Low-friction, spring stabilized bed lift

Abstract

The present invention presents a bed lift designed originally for campervans, but with application to other space-limited locations where a temporary bed or other platform is useful. The invention provides for self-adjusting mounts which allow for installation tolerance in a wide variety of potential areas. The platform is stabilized and counterbalanced to allow for safe usage while simultaneously being able to accommodate a generous load capacity. Importantly, the lift mechanism utilizes low friction operation and a pulley system which allows an operator to raise or lower the platform with or without powered assistance.

Description

[0001] Low-Friction, Spring Stabilized Bed Lift

[0002] FIELD OF THE INVENTION

[0003] The present invention relates generally to space savings for home and camping vehicles. Specifically, it is an apparatus which serves as a stowable platform for bedding in areas where space is limited, such as a camper van or RV.

[0004] BACKGROUND OF THE INVENTION

[0005] Motorhomes are an increasingly popular option for both recreational travel and mobile residence. These vehicles can offer cost savings when visiting many locations and, for many, complement the flexibility of remote employment. However, living in a compact space offers a number of challenges when trying to maximize convenience, comfort, and utility. Further, many vehicles are not large enough to provide a fixed space for each separate function. Stowable furniture is often used to help ease this tension.

[0006] Platform beds with lift assemblies are a way to provide a sleeping space that can be stored when engaging in other activities. Existing options on the market frequently employ a motor or crank to raise and lower the platform along a guiding track. The motor may operate through a chain which can serve as a means to hold the platform at a given level. This requires electrical power from an outlet or the vehicle’s battery. Other systems utilize mechanical assemblies, such as gas struts and scissor arms, to aid in lifting or lowering the platform without power and provide some stability. Either method often requires additional brackets, resting stops, straps, or cables to sufficiently stabilize the platform for use and / or stowage.

[0007] Another common challenge for deploying bed lifts is the variability of the available spaces, restricting or precluding certain options. The typical lift is attached to the floor or one or more walls of the space, stretching from the floor to the ceiling. Additionally, the frame and motor assemblies can take up significant space on their own, limiting the utility of that space even when the bed is in a stowed position. These systems generally require a fixed position and each given frame track must be installed in parallel to each other track. Even where these lifts allow for curved tracks (e.g. to trace the side wall of a vehicle), they don’t allow for spatial irregularities that often arise due to customization of the space. The inability of many lifts to adapt in these circumstances often makes for inconsistent / unsafe installation and noise from a loose, improper fit.

[0008] The present invention attempts to address these concerns with the prior art.

[0009] SUMMARY OF THE INVENTION

[0010] The present invention discloses an apparatus for raising and lowering a bed platform in a confined space. Though the preferred embodiment references camper vans or other recreational vehicles, the invention may be deployed in a variety of similar spaces. Tiny homes, cargo vehicles, apartments, or any number of spaces with similar dimensions may be appropriate to install the invention. Further, larger spaces do not preclude installation of the present invention.

[0011] In one embodiment, the present invention may comprise a platform where a rotating axle is mounted along its side, straps which wind around the axle as the platform is raised or lowered, a locking mechanism used to prevent rotation of the axle when reaching a desired height, an array of constant torque springs wound onto a drum at one end of the axle to provide resistance when lowering the platform, a primary cylindrical rail mounted to one wall of the space in a generally vertical direction, a number of secondary rails mounted to the same wall in a generally vertical direction, a spherical sliding mount connecting the primary rail to the platform, and a number of spherical link mounts corresponding to the secondary rails connecting those rails to the platform. Embodiments may utilize an adjustable array of constant torque springs or such an array of constant force springs. The spherical mounts allow for some variance among the angles of the rails and platform. Further, the link allows for some tolerance in the distance between mounts, including variance in their distance or path as the platform is raised or lowered. In combination, these components allow the platform to slide freely along the rails, even where installation variables may require imprecise and non-parallel component attachments. Additionally, this structure allows for options unavailable in the prior art, such as using curved rails and simple hand operation. The array of springs and / or vertical support structures are adjustable, allowing for a variety of different loads to be accommodated by or mounted to the invention, such as different mattresses, bedding, or a table which might set itself up as the platform is raised. This low-friction, self-adjusting mechanism with counterbalancing is a novel approach introduced by this invention.

[0012] Other embodiments may include several variations on specific components while operating in an essentially similar fashion. Embodiments may employ pressure brakes or ratcheting assemblies as their locking mechanism. Though the preferred embodiment of the invention is intended to preclude the necessity of a motorized lift, motors may still be used to power the lifting operation in some embodiments. Some embodiments may replace the cylindrical rails with slotted rails where the sliding spherical mount is separated into individual sliding and spherical components. Other embodiments may use non-cylindrical rails. Embodiments may also use a horizontally sliding component with the mount rather than a link mount to achieve the self-adjusting functionality. The locking axle and spring array assembly may be placed in alternate locations on the platform or located off of the platform in some embodiments. Such embodiments would require a modification to the routing of straps but are within the scope of the invention. Belts which interact with the axle may also be present in alternative embodiments, replacing one or more of the straps. Passive straps which are independent of the axle may also be employed in some embodiments.

[0013] Additional objectives, features, and potential advantages of the present invention may be gleaned from the detailed description. The drawings and description serve as examples of specific embodiments of the invention; provided as illustrations for those embodiments without limiting the invention to those instances. The present invention also encompasses any changes or adjustments within the scope of the invention which may become apparent to those skilled in the art in reading this description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is an underside view for an embodiment of the present invention.

[0015] FIG. 2 is a left side view for an embodiment of the present invention.

[0016] FIG. 3 is a rear view for an embodiment of the present invention.

[0017] FIG. 4 is an overhead view for an embodiment of the present invention.

[0018] FIG. 5 is a right side view for an embodiment of the present invention.

[0019] FIG. 6 is a rear, cutaway view for an embodiment of the present invention.

[0020] FIG. 7 is a rear left-offset underside view for an embodiment of the present invention.

[0021] FIG. 8 is a front left-offset underside view for an embodiment of the present invention.

[0022] FIG. 9 is a rear left-offset overhead view for an embodiment of the present invention.

[0023] FIG. 10 is a front left-offset overhead view for an embodiment of the present invention.

[0024] FIG. 11 is a detailed view of a primary rail mounting structure for an embodiment of the present invention.

[0025] FIG. 12 is a detailed view of an axle and spring array mechanism for an embodiment of the present invention.

[0026] FIG. 13 is a detailed view of a secondary rail link mounting structure for an embodiment of the present invention.

[0027] FIG. 14 is a detailed view of a slot and hole locking mechanism for an embodiment of the present invention.

[0028] FIG. 15 is a detailed view of a ratcheting lock mechanism for an embodiment of the present invention.

[0029] FIG. 16 is a detailed view of a rail-to-surface mount using spherical washers to account for additional mounting variance in an embodiment of the present invention.

[0030] FIG. 17 is a rear view demonstrating misaligned rails.

[0031] FIG. 18 is a left side view demonstrating misaligned rails.

[0032] FIG. 19 is a rear left-offset view demonstrating misaligned rails.

[0033] FIG. 20 is a detailed view for an embodiment of the present invention utilizing a variation including a belt around the axle alongside a passive strap.

[0034] FIG. 21 is a detailed view of a friction brake assembly alongside a pin lock for an alternate embodiment of the present invention. FIG. 22 is a detailed view depicting a style of link mount for an embodiment of the present invention.

[0035] FIG. 23 is a detailed view of an alternate spring array for an embodiment of the present invention, where the array is wound in the opposite direction.

[0036] FIG. 24 is an overview for an embodiment of the present invention utilizing curved, slotted rails.

[0037] FIG. 25 is a left side view for an embodiment of the present invention utilizing curved rails.

[0038] FIG. 26 is a detailed view of a slider and alternate spherical link mount for an embodiment of the present invention utilizing slotted rails.

[0039] FIG. 27 is a detailed view of a slider mount for an embodiment of the present invention utilizing curved, slotted rails demonstrating allowable variance in relation to the sliding surface.

[0040] FIG. 28 is an overview for an embodiment of the present invention where the brake and torque mechanisms are installed remotely from the platform.

[0041] FIG. 29 is a left side view for an embodiment of the present invention where the brake and torque mechanisms are installed remotely from the platform.

[0042] DETAIL DESCRIPTIONS OF THE INVENTION

[0043] All illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention. All terms are used according to their commonly understood meaning according to one of ordinary skill in the art, unless otherwise defined.

[0044] The present invention relates to a vertical lift apparatus which provides a stable platform along with the capability to raise the platform to a stowed position or lower it to a use position. The preferred embodiment (100) is directed towards the invention’s function as a bed platform. The apparatus comprises a platform (101), one or more pulley mechanisms (102), a rotating axle (103), a locking mechanism (104), an array of constant torque springs (105), two or more rails (106), two or more straps (107), a spherical mount (108), and one or more spherical link mounts (109).

[0045] The following details demonstrate the components of the invention’s preferred embodiment as shown in FIGs 1-13. The platform (101) includes structure for mounting components. The axle (103), pulley mechanisms (102), a primary spherical mount (108), and a stabilizing spherical link mount (109) are attached to the platform (101). The link mount (109) allows the system to be self-adjusting to certain imperfections. This embodiment utilizes cylindrical rails (106). These rails are mounted to the wall of the installation area and must be within a threshold angle of parallel designated by the specific tolerance of the link mount (109). The rails’ (106) distance from each other is such that the corresponding straps (107) work in aggregate to support the weight of the platform, mattress, occupants, and miscellaneous objects such as bed dressing. The axle (103) is mounted along the edge adjacent to where the platform (101) will connect to the rails, underneath the platform. The pulley system (102) is mounted near the axle (103) and used to guide the straps (107) around the platform (101) and into the axle (103). The mounts (108 & 109) are attached near either end of the same platform edge and include a space through which the straps may be threaded as well as a spherical hole configured to be able to slide along the rails (106) in a low-friction manner. The link mount (109) is also configured to self-adjust for some variance in distance between the platform edge and the rails, enabling for some amount of tolerance in the installation angles. The straps (107) are mounted on one end such that they will be able to attach to the top of its corresponding rail (106), with the strap (107) able to wind around the axle (103) as it rotates, move through the pulley mechanism (102), and under the platform (101). The other end of each strap (107) is guided to a mounting surface situated on the opposite side of the axle (103) and pulley system (102), above the platform’s storage position. The constant torque spring mechanism (105) is attached to the axle (103) such that it includes a portion wound around the axle and a freely rotating portion where the springs are configured to resist the unwinding of the straps and downward motion of the platform. The locking mechanism (104) is attached to the axle such that it will prevent rotation when engaged. In some embodiments, the straps (107) are configured to slide along their routes without a pulley system (102). FIGs. 14-16 demonstrate alternate embodiments for specific components. The locking mechanism (103) can utilize a slot and hole locking mechanism (201) or a ratcheting locking mechanism (202). Some embodiments allow for rails to be attached using spherical washers (203) to account for additional variances of installation and operation. FIGs. 17-19 demonstrate misaligned rails, which may still function within the tolerance of the spherical mounts and the linking function.

[0046] FIG. 20 demonstrates an alternate embodiment (300), where it utilizes a timing belt (301) and passive strap (302) in lieu of other straps. In this embodiment, the timing belt (301) runs vertically adjacent to its corresponding rail (106), passing through the axle (103) and / or pulley system (102). The belt is configured to attach at attachment points above the platform’s stowage position and below the platform’s lowest deployment position. These attachment points may be located, respectively, at the top and bottom of the corresponding rails. The passive strap (302) is configured to attach at or near the lower attachment point of the timing belt (301), run along the underside of the platform to the side opposite its corresponding rail (106), and up to an attachment point above the platform’s stowage position. Alternate embodiments would also allow one of the rails to be mounted opposite its typical position, diagonally to the other rail. In such an embodiment, a single axle would still be used to facilitate the lift operations, though some embodiments may be designed for a second axle and spring system.

[0047] FIG. 21 demonstrates a friction brake mechanism (204) as a means to provide support to the platform at a selected height in some embodiments of the invention. FIG.

[0048] 22 displays an embodiment for a link mount (109) zoomed in for additional detail. FIG.

[0049] 23 demonstrates an embodiment for the array of springs where they are wound in the opposing direction from most embodiments (205). FIGs. 24-25 demonstrate embodiments where the rails are curved (206). FIGs. 26-27 demonstrate alternate embodiments utilizing curved, slotted rails (209) alongside an alternate link mount (208) attached to the rail on a slider (207). FIGs. 28-29 demonstrate embodiments where the brake (210) and torque (211) mechanisms are located off the platform.

[0050] Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention.

Claims

CLAIMS1. An apparatus comprising: a platform; a horizontal stabilization structure comprising: two or more spherical mounts, wherein the mounts are attached to the underside of the platform along one of its edges, spaced substantially apart along the edge, are configured to connect the platform with an equivalent number of rails, are configured to allow the mounts to slide along the connected rails, and are configured to self-adjust according to the distance between each mount; and two or more rails, equivalent to the number of mounts, wherein the rails are attached to a substantially vertical surface, are each spaced apart according to a corresponding mount, and are installed into the mounts attached to the platform; and a vertical positioning structure comprising: a rotating axle, wherein the axle is attached to the platform’s underside along one platform edge close to the mounts and corresponding rails, and is configured to rotate; two or more guide straps, wherein the guide straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they each run underneath the platform from the axle, beyond the side opposite the rails up to a correspondingattachment point on a surface above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; two or more support straps, wherein the support straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they run from the axle up to a corresponding attachment point connected to the surface to which the rails are attached and above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; a locking mechanism, wherein the locking mechanism is attached to one end of the axle, and is configured to prevent rotation of the axle when engaged; and a torque mechanism, wherein the torque mechanism comprises an array of one or more springs, and one or more shafts, wherein the array of springs are attached, on opposite ends, to the axle and the one or more shafts, the array of springs are configured to wind around the axle and unwind from the one or more shafts as the axle rotates in a direction to lower the platform, the array of springs are configured to wind around the one or more shafts and unwind from the axle as the axle rotates in a direction to raise the platform, the spring mechanism is attached to the platform alongside the axle, andthe springs are configured to provide a constant torque.

2. The apparatus in Claim 1, wherein the second and subsequent mounts are link mounts.

3. The apparatus in Claim 1, wherein the second and subsequent mounts are configured to adjust by sliding horizontally in relation to each other mount.

4. The apparatus of Claim 1, wherein the rails are cylindrical.

5. The apparatus of Claim 1, wherein rails are slotted and the mounts are configured to be inserted into a slot along each corresponding rail.

6. The apparatus of Claim 1 , wherein the rails are curved to conform to the substantially vertical surface.

7. The apparatus of Claim 1, wherein the one or more springs are constant torque springs.

8. The apparatus of Claim 1, wherein the one or more springs are constant force springs.

9. The apparatus of Claim 1, wherein the torque mechanism further comprises a powering means for rotating the axle and the means is attached to the axle.

10. The apparatus of Claim 9, wherein the powering means is a hand crank.

11. The apparatus of Claim 9, wherein the powering means is a motor assembly.

12. The apparatus of Claim 11, wherein the motor assembly is attached to the axle by a belt.

13. The apparatus of Claim 12, wherein one of the guide straps is the belt connecting the motor assembly to the axle.

14. The apparatus of Claim 12, wherein one of the support straps is the belt connecting the motor assembly to the axle.

15. The apparatus of Claim 1, wherein the locking mechanism is a pin lock device.

16. The apparatus of Claim 1, wherein the locking mechanism is a braking device.

17. The apparatus of Claim 1, wherein the locking mechanism is a ratcheting device.

18. The apparatus of Claim 1, wherein the rails are curved to conform with the substantially vertical surface.

19. The apparatus of Claim 1, wherein the support straps are equal to the number of rails and the corresponding attachment points are connected to the surface through the corresponding rails.

20. The apparatus of Claim 1, further comprising one or more counter-balancing weights wherein the counter-balancing weights are attached to the platform and are arranged to provide a counter-balancing force for the apparatus.

21. An apparatus comprising: a platform; a horizontal stabilization structure comprising: two or more spherical mounts, wherein the mounts are attached to the underside of the platform along one of its edges, spaced substantially apart along the edge, are configured to connect the platform with an equivalent number of rails,are configured to allow the mounts to slide along the connected rails, and are configured to self-adjust according to the distance between each mount; and two or more rails, equivalent to the number of mounts, wherein the rails are attached to a substantially vertical surface, are each spaced apart according to a corresponding mount, and are installed into the mounts attached to the platform; and a vertical positioning structure comprising a means for raising and lowering the platform.

22. The apparatus in Claim 21, wherein the second and subsequent mounts are link mounts.

23. The apparatus in Claim 21, wherein the second and subsequent mounts are configured to adjust by sliding horizontally in relation to each other mount.

24. The apparatus of Claim 21, wherein the means for raising and lowering the platform comprises: rotating axle, wherein the axle is configured to rotate; two or more guide straps, wherein the guide straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they each run underneath the platform from the axle, beyond the side opposite the rails up to a corresponding attachment point on a surface above the platform’s stowed position, andare each configured to be attached to the corresponding attachment point on the strap’s other end; two or more support straps, wherein the support straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they run from the axle up to a corresponding attachment point connected to the surface to which the rails are attached and above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; a locking mechanism, wherein the locking mechanism is attached to one end of the axle, and is configured to prevent rotation of the axle when engaged; and a torque mechanism, wherein the torque mechanism comprises an array of one or more springs, and one or more shafts, wherein the array of springs are attached, on opposite ends, to the axle and the one or more shafts, the array of springs are configured to wind around the axle and unwind from the one or more shafts as the axle rotates in a direction to lower the platform, the array of springs are configured to wind around the one or more shafts and unwind from the axle as the axle rotates in a direction to raise the platform, and the springs are configured to provide a constant torque.

25. The apparatus of Claim 21, wherein the means for raising and lowering the platform is attached to the substantially vertical surface.

26. The apparatus of claim 24, wherein the rails are cylindrical.

27. The apparatus of Claim 24, wherein the locking mechanism is a ratcheting device.

28. The apparatus of Claim 21, wherein the rails are curved to conform with the substantially vertical surface.

29. An apparatus comprising: a platform; a horizontal stabilization structure comprising a means for providing horizontal stability to the platform; and a vertical positioning structure comprising: a rotating axle, wherein the axle is configured to rotate; two or more guide straps, wherein the guide straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they each run underneath the platform from the axle, beyond the side opposite the rails up to a corresponding attachment point on a surface above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; two or more support straps, wherein the support straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position,are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they run from the axle up to a corresponding attachment point connected to the surface to which the rails are attached and above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; a locking mechanism, wherein the locking mechanism is attached to one end of the axle, and is configured to prevent rotation of the axle when engaged; and a torque mechanism, wherein the torque mechanism comprises an array of one or more springs, and one or more shafts, wherein the array of springs are attached, on opposite ends, to the axle and the one or more shafts, the array of springs are configured to wind around the axle and unwind from the one or more shafts as the axle rotates in a direction to lower the platform, the array of springs are configured to wind around the one or more shafts and unwind from the axle as the axle rotates in a direction to raise the platform, the spring mechanism is attached to the platform alongside the axle, and the springs are configured to provide a constant torque.

30. The apparatus of Claim 29, wherein the means for providing horizontal stabilization to the platform comprise: two or more spherical mounts, wherein the mounts are attached to the underside of the platform along one of its edges, spaced substantially apart along the edge,are configured to connect the platform with an equivalent number of rails, are configured to allow the mounts to slide along the connected rails, and are configured to self-adjust according to the distance between each mount; and two or more rails, equivalent to the number of mounts, wherein the rails are attached to a substantially vertical surface, are each spaced apart according to a corresponding mount, and are installed into the mounts attached to the platform.

31. The apparatus in Claim 30, wherein the second and subsequent mounts are link mounts.

32. The apparatus in Claim 30, wherein the second and subsequent mounts are configured to adjust by sliding horizontally in relation to each other mount.

33. The apparatus of Claim 30, wherein the rails are cylindrical.

34. The apparatus of Claim 30, wherein rails are slotted and the mounts are configured to be inserted into a slot along each corresponding rail.

35. The apparatus of Claim 30, wherein the rails are curved to conform to the substantially vertical surface.

36. The apparatus of Claim 29, wherein the vertical positioning structure further comprises a means for raising and lowering the platform.

37. The apparatus of Claim 29, wherein the one or more springs are constant torque springs.

38. The apparatus of Claim 29, wherein the one or more springs are constant force springs and the torque mechanism further comprises a flexible member wherein the flexible member is positioned to apply torque to the axle.

39. The apparatus of Claim 29, wherein the torque mechanism further comprises a powering means for rotating the axle.

40. The apparatus of Claim 39, wherein the powering means is a hand crank.

41. The apparatus of Claim 39, wherein the powering means is a motor assembly.

42. The apparatus of Claim 29, wherein the locking mechanism is a ratcheting device.

43. The apparatus of Claim 29, further comprising one or more counter-balancing weights wherein the counter-balancing weights are attached to the platform and are arranged to provide a counter-balancing force for the apparatus.

44. An apparatus comprising: a platform; a horizontal stabilization mechanism comprising: two or more spherical mounts, wherein the mounts are attached to the underside of the platform along one of its edges, spaced substantially apart along the edge, are configured to connect the platform with an equivalent number of rails, are configured to allow the mounts to slide along the connected rails, the second and subsequent mounts are link mounts; and two or more rails, equivalent to the number of mounts, wherein the rails are attached to a substantially vertical surface, are each spaced apart according to a corresponding mount, and are installed into the mounts attached to the platform;and a vertical positioning mechanism comprising: a rotating axle, wherein the axle is attached to the platform’s underside along one platform edge close to the mounts and corresponding rails, and is configured to rotate; two or more guide straps, wherein the guide straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they each run underneath the platform from the axle, beyond the side opposite the rails up to a corresponding attachment point on a surface above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; two or more support straps, wherein the support straps are attached to the axle on one end of each strap, are configured to wind around the axle as it rotates in a direction to lift the platform into a stowed position, are configured to unwind from the axle as it rotates in a direction to lower the platform into a usage position, are positioned such that they run from the axle up to a corresponding attachment point connected to the surface to which the rails are attached and above the platform’s stowed position, and are each configured to be attached to the corresponding attachment point on the strap’s other end; a locking mechanism, wherein the locking mechanism is attached to one end of the axle, andis configured to prevent rotation of the axle when engaged; a spring mechanism, wherein the spring mechanism comprises an array of one or more constant force springs, one or more belts, and a base surface, wherein the array of constant force springs are each attached, on opposite ends, to the base surface and a belt, the belts are configured to wind around the axle as the axle rotates in a direction to lower the platform, the array of belts are configured to unwind from the axle as the axle rotates in a direction to raise the platform, the array of constant force springs are configured to pull the belts in resistance to the lowering of the platform, and the spring mechanism is attached to the platform alongside the axle.

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