# Patent

## Title
Linear motion synchronizing mechanism and exercise assemblies having linear motion synchronizing mechanism

## Abstract

A linear motion synchronizing mechanism is for an exercise assembly having elongated first and second rocker arms that pivot with respect to each other about a first pivot axis. A first roller is retained on a first roller supporting member and a second roller retained on a opposing second roller supporting member. The first and second rollers are configured to roll along opposite sides of a linear frame member as the body moves in the first and second directions. A tensioner applies a tensioning force between the first roller supporting member and second roller supporting member so that compression forces are applied on the first and second rollers. The compression forces cause the first and second rollers to mechanically resist pivoting of the first and second rocker arms with respect to each other about the first pivot axis.

## Background
FIELD
The present disclosure relates to exercise assemblies.
BACKGROUND
U.S. Pat. No. 7,479,093, which is incorporated herein by reference in entirety discloses an exercise apparatus having a pair of handles pivotally mounted on a frame and guiding respective user arm motions along swing paths obliquely approaching the sagittal plane of the user.
U.S. Pat. No. 7,625,317, which is incorporated herein by reference in entirety discloses an exercise apparatus with a coupled mechanism providing coupled natural biomechanical three dimensional human motion.
U.S. Pat. No. 7,717,833, which is incorporated herein by reference in entirety discloses an adjustable exercise machines, apparatuses, and systems. The disclosed machines, apparatuses, and systems typically include an adjustable, reversible mechanism that utilizes pivoting arms and a floating pulley. The disclosed machines, apparatuses, and systems typically are configured for performing pushing and pulling exercises and may provide for converging and diverging motion.
U.S. Pat. No. 7,918,766, which is incorporated herein by reference in entirety discloses an exercise apparatus for providing elliptical foot motion that utilizes a pair of rocking links suspended from an upper portion of the apparatus frame permitting at least limited arcuate motion of the lower portions of the links. Foot pedal assemblies are connected to rotating shafts or members located on the lower portion of the links such that the foot pedals will describe a generally elliptical path in response to user foot motion on the pedals.
U.S. Pat. No. 7,931,566, which is incorporated herein by reference in entirety discloses an exercise apparatus, which may be an elliptical cross trainer, having a rotating inertial flywheel driven by user-engaged linkage exercising a user. A user-actuated resistance device engages and stops rotation of the flywheel upon actuation by the user.
U.S. Pat. No. 8,272,997, which is incorporated herein by reference in entirety, discloses a dynamic link mechanism in an elliptical step exercise apparatus that can be used to vary the stride length of the machine. A control system can also be used to vary stride length as a function of various exercise and operating parameters such as speed and direction as well as varying stride length as a part of a preprogrammed exercise routine such as a hill or interval training program. In addition the control system can use measurements of stride length to optimize operation of the apparatus.
SUMMARY
This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In certain examples, a linear motion synchronizing mechanism is for an exercise machine having elongated first and second rocker arms that pivot with respect to each other about a first pivot axis. The linear motion synchronizing mechanism comprises a body that is configured to move along a linear frame member of the exercise machine. The linear frame member extends along a linear axis that is perpendicular to the first pivot axis. The body comprises a first roller supporting member and an opposing second roller supporting member. A hub is on the body. The hub is configured to pivotally couple the first and second rocker arms to the body such that pivoting of the first and second rocker arms with respect to each other causes the body to move in a first direction along the linear axis and such that opposite pivoting of the first and second rocker arms with respect to each other causes the body to move in an opposite, second direction along the linear axis. A first roller is retained on the first roller supporting member and a second roller is retained on the opposing second roller supporting member. The first and second rollers are configured to roll along opposite sides of the linear frame member as the body moves in the first and second directions. A tensioner applies a tensioning force between the first roller supporting member and second roller supporting member so that compression forces are applied on the first and second rollers. The compression forces causes the first and second rollers to mechanically resist pivoting of the first and second rocker arms with respect to each other about the first pivot axis.



BRIEF DESCRIPTION OF THE DRAWINGS
Examples of exercise assemblies are described with reference to the following drawing figures. The same numbers are used throughout the drawing figures to reference like features and components.
FIG. 1 is a perspective view of an exercise assembly.
FIG. 2 is a closer view of a front portion of the exercise assembly.
FIG. 3 is an exploded view of one side of the exercise assembly.
FIG. 4 is a side view of the assembly showing vertical stepping motion.
FIG. 5 is a side view of the assembly showing elliptical motion.
FIG. 6 is a perspective view of another embodiment of an exercise assembly.
FIG. 7 is a closer view of a front portion of the exercise assembly shown in FIG. 6.
FIG. 8 is an exploded view of one side of the exercise assembly shown in FIG. 6.
FIG. 9 is a perspective view of another example of an exercise assembly.
FIG. 10 is an exploded view of one portion of the exercise assembly shown in FIG. 9.
FIGS. 11-13 are side views of the portion of the exercise assembly, showing scissors-like motion of a pair of elongated rocker arms shown in FIG. 9.
FIG. 14 is a perspective view of portions of another example of an exercise assembly.
FIG. 15 is a perspective view of a linear motion synchronizing mechanism on the exercise assembly.
FIG. 16 is a perspective view of the linear motion synchronizing mechanism.
FIG. 17 is an exploded view of the linear motion synchronizing mechanism.
FIG. 18 is a view of section 18-18 taken in FIG. 15.
FIG. 19 is a perspective view of another example of a linear motion synchronizing mechanism.
FIG. 20 is a view of section 20-20 taken in FIG. 19.



DETAILED DESCRIPTION OF THE DRAWINGS
In the present description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different assemblies described herein may be used alone or in combination with other apparatuses. Various equivalents, alternatives, and modifications are possible within the scope of the appended claims.
FIGS. 1-3 depict an exercise assembly 10 having a frame 12, a pair of elongated foot pedal members 14, a pair of elongated coupler arms 16, a pair of crank members 18 and a pair of elongated rocker arms 20. Each foot pedal member 14 has a front portion 22 and a rear portion 24. A pair of foot pads 26 is provided for supporting a user's feet. Each foot pad 26 is disposed on the rear portion 24 of one of the pair of foot pedal members 14. Each rocker arm 20 has a lower portion 30 that is pivotally connected to one of the pair of foot pedal members 14 at a location that is between the foot pad 26 and the crank member 18. Any type of pivotal connection can be employed. In this example, an extension member 32 extends vertically upwardly from the foot pedal member 14 and pivotally connects a lower portion 30 of a rocker arm 20 to the foot pedal member 14. A U-shaped bracket 34 and a connecting pin 36 facilitate the connection such that the rocker arms 20 are pivotal with respect to the foot pedal members 14. Each extension member 32 extends upwardly from one of the respective pair of foot pedal members 14 and the U-shaped bracket 34 extends downwardly from the lower portion 30 of the respective rocker arms 20.
Each rocker arm 20 has an upper portion 38 that is directly or indirectly pivotally connected to the frame 12. The manner of connection to the frame 12 can vary. In this example, a rear cross-shaft 40 is secured to the frame 12 and has opposite ends 42, 44 on which the upper portions 38 of the rocker arms 20 are pivotally supported. In this example, the ends 42, 44 extend through respective bearings 41 in the rocker arms 20 to enable the freely rotatable, pivotal connection therewith. Thus, the pair of rocker arms 20 pivot about a common axis A, which extends through the rear cross-shaft 40.
A pair of handles 46 are disposed on the pair of rocker arms 20 and extend upwardly above the cross-shaft 40 such that movement of the handle 46 in a pivoting, rotational motion with respect to the axis A of the rear cross-shaft 40 causes similar, following pivoting, rotational motion of the lower portion 30 of the rocker arm 20.
Elongated link members 48 each have a front portion 50 and a rear portion 52. The rear portion 52 is pivotally connected to one of the pair of rocker arms 20. In this example, the connection between the rear portion 52 of the link member 48 and the rocker arm 20 is provided by a pivotal joint 54. A cross-link member 56 is pivotally connected to the frame 12 at a pivot axis B that extends between the link members 48. The front portions 50 of the link members 48 are pivotally connected to opposite ends of the cross-link member 56. In this example, the connection is made by pivotal joints 54. In this manner, the noted pivoting movement of each rocker arm 20 with respect to the axis A is translated to the other rocker arm 20 via the link members 48 acting on the opposite ends of the cross-link member 56, which in turn pivots about the noted pivot axis B.
The pair of coupler arms 16 each has a lower portion 58 and an upper portion 60. Each crank member 18 has a first end or portion 62 that is pivotally connected to the front portion 22 of one of the pair of foot pedal members 14 and also has a second end or portion 64 that is pivotally connected to the lower portion 58 of one of the pair of coupler arms 16. Connection of the first portion 62 of each crank member 18 is facilitated by a bearing and pin assembly 66 configured such that the crank member 18 freely rotates with respect to the foot pedal member 14. Connection of the second portion 64 of the crank member 18 to the lower portion 58 of the coupler arm 16 is facilitated by a bearing and through shaft assembly 68, wherein a through shaft 70 extends through a hub 59 in the lower portion 58 of the coupler arm 16 so that the coupler arm 16 can freely pivot with respect to the through shaft 70.
A front cross-shaft 72 is connected to the frame 12 by a pair of bearings 74. The front cross-shaft 72 has opposing ends 76, 78 on which the upper portions 60 of the coupler arms 16 freely pivotally rotate. In this example, the front cross-shaft 72 effectively pivotally connects the upper portions 60 of the pair of coupler arms 16 to the frame 12 through bearings in hub 77 in the upper portions 60.
A pair of timing belts 80 having internal grooves 82 is connected at one end to the second portion 64 of the crank members 18 such that movement of the crank members 18 causes rotation of the respective timing belt 80. In this example, a pair of lower timing pulleys 84 is rotatably, fixedly connected to the crank members 18 via the bearing and through shaft assembly 68 such that rotation of the crank members 18 causes rotation of the lower timing pulleys 84. In this example, the fixed rotational connection is provided by locking keys 73. The timing belts 80 are fixedly, rotatably connected at their upper end to the opposing ends 76, 78 of the front cross-shaft 72 such that rotation of the timing belts 80 causes rotation of the front cross-shaft 72. Connection between the timing belts 80 and the front cross-shaft 72 is facilitated by a pair of upper timing pulleys 86. Upper timing pulleys 86 are connected to one end of the front cross-shaft 72 transfer rotational movement of the respective timing belt 80 to the front cross-shaft 72. Each of the upper and lower timing pulleys 84, 86 have external ridges 88 that engage with the internal grooves 82 on the timing belts 80 to thereby transfer the noted rotation between the timing pulleys 84, 86 and timing belts 80. In this example, the fixed rotational connection between the timing pulleys 86 and front cross-shaft 72 is provided by locking keys 75.
A pulley 90 is rotationally fixed with and connected to a center portion of the front cross-shaft 72 such that rotation of the front cross-shaft 72 causes rotation of the pulley 90. A resistance device 92 is connected to the frame 12. The resistance device 92 can include one or more of any conventional resistance device, such as the resistance device having a combination of power generating and eddy current magnetic resistance disclosed in the incorporated U.S. Pat. No. 6,084,325. A pulley belt 94 connects the resistance device 92 to the pulley 90 such that rotation of the pulley 90 (which is caused by rotation of the front cross-shaft 72) is translated to the resistance device 92 by the pulley belt 94. In this example, the resistance device 92 generates power based upon rotation of the pulley 90.
It will thus be seen from drawing FIGS. 1-3 that the present disclosure provides an exercise assembly 10 that extends from a front end 100 to a back end 102 in a length direction L, from a lower end 104 to an upper end 106 in a height direction H that is perpendicular to the length direction L, and from a first side 108 to a second side 110 in a width direction W that is perpendicular to the height direction H and perpendicular to the length direction L. In these examples, the assembly 10 has the noted pair of elongated foot pedal members 14, each of which extend in the length direction L between the front portion 22 and rear portion 24. The pair of foot pads 26 is disposed on the rear portion 24 of one of the foot pedal members 14. The pair of elongated coupler arms 16 extends in the height direction H between a lower portion 58 and an upper portion 60. The pair of crank members 18 extend between the first portion 62 that is pivotally connected to the front portion 22 of one of the pair of foot pedal members 14 and the second portion 64 that is pivotally connected to the lower portion 58 of one of the coupler arms 16, such that each crank member 18 is rotatable in the circular path C (see FIG. 4) with respect to the coupler arm 16 and foot pedal member 14 when viewed from the first and second sides 108, 110. The pair of elongated rocker arms 20 each has the lower portion 30 that is pivotally connected to one of the pair of foot pedal members 14 in between the foot pad 26 and the crank member 18. As described further herein below, the pair of foot pedal members 14 are each movable along generally elliptical, vertical and horizontal paths of differing dimensions when viewed from the first and second sides 108, 110. The pair of elongated link members 48 extends in the length direction L between a front portion 50 and a rear portion 52 that is pivotally connected to one of the pair of rocker arms 20. The cross-link member 56 extends in the width direction W between opposite ends. The front portions 50 of the link members 48 are pivotally connected to one of the opposite ends of the cross-link member 56. The cross-link member 56 pivots about the axis B disposed between the pair of link members 48 in the width direction W.
FIGS. 4 and 5 depict the exercise assembly 10 during certain exercise motions. In FIG. 4, the operator applies a generally vertical, up and down stepping motion onto the foot pads 26, which causes the foot pedal members 14 to vertically reciprocate as shown in phantom line in FIG. 4. Simultaneously, the user grasps the handles 46. The handles 46 can be maintained generally stationary with respect to the length direction L during vertical reciprocation of the foot pedal members 14. During the movements described above, the crank members 18 pivot in a generally circular path with respect to the foot pedal members 14 and coupler arms 16, as shown by the arrow C. The movement shown at line C can occur in both clockwise and counter-clockwise directions to exercise different muscle groups. During workout activities, the amount of operator hand motion on the handles 46 will help determine the shape of the path of the foot pedal members 14. The stride length of the path can be dynamically changed from short to long or from long to short.
FIG. 5 shows the assembly 10 during an extended stride exercise wherein the user applies movement as shown at line D to the foot pads 26 on the foot pedal members 14. The movement shown at line D can occur in both clockwise and counter-clockwise directions to exercise different muscle groups. The user also applies opposing back and forth motions in the length direction L onto the handles 46. These motions cause the rocker arms 20 and coupler arms 16 to pivot about the respective cross-shafts 40, 72, as shown in phantom line in FIG. 5. Again, the crank members 18 rotate in a generally circular pathway as shown at arrow C.
The noted circular movement of the crank members 18 is transferred to the lower timing pulleys 84, timing belt 80, upper timing pulleys 86, front cross-shaft 72, pulley belt 94, and ultimately to the resistance device 92 for braking function and power generating, per the description in the incorporated U.S. Pat. No. 6,084,325.
As those having ordinary skill in the an would understand, the exercise assembly 10 thus facilitates a movement of the foot pedal members 14 along elliptical, vertical and horizontal paths of differing dimensions when viewed from the first and second sides 108, 110.
FIGS. 6-8 depict another embodiment of an exercise assembly 210. The exercise assembly 210 has many features in common with or functionally similar to the exercise assembly 10 shown in FIGS. 1-5. Many of the features that are the same or similar in structure and/or function are given like reference numbers. However, all of the reference numbers provided in FIGS. 1-5 are not necessarily provided in FIGS. 6-8 to avoid clutter and maintain clarity of this description.
The exercise assembly 210 differs from the exercise assembly 10 in that it does not include the elongated link members 48, pivotal joints 54, and cross-link member 56. Instead, the exercise assembly 210 includes a cross-linking mechanism 212 that pivotally connects the pair of rocker arms 20 together such that movement of one of the pair of rocker arms 20 causes counteracting, opposite movement in the other of the pair of rocker arms 20. The cross-linking mechanism 212 includes a “four-bar mechanism” having a cross-linking shaft 214. A pair of first elongated link members 216 each have a rear portion 218 that is pivotally coupled to one of the pair of rocker arms 20. More specifically, the rear portions 218 are pivotally coupled to extension members 220 that are fixedly coupled to one of the pair of rocker arms 20. In this manner, the pair of first elongated link members pivot with respect to the extension members 220, and thus with respect to the pair of rocker arms 20.
A pair of second elongated link members 222 each have a first portion 224 that is pivotally coupled to a front portion 226 of one of the pair of first elongated link members 216 and a second portion 228 that is fixedly coupled to the cross-linking shaft 214, such that rotation of one of the pair of second elongated link members 222 causes rotation of the cross-linking shaft 214 about its own axis, and rotation of the other of the pair of second elongated link members 222.
In this example, the respective pairs of first and second elongated link members 216, 222 are oppositely oriented with respect to each other and the cross-linking shaft 214. That is, as shown in FIG. 7, the first and second elongated link members 216, 222 on the first side 108 are vertically oriented downwardly, whereas the first and second elongated link members 216, 222 on the opposite side 110 are vertically oriented upwardly. The particular orientation of the respective link members 216, 222 can vary from that which is shown.
Movement of one of the pair of rocker arms 20 causes pivoting movement of one of the pair of first elongated link members 216 via the fixed extension member 220. Pivoting movement of the first elongated link member 216 causes pivoting movement of a corresponding one of the pair of second elongated link members 222. Pivoting movement of the second elongated link member 222 causes rotation of the cross-linking shaft 214 about its own axis, which is translated to the other of the pair of second elongated link members 222, which in turn causes pivoting movement of the other of the first elongated link member 216. Movement of the other of the first elongated link member 216 is translated to the other of the pair of rocker arms 20 via the extension member 220. Thus, the cross-linking mechanism 212 operably connects the pair of rocker arms 20 together.
The exercise assembly 210 shown in FIGS. 6-8 also differs from the exercise assembly 10 in that it includes a pair of belt tightening mechanisms 230 for adjusting tension in the pair of timing belts 80. Each pair of belt tightening mechanisms includes an idler wheel 232 that is coupled to one of the pair of coupler arms 16 by a joint 234. The joint 234 includes a plate 236 having at least one slot 238 that receives a fixing screw 240. The fixing screw can be fixed to the plate at different slot locations along the length of the slot 238 such that the idler wheel 232 is fixed at different locations with respect to the coupler arm 16. Adjusting the position of the idler wheel 232 transversely outwardly with respect to the elongated coupler arm 16 forces the outer radius of the idler wheel 232 against the internal grooves 82 on the timing belt 80, thus tensioning the timing belt 80. Opposite movement of the idler wheel 232 via the movable joint 234 releases tension on the timing belt 80.
The exercise assembly 210 shown in FIGS. 6-8 also differs from the exercise assembly 10 in that it includes a pair of resistance devices 92a, 92b. As discussed above, regarding the exercise assembly 10, the number and configuration of the resistance devices can vary.
FIGS. 9-13 depict another example of an exercise assembly 300 having a frame 302, a pair of elongated foot pedal members 304, a pair of elongated coupler arms 306, a pair of crank members 308 and a pair of elongated rocker arms 310a, 310b. Each foot pedal member 304 has a front portion 312 and a rear portion 314. A pair of foot pads 316 is provided for supporting a users feet. Each foot pad 316 is disposed on the rear portion 314 of one of the pair of foot pedal members 304. Each rocker arm 310a, 310b has a lower portion 318 that is pivotally connected to one of the pair of foot pedal members 304 at a location that is between the foot pad 316 and the crank member 308. Any type of pivotal connection can be employed. The manner of connection of the rocker arms 310a, 310b to the foot pedal members 304 is similar to the embodiments described herein above and therefore is not here described, for brevity.
As in the previous embodiments, each rocker arm 310a, 310b has an upper portion 320 that is directly or indirectly pivotally connected to the frame 302. The manner of connection to the frame 302 can vary. In this example, a rear cross-shaft 322 (see FIG. 10) is secured to the frame 302 and has opposite ends 324, 326 on which the upper portions 320 of the rocker arms 310a, 310b are pivotally supported. In this example, the ends 324, 326 extend through respective bearings 328 in the rocker arms 310a, 310b to enable the freely rotatable, pivotal connection therewith. Thus, the pair of rocker arms 310a, 310b pivot about a common pivot axis A, which extends through the rear cross-shaft 322.
A pair of handles 328 is disposed on the pair of rocker arms 310a, 310b and extends upwardly above the cross-shaft 322 such that movement of the handles 328 in a pivoting, scissors-like motion with respect to the axis A causes similar, following pivoting, scissors-like motion of the lower portion 318 of the rocker arm 310a, 310b. 
The coupler arms 306, crank members 308 and an associated bearing and through shaft assembly 332, a pair of timing belts 334, pulley 336 and resistance device 338 can be constructed to function in a similar manner to the embodiments described herein above regarding FIGS. 1-8 and therefore are not further here described, for brevity.
Instead of the elongated link members 48, and cross-link member 56 of the embodiment shown in FIGS. 1-5, and instead of the cross-linking mechanism 212 shown in the embodiment of FIGS. 6-8, the exercise assembly 300 includes a linear motion synchronizing mechanism 340 (see FIG. 10) that provides symmetric left-right synchronization of the rocker arms 310a, 310b. The linear motion synchronizing mechanism 340 can allow for a compact design and flexible mounting orientation in comparison to other linking arrangements.
The linear motion synchronizing mechanism 340 includes a slider 342 having a slider body 344 that slides along a linear axis L (see FIGS. 11-13) extending through and perpendicular to the pivot axis A. A linkage pivotally couples the first and second rocker arms 310a, 310b to the slider body 344. As will be discussed further herein below, pivoting the first and second rocker arms 310a, 310b with respect to each other causes the slider body 344 to slide in a first direction along the linear axis L. Opposite pivoting of the first and second rocker arms 310a, 310b with respect to each other causes the slider body 344 to slide in an opposite, second direction along the linear axis L. The slider 342 and the linkage together restrict pivoting motion of the first and second rocker arms 310a, 310b to opposite directions and at an equal angular velocity with respect to each other.
The linkage includes a first linkage portion 348 for the first rocker arm 310a and an oppositely oriented second linkage portion 350 for the second rocker arm 310b. The first and second linkage portions 348, 350 are pivotally connected to the slider 342 at a second pivot axis B. The second pivot axis B extends parallel to the first pivot axis A. Each of the first and second linkage portions 348, 350 includes a linear extension arm 352 having first and second ends 354, 356 and a radial crank arm 358 having first and second ends 360, 362. The first end 354 of the extension arm 352 is pivotally coupled to the slider 342 at the second pivot axis B. The second end 356 of the extension arm 352 is pivotally coupled to the first end 360 of the crank arm 358. The second end 362 of the crank arm 358 is fixed to and rotates with one of the first and second rocker arms 310.
The slider 342 includes a bed 343 and pivot shaft 364 that extends along the noted second pivot axis B between the first ends 354 of the extension arms 352. The slider 342 also includes a stationary base 366 and linear bearings 368 that slide along linear tracks 370 on the stationary base 366. The linear bearings 368 include two pairs of spaced apart linear bearings. A pair of spaced apart and parallel linear tracks 370 extends parallel to the linear axis L. The bed 343 and pairs of spaced apart linear bearings 368 together slide on the pair of linear tracks 370, as shown in FIGS. 11-13, when the first and second rocker arms 310a, 310b are pivoted with respect to each other in the noted scissors-like motion about the first pivot axis A.
The slider 342 also includes the pivot shaft 364 that extends along the second pivot axis B between the first ends 354 of the extension arms 352. The first end 360 of the crank arm 358 of the first linkage 346 is located on and pivots about a first side of the pivot shaft 364. The first end 360 of the crank arm 358 of the second linkage 350 is located on and pivots about a second, opposite side of the pivot shaft 364. As shown in the side views of FIGS. 10-13, the crank arms 358 of the first and second linkages 348, 350 extend at opposite radial angles from the first pivot axis A.
The linear motion synchronizing mechanism 340 can optionally include a mechanical stop that prevents over-rotation of the first and second rocker arms 310. The mechanical stop can include first and second stop arms 374, 376 that are fixed to and rotate with the respective first and second rocker arms 310. The first and second stop arms 374, 376 extend at equal radial angles from the first pivot axis A. In this example, first and second fixed spring members 378, 380 are fixed to the frame 302 for engaging with the first and second stop arms 374, 376, thus preventing the noted over-rotation of the first and second rocker arms 310.
FIG. 14 depicts another example of an exercise assembly 402 having first and second rocker arms 404a, 404b that pivot with respect to each other about a first pivot axis A. As in the previously described embodiments, the exercise assembly 402 has a linear frame member 406 that extends along a linear axis L that extends perpendicular to the first pivot axis A. The exercise assembly 402 has extension arms 408a, 408b that are connected to crank arms 410a, 410b on a rear cross shaft 413 that extends between the rocker arms 404a, 404b along the first pivot axis A. This arrangement is similar to the embodiment shown in FIGS. 10-13. Similar to that embodiment, pivoting of the rocker arms 404a, 404b, causes pivoting of the crank arms 410a, 410b and extension arms 408a, 408b. 
As shown in FIGS. 15-18, the extension arms 408a, 408b are connected to a linear motion synchronizing mechanism 412 having a body 414 that is configured to move along the linear frame member 406. A hub 416 is on the body 414 and is configured to pivotably couple the first and second rocker arms 404a, 404b to the body 414 (here, via the linkages 408a, 408b, 410a, 410b) such that pivoting of the first and second rocker arms 404a, 404b with respect to each other about the first pivot axis A causes the body 414 to move in a first direction 418 along the linear axis L and such that opposite pivoting of the first and second rocker arms 404a, 404b with respect to each other causes the body 414 to move in an opposite, second direction 420 along the linear axis L.
The exact configuration of the body 414 can vary from that which is shown. In this example, the body 414 has a first roller supporting member 422 and an opposing second roller supporting member 424 disposed on an opposite side of the linear frame member 406. The body 414 also includes a third roller supporting member 426 and an opposing fourth roller supporting member 428. In this example, the first and second roller supporting members 422, 424 are side frames. The third roller supporting member 426 is a top frame. The fourth roller supporting member 428 is a bottom frame. The first, second, third and fourth roller supporting members 422, 424, 426, 428 are connected together by fasteners, which in this example include bolts.
The hub 416 on the body 414 includes a stationary shaft 432 that extends from opposite sides of the body 414. The first end 434 of the shaft 432 is pivotably connected to the first rocker arm 404a via a first linkage that includes a combination of the extension arm 408a and crank arm 410a. The second end 436 of the shaft 432 is pivotably connected to the second rocker arm 404b via a second linkage that includes a combination of the extension arm 408b and crank arm 410b. 
A plurality of rollers are supported on the first, second, third and fourth roller supporting members 422, 424, 426, 428. The number and orientation of the rollers can vary from that which is shown. In this particular example, a pair of first rollers 438a, 438b are retained on the first roller supporting member 422. A pair of second rollers 440a, 440b are retained on the opposing second roller supporting member 424. The first and second rollers 438, 440 are configured to roll along opposite sides of the linear frame member 406 as the body 414 moves in the first and second directions 418, 420. The pair of first rollers 438a, 438b are connected to the first roller supporting member 422 by a pair of first axles 442a, 442b. The pair of second rollers 440a, 440b are connected to the second roller supporting member 424 by a pair of second axles 444a, 444b. 
A third pair of rollers 446a, 446b is retained on the third roller supporting member 426. An opposing fourth roller 448 is retained on the opposing fourth roller supporting member 428. The third and fourth rollers 446a, 446b, 448 are connected to the third and fourth roller supporting members 426, 428 by axles 450, 452. In this example, the first-fourth axles 442, 444, 450, 452 are formed by bolts.
The first, second, third and fourth roller supporting members 422, 424, 426, 428 are located on different respective sides of the linear frame member 406, such that the first roller supporting member 422 is located opposite the second roller supporting member 424 with respect to the linear frame member 406 and such that the third roller supporting member 426 is located opposite the fourth roller supporting member 428 with respect to the linear frame member 406. In the example shown in FIGS. 14-17, the linear frame member 406 is made of metal and has metal side surfaces 454 (see FIG. 15). Each roller in the plurality of rollers is made of a resilient material, such as polyurethane. The resilient characteristics of the rollers provides a spring characteristic with respect to the metal side surfaces 454.
The linear motion synchronizing mechanism 412 also includes a tensioner that applies tensioning force between the first roller supporting member 422 and second roller supporting member 424 so that compression forces are applied on the first and second rollers 438, 440. The compression forces cause the first and second rollers 438, 440 to mechanically resist pivoting of the first and second rocker arms 404a, 404b with respect to each other about the first pivot axis A. More specifically, the tensioning force pulls the first and second roller supporting members 422, 424 towards each other and towards the linear frame member 406 such that compression forces are generated by the first and second rollers 422, 424 being forced against the opposite side surfaces 454 of the linear frame member 406. The compression forces are transversely oriented to and act on the first and second axles 442, 444 when the first and second rollers 438, 440 are compressed onto the opposite side surfaces 454 of the linear frame member 406.
The type of tensioner can vary from that which is shown. In this example, the tensioner includes a plurality of tensioning bolts 456 located on opposite corner portions of the first and second roller supporting members 422, 424. Each of the bolts 456 has threads 458 and extends through one of the first and second roller supporting members 422, 424 and connects to the other of the first and second roller supporting members 422, 424. As such, tightening of each respective bolt 456 creates and/or increases the noted tensioning force by pulling the first and second roller supporting members 422, 424 towards each other. Conversely, loosening each respective bolt 456 decreases the noted tensioning force by allowing the first and second roller supporting members 422, 424 to separate from each other. Similarly, axles (bolts) 442, 444, each having threads 462 connect the third and fourth roller supporting members 426, 428 together and in some examples could function in a similar manner to that described herein above regarding the bolts 456.
It will thus be seen that the present disclosure provides a linear motion synchronizing mechanism 412 having a tensioner that allows an operator or technician to adjust/modify a resistance force provided by the linear motion synchronizing mechanism 412 to the rocker arms 404a, 404b. 
FIGS. 19 and 20 depict another example of a linear motion synchronizing mechanism 412a. The mechanism 412a differs from the mechanism 412 shown in FIGS. 14-18 in that the rollers 438, 440, 446, 448 are made of metal. Polyurethane surfaces 472 are disposed along opposite side surfaces 454 of the linear frame member 406. The rollers 438, 440 are configured to ride along the polyurethane surfaces 472. In this example, the surfaces 472 provide the noted resiliency, which causes resistance to pivoting motion of the rocker arms 404a, 404b when the tensioner applies the noted tensioning force. In certain examples, each polyurethane surface 472 can have a contour shown schematically at 474 that causes the compression forces to vary as the body 414 moves in the first and second directions 418, 420. For example, the contour 474 can have a valley or a ramp or other deviation from a plane extending along the linear axis L. Such deviations increase/decrease the compression force and thus affect the resistance to the rocker arms 404a, 404b. 
In the above description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different systems and method steps described herein may be used alone or in combination with other systems and methods. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims.

## Claims

1. A linear motion synchronizing mechanism for an exercise machine having elongated first and second rocker arms that pivot with respect to each other about a first pivot axis, the linear motion synchronizing mechanism comprising:
a body that is configured to move along a linear frame member of the exercise machine, the linear frame member extending along a linear axis that is perpendicular to the first pivot axis, wherein the body comprises a first roller supporting member and an opposing second roller supporting member;
a hub on the body, the hub being configured to pivotally couple the first and second rocker arms to the body such that pivoting of the first and second rocker arms with respect to each other causes the body to move in a first direction along the linear axis and such that opposite pivoting of the first and second rocker arms with respect to each other causes the body to move in an opposite, second direction along the linear axis;
a first roller retained on the first roller supporting member and a second roller retained on the opposing second roller supporting member, wherein the first and second rollers are configured to roll along opposite sides of the linear frame member as the body moves in the first and second directions; and
a tensioner that applies a tensioning force between the first roller supporting member and second roller supporting member so that compression forces are applied on the first and second rollers, the compression forces causing the first and second rollers to mechanically resist pivoting of the first and second rocker arms with respect to each other about the first pivot axis.

2. The linear motion synchronizing mechanism according to claim 1, wherein the tensioning force pulls the first and second roller supporting members towards each other so that the compression forces are generated by the first and second rollers being forced against the opposite sides of the linear frame member.

3. The linear motion synchronizing mechanism according to claim 1, wherein the first roller is connected to the first roller supporting member by a first axle, wherein the second roller is connected to the second roller supporting member by a second axle, and wherein the compression forces are transversely oriented to and act on the first and second axles when the first and second rollers are compressed onto the opposite sides of the linear frame member.

4. The linear motion synchronizing mechanism according to claim 2, wherein the tensioner comprises a bolt having threads, the bolt extending through one of the first and second roller supporting members and connecting to the other of the first and second roller supporting members, wherein tightening the bolt increases the tensioning force by pulling the first and second roller supporting members towards each other and wherein loosening the bolt decreases the tensioning force.

5. The linear motion synchronizing mechanism according to claim 4, wherein the bolt is one of a plurality of bolts located on opposite corner portions of the first and second roller supporting members, each bolt in the plurality of bolts having threads and extending through the one of the first and second roller supporting members and connecting the other of the first and second roller supporting members, wherein tightening of each bolt increases the tensioning force by pulling the first and second roller supporting members towards each other and wherein loosening the bolt decreases the tensioning force.

6. The linear motion synchronizing mechanism according to claim 5, comprising a third roller supporting member, a third roller retained on the third roller supporting member, an opposing fourth roller supporting member, and a fourth roller retained on the opposing fourth roller supporting member; wherein the first, second, third and fourth roller supporting members are each configured to be located on a different side of the linear frame member, respectively, such that the first roller supporting member is located opposite the second roller supporting member with respect to the linear frame member and such that the third roller supporting member is located opposite the fourth roller supporting member with respect to the linear frame member.

7. The linear motion synchronizing mechanism according to claim 6, wherein the first roller is one of a pair of rollers on the first roller supporting member and wherein the second roller is one of a pair of rollers on the opposing second roller supporting member.

8. The linear motion synchronizing mechanism according to claim 7, wherein the third roller is one of a pair of rollers on the third supporting member.

9. The linear motion synchronizing mechanism according to claim 8, wherein the first and second roller supporting members are side frames, wherein the third roller supporting member is a top frame and wherein the fourth roller supporting member is a bottom frame, and wherein the first, second, third and fourth roller supporting members are connected together by fasteners.

10. The linear motion synchronizing mechanism according to claim 1, wherein the first and second rollers are made of polyurethane.

11. The linear motion synchronizing mechanism according to claim 1, wherein the first and second rollers are made of metal and further comprising polyurethane surfaces configured to be disposed along the opposite sides of the linear frame member, wherein the first and second rollers are configured to roll along the polyurethane surfaces.

12. The linear motion synchronizing mechanism according to claim 11, wherein the polyurethane surfaces each have a contour that causes the compression forces to vary as the body moves in the first and second directions.

13. The linear motion synchronizing mechanism according to claim 12, wherein the contour comprises at least one valley.

14. The linear motion synchronizing mechanism according to claim 12, wherein the contour comprise at least one ramp.

15. The linear motion synchronizing mechanism according to claim 1, wherein the hub comprises a shaft that extends from opposite sides of the body, wherein a first end of the shaft is configured to pivotably connect to the first rocker arm via a first linkage and wherein a second end of the shaft is configured to pivotably connect to the second rocker arm via a second linkage.

16. The linear motion synchronizing mechanism according to claim 1, wherein the hub comprises a shaft that extends from opposite sides of the body, wherein a first end of the shaft is pivotably connected to the first rocker arm via a first linkage and wherein a second end of the shaft is pivotably connected to the second rocker arm via a second linkage.

17. The linear motion synchronizing mechanism according to claim 1, further comprising first and second axles supporting the first and second rollers, wherein the compression forces are transversely oriented to and act on the first and second axles.

18. An exercise assembly, comprising:
elongated first and second rocker arms that pivot with respect to each other about a first pivot axis;
a linear frame member that extends along a linear axis that is perpendicular to the first pivot axis;
a body that is configured to move along the linear frame member, wherein the body comprises a first roller supporting member and an opposing second roller supporting member;
a hub on the body, the hub pivotally coupling the first and second rocker arms to the body such that pivoting of the first and second rocker arms with respect to each other causes the body to move in a first direction along the linear axis and such that opposite pivoting of the first and second rocker arms with respect to each other causes the body to move in an opposite, second direction along the linear axis;
a first roller retained on the first roller supporting member and a second roller retained on the opposing second roller supporting member, wherein the first and second rollers are configured to roll along opposite sides of the linear frame member as the body moves in the first and second directions; and
a tensioner that applies a tensioning force between the first roller supporting member and second roller supporting member so that compression forces are applied on the first and second rollers, the compression forces causing the first and second rollers to mechanically resist pivoting of the first and second rocker arms with respect to each other about the first pivot axis.

19. The exercise assembly according to claim 18, wherein the tensioning force pulls the first and second roller supporting members towards each other so that the compression forces are generated by the first and second rollers being forced against the opposite sides of the linear frame member.

20. The exercise assembly according to claim 18, wherein the first roller is connected to the first roller supporting member by a first axle, wherein the second roller is connected to the second roller supporting member by a second axle, and wherein the compression forces are transversely oriented to and act on the first and second axles when the first and second rollers are compressed onto the opposite sides of the linear frame member.

21. The exercise assembly according to claim 20, wherein the tensioner comprises a bolt having threads, the bolt extending through one of the first and second roller supporting members and connecting to the other of the first and second roller supporting members, wherein tightening the bolt increases the tensioning force by pulling the first and second roller supporting members towards each other and wherein loosening the bolt decreases the tensioning force.

22. The exercise assembly according to claim 21, wherein the bolt is one of a plurality of bolts located on opposite corner portions of the first and second roller supporting members, each bolt in the plurality of bolts having threads and extending through the one of the first and second roller supporting members and connecting the other of the first and second roller supporting members, wherein tightening of each bolt increases the tensioning force by pulling the first and second roller supporting members towards each other and wherein loosening the bolt decreases the tensioning force.

23. The exercise assembly according to claim 22, comprising a third roller supporting member, a third roller retained on the third roller supporting member, an opposing fourth roller supporting member, and a fourth roller retained on the opposing fourth roller supporting member; wherein the first, second, third and fourth roller supporting members are each configured to be located on a different side of the linear frame member, respectively, such that the first roller supporting member is located opposite the second roller supporting member with respect to the linear frame member and such that the third roller supporting member is located opposite the fourth roller supporting member with respect to the linear frame member.

24. The exercise assembly according to claim 23, wherein the first roller is one of a pair of rollers on the first roller supporting member and wherein the second roller is one of a pair of rollers on the opposing second roller supporting member.

25. The exercise assembly according to claim 24, wherein the third roller is one of a pair of rollers on the third supporting member.

26. The exercise assembly according to claim 25, wherein the first and second roller supporting members are side frames, wherein the third roller supporting member is a top frame and wherein the fourth roller supporting member is a bottom frame, and wherein the first, second, third and fourth roller supporting members are connected together by fasteners.

27. The exercise assembly according to claim 18, wherein the first and second rollers are made of polyurethane.

28. The exercise assembly according to claim 18, wherein the first and second rollers are made of metal and further comprising polyurethane surfaces disposed along the opposite sides of the linear frame member, wherein the first and second rollers are configured to roll along the polyurethane surfaces.

29. The exercise assembly according to claim 28, wherein the linear frame member is made of metal.

30. The exercise assembly according to claim 28, wherein the polyurethane surfaces each have a contour that causes the compression forces to vary as the body moves in the first and second directions.

31. The exercise assembly according to claim 30, wherein the contour comprises at least one of a valley and a ramp.

32. The exercise assembly according to claim 18, further comprising first and second axles supporting the first and second rollers, wherein the compression forces are transversely oriented to and act on the first and second axles.