Fall Arrest System for use with a Crane

DESCRIPTION

1. Technical Field

The invention generally relates to a safety device attachable to a crane and more particularly is concerned, for example, with a fall arrest system therefore.

Specifically, the invention includes a winch facilitating engagement and

disengagement between a cable, retractable into and extendable from a fall arrest unit, and a sensor so that the sensor may enable functionality of a crane when the fall arrest system is not in use and may disable functionality of a crane when the fall arrest system is in use.

2. Background Art

The benefits of a crane often require at least one person to work within an area immediately adjacent to the crane. In one non-limiting example, a worker may be required to secure an object suspended from a crane to another object. Often the objects are either large or positioned at a height above the ground, thus requiring a worker to perform activities above ground level. Therefore, many crane-related activities expose a worker to fall-related hazards.

Fall arrest equipment may be employed to prevent or minimize the occurrence of fall-related injuries. In some applications, the fall arrest equipment must be secured to a crane so as to minimize constraints imposed by the safety device on the activities performed by a worker.

Unfortunately, attachment of fall arrest equipment to a crane introduces other hazards. In one example, the fall arrest equipment may permit the unintended movement of a worker tethered to a crane. In another example, the fall arrest equipment may permit entanglement of or impact by a worker tethered to a crane with an object adjacent to the crane.

Accordingly, what is required is a fall arrest system that avoids the hazards created by a fall arrest unit when attached to a crane.

3. Disclosure of the Invention

An object of the invention is to provide a fall arrest system that avoids the hazards created by a fall arrest unit when attached to a crane. In accordance with embodiments of the invention, the fall arrest system includes a winch, a fall arrest unit, and a sensor assembly. The winch further includes a winch cable extendable and retractable therefrom. The fall arrest unit further includes an arrest cable extendable and retractable therefrom. The sensor assembly further includes a sensor. The sensor assembly is disposed between the winch and the fall arrest unit. The winch cable is attachable to the arrest cable so that the winch cable causes the arrest cable to move across the sensor when the winch cable is retracted and the winch cable allows the arrest cable to move away from the sensor when the winch cable is extended.

In accordance with other embodiments of the invention, the fall arrest system further comprises a track attachable to the crane. The winch, the sensor assembly, and the fall arrest unit are attached to the track.

In accordance with other embodiments of the invention, the fall arrest unit is movable along the track.

In accordance with other embodiments of the invention, the winch cable is attachable to the arrest cable via a counterweight. The counterweight facilitates separation between the arrest cable and the sensor when the winch cable is extended.

In accordance with other embodiments of the invention, the sensor is a proximity sensor.

In accordance with other embodiments of the invention, the sensor is an optical sensor.

In accordance with other embodiments of the invention, the sensor is a contact sensor.

In accordance with other embodiments of the invention, the sensor assembly includes a frame with the sensor attached thereto.

In accordance with other embodiments of the invention, the frame is attached to a track.

In accordance with other embodiments of the invention, the frame permits adjustment to the distance between the sensor and the fall arrest unit and the distance between the sensor and the winch.

In accordance with other embodiments of the invention, the sensor assembly includes at least one guide attached thereto. The guide aligns the arrest cable with the sensor. In accordance with other embodiments of the invention, two guides are disposed about the sensor to provide a guide channel that narrows in the direction of the sensor.

In accordance with other embodiments of the invention, each guide is triangular shaped.

In accordance with other embodiments of the invention, the guide comprises a low-friction material.

In accordance with other embodiments of the invention, a function of the crane is enabled when a portion of the arrest cable is disposed across sensor and the function of the crane is disabled when a portion of the arrest cable is separated from the sensor.

In accordance with other embodiments of the invention, the function is movement of the crane.

In accordance with other embodiments of the invention, the function is movement by the crane.

In accordance with other embodiments of the invention, the crane is enabled by communicating power to the crane and is disabled by interrupting power to the crane.

In accordance with other embodiments of the invention, the sensor

communicates directly to the crane.

In accordance with other embodiments of the invention, the sensor

communicates indirectly to the crane.

Several exemplary advantages are notable.

The invention facilitates access by a worker to equipment adjacent to a crane and above ground level while minimizing the risk of injury.

The invention prevents movement of a crane when a cable is extended from a fall arrest unit and attached to a safety hardness worn by a worker.

The invention prevents movement of objects by a crane when a cable is extended from a fall arrest unit and attached to a safety hardness worn by a worker.

The above and other objectives, features, and advantages of the preferred embodiments of the invention will become apparent from the following description read in connection with the accompanying drawings, in which like reference numerals designate the same or similar elements. 4. Brief Description of the Drawings

Additional aspects, features, and advantages of the invention will be understood and will become more readily apparent when the invention is considered in the light of the following description made in conjunction with the accompanying drawings:

FIG. 1 is a perspective view illustrating a fall arrest system including a sensor assembly disposed between a winch and a pair of fall arrest units in accordance with an embodiment of the invention;

FIG. 2 is a side view illustrating arrangement of a winch, a sensor assembly, and a fall arrest unit along a track in accordance with an embodiment of the invention;

FIG. 3 is an enlarged side view illustrating attachment of a winch to a pair of rails along a track in accordance with an embodiment of the invention;

FIG. 4 is a perspective view illustrating attachment of a sensor assembly including a frame attached at one end to a pair of rails along a track and attached an another end to sensors and guides in accordance with an embodiment of the invention;

FIG. 5 is an enlarged view illustrating arrangement of sensors and guides along an adjustment bracket of a frame in accordance with an embodiment of the invention;

FIG. 6 is an enlarged view illustrating attachment of a sensor and guides to an adjustable bracket and engagement of an arrest cable with the sensing end of a sensor in accordance with an embodiment of the invention;

FIG. 7 is an enlarged view illustrating a lower end of a counterweight and attachment of arrest cables to attachment brackets in accordance with an embodiment of the invention;

FIG. 8 is a perspective view from ground level illustrating extension of arrest cables and winch cable from a fall arrest system with a counterweight attached to the end of the cables in accordance with an embodiment of the invention;

FIG. 9 is a perspective view from ground level illustrating placement of a fall arrest system along the underside of an overhead crane in accordance with an embodiment of the invention;

FIG. 10 is a schematic diagram illustrating connectivity between a winch, a fall arrest unit, a sensor, a control unit, a relay unit, and a crane in accordance with an embodiment of the invention; FIG. 11 is a circuit diagram illustrating circuitry for disabling functionality of a crane when an arrest cable is extended from a fall arrest unit and for enabling functionality of the crane when an arrest cable is retracted into a fall arrest unit in accordance with an embodiment of the invention;

FIG. 12 is a circuit diagram illustrating a fall restraint relay box for the diagram in FIG. 11 ;

FIG. 13 is a diagram illustrating a relay box terminal strip for the diagrams in FIGS. 11-12;

FIG. 14 is a diagram illustrating a relay box for the diagrams in FIGS. 11-13; and

FIG. 15 is a diagram illustrating a remote junction box for the diagrams in FIGS. 11-14.

5. Modes for Carrying Out the Invention

Reference will now be made in detail to several embodiments of the invention illustrated in the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts. The drawings are in simplified form and are not to precise scale.

While features of various embodiments are separately described, it is understood that two or more such features could be combined to form other embodiments.

Referring now FIGS. 1 and 2, the fall arrest system 1 is shown including a sensor assembly 2 disposed between a winch 3 and a pair of fall arrest units 4. While one winch 3, one sensor assembly 2, and a pair of fall arrest units 4 are illustrated in FIGS. 1 and 2, it is understand that one or more of each such component are applicable to various embodiments of the present invention.

Referring again to FIGS. 1 and 2, some embodiments of the fall arrest system 1 may further include a track 5. The fall arrest unit 4 may be secured to the track 5 with or without the sensor assembly 2 and/or the winch 3, whereby the latter two components may be attached directly to either the track 5 or a crane (not shown). In yet other embodiments, the sensor assembly 2, the winch 3, and the fall arrest unit 4 may be secured directly to a crane via means understood in the art.

Referring again to FIGS. 1 and 2, the winch 3 is understood to be a device capable of extending and retracting a winch cable 38 via motorized or non-motorized means. The winch cable 38 should be sufficiently strong so as to support a mechanical load applied to the end thereof by one or more arrest cables 28 and a counterweight 34. The winch cable 38 should be sufficiently long so as to extend from the winch 3 to a height at or above ground level thereby enabling attachment and detachment of the winch cable 38 with respect to a U-shaped bracket 37 along the counterweight 34. The winch cable 38 may be composed of a metal or other generally flexible material suitable for the intended use. The winch 3 should be sufficiently powered or capable of lifting and lowering at least the winch cable 38, one or more arrest cables 28, and the counterweight 34. One non-limiting example of the winch 3 is the Power Tagline, Model No. 8102101, sold by D B Industries, LLC (doing business as Capital Safety USA) with an office in Red Wing, Minnesota.

Referring again to FIGS. 1 and 2, the fall arrest unit 4 is understood to be a connecting device that may include a retractable arrest cable 28 or other suitable cord, strap, chain, or cable connectable at one end to a safety harness worn by a worker. The arrest cable 28 should be sufficiently strong so as to support a mechanical load applied to one end thereof by a worker's body. The arrest cable 28 should be sufficiently long so as to extend from the fall arrest unit 4 to a height at or above ground level that enables attachment and detachment of the arrest cable 28 with respect to the counterweight 34 and a safety harness worn by a worker. The arrest cable 28 may be composed of a metal or other generally flexible material suitable for such use and compatible with the sensing methodology incorporated into the invention. One non-limiting example of a fall arrest unit 4 is the Miller® Falcon™ Self-Retracting Lifeline, Model No. MP20SS, sold by Honeywell International, Inc. with an office in Morristown, New Jersey.

Referring now to FIGS. 1, 2, and 3, the track 5 is understood to be a device that includes one or more rails 6 separately facilitating attachment of one or more fall arrest units 4 thereto. The track 5 may be secured to the structure comprising a crane via means understood in the art. One non-limiting example of a track 5 is the Tether Track ^® System, dual trussed (rail) track with trolleys, sold by Gorbel, Inc. with an office in Fishers Run, New York.

Referring now to FIG. 3, the winch 3 may be directly fastened and fixed to the rails 6 along the track 5. An upper bracket 14 and a lower bracket 15 may be positioned in an opposed arrangement about the rails 6. The upper and lower brackets 14, 15 may be secured to the rails 6 via two or more fasteners 16. A bolt-type fastener 16 may pass through a complementary-sized hole along each of the upper and lower brackets 14, 15 and tightened thereto so that the upper and lower brackets 14, 15 are pressed onto and thereby secured to the rails 6. A vertical portion of a generally L- shaped bracket 17 may be secured at an upper end to the lower bracket 15 via bolt- type fasteners 18. The winch 3 may be supported along the horizontal portion of the L-shaped bracket 17 and secured thereto via bolt-type fasteners 19. In preferred embodiments, the bottom of the winch 3 is positioned at a height above the bottom of the fall arrest unit 4.

Referring now to FIG. 4, each rail 6 may include a trolley 7 disposed along the rail 6 in a slidable fashion. Each trolley 7 may further include a ring 8 extending downward therefrom. A clip 9 may engage and interlock with the ring 8 along the trolley 7 and a ring 10 disposed at the upper end of the fall arrest unit 4. The clip 9 may be a carabiner or other functionally similar device capable of securing one component to another component while supporting the weight of the second component and other objects suspended therefrom. The trolley 7 allows the fall arrest unit 4 attached thereto to translation along the rail 6 thereby permitting a wider range of motion by a worker connected to the fall arrest unit 4 via the arrest cable 28.

Referring again to FIG. 4, the sensor assembly 2 is understood to properly position and secure at least one sensor 12 between the fall arrest unit 4 and the winch 3. The upper end of the sensor assembly 2 may be fixed to the rails 6. The sensor 12 is positioned at and secured adjacent to the lower end of the sensor assembly 2.

Referring again to FIG. 4, the support structure comprising the sensor assembly 2 may include a variety of designs suitable for properly positioning and fixing one or more sensors 12. In one non-limiting example, the support structure may be a frame 11 fabricated from generally L-shaped elements welded and/or fastened to the required shape and dimensions.

Referring again to FIG. 4, an upper bracket 20 may be positioned at one end of a pair of substantially parallel vertical brackets 23. The upper bracket 20 may be fixed to each vertical bracket 23 via a weld 42 (right side weld 42 not shown). The upper bracket 20 may contact the top side of each rail 6 so that the vertical brackets 21 are disposed about and extend downward from the rails 6. A lower bracket 21 may be positioned between the vertical brackets 23 so as to contact the bottom side of each rail 6. The upper and lower brackets 20, 21 may be secured to the rails 6 via two or more fasteners 22. A bolt-type fastener 22 may pass through a complementary-sized hole along each of the upper and lower brackets 20, 21 and tightened so that the upper and lower brackets 20, 21 are pressed onto and thereby secured to the rails 6 so as to fix the frame 11 to the track 5 via the rails 6.

Referring now to FIGS. 4 and 5, an adjustable bracket 24 may be secured adjacent to the lower end of each vertical bracket 23. A slot 25 may extend along a portion of the length of the respective vertical bracket 23. A pair of bolt-type fasteners 26 may separately extend through a complementary-sized hole along each end of the adjustable bracket 24. Each fastener 26 may align with and engage one slot 25. The adjustable bracket 24 may be secured to the vertical brackets 23 when the fasteners 26 are tightened. The height of the adjustable bracket 24 relative to the winch 3 and the fall arrest unit 4 may be adjusted upward and downward along the slots 25 when the fasteners 26 are loosened. This adjustability facilitates refinements to the distances between the sensor 12 and each of the winch 3 and the fall arrest units 4.

Referring again to FIG. 4, it may be advantageous in some embodiments to include one or more guides 13. The guide(s) 13 may be secured to the adjustable bracket 24 adjacent to each sensor 12. In preferred embodiments, each guide 13 may extend downward and away from the sensor 12.

Referring again to FIG. 4, wiring to and from a sensor 12 may be secured to the frame 11. For example, it may be advantageous in some embodiments to secure a cable 43 extending from a sensor 12 to a vertical bracket 23 so as to prevent entanglement with other components within or adjacent to the fall arrest system 1. Each cable 43 may be secured to the frame 11 at one or more locations via a strap 44. One non-limiting example of a strap 44 is a zip tie. Other attachment means suitable for cabling are likewise applicable to the present invention.

Referring now to FIGS. 4, 5, and 6, one or more guides 13 may contact the bottom surface of the adjustable bracket 24 and extend downward therefrom. Each guide 13 may include a hole 29. A strap 30 may pass through the hole 29 and encircle the adjustable bracket 24 and the upper end of the guide 13 thereby securing the guide 13 to the adjustable bracket 24 when the strap 30 is tightened. One non-limiting example of a strap 30 is a zip tie. Other mechanical and non-mechanical means suitable for attaching a guide 13 to an adjustable bracket 24 are likewise applicable to the present invention.

Referring again to FIGS. 4, 5, and 6, a guide 13 is positioned below and adjacent to each sensor 12. One or more guides 13 may be required to provide a mechanical means for properly aligning an arrest cable 28 extending from a fall arrest unit 4 with a sensor 12. In preferred embodiments, the guide(s) 13 should provide a guide channel 33 adjacent to the sensor 12. The guide channel 33 should restrict lateral movement of an arrest cable 28 relative to the sensing end of a sensor 12 when an arrest cable 28 extending from a fall arrest unit 4 is pulled across the sensor assembly 2 via a winch cable 38. For example, two guides 13 may be shaped and positioned so that the width of the guide channel 33 decreases in the direction of the sensor 12.

Referring again to FIGS. 4, 5, and 6, the shape and orientation of the guide channel 33 should minimize mechanical impediments to alignment of an arrest cable 28 with a sensor 12. In preferred embodiments, each guide 13 may be triangular shaped and disposed in a symmetric arrangement about a sensor 12 to form a guide channel 33 that is substantially triangular shaped; however, it is understood that other shapes are possible for the guide channel 33. In yet other preferred embodiments, each guide 13 may be composed of a low-friction material that reduces friction between an arrest cable 28 and guides 13 during retraction and extension of the arrest cable 28. Exemplary low-friction materials include, but are not limited to,

polypropylene, polytetrafluoroethylene (PTFE), and polyethylene.

Referring now to FIG. 6, the sensor 12 may be mechanically secured to the adjustable bracket 24 via one or more fasteners 32. In preferred embodiments, the sensor 12 is positioned along the adjustable bracket 24 adjacent to the fall arrest unit 4 so that at least a portion of the sensor 12 extends below the fall arrest unit 4. This arrangement ensures general alignment between the arrest cable 28 and sensor 12. In some embodiments, the detection end 31 of the sensor 12 may extend in part of whole beyond the adjustable bracket 24, whereby the latter may require a notch or the like along the horizontal portion of the adjustable bracket 24. In yet other preferred embodiments, one sensor 12 is provided for each fall arrest unit 4 and the sensors 12 and fall arrest units 4 are positioned so that one arrest cable 28 engages one sensor 12. Referring again to FIG. 6, the guide(s) 13 is/are positioned so that the upper end of each guide 13 is adjacent to the detection end 31 of a sensor 12. This arrangement provides a pathway enabling engagement between the arrest cable 28 and the detection end 31 for proper detection of the arrest cable 28 by the sensor 12. In preferred embodiments, the sensor 12 may be a proximity-type device that detects the arrest cable 28 without physical contact between the sensor 12 and the arrest cable 28. Detection means may include, but is not limited to, capacitive, Doppler, eddy- current, inductive, magnetic, radar, sonar, or ultrasonic. One non-limiting example of a proximity -type device is the inductive sensor, model no. BI15-CP40-FDZ30X2- B 1131, sold by Turck, Inc. with an office in Minneapolis, Minnesota. In other embodiments, the sensor 12 may be an optical-type device that detects the arrest cable 28 with or without physical contact between the sensor 12 and the arrest cable 28. Detection means may include, but is not limited to, heat, visible light, or invisible light. In yet other embodiments, the sensor 12 may be a contact-type sensor that detects the arrest cable 28 when physical contact occurs between the sensor 12 and the arrest cable 28. Detection means may include, but is not limited to, force, pressure, vibration, or acceleration.

Referring now to FIGS. 2, 6, and 7, the arrest cable 28 engages the sensor 12 in a retracted configuration when the winch cable 38 is retracted. This arrangement aligns the arrest cable 28 across the sensor assembly 2 so that the end of the arrest cable 28 is adjacent to the winch 3. A portion of the arrest cable 28 extending from the fall arrest unit 4 is disposed about the sensor assembly 2 in a generally U-shaped configuration so that the arrest cable 28 resides between the guides 13 and interacts with the sensor 12.

Referring again to FIGS. 2, 6, and 7, each arrest cable 28 may be secured to the winch cable 38 via the counterweight 34. The winch cable 38 may be secured to the counterweight 34, as illustrated in FIG. 2. The arrest cable 28 is secured to a U- shaped bracket 35 via a latch 36, as illustrated in FIG. 7. The latch 36 may be a carabiner or other similar device. In other embodiments, it may be desired to directly secure the winch cable 38 to the arrest cable(s) 28 with or without the counterweight 34, the latter possibly requiring an alternate means for overriding the self-retracting functionality of the fall arrest units 4. Examples of the latter may include a rope or a pole with hook means allowing a worker to pull on the arrest cable 28 as the winch cable 38 is extended.

Referring now to FIG. 8, each arrest cable 28 attached to the counterweight 34 moves downward and away from the sensor assembly 2 in an extended configuration when the winch cable 38 is extended. The downward motion of the counterweight 34 separates each arrest cable 28 from its respective sensor 12 thereby indicating use of the arrest cables 28 by a worker. Information from the sensor 12 representative of this configuration may be communicated either directly or indirectly to a crane (not shown) for the purpose of disabling some or all functionality of the crane. When the arrest cables 28 are extended to a length accessible by a worker possible, the worker detaches the counterweight 34 from each arrest cable 28. The arrest cables 28 are then attached to one or more safety harnesses worn by one or more workers via means understood in the art. Thereafter, the winch cable 38 with or without the

counterweight 34 may be retracted into the winch 3. After use of the arrest cables 28, the winch cable 38 is re-extended to allow for reattachment of the winch cable 38 and the arrest cables 28 to the counterweight 34 as described herein. The winch cable 38 is retracted into the winch 3 thereby pulling the counterweight 34 and the arrest cables 28 upward and across the sensor assembly 2 so that the arrest cables 28 reengage the sensors 12. Information from the sensor 12 representative of this configuration may be communicated either directly or indirectly to a crane (not shown) for the purpose of re-enabling functionality of the crane. The arrest cables 28 are retracted into the respective fall arrest units 4 via the self-retracting feature of the fall arrest units 4.

Referring again to FIG. 8, the preferred motion of the counterweight 34 is downward due to gravitational effects. This preferred motion means that the counterweight 34 falls away from the track 5, the sensor assembly 2 and the fall arrest units 4 when the winch cable 38 is extended from the winch 3 and that the

counterweight 34 must be pulled upward and toward the track 5, the sensor assembly 2 and the fall arrest units 4 by the winch 3 when the winch cable 38 is retracted.

Referring again to FIG. 8, the weight of the counterweight 34 should be sufficient so as to pull on and extend the otherwise retractable arrest cables 28 from the fall arrest units 4. The counterweight 34 may be composed of one or more materials suitable for such use. It is understood that the weight of the counterweight 34 is design dependent based on various factors including, but not limited to, the number of arrest cables 28 attached to the counterweight 34 and the retraction force applied by each arrest cable 28. For example, a weight of 20 pounds was sufficient in preferred embodiments to extend a pair of arrest cables 28 from the Miller® Falcon™ Self-Retracting Lifeline identified herein.

Referring now to FIG. 9, the fall arrest system 1 is shown attached to the underside of an overhead industrial crane 39 in one exemplary embodiment. The fall arrest system 1 may be mechanically attached to the crane 39 via means understood in the art. It is also understood that the fall arrest system 1 is applicable to a variety of crane systems, examples including, but not limited to, industrial cranes, process and specialty cranes, portal cranes, telescoping cranes, boom cranes, and the like.

Referring now to FIG. 10, a control unit 40 may communicate with the winch 3 via wire or wireless means understood in the art. In some embodiments, the control unit 40 may be specifically designed for use with the winch 3 and thereby sold as a component to the winch 3. In other embodiments, the control unit 40 may be adapted or modified for use with the winch 3 and therefore comprise one or more devices sold separate and apart from the winch 3. The control unit 40 should at least enable extension and retraction of the winch cable 38 from the winch 3.

Referring again to FIG. 10, the winch 3 and the fall arrest unit 4 separately include a winch cable 38 and an arrest cable 28, respectively. The winch cable 38 and arrest cable 28 are both extendable from and retractable into the respective devices. The winch cable 38 and the arrest cable 28 are coupled to the counterweight 34 during extension (lowering) and retraction (raising) of the winch cable 38 prior to use of the arrest cable 28 by a worker. The arrangement of the winch 3 and the fall arrest unit 4 about the sensor 12 ensures the arrest cable 28 engages the sensor 12 when the winch cable 38 is retracted and disengages the sensor 12 when the winch cable 38 is extended. This arrangement couples the electrical output from the sensor 12 to the mechanical action of the winch cable 38 and the arrest cable 28 with respect to the sensor 12.

Referring again to FIG. 10, the sensor 12 may communicate with a crane 39 either directly or indirectly. Direct communication may permit the sensor 12 to electrically communicate output from the sensor 12 to a control circuit in the crane 39 so that the output signals are processed either to disable or to enable functionality of the crane 39 via methods used to process input from other control devices communicable with the crane 39. Indirect communication may permit a relay unit 41 either to electrically communicate output from the sensor 12 to a control circuit in the crane 39 or to open and close a circuit thereby powering and depowering the crane 39.

Regardless of the specific control approach, information from the sensor 12 may be used to disable and to enable functionality of the crane 39 in part or whole. In one non-limiting example, movement of the crane 39, namely, travel by a trolley along runway beams in an overhead-type crane system, may be enabled when the winch cable 38 is retracted and the arrest cable 28 is sensed by the sensor 12 and disabled when the winch cable 38 is extended and the arrest cable 28 is not sensed by the sensor 12. In another non-limiting example, movement by the crane 39, namely, lifting and lowering by a hoist via cable and hook block in an overhead-type crane system, may be enabled when the winch cable 38 is retracted and the arrest cable 28 is sensed by the sensor 12 and disabled when the winch cable 38 is extended and the arrest cable 28 is not sensed by the sensor 12. In yet another non-limiting example, movement of and by the crane 39 may be concurrently disabled and enabled as described above. In preferred embodiments, other means for controlling the crane 39 may also be disabled or ignored to the extent or in addition to the various

functionality of the crane 39 that is/are disabled by the fall arrest system 1.

Referring now to FIGS. 11-15, an exemplary circuit for indirect

communication between a sensor 12 and a crane 39 is shown and further described with reference to various elements in FIGS. 1-10. Specifically, FIGS. 11-15 illustrate an indirect means for controlling a crane 39 via a relay unit 41 when the fall arrest system 1 includes a pair of fall restrain units 4 separately interacting with a pair of induction-type sensors 12. FIG. 11 illustrates circuitry pertaining to a Fall Restraint Interlock (FRI) relay enabling functionality that interrupts power to a crane 39 when contacts are OPEN and un-interrupts power to a crane 39 when contacts are

CLOSED. FIG. 11 further illustrates circuitry whereby power is also communicated to the winch 3. While specific values are shown for some components, it is understood that actual values may differ from those shown based on the design and application of the system. FIG. 12 illustrates circuitry pertaining to the sensors 12 that enables the FRI relay to be either OPEN when the arrest cable 28 is extended or CLOSED when the arrest cable 28 is retracted. FIG. 13 illustrates a terminal strip for electrical connections for the sensors 12 enabling functionality of the relay unit 41. FIG. 14 illustrates relay socket pins for electrical connections enabling functionality of the relay unit 41. FIG. 15 illustrates terminal connections for connectivity of the winch 3 and sensors 12 enabling functionality of the relay unit 41.

The description above indicates that a great degree of flexibility is offered in terms of the present invention. Although various embodiments have been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

6. Industrial Applicability

The invention may be used within a variety of applications wherein a worker must work above ground level adjacent to lifting equipment, one specific non-limiting example being a crane whereby a component is elevated for assembly with another component during construction of industrial equipment.