Weight Lifting And Selector Pin Assembly

Abstract

A permanently affixed and travelling selector pin, car and weight plate selection mechanism for use with physical fitness equipment is disclosed including a segmented track and/or cut out cavern within the plate body for the car to travel within in either vertically or horizontally in order to select a different weight plate or cumulatively, more or less weight for an exercise. The selector pin and car mechanism features a selector pin which is not removable from the car and is inserted through the car which is contained by the track and or plate body shape and into a throughbore in the weight plate in order to engage with the selector stem.

Claims

1-10. (canceled)

11. A weight lifting assembly, comprising: a weight stack comprising a plurality of weight plates in an aligned arrangement, each weight plate having first side that defines a lower catch, a second side that defines an upper catch, and a peripheral edge therebetween, the plurality of weight plates are aligned such that the lower catch and the upper catch of adjacent weight plates cooperatively align with each other; each weight plate of the plurality of weight plates defining: a u-shaped stem cavity disposed in an intermediate region of the plate, each stem cavity of the plurality of weight plates are aligned with each other, and a weight throughbore that extends axially between the peripheral edge and the stem cavity; a selector stem that extends through the stem cavities of the plurality of weigh plates to retain one or more of the plurality of weight plates for exercise; and a selector pin having a knob and an elongated axial shaft extending therefrom, the shaft including a distal end; wherein the axial shaft of the selector pin is sized to extend through the weight throughbore of a selected weight plate of the plurality of weight plates to achieve union between the selector pin, the selected weight plate, and the selector stem, in an engaged position, thereby retaining one or more of the plurality of weight plates for exercise that are disposed on the first side of the selected weight plate.

12. The assembly defined in claim 21, wherein each weight plate of the plurality of weight plates is of unitary construction.

13. The assembly defined in claim 21, wherein the weight stack in oriented in a horizontal stack such that, when engaged, the selector pin retaining one or more of the plurality of weight plates for exercise that are disposed on the first side of the selected weight plate.

14. The assembly defined in claim 21, wherein the lower catches and the upper catches of the plurality of weight plates are cooperatively formed such that each lower catch can lift the adjacent upper catch.

15. The assembly defined in claim 21, wherein the lower catches and the upper catches of the plurality of weight plates are cooperatively formed to inhibit lateral movement between adjacent weight plates.

16. The assembly defined in claim 15, wherein the lower catches and the upper catches of the plurality of weight plates are cooperatively angled in a V-shape configuration to inhibit lateral movement between adjacent weight plates.

17. The assembly defined in claim 21, further comprising a movement arm pivotally coupled to the selector stem to displace one or more of the weight plates for exercise.

18. The assembly defined in claim 17, wherein the movement arm includes a four-bar linkage configured to maintain the selector stem in a fixed orientation relative to the ground throughout a range of operation, while displacing one or more of the weight plates for exercise.

19. The assembly defined in claim 18, wherein the movement arm includes two bars aligned parallel to each other throughout the range of operation.

20. The assembly defined in claim 18, wherein the weight stack in oriented in a horizontal stack such that, when engaged, the selector pin retaining one or more of the plurality of weight plates for exercise that are disposed on the first side of the selected weight plate.

21. A weight lifting assembly, comprising: a weight stack comprising a plurality of weight plates in an aligned arrangement, each weight plate having first side that defines a lower catch, a second side that defines an upper catch, and a peripheral edge therebetween, the plurality of weight plates are aligned such that the lower catch and the upper catch of adjacent weight plates cooperatively align with each other; each weight plate of the plurality of weight plates defining a u-shaped stem cavity disposed in an intermediate region of the plate, each stem cavity of the plurality of weight plates are aligned with each other, the weight stack having: a plurality of engagement points corresponding to the plurality of weight plates, and a track defined by the weight stack for guiding between the plurality of engagement points; a selector stem that extends through the stem cavities of the plurality of weigh plates to retain one or more of the plurality of weight plates for exercise via the plurality of engagement points; and a selector pin having a knob and an elongated axial shaft extending therefrom, the shaft including a distal end, the pin includes a retaining portion disposed between the knob and the distal end on the shaft; wherein the axial shaft of the selector pin is sized to achieve union between the selector pin, the selected weight plate, and the selector stem, in an engaged position, thereby retaining one or more of the plurality of weight plates for exercise that are disposed on the first side of the selected weight plate, and, in a disengaged position, the retaining portion is captured within the track so as to preclude the removal of the selector pin, wherein further, in the disengaged position, the retaining portion of the selector pin is confined by the track such that the selector pin can travel along the track to enable selection of a weight plate of the plurality of weight plates.

22. The assembly defined in claim 21, wherein the weight stack in oriented in a horizontal stack such that, when engaged, the selector pin retaining one or more of the plurality of weight plates for exercise that are disposed on the first side of the selected weight plate.

23. The assembly defined in claim 21, further comprising a movement arm pivotally coupled to the selector stem to displace one or more of the weight plates for exercise.

24. The assembly defined in claim 23, wherein the movement arm includes a four-bar linkage configured to maintain the selector stem in a fixed orientation relative to the ground throughout a range of operation, while displacing one or more of the weight plates for exercise.

25. The assembly defined in claim 24, wherein the weight stack in oriented in a horizontal stack such that, when engaged, the selector pin retaining one or more of the plurality of weight plates for exercise that are disposed on the first side of the selected weight plate.

26. The assembly defined in claim 21, wherein the retaining portion is movably disposed on the shaft, the retaining portion slides axially along the shaft between the engaged position and the disengaged position, in which, in the disengaged position, the retaining portion is captured within the track so as to preclude the removal of the selector pin, wherein further, in the disengaged position, the retaining portion of the selector pin is confined by the track such that the selector pin can travel along the track to enable selection of a weight plate of the plurality of weight plates.

27. The assembly defined in claim 21, wherein the shaft defines a first detent proximate to the knob and a second detent proximate to the distal end of the shaft, such that the axial movement of the retaining portion along the selector pin is confined between the first detent and the second detent.

28. The assembly defined in claim 21, wherein the retaining portion is retained in the track in both the engaged position and the disengaged position.

29. The assembly defined in claim 21, wherein the lower catches and the upper catches of the plurality of weight plates are cooperatively formed to inhibit lateral movement between adjacent weight plates.

30. The assembly defined in claim 29, wherein the lower catches and the upper catches of the plurality of weight plates are cooperatively angled in a V-shape configuration to inhibit lateral movement between adjacent weight plates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a side view of a weight plate assembly known in the prior art.

[0031] FIG. 2 is a front view of the weight plate stack with guide rods and a selector stem as known in the prior art.

[0032] FIG. 3 is a perspective in situ view of the weight plate stack with guide rods and selector stem shown of FIG. 2 in the assembled condition with the selector pin in the engaged position.

[0033] FIG. 4 is an exploded view of a weight plate and selector pin engagement as known in the prior art

[0034] FIG. 5 shows a side view of a weight stack assembly in accordance with some of the preferred embodiments of the present invention.

[0035] FIG. 6 shows a side view of a weight stack assembly in accordance with some of the preferred embodiments of the present invention in operation wherein the user has selected to lift all weights in the stack, leaving the tray empty.

[0036] FIG. 7 shows a side view of a weight stack assembly in accordance with some of the preferred embodiments of the present invention in operation wherein the user has selected to lift only a portion of the weights in the stack, leaving the remaining weight plates in the tray.

[0037] FIG. 8a shows an exploded perspective view of the weight plate and selector pin engagement in accordance with some of the preferred embodiments of the present invention.

[0038] FIG. 8a shows an exploded perspective view of the weight plate and selector pin engagement in accordance with additional preferred embodiments of the present invention.

[0039] FIGS. 8b and 8c show an perspective view a four bar linkage variant of the selector pin engagement shown in FIG. 8a in accordance with some of the preferred embodiments of the present invention.

[0040] FIG. 9 is an exploded view of the selector pin showing the knob and slider features for engaging with the weight plate cavity of some preferred embodiments of the present invention.

[0041] FIG. 10 is a perspective view of the weight stack engaging the movement arm while at rest in the tray as used in some preferred embodiments of the present invention.

[0042] FIG. 11 is a side view of a weight plate as used in some preferred embodiments of the present invention.

[0043] FIG. 12 is a perspective view of a weight plate as used in some preferred embodiments of the present invention.

[0044] FIG. 12a is a perspective view of an alternative configuration weight plate as used in some preferred embodiments of the present invention

[0045] FIG. 13 is a profile view of a weight plate as used in some preferred embodiments of the present invention.

[0046] FIG. 14 is a perspective view of the weight stack partially engaged with the selector stem as shown in FIG. 7.

[0047] FIG. 15 is an exposed side view of an engaged selector pin and weight stack in operational engagement with the pivot point and movement arm plate as used in some preferred embodiments of the present invention.

[0048] FIG. 16 is an exposed side view of an disengaged selector pin and weight stack in operational engagement with the pivot point and movement arm plate as used in some preferred embodiments of the present invention.

[0049] FIG. 17a-b are exposed profile views of the selector pin car and track, respectively as used in some preferred embodiments of the present invention.

[0050] FIG. 18a-b are exposed profile views of the selector pin and selector pin car in disengaged and engaged positions, respectively, as used in some preferred embodiments of the present invention.

[0051] FIG. 19a-b are exposed profile views showing details of the selector pin and the stubby plunger used in some preferred embodiments of the present invention.

[0052] FIG. 20a-b are side and exposed side views of the stubby plunger, including the ball bearing component used in some preferred embodiments of the present invention.

[0053] FIG. 21a-b are exploded profile views showing the selector pin and cart combination and the weight plate with cart cavity as used in some preferred embodiments of the present invention.

[0054] FIG. 22 is an exploded perspective view of the selector pin and cart and weight stack as details in FIG. 21a-b.

[0055] FIG. 23 is an exploded perspective view of an attachable selector pin track used in some preferred embodiments of the present invention.

[0056] FIG. 24 is a front view showing the detail of track elements of the attachable selector pin track shown in FIG. 23.

[0057] FIG. 25 is a top view showing the profile of a track element as shown in FIG. 24.

[0058] FIG. 26 is a side view of a selector pin and selector pin cart for use the some preferred embodiments of the present invention.

[0059] FIG. 27a-b is a front view of the selector pin cart are front and top profile views of the selector pin cart of FIG. 26 in operational engagement with the attachable selector pin track shown in FIG. 25.

[0060] FIG. 28 shows an exploded profile view showing an alternative of the weight plate with a bulbous pin cavity as used in some preferred embodiments of the present invention.

[0061] FIGS. 29a-b depict side views of a further selection pin configuration in accordance with another alternative embodiment of the present invention in disengaged and engaged positions, respectively.

DETAILED DESCRIPTION OF THE INVENTION

[0062] Set forth below is a description of what is currently believed to be the preferred embodiment or best examples of the invention claimed. Future and present alternatives and modifications to this preferred embodiment are contemplated. Any alternatives or modifications which make insubstantial changes in function, in purpose, in structure or in result are intended to be covered by the claims in this patent.

[0063] A typical weight lifting apparatus 10 as known in the prior art is shown by way of example in FIGS. 1-4. Generally, such an apparatus 10 includes a weight stack assembly 20, a movement assembly 40 for receiving work or force from a user, and a pulley system 50 to facilitate or translate the gravitational force from the weight stack assembly 20 so as to provide resistance to the movement assembly 40. The movement assembly 40 typically includes a movement arm 42 which is displaced by the user during exercise, and a pivot point 44 which permits rotation of the user's force against the resistance of the weight stack assembly.

[0064] As shown in FIG. 2, the weight stack assembly 20 typically comprises a selector pin 22 so that the user can select the appropriate level of weight or resistance, a series of guide rods 24 for aligning and supporting the weight stack assembly 20 during exercise, and a series of plates 26, each plate having a weight plate throughbore 28 for receiving a selector pin 22. Thus, as a user selects a given weight plate throughbore 28, only that portion of weight stack assembly 20 which is at the level of the selector pin or above is engaged.

[0065] As shown in FIG. 3, the connection between the selector pin 22 and the cable 52 of pulley system 50 is accomplished by a selector stem 30. The selector stem 30 is typically permanently attached to the weight plate 26 which is at the top of the stack. The selector stem further includes a series of throughbores 32 which receive the selector pin 22 extending through the weight plate throughbore 28. As shown in FIG. 4, the weight stack assembly 20 further includes a selector stem bore 34 and guide rod bores 36 for receiving the selector stem 30 and guide rods 24, respectively.

[0066] By comparison, a first preferred embodiment of a weight lifting apparatus 110 of the present invention is shown in FIGS. 5-7. In this embodiment, the weight lifting apparatus, includes a movement assembly 140 comprising movement arm 142 and pivot point 144, a weight stack assembly 120 (which is supported at rest by tray 125), and a selector stem 130. However, in this embodiment, the selector stem 130 extends horizontally and is integral with or attached directly to the movement arm 142, and is preferably permanently attached to and inseparable from the movement arm. Thus, there are no pulley systems required between the weight plates and the movement arm, making it the present embodiment inherently safer, as there are no “pinch points” where a user or bystander can injure a finger or other body part. The weight stack assembly comprises a series of weight plates 126, and the “first” plate (i.e., the weight plate 126 closest to movement arm 142) may be permanently attached to the union of the movement arm 142 and the selector stem 130 which, when moved around a pivot point 144, makes the movement arm heavier at the selector stem end than at the pivot point end. Thus, when the user performs the exercise, the selector stem 130 and the first plate travel upwards against the force of gravity to provide resistance to the user.

[0067] In this embodiment, each individual weight plate 126 is of a similar or identical size and shape and are arranged in a horizontal stack, in similar fashion to books on a bookshelf. As shown in FIG. 10, the weight plates 126 at rest are located in a basket or tray 125 or the like, which is permanently attached to and immoveable from the weight lifting apparatus 110. As shown in FIGS. 8-9 and 11, each of the weight plates 126 include an identical, “U shaped” upward radiating cavity 121 so as to permit movement of the selector stem 130 when a given weight plate is not selected. Each weight plate further includes an additional frontward radiating, contoured cavity 127 which forms a track. The engagement of the frontward radiating cavity 127 and the selector pin 122 and slider 123 (which is a type of a car or cart) creates a track for engagement such that the selector pin can be moved from one weight plate 126 to another, while preventing the selector pin 122 from being removed from the weight stack assembly 120. Each weight plate 126 plate has a selector pin throughbore 133 connecting the frontward radiating cavity 127 with the upward radiating cavity to as to be able to receive selector pin 122. Likewise, the selector stem contains a selector pin throughbores 132 such that the selector pin may traverse the weight plate 126 and selector stem 130 when in the engaged position.

[0068] As shown in FIGS. 8B and 8C, this invention also works with selector stem engagement with a movement arm 142 using a four bar linkage. As the user pushes down on the handle (not shown, opposite pivot point 144 and movement are 142), the movement arm 142 pivots around 144. Since all of the other pivot points are hinged joints, and the distance between the pivot points remains constant, the system pivots at these joints as well. When this happens, and since the linkage bar is solid, the machine frame is solid, the movement arm is solid and the base of the selector stem is solid, the selector stem 130 remains parallel to the ground as the handle is pushed down.

[0069] As shown in FIGS. 12-14, this embodiment also includes the use of a configuration for a weight plate 126 that provides for horizontal stacking such that a single selector pin 122, when engaged, can support the lifting of multiple weight plates 126. Each weight plate 126, when viewed from front position, preferably includes an overlapping flange 134 or similar shape that overlaps and forms a union with the lower portion of the adjoining weight plate 126 farther away from the union of the movement arm 142 and the selector stem 130, and is overlapped by and a union is formed by the upper portion of the adjoining weight plate 126 closer to the union of the movement arm 142 and the selector stem 130. In the case of FIG. 12A, the overlapping flange is V-shaped, when viewed from the front, so as to inhibit unwanted lateral movement during operation. The farthest weight plate 126 from the union of the movement arm 142 and the selector stem 130 is of similar or identical size and shape as the other plates in the weight stack 120 but, being the farthest plate in the stack from the union of the movement arm and the selector stem has no farther plate to form a union with and instead overlaps and forms a union with the tray 125.

[0070] FIGS. 15 and 16 show the engagement and disengagement of the selector pin 122 in this embodiment. When the movement arm 142 and weight plates 126 are in the “at rest position” and there is no user on the machine, the selector stem 130 and permanently attached “First Plate” end of the movement arm, due to the force of gravity, come to rest within the upwardly radiating cavity 121 of weight plates 126, which in tum are held solidly and reliably in place by their overlapping flanges 134 and the tray 125. The user then selects the desired amount of resistance by withdrawing the selector pin into the “disengaged position” and sliding the selector pin 122 using the slider which is sized to slide along the channel formed by the accumulation of front facing cavities 127 formed by the weight plates. If the user desires greater resistance (more weight), the combination of the selector pin 122 and slide 123 is moved outward away from the union of the selector stem 130 and the movement arm 142, and inward towards the union of the selector stem 130 and movement arm 142 if he desires less resistance (less weight). Then the user inserts the selector pin 122 into the “engaged position” through the selector pin throughbore 132 of the weight plate 126 and through the selector pin throughbore 132 in the selector stem 132, the throughbores being properly spaced in order to form a mechanical union between selector pin 122, weight plate 126 and selector stem 130. The user then performs the exercise and is provided resistance based on the number of weight plates 126 located between the insertion point of the selector pin 122 and the union of the movement arm 142 and selector stem 130 due to the overlapping design of the weight plates 126.

[0071] This embodiment provides several benefits. Because the union of the movement arm 142, selector stem 130 and first plate 126 is an integrated, there is no need for pulleys, cables or belts between the source of resistance and the movement arm 142. The resistance is effectively and safely put on the movement arm 142 itself. Unlike the traditional weight stack 20, this embodiment has less moving parts and therefore there is less likelihood for mechanical failure and subsequent injury making it inherently safer. Additional design safety comes from the fact that since there are no pulleys, belts or cables, there are no “pinch points” caused by these mechanisms which exist as “necessary evils” on the traditional horizontal weight stack. Further benefit is derived from the fact that due to the fact that there are no guide rods requiring lubrication. With fewer moving parts, breakable mechanisms, or the like, the invention will be less expensive to manufacture and maintain than the traditional horizontal weight stack.

[0072] Additionally, due to the non-removable selector pin mechanism the likelihood of the user using the wrong pin in the wrong machine which is a common occurrence and safety hazard in traditional horizontal weight stacks, often resulting in injury and the cost of replacing lost or stolen pins is greatly minimized. Also, due to the overlapping flange design feature, the embodiment only requires the use of one, non-removable selector pin 122 mechanism versus several. The invention is thereby more intuitive and eliminates potential injury and confusion due to inappropriate resistance selection and the need to engage more than one selection mechanism or a different selection mechanism to select a different amount of resistance. Additionally, since there are fewer selection mechanisms and since all plates are of identical size, weight and shape, the cost of manufacture will be less. Unlike the approach commonly referred to in the commercial fitness industry as “plate loaded” equipment, this embodiment also represents a significant improvement for several reasons. Due to the tray 125 and flange 134/overlapping weight plate 126 design, the weight stack assembly 120 is permanently attached to the weight lifting apparatus 110, eliminating the need for the user to locate, gather, lift up and load matching weight plates onto each of the two the movement arms of the equipment which is how current “plate loaded” equipment must be made ready for exercise. This process in and of itself is dangerous as numerous injuries have resulted from the act of loading and unloading the “plate loaded” equipment.

[0073] In addition, this embodiment eliminates the need for not only the purchase of weight plates by the health club owner, but storage racks for those weight plates as well. It also leads to a neater and better organized and safer exercise environment. It is a common occurrence for not all users to unload the traditional “plate loaded” equipment after completing their exercise session, leaving the next potential user in the unsafe or compromised position of having to unload the weight plates from the loaded piece of equipment to achieve the desired amount of weight or resistance or, in the event that the loaded weight plates are too heavy to unload, simply get discouraged and not use the piece of exercise equipment at all.

[0074] Of course, the present invention includes other embodiments which include other types of weight stack assemblies, even including prior art weight lifting assemblies such as those discloses in FIGS. 1-4. For instance, as shown in FIGS. 17-20, the invention can simply address embodiments which rely upon a selector pin 122 which uses a car 160 or similar sliding mechanism to engage a track 164 or similar channel, but includes a stubby plunger 162 or similar bias and detent mechanism for permanently retaining the selector pin 122 in the car 160, and in turn in the track 164. For instance, as shown in FIGS. 19a-b, the selector pin includes grooves 166, with the groove furthest from the knob for a “disengaged” position, and the groove closes to the knob for an “engaged” position. As shown in FIGS. 20a-b, the stubby plunger 162 is permanently fixed inside the car 160 and includes a ball bearing 168 which is biased inwards by a spring (not shown). Thus, when the selector pin 122 is inserted or removed by a user, the ball bearing 168 couples with a groove 166 to provide a locking mechanism for the “engaged” or “disengaged” positions.

[0075] In yet another embodiment, the selector pin 222 and car 224 combination can be sized to fit within a contoured cavity 228 located within a conventional shaped vertically stacked group of weight plates. In this embodiment as shown in FIGS. 21-22, the car includes ball bearings 225 to slide up and down the weight stack 220 until the user selects a desired weight plate corresponding to a desire weight level.

[0076] As shown in FIGS. 23-27, the present invention can be used with a selector pin and cart which in connected to a weight stack via an attachable track. In other words, using this embodiment of the present invention permits the present invention to be retrofitted to existing weight lifting devices. In this embodiment, the track 360 is comprised of individual track elements 362 which are permanently affixed to corresponding weight plates 326 in a weight stack 320, each track element 326 having a selector pin throughbore 364, and each element being capable of locking or connecting to other, similar elements using male 366 and female 368 connectors. Collectively, the track provides a channel for a cart 324 to slide through, the cart having ball bearings 325 to enable sliding up and down the track to the desired level in the track 360 corresponding to a desired level in the weight stack 320, such that the selector pin 322 (which is permanently connected to cart 324) can extend through the selector pin throughbore 364 and the weight plate 326, using grooves 370 to facilitate engaged and disengaged positions.

[0077] In yet another alternative embodiment as shown in FIG. 28, the selector pin 422 can be in the shape of a bulbous pin sized to fit within a contoured cavity 428 located within a conventional shaped vertically stacked group of weight plates. In this embodiment, the selector pin 422 is embedded and unremoveable from the weight plates due to contoured, enveloping cavity 428 within in each plate while still allowing for freedom of selection on a piece of variable resistance.

[0078] The selector pin 422 has a knob 424 on the user end that the user grasps to disengage the union between the selector pin 422 and the selector stem 30, which runs vertically downward through the center of each plate. The “front end” of the pin, the end opposite the “knob end” is bulbous and larger in radius, diameter and circumference at the tip than at the shaft of the pin, which is consistent in size, but thinner than the tip. The bulbous tip 426 of the pin is slightly smaller than the weight plate throughbores 32 running horizontally through each plate allowing for insertion and union with the selector stem 30. However, the bulbous tip 426 is slightly larger than the entrance to the contoured, enveloping cutout in each plate, thus preventing complete removal from any plate in the when the pin 422 is moved by the user into the extracted position, breaking the union between the selector pin and the selector stem.

[0079] When the invention is in the extracted position the bulbous tip 426 of the pin 422 is free to travel up and down inside a contoured, enveloping cutout cavity that is formed by an identical cutout in each plate, shaped identically to, but slightly larger than the profile of the extracted bulbous tip 426. This forms a continuous cavity running vertically along the face of the weightstack such that the bulbous end of the tip cannot be removed from, with the bulbous tip being enveloped by the contoured cavity and the shaft, being thinner, extrudes from the entrance of the cavity. This creates a system where the pin, when put in the extracted position by the user so as to be disengaged from the union with selector stem and removed to a position where the bulbous tip is located in the enveloping cavity, can travel vertically from one plate to another while remaining unremoveable from the weightstack itself. In this system, the knob 424 is too large to be inserted into the contoured cavity 428 and the bulbous tip 426 is too large to be removed from the cavity. However, freedom of selection is still allowed by the system as a whole when the weight plates are in the “stacked” continuous fashion. Therefore, when the user is not using the machine for exercise and the weight plates are stacked one on top of the other, the user can slide the pin up and down uninterrupted without fully removing the pin from the stack in order to select what weight amount he wants to lift by then inserting the pin into the horizontal throughbore in any plate into the engaged position forming a union with the selector stem 30. This allows the user to select the desired weight level or resistance. The cutout or contoured cavity on the bottom most plate and the plate directly below the topmost plate i.e. the second plate, do not extend to its full cavity size (i.e., such that the bulbous tip 426 cannot pass freely therethrough) vertically from surface to surface of those two plates exclusively in order to trap the pin within the weightstack when extracted from the selector stem and in the disengaged position. Such a cavity can be tapered or simply discontinue at the appropriate point in the bottom most plate or the second plate as desired in order to best trap the bulbous tip 426, and by extension, the selector pin.

[0080] As seen in FIGS. 29a-b, yet another alternative embodiment of the selector pin 522 is shown. The selector pin 522 in this embodiment is in the shape of a bulbous pin sized to fit and operate within a contoured cavity (not shown) just like the weight plate shown in FIG. 28. In this alternative, the selector pin 522 has a knob 524 on the user end that the user grasps to disengage the union between the selector pin 522 and the selector stem (not shown). The selector pin 522 further includes a bulb 526 which slidingly engages the shaft 528 of the selector pin 522. The shaft 528 further includes detents 530, 532 near the knob 524 and at the tip 534 of the pin, respectively, which can engage an interior ridge (not shown) inside the bulb 526. This detent/ridge engagement limit the amount of sliding by the bulb 526 on the shaft 528 so as to ensure that the bulb 526 stays attached to the selector pin 522 at all time during normal operation. The bulb 526 is slightly larger than the entrance to the contoured, enveloping cutout in each plate, thus preventing complete removal from any plate in the when the pin 522 is moved by the user into the extracted position (FIG. 29a), breaking the union between the selector pin and the selector stem. However, when the user slides the selector pin 522 forward (as shown in FIG. 29b), the tip 534 and the nearby portion of the shaft 528 is slightly smaller than the weight plate throughbores 32 running horizontally through each plate, thus allowing for insertion and union with the selector stem 30. However, the bulb 526 is slightly larger than such throughbores, thus keeping the bulb 526 in the contoured, enveloping cutout in each plate.

[0081] The above description is not intended to limit the meaning of the words used in the following claims that define the invention. Rather, it is contemplated that future modifications in structure, function or result will exist that are not substantial changes and that all such insubstantial changes in what is claimed are intended to be covered by the claims. For instance, the particular plate geometry and the presence or absence of guide rods may or may not vary depending upon (for instance) the particular weight lifting exercise. Similarly, while the preferred embodiments of the present invention focus upon the direct translation of the user's energy from the movement arm to the weight stack without the need for pulleys belts and the like, those of skill will understand the applicability of the present invention (e.g., the selector pin/car feature) to other weight lifting devices which require such machines. Also, the cart and track connection could be configured such that the cart surrounds the track, instead of being contained within a channel of the track. Likewise, it will be appreciated by those skilled in the art that various changes, additions, omissions, and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the following claims.