Strapping device tension wheel with a helical toothing pattern

Abstract

Various embodiments of the present disclosure provide a tension wheel for a strapping device. The tension wheel includes a body including a cylindrical outer surface having a longitudinal axis and multiple teeth on the outer surface of the body. The teeth are arranged along a helical path around the outer surface. Various embodiments of the present disclosure provide a strapping device including the tension wheel, a tension plate, a motor, and a strap stop near the tension plate. The helical path is configured such that, when a strap layer is introduced between the tension wheel and the tension plate and the motor is activated, the motor rotates the tension wheel in a tensioning rotational direction, causing the teeth to impose a longitudinal force on the strap layer in a longitudinal strap direction and a transverse force on the strap layer toward the strap stop in a transverse strap direction.

Description

STRAPPING DEVICE TENSION WHEEL WITH A HELICAL TOOTHING PATTERNPriority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 675,428, filed July 25, 2024, the entire contents of which is incorporated herein by reference.Field

[0002] The present disclosure relates to strapping devices, and more particularly to strapping devices configured to tension strap around a load and to attach overlapping layers of the strap to one another to form a tensioned strap loop around the load.Background

[0003] Strapping devices are configured to tension strap around a load and to attach overlapping layers of the strap to one another to form a tensioned strap loop around the load. To use one of these strapping devices to form a tensioned strap loop around a load, an operator pulls strap leading end first from a strap supply, wraps the strap around the load, and positions a lower layer of the strap including the leading end of the strap below an upper layer of the strap. The operator separates a tension wheel from a tension plate, introduces the overlapped strap layers between the tension wheel and the tension plate, and presses a button to initiate a tensioning cycle. During the tensioning cycle, the tension wheel rotates to move the upper strap layer over the lower strap layer in a longitudinal strap direction and in doing so tensions the strap around the load. After completion of the tensioning cycle, a sealing cycle is initiated. During the sealing cycle, a sealing device (such as a friction welder) creates a strap joint by joining portions of the overlapping strap layers together, thereby attaching the upper and lower strap layers to form the tensioned strap loop.

[0004] The geometry of the components of the strapping device and the configuration of those components when assembled can result in the upper strap layer moving in a transverse strap direction — i.e., side-to-side — during the tensioning cycle. This can result in the upper and lower strap layers being misaligned after completion of the tensioning cycle, which can in turn lead to suboptimal joint strength when these misaligned strap layers are joined during the sealing cycle.Summary

[0005] Various embodiments of the present disclosure provide a strapping device including a tension wheel, a tension plate, a motor operably connected to the tension wheel to rotate the tension wheel in a tensioning rotational direction, and a strap stop near the tension plate. The tension wheel includes a body including a cylindrical outer surface having a longitudinal axis and multiple teeth on the outer surface of the body. The teeth are arranged along a helical path around the outer surface of the body. The helical path is configured such that, when a strap layer is introduced between the tension wheel and the tension plate and the motor is activated to rotate the tension wheel in the tensioning rotational direction, the teeth impose: (a) a longitudinal force on the strap layer in a longitudinal strap direction; and (b) a transverse force on the strap layer toward the strap stop in a transverse strap direction.

[0006] Various embodiments of the present disclosure provide a tension wheel for a strapping device. The tension wheel includes a body including a cylindrical outer surface having a longitudinal axis and multiple teeth on the outer surface of the body. The teeth are arranged along a helical path around the outer surface of the body.Brief Description of the Figures

[0007] Figure l is a perspective view of one example embodiment of a strapping device of the present disclosure.

[0008] Figures 2A-2C are diagrammatic views of the strapping device of Figure 1 securing a load to a pallet.

[0009] Figure 2D is a perspective view of a friction- weld strap joint formed by the strapping device of Figure 1 to attach two overlapping strap layers.

[0010] Figure 3 is a perspective view of the working assembly of the strapping device of Figure 1.

[0011] Figure 4 is a perspective view of the tension wheel of the working assembly of Figure 3.

[0012] Figure 5 is a perspective view of the helical path along which the teeth of the tension wheel of Figure 4 are arranged.

[0013] Figure 6 is a front elevational view of the tension wheel of Figure 4.

[0014] Figures 7A-7C are front elevational views of the tension wheel of Figure 4, the tension plate of the working assembly of Figure 3, the strap stop of the working assembly of Figure 3, and overlapping upper and lower strap layers between the tension wheel and the tension plate during the tensioning cycle.Detailed Description

[0015] While the systems, devices, and methods described herein may be embodied in various forms, the drawings show and the specification describes certain exemplary and nonlimiting embodiments. Not all of the components shown in the drawings and described in the specification may be required, and certain implementations may include additional, different, or fewer components. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of connections of the components may be made without departing from the spirit or scope of the claims. Unless otherwise indicated, any directions referred to in the specification reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. Further, terms that refer to mounting methods, such as mounted, connected, etc., are not intended to be limited todirect mounting methods but should be interpreted broadly to include indirect and operably mounted, connected, and like mounting methods. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the present disclosure and as understood by one of ordinary skill in the art.

[0016] Figures 1-7C show one example embodiment of a strapping device of the present disclosure in the form of a battery-powered portable strapping device 10 and certain subassemblies and components thereof. As shown in Figures 2A-2C, the strapping device 10 is configured to carry out a strapping cycle to tension and seal strap S (plastic strap in this example embodiment) around a load L on a pallet P to form a tensioned strap loop that secures the load L to the pallet P. An operator pulls strap S from a strap supply (not shown) and wraps the strap around the load L and through the openings in the pallet P until a lower strap layer LL of the strap S (which includes the leading end of the strap S) is positioned below an upper strap layer UL of the strap S, as shown in Figure 2A. The operator then introduces the overlapping upper and lower strap layers UL and LL of the strap S into the strapping device 10 and actuates one or more buttons to initiate the strapping cycle. As shown in Figure 2B, a motor drives a tensioning assembly to carry out a tensioning cycle during which the strapping device 10 tensions strap S around the load L. Once a preset tension is reached in the strap S, as shown in Figure 2C, the motor drives a sealing assembly to carry out a sealing cycle during which the strapping device 10 connects the upper and lower strap layers UL and LL of the strap S to one another via friction welding to form a strap joint SJ, as shown in Figure 2D, and cuts the strap S from the strap supply.

[0017] The strapping device 10 includes a housing 20, a working assembly 30, one or more input devices, a power supply 90, and a controller.

[0018] The housing 20, shown in Figure 1, is formed from multiple components (not individually labeled) that collectively at least partially enclose and / or support some (or all) of the other subassemblies and components of the strapping device 10. In this example embodiment, the housing 20 includes a front housing section that at least partially encloses the workingassembly 30, a rear housing section that at least partially encloses and that supports the power supply 90 and the controller, and a handle extending between and connecting the front and rear housing sections. The handle is held by the operator during operation of the strapping device 10. The housing 10 may be formed from any suitable quantity of components joined together in any suitable manner. In this example embodiment, the housing 10 is formed from plastic, though it may be made from any other suitable material in other embodiments.

[0019] The working assembly 30, which is best shown in Figure 3, includes most of the subassemblies and components of the strapping device 10 that are configured to carry out the strapping cycle to tension the strap around the load and attach the overlapping layers of the strap to one another. The working assembly 30 includes a support 40, a tensioning assembly 50, a sealing assembly 60, a trigger 70, a transmission 80, and a motor M.

[0020] The support 40, which is best shown in Figures 3 and 7A-7C, serves as a direct or indirect common mount for the tensioning assembly 50, the sealing assembly 60, the trigger 70, the transmission 80, and the motor M. The support 40 supports a toothed tension plate 42, a strap stop 44 adjacent an inner side of the tension plate 42 and extending above the toothed surface of the tension plate 42, and a toothed weld plate 49 rearward of the tension plate 42 in a longitudinal strap direction L identified in Figure 3.

[0021] The tensioning assembly 50, which is best shown in Figures 3-7C, is operable via the motor M to tension the strap around the load during the tensioning cycle. The tensioning assembly 50 includes a rocker, tensioning-assembly gearing, and a tension wheel 100. The rocker supports the tensioning-assembly gearing. The tensioning-assembly gearing supports the tension wheel 100, operably connects the transmission 80 to the tension wheel 100, and is configured to rotate the tension wheel 100 about an axis Aioo in a tensioning rotational direction to tension the strap around the load. The tensioning assembly 50 is pivotably mounted to the support 40 via the rocker and a suitable shaft such that the tension wheel 100 is above and adjacent to the tension plate 42. The tensioning assembly 50 is configured to pivot relative to the support 40 to increase the distance between the tension wheel 100 and the tension plate 42. Theweight of the tensioning assembly 50 and one or more springs bias the tensioning assembly 50 to toward the tension plate 42.

[0022] The tension wheel 100 is configured such that, when engaging the upper strap layer UL and when rotated in the tensioning rotational direction, the tension wheel 100 exerts a longitudinal force and a transverse force on the upper strap layer UL. The longitudinal force results in movement of the upper strap layer UL over the lower strap layer LL in the longitudinal strap direction L. If the upper strap layer UL is spaced apart from the strap stop 44 in a transverse strap direction T (identified in Figure 3), the transverse force moves the upper strap layer UL over the lower strap layer LL toward the strap stop 44 and, after the upper strap layer UL engages the strap stop 44, maintains the upper strap layer UL against the strap stop 44. As best shown in Figures 4-6, the tension wheel 100 includes a body 110, multiple exterior teeth 120, and multiple interior teeth 130. The body 110 is annular and has a first end 110a, a second end 110b opposite the first end 110a, and a cylindrical outer surface 110s extending between the first and second ends 110a and 110b. The axis Aioo is the central longitudinal axis of the outer surface 110s of the body 110. The exterior teeth 120 are arranged along a helical path lOOp around the outer surface 110s of the body 110, and the interior teeth 130 are arranged in the form of a ring gear on an inner cylindrical surface (not labeled) of the body 110.

[0023] The axis Aioo is the axis of the helical path lOOp, which is the line of symmetry about which the helical path lOOp is wound. The helical path lOOp has a diameter D, a quantity of two or more complete turns, and a pitch P defined as the distance between any two points on the helical path lOOp that are exactly one turn apart measured parallel to the axis Aioo. In this example embodiment, the diameter D of the helical path lOOp and the diameter of the outer surface 110s of the body 100 are substantially the same, the helical path lOOp includes five complete turns, and the pitch P is approximately 5 millimeters, though these values may differ in other embodiments. In this example embodiment, the helical path lOOp has a left-handed orientation, though it may have a right-handed orientation in other embodiments. The helical path lOOp begins at the first end 110a of the body 110 and ends at the second end 110b of thebody 110, though in other embodiments the helical path begins and / or ends inward of the first end 110a and / or the second end 110b. As best shown in Figure 6, the exterior teeth 120 (and partial teeth) are arranged adjacent to one another as they follow the helical path 1 lOp. In this example embodiment, each of the teeth of a first one of the complete turns of the helical path 11 Op is adjacent to one of the teeth of a second one of the complete turns of the helical path 1 lOp, though this may not be the case in other embodiments. In this example embodiment, each complete turn of the helical path lOOp includes at least thirty exterior teeth, though it may include any suitable quantity of exterior teeth in other embodiments. In this example embodiment, the helical path is a circular helical path, but it may not be in other embodiments. In this example embodiment, the tips of the exterior teeth 120 are pointed, though they may have flat-surfaced tips in other embodiments.

[0024] As best shown in Figures 7A-7C, the orientation of the helical path lOOp is configured such that rotation of the tension wheel 100 in the tensioning rotational direction results in the exertion of: (a) a longitudinal force FL on the upper strap layer UL in the longitudinal strap direction L and toward the weld plate 49; and (b) a transverse force FT on the upper strap layer UL in the transverse strap direction T and toward the strap stop 44 in the transverse strap direction T (which is perpendicular to the longitudinal strap direction L). Figure 7A shows the tension wheel 100 engaging an upper surface of an upper strap layer UL of strap S and forcing a lower surface of a lower strap layer LL of the strap S against the tension plate 42. The lower strap layer LL is engaging the strap stop 44 and thus properly positioned, while the upper strap layer UL is disengaged from the strap stop 44 and offset from the lower strap layer LL in the transverse strap direction T. As the tension wheel 100 is rotated in the tensioning rotational direction, as shown in the progression from Figure 7A-7C, the longitudinal and transverse forces FL and FT result in the exterior teeth 120 forcing the upper strap layer UL to move in both the longitudinal strap direction L (into the page from the viewpoint shown in Figures 7A-7C) and the transverse strap direction T toward the strap stop 44. Once the upper strap layer UL engages the strap stop 44, the strap stop 44 prevents further movement in thetransverse strap direction T while the tension wheel 100 continues rotating in the tensioning rotational direction. The orientation of the helical path lOOp is configured such that the transverse force FT is large enough to overcome the frictional force between the upper and lower strap layers UL and LL (to enable the upper strap layer to move relative to the lower strap layer) but low enough so as not to deform or damage the upper strap layer UL after it engages the strap stop 44 and so as not to cause the upper strap layer UL to move over the strap stop 44.

[0025] The tension wheel of the present disclosure — and in particularly the fact that the exterior teeth are arranged along a helical path — improves upon existing tension wheels because it exerts the transverse force on the upper strap layer to move it toward and maintain it against the strap stop during the tensioning cycle. This not only results in the tension wheel accurately repositioning a misaligned upper strap layer during the tensioning cycle, but also prevents the tension wheel from itself misaligning the upper strap layer during the tensioning cycle. As a result, upper strap layer will be positioned in a desired (and predictable) manner after completion of the tensioning cycle, which improves repeatability and leads to move consistent strap joints.

[0026] The sealing assembly 60, which is shown in Figure 3, is operable via the motor M to attach overlapping portions of the strap to one another to form a tensioned strap loop around the load during the sealing cycle via friction welding. The sealing assembly 60 includes a weld shoe 62 that is above and adjacent to the weld plate 49. The weld shoe 62 is pivotable toward and away from the weld plate 49 to engage and disengage the upper strap layer during and after the sealing cycle and is also oscillatable in the transverse strap direction T during the sealing cycle to form the strap joint. In this example embodiment, the sealing assembly includes a linkage operably connecting the transmission 80 to the weld shoe 62 to pivot the weld shoe 62 and an eccentric shaft operably connecting the transmission 80 to the weld shoe 62 to oscillate the weld shoe 62.

[0027] The trigger 70, which is shown in Figure 3, is operable (here, pivotable) to raise the tensioning assembly 50 to separate the tension wheel 100 from the tension plate 42. Inthis example embodiment, when the trigger 70 is pulled it triggers a switch that causes the motor M to cooperate with the tensioning assembly 50 to pivot the tensioning assembly 50 upwards. In other embodiments, the trigger 70 is operably connected to the tensioning assembly 50 via one or more mechanical linkages such that pulling the trigger 70 forces the tensioning assembly 50 to pivot upwards.

[0028] The transmission 80, which is shown in Figure 3, is driven by the motor M, is operably connected to the tensioning assembly 50 and configured to cause the tension wheel 100 to rotate in the tensioning rotational direction to tension the strap, and is operably connected to the sealing assembly 60 and configured to cause the sealing assembly 60 to attach the overlapping portions of the strap to one another. The transmission 80 includes transmission gearing supported by the support 40. The transmission gearing includes suitable components (such as gears, bearings, and freewheels) that transmit rotational movement of the output shaft of the motor M: (a) in a first drive direction to the tensioning-assembly gearing of the tensioning assembly 50, which in turn rotates the tension wheel 100; and (b) in a second drive direction opposite the first drive direction to the sealing assembly 60 to force the linkage to pivot the weld shoe 62 toward the weld plate 49 and to drive the eccentric shaft to oscillate the weld shoe 62. This is merely one example transmission assembly, and the strapping device may include any suitable transmission assembly or assemblies operably connecting one or more motors to the tensioning and sealing assemblies to drive those assemblies.

[0029] The motor M, which is shown in Figure 3, is operably connected to (via the transmission 80) the tensioning assembly 50 and the sealing assembly 60 and is configured to drive those assemblies as explained herein. The motor M includes the output shaft (not shown) referenced above. The motor M is an electric motor in this example embodiment but may be any suitable motor.

[0030] The one or more input devices of the strapping device 10 are operable to initiate the tensioning and / or sealing cycles. They may include pushbutton actuators, a touch screen, or any other suitable input device.

[0031] The controller of the strapping device 10 includes a processing device (or devices) communicatively connected to a memory device (or devices). For instance, the controller may be a programmable logic controller. The processing device may include any suitable processing device such as, but not limited to, a general-purpose processor, a specialpurpose processor, a digital-signal processor, one or more microprocessors, one or more microprocessors in association with a digital-signal processor core, one or more applicationspecific integrated circuits, one or more field-programmable gate array circuits, one or more integrated circuits, and / or a state machine. The memory device may include any suitable memory device such as, but not limited to, read-only memory, random-access memory, one or more digital registers, cache memory, one or more semiconductor memory devices, magnetic media such as integrated hard disks and / or removable memory, magneto-optical media, and / or optical media. The memory device stores instructions executable by the processing device to control operation of the strapping device 10. The controller is communicatively and operably connected to the motor M and the one or more input devices and is configured to receive signals from and to control those components. The controller may also be communicatively connectable (such as via Wi-Fi, Bluetooth, near-field communication, or other suitable wireless communications protocol) to an external device, such as a computing device, to send information to and receive information from that external device.

[0032] The controller is configured to operate the strapping device 10 in one of three operating modes to carry out the strapping cycle: (1) a manual operating mode; (2) a semiautomatic operating mode; and (3) an automatic operating mode. In the manual operating mode, the controller operates the motor M to cause the tension wheel 100 to rotate responsive to a first of the one or more input devices being actuated and maintained in its actuated state. The controller operates the motor M to cause the sealing assembly 60 to carry out the sealing cycle responsive to a second of the one or more input devices being actuated. In the semi-automatic operating mode, the controller operates the motor M to cause the tension wheel 100 to rotate responsive to the first input device being actuated and maintained in its actuated state. Once thecontroller determines that the tension in the strap reaches the (preset) desired strap tension, the controller automatically operates the motor M to cause the sealing assembly 60 to carry out the sealing cycle (without requiring additional input from the operator). In the automatic operating mode, the controller operates the motor M to cause the tension wheel 100 to rotate responsive to the first input device being actuated. Once the controller determines that the tension in the strap reaches the (preset) desired strap tension, the controller automatically operates the motor M to cause the sealing assembly 60 to carry out the sealing cycle (without requiring additional input from the operator).

[0033] The power supply 90 is electrically connected to (via suitable wiring and other components) and configured to power several components of the strapping device 10, including the motor M and the controller. The power supply 90 includes a rechargeable battery (such as a lithium-ion or nickel cadmium battery) in this example embodiment, though it may be any other suitable electric power supply in other embodiments.

[0034] Use of the strapping device 10 to carry out a strapping cycle to form a tensioned strap loop around a load is now described below. The strapping device 10 is in the automatic mode for the purposes of this example.

[0035] The operator pulls the strap S leading-end first from a strap supply, wraps the strap S around the load, and positions a lower strap layer LL including the leading end of the strap S below the upper strap layer UL of the strap S. The operator then pulls the trigger 70 to lift the tensioning assembly 50 and separate the tension wheel 100 from the tension plate 42. While continuing to pull the trigger 70, the operator introduces the overlapping upper and lower strap layers UL and LL of the strap S between the tension wheel 100 and the tension plate 42 and between the weld shoe 62 and the weld plate 49. The operator then releases the trigger 70, enabling the appropriate biasing elements to force the tensioning assembly 50 descend and sandwich the overlapping upper and lower strap layers UL and LL between the tension wheel 100 and the tension plate 42.

[0036] The operator then actuates the first input device, and in response the controller starts the tensioning cycle by controlling the motor M to rotate the output shaft in the first drive direction. As explained above, the transmission 80 transmits this rotational movement of the output shaft to the tensioning-assembly gearing which, in turn, rotates the tension wheel 100 in the tensioning rotational direction. As the tension wheel 100 rotates, it pulls the upper strap layer UL of the strap S over the lower strap layer LL of the strap S in the longitudinal strap direction L — thereby tensioning the strap S around the load — and (if necessary) moves the upper strap layer UL toward the strap stop 44 in the transverse strap direction T and afterwards maintains the upper strap layer UL against the strap stop 44. Throughout the tensioning cycle, the controller monitors the current drawn by the motor M. When this current reaches a preset value that is correlated with the (preset) desired strap tension for this strapping cycle, the controller stops the motor M, thereby terminating the tensioning cycle.

[0037] After completion of the tensioning cycle, the controller automatically starts the sealing cycle by controlling the motor M to begin rotating the output shaft in the second drive direction. This causes the transmission 80 to begin oscillating the weld shoe 62 and to pivot the weld shoe 62 downward to force the overlapping upper and lower strap layers UL and LL against the weld plate 49. The oscillation of the weld shoe 62 is fast enough to generate friction and heat substantial enough to locally melt and join the portions of the overlapping strap layers, thereby attaching the upper and lower strap layers UL and LL to form the tensioned strap loop. The controller controls the motor M to stop rotating the output shaft, completing the sealing cycle.

[0038] The above-described example embodiment of the strapping device includes a single motor configured to drive both the tensioning assembly and the sealing assembly. In other embodiments, the strapping device includes separate motors configured to drive the respective tensioning and sealing assemblies and may include separate transmissions for each motor.

[0039] Other embodiments of the strapping device may include fewer assemblies, components, and / or features than those included in the strapping device 10 described above and shown in the Figures. In other words, while the strapping device 10 includes all of theassemblies, components, and features described above, they are independent of one another and may be independently included in other strapping devices.

[0040] While the strapping device described above is a handheld strapping device, the strapping device may be any other suitable strapping device in other embodiments, such as a standalone automatic or semi-automatic strapping machine.

[0041] In the strapping device described above, the movable rocker supports the tension wheel and moves the tension wheel relative to the stationary tension plate. In other embodiments, the movable rocker supports the tension plate and the support of the working assembly supports the tension wheel. In these embodiments, the movable rocker moves the tension plate relative to the stationary tension wheel as the rocker pivots.

Claims

Claims1. A strapping device comprising: a tension wheel comprising a body comprising a cylindrical outer surface having a longitudinal axis and multiple teeth on the outer surface of the body, wherein the teeth are arranged along a helical path around the outer surface of the body; a tension plate; a motor operably connected to the tension wheel to rotate the tension wheel in a tensioning rotational direction; and a strap stop near the tension plate, wherein the helical path is configured such that, when a strap layer is introduced between the tension wheel and the tension plate and the motor is activated to rotate the tension wheel in the tensioning rotational direction, the teeth impose: (a) a longitudinal force on the strap layer in the longitudinal strap direction; and (b) a transverse force on the strap layer toward the strap stop in a transverse strap direction.

2. The strapping device of claim 1, wherein the helical path comprises multiple complete turns.

3. The strapping device of claim 2, wherein the outer surface of the body of the tension wheel comprises a first end and an opposing second end, wherein the helical path begins near the first end and ends near the second end.

4. The strapping device of claim 2, wherein each complete turn of the helical path comprises at least 30 of the teeth.

5. The strapping device of claim 4, wherein each of the teeth of a first one of the complete turns is adjacent to one of the teeth of a second one of the complete turns.

6. The strapping device of claim 1, wherein the tension plate has an inner side and an outer side and the strap stop is near the inner side of the tension plate.

7. The strapping device of claim 1, further comprising a strap connector rearward of the tension wheel and the tension plate in the longitudinal strap direction.

8. The strapping device of claim 1, wherein one of the tension wheel and the tension plate is movable relative to the other of the tension wheel and the tension plate to change a distance between the tension wheel and the tension plate.

9. The strapping device of claim 8, further comprising an input device actuatable to separate the tension wheel and the tension plate.

10. The strapping device of claim 1, wherein the strap stop is positioned to prevent further movement of the strap layer in the transverse strap direction after the strap layer engages the strap stop.

11. A tension wheel for a strapping device, the tension wheel comprising: a body comprising a cylindrical outer surface having a longitudinal axis; and multiple teeth on the outer surface of the body, wherein the teeth are arranged along a helical path around the outer surface of the body.

12. The tension wheel of claim 11, wherein the helical path comprises multiple complete turns.

13. The tension wheel of claim 12, wherein the helical path comprises a diameter that is substantially equal to a diameter of the outer surface of the body.

14. The tension wheel of claim 12, wherein the outer surface of the body comprises a first end and an opposing second end, wherein the helical path begins near the first end and ends near the second end.

15. The tension wheel of claim 12, wherein the helical path comprises at least five complete turns.

16. The tension wheel of claim 15, wherein each complete turn of the helical path comprises at least thirty of the teeth.

17. The tension wheel of claim 16, wherein each of the teeth of a first one of the complete turns is adjacent to one of the teeth of a second one of the complete turns.

18. The tension wheel of claim 12, wherein the helical path is left-handed.

19. The tension wheel of claim 12, wherein the helical path comprises a circular helical path.

20. The tension wheel of claim 12, wherein the body is annular and comprises a cylindrical inner surface comprising a ring of multiple inner teeth sized and shaped to be engaged by gearing.

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