Patent Description:
Modem belts have many desirable characteristics. They can be lightweight, low-maintenance, and have high strength under tension. Many new and old applications of modem belts are currently being adapted. <CIT> shows apparatuses, systems, and methods for belt driven linear actuator systems.

A mechanism according to the present invention is defined in claim <NUM>. Advantageous further developments of the present invention are set out in the dependent claims. In general, the present invention involves a self-reeling belt drive mechanism that includes a capstan configured to draw a belt from or pay the belt out to a belt actuated system and an idler shaft coupled to the capstan via the belt. The idler shaft is configured to rotate in a drawing direction when the capstan rotates in a drawing direction and the idler shaft rotates in a payout direction when the capstan rotates in a payout direction. The idler shaft includes a first end configured to accept one or more turns of the belt, a second end coupled to a first one-way locking bearing, and a first gear connected to the first one-way locking bearing. The first one-way locking bearing engages when the idler shaft rotates in the drawing direction, causing the first gear to rotate with the rotating idler shaft. The first one-way locking bearing disengages when the idler shaft rotates in the pay-out direction, permitting relative motion between the first gear and the idler shaft. The belt drive mechanism further includes a spool that receives or pays out a portion of the belt, the spool including an outer hub which is configured to rotate and wind or unwind the portion of the belt around the periphery of the outer hub and a second gear frictionally engaged with the outer hub. The second gear is configured to be driven by the first gear such that the first gear drives the second gear, causing the outer hub to rotate in a direction to wind the portion of the belt when the idler shaft rotates in the drawing direction.

Implementations can optionally include one or more of the following features.

In some implementations, the spool includes an inner hub connected to a central axle via a second one-way locking bearing. The second one-way locking bearing permitting the inner hub to rotate with respect to the central axle when the outer hub is rotated in a direction to wind the portion of the belt. The second one-way locking bearing prevents rotation between the inner hub and the central axle when the outer hub is rotated in a direction to unwind the portion of the belt. The inner hub can be frictionally engaged with the outer hub such that the outer hub overcomes a frictional force between the inner hub and the outer hub to rotate with respect to the inner hub when rotating in a direction to unwind the portion of the belt.

In some implementations, the first gear of the belt drive mechanism is a bevel gear and the second gear is a ring gear.

In some implementations, the second gear is configured to overdrive the outer hub, rotating faster than the outer hub by at least <NUM>%.

In some implementations the belt passes through the belt actuated system and returns to the belt drive mechanism such that a first end and a second end of the belt are both within the belt drive mechanism and drawing or paying out of the belt actuates the belt actuated system. In some implementations, the belt actuated system includes a block and tackle system that expands or contracts as the belt is drawn from or payed out to the belt actuated system.

In some implementations, at least one end of the belt is electrically connected to a circuit in the belt drive mechanism. The circuit can measure at least one electrical parameter associated with the belt.

In some implementations, the belt drive mechanism includes an encoder wheel that includes an outer surface with ribs, the ribs engaging with notches in the belt. An axle of the encoder wheel can be connected to an encoder.

This invention describes a belt drive mechanism which can be used to pay out to or draw belt from a belt actuated system (or belt driven system). The mechanism features a self-winding spool which can automatically wind or unwind portions of the belt as they are withdrawn from or fed to the belt actuated system. Belt driven systems can have many advantages over other similar systems. For example, a belt driven linear actuator can require less maintenance, be lighter weight, and be capable of more cycles than a similar hydraulic linear actuator. Many belt drive mechanisms include a capstan, which can receive one or more turns or partial turns of a belt and provide rotational force to draw/take in, or pay out, the belt. The capstan can be powered by, for example, an electric motor via a set of reduction gears or a hydraulic motor, among other things. In some implementations, a second rotational axle (e.g., idler shaft) with one or more sheaves (e.g., pulley's or rollers) can be rotationally coupled to the capstan via the belt and can be utilized to drive additional mechanisms in the belt drive mechanism, such as the winding mechanism as described below.

Implementations can include one or more of the following advantages. In certain implementations, the belt drive mechanism includes a frictionally driven spool, which permits varying rotation speed of the spool independently of the belt drive capstan and idler shaft. This ensures tension is maintained throughout operations of the belt drive mechanism, without requiring variable gearing or other complex systems to manage the rotation speeds of various components. A system of one-way locking bearings and frictional surfaces result in a self-reeling mechanism that is mechanically simple, compact, yet robust throughout the range of operations of the belt drive mechanism.

During constant rate winding, as the belt wraps around the spool, the effective diameter of the spool will increase. Similarly, the effective diameter of the spool will decrease during unwinding. Since the diameter is not constant, the rotational speed of the spool can be changed to continue drawing (or paying out) the belt at a constant rate. As described in greater detail below, the spool can be driven by the idler shaft via a frictional interaction, allowing a difference in rotational speed between the spool and the idler shaft. For example, the idler shaft can have a bevel gear or miter gear affixed to one end, which engages a ring gear that is frictionally engaged with a side of the spool. The gearing between the bevel gear and the ring gear can be such that the ring gear will rotate faster than the necessary rotation of the spool as it winds in the belt. The ring gear can be pressed against the side of the spool (e.g., via a spring) and the spinning ring gear can frictionally drive the spool at a slower rate. The slower rate can be limited by tension in the belt. As the spool fills with belt, and its effective diameter increases, it can slow, while still being driven frictionally by the rotating ring gear.

During unwinding, tension provided by the belt can provide the motive force to cause the spool to unwind. If the spool were to rotate freely in the unwinding direction, however, additional problems can occur. For example, as the spool gains angular momentum, it can tend to continue to rotate after the capstan has stopped, potentially introducing slack into the system and causing the capstan to lose traction with the belt. A second mechanism can be provided, which adds rotational friction to the spool that will only be applied when the spool is unwinding, thus preventing slack introduction from a freely rotating spool. In one implementation, the spool can include an outer hub, around which the belt winds, and an inner hub, that is frictionally engaged with the outer hub, such that the outer hub must overcome a predetermined amount of friction to rotate relative to the inner hub. In this implementation, the inner hub can be mounted to an axle via a one-way locking bearing, which allows the inner hub to rotate about the axle in one direction (e.g., when the spool is winding in belt) and prevents movement of the inner hub relative to the axle in a second direction (e.g., when the spool is unwinding). In this manner, during unwinding, the inner hub remains stationary, while the outer hub is rotated about the inner hub via the belt, overcoming friction between the inner hub and outer hub.

To describe technical solutions in the implementations of the present specification or in the existing technology more clearly, the following briefly describes the accompanying drawings needed for describing the implementations or the existing technology. Apparently, the accompanying drawings in the following descriptions merely show some implementations of the present specification, and a person of ordinary skill in the art can still derive other drawings from these accompanying drawings without creative efforts.

To help a person skilled in the art better understand the technical solutions in the present specification, the following clearly and comprehensively describes the technical solutions in the implementations of the present specification with reference to the accompanying drawings in the implementations of the present specification. Apparently, the described implementations are merely some rather than all of the implementations of the present specification. All other implementations obtained by a person of ordinary skill in the art based on one or more implementations of the present specification without creative efforts shall fall within the protection scope of the implementations of the present specification.

<FIG> depict an example linear actuator <NUM> including a belt drive system <NUM> coupled with a belt actuated mechanism <NUM>. As illustrated, the linear actuator with a belt drive mechanism <NUM> can assume a form factor similar to a standard hydraulic cylinder. In this example, the belt actuated mechanism <NUM> can include one or more blocks and tackles with multiple free spans of belt between. Drawing belt from the belt actuated mechanism <NUM> can cause it to contract. Similarly, paying belt out to the belt actuated mechanism <NUM> can permit it to expand. As illustrated and for simplicity, a single belt drive mechanism 101is applied and applies motive force in only one direction (e.g., the contracting direction) and depends on gravity or other forces to expand the belt actuated mechanism <NUM>. In some implementations, multiple belt drive mechanisms <NUM>, or different configurations of the belt actuated mechanism <NUM> can be provided to accommodate two way application of motive force (e.g., the powered expansion and contraction). Additionally, although illustrated as a linear actuator, belt actuated mechanism <NUM> can be any system configured to use a belt to operate. The present invention contemplates many belt actuated mechanisms such as, linear actuators, rotational actuators, cranes, pumps, conveyors, and other belt actuated systems.

<FIG> depicts a right side view of the belt drive mechanism <NUM>. Some structural and housing components are not shown in <FIG> for clarity. A motor and gearbox (e.g., electric motor) or other device can rotate the driven shaft <NUM>, which provides the motive force for operation of the belt drive mechanism <NUM>. A capstan <NUM> can be configured to accept multiple turns of a belt <NUM>, each turn providing more friction and increasing the amount of tension the capstan <NUM> can apply to the belt <NUM>. As shown in <FIG>, the belt <NUM> completes three half-turns around the capstan <NUM> with the remaining three half turns passing around an idler shaft <NUM>. A space between the idler shaft <NUM> and the capstan <NUM> creates multiple free spans of belt minimizing the twist rate and fleet angles of the belt <NUM> for reduced wear. The idler shaft <NUM> which can share turns with the capstan <NUM> can be supported by one or more bearings, which allow the idler shaft <NUM> to rotate as the belt <NUM> passes around it. In this manner, the idler shaft <NUM> and the driven shaft <NUM> rotate in generally the same direction, although their axes may not coincide. A bevel gear <NUM> can be connected on one end of the idler shaft. While illustrated as a bevel gear, any suitable gear (e.g., spur gear, screw gear, worm gear, miter gear etc.) can be used.

The bevel gear <NUM> engages with a ring gear <NUM> that is frictionally engaged with a spool <NUM>, such that rotation of the bevel gear <NUM> causes rotation of the ring gear <NUM> which imparts a frictional force to rotate the spool <NUM>. As illustrated, the capstan <NUM> can rotate in a drawing direction, removing belt <NUM> from the belt actuated mechanism <NUM>, or in a pay-out direction allowing belt <NUM> to enter the belt actuated mechanism <NUM>. As illustrated in this example, removing belt <NUM> from the belt actuated mechanism <NUM> will cause the associated block and tackle to contract, shortening the spans of belt between the blocks in the belt actuated mechanism <NUM>. Paying out belt <NUM>, or allowing belt <NUM> to enter the belt actuated mechanism <NUM>, can cause the belt actuated mechanism <NUM> to expand, or the distance of the spans in the belt actuated mechanism <NUM> can increase.

In some implementations, the bevel gear <NUM> is connected to the idler shaft <NUM> via a one-way locking bearing, which permits rotation between the idler shaft <NUM> and the bevel gear in one direction, but prevents rotation between the idler shaft <NUM> and the bevel gear in the second direction. For example, when the capstan <NUM> (and likewise the idler shaft <NUM>) rotates in a drawing direction to take in belt <NUM> from the belt actuated mechanism <NUM>, the one-way locking bearing in the bevel gear can engage, causing the bevel gear to rotate with the idler shaft. In this manner, the capstan <NUM> drives the spool via the idler shaft <NUM>, bevel gear <NUM>, and ring gear <NUM>, when the capstan rotates in the drawing direction.

In the illustrated example, the belt <NUM> passes through the belt actuated mechanism <NUM> such that both ends of the belt <NUM> are located in the belt drive mechanism <NUM>. A first end of the belt <NUM> can be connected with an electrical connector <NUM>, which can be used for monitoring electrical parameters associated with the belt <NUM> (e.g., continuity, resistance, capacitance, reflectometry of supportive structures within the belt <NUM>, etc.). A second end of the belt <NUM> can be affixed to the spool <NUM>, which can wind and unwind, taking in portions of the belt <NUM> as they are drawn from the belt actuated mechanism <NUM>. In some implementations, the belt <NUM> in the belt driven system can include internal wiring or circuitry or be constructed with electrical properties that change under load. For example, belts frequently have conductive reinforcement structures throughout. In this example, the belt drive system can perform continuity checks, measuring the impedance or resistance between one or more ends of the conductive reinforcement structures and thus determine if they have broken and therefore compromised the structural integrity of the belt <NUM>. In another example, a continuity between the internal conductive material of the belt <NUM> and the housing of the drive mechanism can be measured. Continuity between the internal conductive material of the belt <NUM> and the housing can indicate that a portion of the belt <NUM> is worn or damaged and the belt <NUM> should be replaced or repaired. In some implementations, the belt <NUM> includes materials which have varying electrical properties under varying loads. For example, as tension in the belt <NUM> increases, its resistance or impedance can also increase. An electrical connection at one or both ends of the belt <NUM> can be provided to permit measurement of one or more electrical properties, which can be used to determine the status of the belt <NUM> (e.g., tension, temperature, configuration etc.).

<FIG> depicts a left side view of the belt drive mechanism <NUM>. Various structural components are not illustrated for simplicity. Spool <NUM> is mounted to an inner hub <NUM>. In some implementations, the inner hub <NUM> and the spool <NUM> are frictionally engaged, such that the spool <NUM> can rotate about the inner hub <NUM> if a friction force between the inner hub <NUM> and the spool <NUM> is overcome. In some implementations, the spool <NUM> is spring biased into a wear surface of the inner hub <NUM>. The inner hub <NUM> can be mounted on a fixed axle, via a one-way locking bearing which can be similar to or different from the one-way locking bearing described above with reference to the bevel gear <NUM>. When the spool <NUM> is rotating in a winding direction, driven by the ring gear <NUM>, the inner hub can rotate with the spool <NUM>, minimizing friction and allowing the spool to wind in belt <NUM>. During pay out operations, when the capstan <NUM> is rotating in the pay-out direction, the bevel gear <NUM> spins freely, independent of the idler shaft <NUM>, and permits rotation of the spool <NUM> in the unwinding direction. If the spool <NUM> were to accumulate significant angular momentum in the unwinding direction it could continue to pay out belt <NUM> after the capstan has stopped rotating, therefore introducing slack into the system potentially causing a loss of control or other problem with the belt drive mechanism <NUM>. To ensure the spool <NUM> stops when the capstan <NUM> stops, the inner hub <NUM> and its associated one-way bearing lock to the central axle, preventing rotation of the inner hub <NUM>. During pay-out, the spool rotates <NUM> around the inner hub <NUM>, the tension in the belt <NUM> overcoming the friction between the spool <NUM> and the inner hub <NUM>.

Also illustrated in <FIG> is the anchor <NUM>, which affixes one end of the belt <NUM> to the belt drive mechanism <NUM>. The anchor is located at a high tension end of the belt <NUM> and provides a fixed reference point for the belt <NUM> within the belt drive mechanism <NUM>. The belt <NUM> passes from the anchor <NUM> over the tension sensor <NUM>, and into the belt actuated mechanism <NUM>. A more detailed description of the belt's path through the belt drive mechanism <NUM> and the belt actuated mechanism <NUM> is discussed below with respect to <FIG>.

Still referring to <FIG>, in some implementations, the belt drive mechanism <NUM> includes an encoder wheel <NUM>. The encoder wheel <NUM> can have bumps or protrusions on its outer surface that are configured to mate with notches or grooves in the belt <NUM>, ensuring the belt <NUM> does not slide across the encoder wheel <NUM>. The encoder wheel <NUM> can be mounted to an encoder, which can provide an accurate position indication of the encoder wheel <NUM>, and therefore an accurate position indication of the belt <NUM>. The belt actuated mechanism <NUM> can have a position that is directly related to the belt position. For example, where the belt actuated mechanism <NUM> is part of a linear actuator, the distance the actuator has been expanded or contracted can be directly determined from the encoder position.

The tension sensor <NUM>, as shown in <FIG>, can have a sheave that redirects the belt <NUM>. As the sheave on the tension sensor <NUM> redirects the belt <NUM>, a reaction force proportional to the tension in the belt <NUM> is generated on the sheave. The sheave can be affixed to a translating component (e.g., piston or cylinder) which is spring biased against the reaction force. In this configuration, as tension in the belt <NUM> increases, the reaction force will increase, compressing the spring and translating the sheave (upward in the illustration provided in <FIG>). A position indicator on the translating component can measure the translation of the sheave and translating component, which is proportional to the tension in the belt <NUM>. The position indicator can be electronic (e.g., one or more Hall Effect sensors, or strain gauges) or mechanical (e.g., painted or engraved position indication). The tension sensor <NUM> can be used for automatic safety action (e.g., emergency payout) or to calculate expected wear and determine service life of the belt <NUM> or of the belt drive.

<FIG> depicts the belt <NUM> of the belt drive mechanism <NUM> and the belt actuated mechanism <NUM>. Referring to <FIG>, a first end <NUM> of the belt <NUM> can be connected to an electrical connector (e.g., belt connector <NUM> as described with reference to <FIG>) and mounted to a circuit board or other device within the belt drive mechanism <NUM>. The belt <NUM> can then pass through an anchor which creates a high friction anchor bend <NUM>, ensuring that the first end <NUM> of the belt <NUM> is not under tension, and that the belt <NUM> is fixed about the anchor bend <NUM>. The belt <NUM> can then pass over a tension sensor (e.g., tension sensor <NUM> as described with respect to <FIG>) creating the tension sensor bend <NUM>.

The belt <NUM> then enters the belt <NUM> actuated mechanism at the belt actuated mechanism entrance <NUM>. The illustrated example depicts the belt <NUM> passing through a block and tackle system with a number of free spans within the belt actuated mechanism. The belt <NUM> then returns to the belt drive mechanism via the belt actuated mechanism return <NUM>, where it passes around the capstan and the idler shaft causing one or more bends around both the capstan axis <NUM> and the idler axis <NUM>. Following its final turn around the capstan axis <NUM> and idler axis <NUM>, the belt <NUM> passes into the spool windings <NUM>, where it is spooled or unspooled according to the operations of the belt drive mechanism. A second end <NUM> can terminate the belt <NUM> and be affixed to the spool.

<FIG> depicts a cutaway of the belt drive mechanism <NUM> including a retaining belt and tension roller which can be used as a slack removal device. In some belt driven systems, it is desirable to minimize slack in the system. In other words, it is preferable to keep the belt <NUM>, or a portion of the belt <NUM> under tension at all times. In a system with two shafts, one that is powered and one that is driven by the belt <NUM> (e.g., a capstan and idler shaft) a system for assuring positive tension in the belt <NUM> can be provided. A first retaining device, such as a belt or roller can force the belt <NUM> against a portion of the capstan, ensuring traction between the capstan and the belt <NUM> regardless of belt tension. A second retaining device can apply pressure to the belt <NUM> on the idler shaft, and ensure positive contact with the idler shaft. In this way, in the event of slack, the capstan can withdraw slack from between the first retaining device and the second retaining device, and thus ensure the idler gear rotates with the capstan to remove any remaining slack from the system.

A slack main belt <NUM> in the belt drive mechanism can cause problems to arise during operation. For example, a slack belt <NUM> can come off one or more sheaves, or fold over itself causing a blockage and jamming the belt drive mechanism. Additionally, a slack or loose belt <NUM> can reduce the amount of friction or traction between the capstan and the belt <NUM>, causing the capstan to be unable to move the belt <NUM>. In this scenario, the idler shaft may rotate inconsistently with the capstan, as positive friction is not assured.

Still referring to <FIG>, a retaining belt <NUM> can be a separate belt from the main belt <NUM> of the belt drive mechanism and can be under a predetermined tension and positioned to apply force to one or more turns of the main belt <NUM> on the capstan <NUM>. In some implementations, the retaining belt <NUM> applies pressure to the lowest tension turn of the main belt <NUM> on the capstan <NUM>. This pressure ensures positive contact and therefore positive traction between the main belt <NUM> and the capstan <NUM>, even when the main belt <NUM> is in a slacked condition. In addition to the retaining belt <NUM>, a tension roller <NUM> can be positioned to apply pressure to one or more turns of the belt <NUM> on the idler shaft <NUM>, ensuring positive contact between the belt <NUM> and the idler shaft at the tension roller <NUM>. In a situation where the main belt <NUM> is loose or has slack present, it is assured that the capstan <NUM> can rotate and draw slack out of the span between the capstan <NUM> and the tension roller <NUM> because the retaining belt <NUM> ensures traction for a portion of the capstan <NUM>. Once slack is removed from the span between the capstan <NUM> and the tension roller <NUM>, the idler shaft <NUM> will begin to rotate via the main belt <NUM>, and so slack can be withdrawn from the rest of the system.

<FIG> depicts a cutaway diagram of a portion of the belt drive mechanism <NUM> as shown in <FIG>, including a self-reeling mechanism <NUM>. The idler shaft <NUM> can rotate about the idler axis <NUM> in either the drawing direction or the pay-out direction, and is driven by the belt <NUM> via the capstan. A bevel gear <NUM> is connected to the idler shaft <NUM> via one-way bearing 604A. One-way bearing 604A permits rotation between the bevel gear <NUM> and the idler shaft <NUM> when the idler shaft rotates in the pay-out direction relative to the bevel gear <NUM>. The one-way bearing 604A prohibits rotation between the idler shaft <NUM> and the bevel gear <NUM> in the drawing direction. While illustrated as a bevel gear <NUM>, any suitable gear type or one-way locking mechanism can be used. The bevel gear <NUM> engages with a ring gear <NUM>, which is in frictional contact with the spool <NUM>. A spring 608A ensures positive engagement between the ring gear <NUM> and the spool <NUM>. The spool <NUM> is frictionally engaged with an inner hub <NUM>. The inner hub <NUM> and the spool <NUM> can be pressed together by spring 608B. A wear surface (e.g., brake pad, or friction disk) can be provided between the spool <NUM> and the inner hub <NUM>, which can ensure the desired level of friction between the inner hub <NUM> and the spool <NUM> is attained. The inner hub <NUM> can be mounted to a hub axle <NUM> via a one-way locking bearing 604B. The one-way locking bearing 604B permits rotation of the inner hub <NUM> about the hub axle <NUM> in the winding direction (as indicated by the arrows on spool axis <NUM>) but prohibits rotation of the inner hub <NUM> about the hub axle <NUM> in the pay-out direction.

The self-reeling mechanism serves two functions. It ensures that tension is maintained in the belt <NUM> as the belt <NUM> is wound around the spool during drawing operations of the belt drive mechanism (e.g., belt drive mechanism <NUM> as shown and described with reference to <FIG>). The self-reeling mechanism also maintains tension in the belt <NUM> during pay-out operations.

During drawing operations, the belt drive mechanism is withdrawing belt <NUM> from the belt actuated mechanism (e.g., belt actuated mechanism <NUM> of <FIG>). The idler shaft <NUM> rotates about idler axis <NUM> and engages the one-way locking bearing 604A, which causes the bevel gear <NUM> to rotate with the idler shaft <NUM>. The drawing direction is as indicated by the arrows on the idler axis <NUM>.

As the bevel gear <NUM> rotates, it drives the ring gear <NUM>, which applies a twisting force to the spool <NUM> to cause the spool <NUM> to rotate about the spool axis <NUM> in the winding direction. The winding direction is as indicated by the arrows on the spool axis <NUM>. As the spool <NUM> winds in an increasing amount of belt <NUM>, the effective diameter of the spool <NUM> increases as belt <NUM> overlaps. For a constant drawing rate of the belt drive mechanism, the spool <NUM> must slow. In other words, the rotation rate of the spool <NUM> must be faster when the spool <NUM> is empty than when the spool <NUM> is full. In order to compensate for this variable speed requirement of the spool <NUM>, the ring gear <NUM> is not directly affixed to the spool <NUM>, but rotates along the side of the spool <NUM> imparting a frictional force. The gearing between the bevel gear <NUM> and the ring gear <NUM> can be selected such that the ring gear will overdrive (e.g., rotate faster than) the spool <NUM> for the entire range of operation of the spool <NUM>. In some implementations, the ring gear <NUM> overdrives the spool by <NUM>% when the spool <NUM> is empty, and <NUM>% when the spool <NUM> is full. The overdriven ring gear <NUM> ensures spool <NUM> applies tension to the belt <NUM> throughout the drawing operations.

During drawing operations, when the spool <NUM> is rotating in the winding direction, the inner hub <NUM> rotates freely about the hub axle <NUM>. The spool <NUM> and the inner hub <NUM> rotate together.

During pay-out operations, tension must still be maintained in the belt <NUM>. During pay-out the idler shaft <NUM> rotates in the payout direction (opposite the indicated arrows on the idler axis <NUM>) and one-way bearing 604A disengages, permitting independent rotation of the idler shaft <NUM> and the bevel gear <NUM>. This permits the idler shaft <NUM> and the spool <NUM> to rotate at different speeds as necessary for pay-out of the belt <NUM> from the spool <NUM>. One-way bearing 604B engages, prohibiting rotation of the inner hub <NUM> in the unwinding direction (opposite the indicated arrows on the spool axis <NUM>). The tension in the belt <NUM> pulls the spool <NUM> around the inner hub <NUM>, overcoming friction between the inner hub <NUM> and the spool <NUM>. Because the spool must overcome friction to rotate in the pay-out direction, it ensures that tension is maintained in the belt <NUM> during pay-out operations. In some implementations, the ring gear <NUM> and the bevel gear <NUM> rotate with the spool <NUM>, as one way bearing 604A is disengaged.

<FIG> depict a hand operated crane showing an alternate implementation of the belt drive mechanism. Crane <NUM> can include a boom <NUM> and a load block <NUM> which form a belt actuated mechanism <NUM>. In this implementation, the belt actuated lifting mechanism <NUM> is a lifting device. A self-reeling belt drive mechanism <NUM> can be used to operate the crane <NUM>. In this implementation, the belt drive mechanism <NUM> is hand operated by a hand crank <NUM>. In this implementation, mechanical advantage can be provided to the user based on the diameter of the capstan and hand crank handle as well as, optionally, one or more block and tackle systems housed within the boom <NUM> (not shown). <FIG> illustrates a close up view of the belt drive mechanism <NUM> with various structural components removed for simplicity. Similar to belt drive mechanism <NUM>, a capstan <NUM>, belt <NUM>, spool <NUM>, and idler shaft <NUM> are shown.

In some implementations, multiple belt drive mechanisms <NUM>, or different configurations of the belt actuated mechanism <NUM> can be provided to accommodate two way application of motive force (e.g., the powered expansion and contraction). For example, a pair of block and tackle systems can be coupled together, and configured to operate counter to each other (e.g., one belt pays out while the other is drawn in). Providing both powered expansion and contraction of the linear actuator.

While illustrated as having a rectangular cross section throughout, the belt <NUM> can be any suitable shape. For example, the belt <NUM> can have square, triangular, trapezoidal, or any combination thereof of cross sections. In some implementations, one portion of the belt <NUM> may have a trapezoidal cross section, while another portion can be triangular. The present invention is not limiting thereto. Additionally, the belt <NUM> can be constructed of any suitable material, for example, braided steel, Kevlar, rubber, leather, or a combination thereof.

Although the reeling mechanism has been illustrated with an angled idler shaft and a spool affixed to the side of the belt drive mechanism, in some implementations the spool can be on top of, or below the belt drive mechanism. In some implementations the idler shaft can protrude from the rear of the belt drive mechanism and rotate a spool that is remote from the belt drive mechanism.

Claim 1:
A self-reeling belt drive mechanism (<NUM>) comprising:
a capstan (<NUM>) configured to draw a belt (<NUM>) from, or pay out the belt to a belt actuated system (<NUM>);
an idler shaft (<NUM>) coupled to the capstan via the belt, wherein the idler shaft is configured to rotate in a drawing direction when the capstan rotates in a direction to draw the belt, and wherein the idler shaft is configured to rotate in a pay-out direction when the capstan rotates in a direction to pay out the belt, the idler shaft comprising:
a first end configured to accept one or more turns of the belt;
characterized in that the self-reeling belt drive mechanism further comprises: a second end coupled to a first one-way locking bearing (604A):
a first gear (<NUM>) connected to the first one-way locking bearing, wherein the first one-way locking bearing engages when the idler shaft rotates in the drawing direction, causing the first gear to rotate with the rotating idler shaft, and wherein the one-way locking bearing disengages when the idler shaft rotates in the pay-out direction, permitting relative rotation between the first gear and the idler shaft; and
a spool (<NUM>) configured to receive or pay out a portion of the belt, the spool comprising:
an outer hub configured to rotate and wind or unwind the portion of the belt around a periphery of the outer hub; and
a second gear (<NUM>) frictionally engaged with the outer hub, wherein the second gear is configured to be driven by the first gear such that the first gear drives the second gear, causing the outer hub to rotate in a direction to wind the portion of the belt when the idler shaft rotates in the drawing direction.