddown assembly ( 1 . 4 ) used in the bent leg configuration of this machine ( fig2 b and 3b ) is actuated to move up and down along the axis of the engaging telescoping rectangular tubes ( 1 . 3 and 1 . 4 ) by an engaging pair of internal and external threads , as shown in detail in fig4 b . as shown in fig4 b , the bottom end of the internal thread ( 101 ) is axially and radially anchored to the lower end of the external ( frame - mounted ) rectangular tube ( 1 . 3 ) by a transverse pin ( 102 ). the upper end of the internal thread ( 101 ) engages the lower end of the external thread ( 103 ). the upper end of the external thread ( 103 ) is axially but not radially anchored to the transverse flat steel bar at the top of the &# 34 ; t &# 34 ; shaped leg holddown assembly ( 1 . 4 ). attached to the top of the external thread ( 103 ) is a hand - actuated knob ( 105 ) which is used in operating the adjusting mechanism . as shown in fig2 and 3 , both configurations of this machine contain stationary frame - mounted ankle constraining pads ( 5 . 4 ). in the straight leg configuration of the machine ( fig2 a and 3a ), these pads ( 5 . 4 ) are attached to a steel bracket ( 1 . 7 ) which is welded to the central loop of the machine ( 1 . 1 ) in a position generally along the bottom side of its top forward flat section . as shown in fig3 a , these pads ( 5 . 4 ) are located , relative to the rotational axis of the foot - engaging force - transmitting assembly ( axis a ), in such a position that they will engage the front of the operator &# 39 ; s shins just above the ankles ( one on each side ) when the operator is in the operating position with his ankles axes of rotation approximately common with the axis of rotation of the foot - engaging force - transmitting assembly ( assembly 2 . 0 ). in the bent leg configuration of the machine ( fig2 b and 3b ), these pads ( 5 . 4 ) are attached to a steel bracket ( 1 . 7 ) which is welded to the lower forward side of the frame - mounted stationary rectangular tube ( 1 . 3 ). as shown in fig3 b , these pads ( 5 . 4 ) are located , relative to the rotational axis of the foot - engaging force - transmitting assembly ( axis a ), in such a position that they will engage the front of the operator &# 39 ; s shins just above the ankles ( one on each side ) when the operator is in the operating position with his ankles axes of rotation approximately common with the axis of rotation of the foot - engaging force - transmitting assembly ( assembly 2 . 0 ). as shown in fig2 and 3 , both configurations of this machine contain a rotating foot - engaging force - transmitting assembly ( assembly 2 . 0 ) which rotates about an axis ( axis a ) which is both common with the axes of rotation of the operator &# 39 ; s ankles while in the operating position , and which is parallel with the ground plane . this rotating assembly is journaled in bearings which are journaled in frame - attached flanges ( 1 . 8 ) which are attached to the machine &# 39 ; s central loop ( 1 . 1 ) in positions corresponding to approximately where the operator &# 39 ; s ankles axes of rotation would be when seated with legs in approximately parallel planes and extended approximately straight ( straight leg configuration ), or with legs in approximately parallel planes and bent approximately 90 at the knee joints ( bent leg configuration ), as shown in fig3 a and 3b respectively . the foot - engaging force - transmitting assembly ( assembly 2 . 0 ), in both configurations , is symmetrical about the machine &# 39 ; s plane of symmetry which is perpendicular to its axis of rotation . it is composed of five rigid parts , as shown in detail in fig5 a and 5b . the first two parts ( 2 . 1 ), one on each side of center , are flat steel plates which lie in parallel planes which are perpendicular to the assembly &# 39 ; s axis of rotation , and positioned just to the outsides of the bearings which journal the assembly in the machine &# 39 ; s frame . perpendicular to these two parallel plates is a third relatively flat transverse steel bar ( 2 . 2 ) which is welded to these two parallel plates ( 2 . 1 ), giving the assembly its integrity . this transverse member ( 2 . 2 ) extends outward approximately 5 &# 34 ; past each parallel plate ( 2 . 1 ) to each side of the assembly , and is placed , relative to the axis of rotation of the assembly ( which corresponds with the axes of rotation of the operator &# 39 ; s ankles ), in such a position that it will engage the balls of the operator &# 39 ; s feet ( one on each side of the assembly ), as shown . the last two members ( 2 . 3 ) of this rotating assembly ( one on each side ) are perpendicularly attached to the two parallel members ( 2 . 1 ). these members ( 2 . 3 ) each extend out approximately 5 &# 34 ; from the outer surfaces of the parallel members ( 2 . 1 ) and are placed , relative to the axis of rotation of the assembly ( which corresponds with the axes of rotation of the operator &# 39 ; s ankles ), in positions where they will engage the backs of the operator &# 39 ; s heels ( one on each side of the assembly ), as shown . this assembly ( assembly 2 . 0 ) is mounted to its bearings by a steel pin which is centered on the assembly &# 39 ; s axis of rotation ( axis a ) in two holes ( one in each of the parallel plates - 2 . 1 ). offset from these two holes ( one in each plate ) which lie on the assembly &# 39 ; s axis of rotation are two more holes ( one in each plate ) which are centered on the same axis ( axis c ) which is both parallel with and offset from the assembly &# 39 ; s axis of rotation ( axis a ) by a distance of 3 . 0 &# 34 ;, as shown in fig6 a and 6b . when the rotating foot - engaging force - transmitting assembly ( assembly 2 . 0 ) is in its starting position ( which corresponds to the point where the angle formed between the bottoms of the operator &# 39 ; s feet and his tibea bones is 70 °, as shown in fig6 a and 6b ), the angle formed between the line connecting axis a with axis c and the line connecting axis a with axis b must be 80 ° in the straight leg configuration , as shown in fig6 a , and 122 . 5 ° in the bent leg configuration , as shown in fig6 b , in order for the corresponding force - varying mechanisms to yield the corresponding outputs shown in the corresponding graphs for the straight leg configuration ( fig7 a ), and the bent leg configuration ( fig7 b ). as shown in fig2 and 3 , both configuration of this machine contain a rotating weight arm assembly ( assembly 3 . 0 ) which rotates about an axis ( axis b ) which is parallel with the axis of rotation of the rotating foot - engaging force - transmitting assembly ( axis a ), separated from it by a specific distance , and placed so that the assembly and any weights mounted at its distal end will clear any obstructions throughout their range of motion . in the straight leg configuration ( fig2 a and 3a ), the rotating weight arm assembly ( assembly 3 . 0 ) is journaled in bearings which are journaled in frame - attached flanges ( 1 . 9 ) which are welded to the back side of the lower forward portion of the frame &# 39 ; s central loop ( 1 . 1 ). in this configuration , the distance between the rotational axes of these two rotating assemblies ( assemblies 2 . 0 and 3 . 0 ) is 16 . 0 &# 34 ;, as shown in fig6 a . in the bent leg configuration ( fig2 b and 3b ), the rotating weight arm assembly ( assembly 3 . 0 ) is journaled in bearings which are journaled in frame - attached flanges ( 1 . 9 ) which are welded to the bottom sides of the two frame side loops ( 1 . 2 ) approximately at the &# 34 ; cross &# 34 ; junction where they butt into the central loop of the machine ( 1 . 1 ). in this configuration , the distance between the rotational axes of these two rotating assemblies ( assemblies 2 . 0 and 3 . 0 ) is 22 . 0 &# 34 ;, as shown in fig6 b . the rotating weight arm assembly ( assembly 3 . 0 ), in both configurations , is symmetrical about the machine &# 39 ; s plane of symmetry which is perpendicular to its axis of rotation . this rotating weight arm assembly ( assembly 3 . 0 ), in both configurations , is primarily composed of two parallel triangularly shaped flat steel plates ( 3 . 1 ) which contain bearings for rotation of the assembly at one angle , bearings for connecting a connecting link between the two rotating assemblies at another angle , and a transversely mounted weight support bar ( 3 . 2 ) at the third angle , as shown in the side views ( fig3 a and 3b ). the axis of rotation of the assembly ( axis b ), the axis for connecting the connecting link between the two assemblies ( axis d ), and the axis of the weight support bar are all parallel . the distance between the axis of rotation of the assembly ( axis b ) and the connecting link &# 39 ; s axis of connection ( axis d ) is 8 . 0 &# 34 ; in the straight leg configuration , as shown in fig6 a , and 7 . 0 &# 34 ; in the bent leg configuration , as shown in fig6 b . the distance between the axis of rotation of the assembly ( axis b ) and the axis of the weight support bar ( 3 . 2 ) is 16 . 0 &# 34 ;, in both configurations , as shown in fig6 a and 6b . the two rotating assemblies on this machine ( assemblies 2 . 0 and 3 . 0 ) are mechanically linked to each other by a rigid steel bar ( 4 . 0 ) which contains parallel bushings at its opposite ends . one end of this connecting link ( 4 . 0 ) connects , by way of a steel pin , to the rotating foot - engaging force - transmitting assembly ( assembly 2 . 0 ) at axis c , as shown in fig3 and 6 . the opposite end of this connecting link ( 4 . 0 ) connects , by way of another steel pin , to the rotating weight arm assembly ( assembly 3 . 0 ) at axis d , as shown in fig3 and 6 . the distance between the axes of the parallel bushings on this connecting link ( 4 . 0 ) is 19 . 0 &# 34 ; in the straight leg configuration , as shown in fig6 a , and 21 . 0 &# 34 ; in the bent leg configuration , as shown in fig6 b . when the rotating foot - engaging force - transmitting assembly is in its starting position ( which , as stated earlier , corresponds to the point where the angle formed between the bottoms of the operator &# 39 ; s feet and his tibea bones is 70 °), the angle formed between the line connecting the axis of rotation of the weight arm assembly with the axis of the weight bar and the horizontal must be approximately 10 ° below horizontal in the straight leg configuration , as shown in fig6 a , and approximately 20 ° below horizontal in the bent leg configuration , as shown in fig6 b , in order for the corresponding force - varying mechanisms to yield the corresponding outputs shown in the corresponding graphs for the straight leg configuration ( fig7 a ), and the bent leg configuration ( fig7 b ). in the straight leg configuration of the machine , a bumper ( 3 . 4 ) is attached to a flat steel connecting piece ( 3 . 3 ) which is welded transversely between the two parallel plates ( 3 . 1 ) at the bottom of the rotating weight arm assembly ( assembly 3 . 0 ) in a position just behind the bearings where the connecting link attaches , as shown in fig3 a . in the straight leg configuration of the machine , a disengageable weight support assembly ( assembly 6 . 0 ) is journaled in bearings which are journaled in frame - attached flanges ( 1 . 10 ) which are located generally below the position of the weight supporting bar ( 3 . 2 ). this weight support assembly ( assembly 6 . 0 ) is composed of a weight support arm ( 6 . 1 ) which extends radially away from the assembly &# 39 ; s axis of rotation . integral to and sharing a common axis of rotation with this weight support arm is a hand lever ( 6 . 2 ) which extends generally upward when it ends in a hand grip ( 6 . 3 ) at its distal end which is located in a position just in front of the operator , as shown in fig2 a and 3a . in the bent leg configuration of the machine , a stationary weight support bracket ( 6 . 0 ) is welded to the frame of the machine in a position generally below the weight support bar ( 3 . 2 ), as shown in fig2 b and 3b . as is illustrated in fig6 a ( straight leg configuration ) and fig6 b ( bent leg configuration ) the rotating foot - engaging force - transmitting assembly ( assembly 2 . 0 ), the rotating weight arm assembly ( assembly 3 . 0 ), the connecting link ( part 4 . 0 ), and the frame of the machine ( assembly 1 . 0 ) join to form a 4 - bar linkage . this 4 - bar linkage , as described in fig6 a ( straight leg configuration ) or fig6 b ( bent leg configuration ), when working in conjunction with the sinusoidally changing values of force applied by the respective configuration &# 39 ; s rotating weight arm as the weights swing through a circular path through the gravitational field , yields the variably resistive force shown in fig7 a ( straight leg configuration ) or fig7 b ( bent leg configuration ), which closely corresponds to the strength - to - position capabilities of the average operator in this body movement . to use the machine , an operator would simply sit on the seat portion and position his feet in the rotating foot - engaging force - transmitting assembly ( entering in from the sides where there is open access ). he would then adjust the telescoping tube actuating hand knob ( 105 ) until the axis of rotation of his ankles were approximately common with the axis of rotation of the rotating foot - engaging force - transmitting assembly . if in the straight leg configuration of the machine , he would then pull back on the disengageable weight support hand grip ( 6 . 3 ) and lower the weights to the starting position ( which , as stated earlier , corresponds to the point where the angle formed between the shins of the legs and the bottoms of the feet is 70 ). once in the starting position , he would then begin the exercise by contracting his calf muscles which would extend his feet ( plantar flexion ). the muscle developing resistance to this movement would be variably applied to the balls of the operator &# 39 ; s feet through circular paths about his ankles axes of rotation through body - machine contact with the transverse member of the foot - engaging force - transmitting assembly ( 2 . 2 ) which is mechanically linked to the weights loaded on the weight support bar ( 3 . 2 ) through the rigid members of the 4 - bar linkage / rotating weight arm force - varying mechanism . because the machine disclosed in this application applies resistive force to the balls of the feet through circular paths about the ankle axes , which is the same path which the balls of the feet move through in pure extension ( plantar flexion ) of the feet , relative motion between the balls of the feet and the body - machine contact surfaces which they come in contact with is eliminated . this , in turn , results in reduced wear to the balls of the feet and shoes , and increased isolation of the foot extending calf muscles . this machine applies a resistive force to the balls of the feet which both varies as a function of ankle axes rotation and is correlated to the normal strength - to - position capabilities of an average operator &# 39 ; s foot - extending calf muscles . this variably resistive force is obtained through the use of a 4 - bar linkage acting in conjunction with a rotating weight arm . this force - varying mechanism consist of only three moving parts connected to each other and to the frame of the machine at a total of only four pivotal joints , making the machine inherently more reliable , less noisy , and more friction free than a machine utilizing cams , chains , or cables .
a calf exercising machine which utilizes a frame - journaled rotating foot - engaging assembly , which rotates about an axis which is approximately common with the axes of rotation of the operator &# 39 ; s ankle joints , to apply resistive force to the balls of an operator &# 39 ; s feet through circular paths about the axes of rotation of the operator &# 39 ; s ankle joints . the machine fixes the positions of the operator &# 39 ; s ankle joints , through the use of body - machine contact surfaces which apply constraining forces to the operator &# 39 ; s body , which balance the components of force applied at the ball - of - the - foot - engaging force - transmitting contact surfaces , throughout the range of the exercise movement . a second rotating body , which contains provision for loading weight onto , is journaled to the machine &# 39 ; s frame and is mechanically linked to the rotating foot - engaging assembly . together , these two rotating bodies , the link joining them , and the frame of the machine form a 4 - bar linkage , which acts in conjunction with the rotating weight arm , to vary the resistive force applied to the balls of the operator &# 39 ; s feet , throughout the exercise movement .