FALL ARREST ASSEMBLY
A fall arrest assembly that includes a rotational drum, at least one pawl and a catch is provided. The rotational drum is configured to rotate in response to a movement of a lifeline. The least one pawl is in rotational communication with the rotational drum. The at least one pawl is further configured to pivot about a pivot connection in response to select rotational velocities of the rotational drum. The at least one pawl is also configured to engage the catch when the at least one pawl pivots in response to the select rotational velocities of the rotational drum to stop the rotation of the rotational drum and movement of the lifeline. An elastic bushing for each pivot connection is also used. Each elastic bushing is positioned about an associated pivot connection of an associated pawl. The elastic bushings deform in shape as an associated pawl engages the at least one portion of the catch.
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This application claims priority to U.S. Provisional Application Ser. No. 61/196,716, entitled “Climb Assist System,” filed on Mar. 2, 2009, and Provisional Application Ser. No. 61/167,459 entitled “Climb Assist System,” filed on Apr. 7, 2009, which are both incorporated in their entirety herein by reference. This Application is further related to U.S. Utility application Ser. No. ______ (Attorney Docket No. 221P249USU1), entitled “Climb Assist System,” filed on even date herewith which is also incorporated in its entirety herein by reference.
BACKGROUNDThe ability to service devices that are elevated requires a system for getting a service technician to the device. One common system used to reach elevated locations is a ladder. However, when the distance to reach the device is significant, the use of a ladder is restricted to only those individuals that are physically capable of climbing the distance of the ladder. Safety issues also have to be considered. The more fatigue a worker is experiencing, the more likely an accident could occur such as slipping and falling. Hence, fatigue that comes with climbing great distances should be taken into consideration when implementing a system to reach a device at an elevated location.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an effective and safe means to assist a worker climb a ladder.
SUMMARY OF INVENTIONThe above-mentioned problems of current systems are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the invention.
A fall arrest assembly is provided. The fall arrest assembly includes a rotational drum, at least one pawl and a catch. The rotational drum is configured to rotate in response to a movement of a lifeline. The least one pawl is in rotational communication with the rotational drum. The at least one pawl is further configured to pivot about a pivot connection in response to select rotational velocities of the rotational drum. The at least one pawl is also configured to engage the catch when the at least one pawl pivots in response to the select rotational velocities of the rotational drum to stop the rotation of the rotational drum and movement of the lifeline. An elastic bushing for each pivot connection is also used. Each elastic bushing is positioned about an associated pivot connection of an associated pawl. The elastic bushings deform in shape as an associated pawl engages the at least one portion of the catch.
The present invention can be more easily understood and further advantages and uses thereof more readily apparent, when considered in view of the detailed description and the following figures in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention. Reference characters denote like elements throughout Figures and text.
DETAILED DESCRIPTIONIn the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the claims and equivalents thereof.
Embodiments of the present invention provide a system that assists a user climb up and down a ladder. In embodiments, a looped cable or similar attaching means such as a looped rope is operatively coupled to the user. The cable provides a select pulling force on the user as the user climbs up or down on the ladder. Hence part of the user's weight is reduced when climbing or descending thereby reducing the effort needed by the user. In some embodiments, the climb assist detects when a user has stopped and in response, ceases the pulling force. In these embodiments, the climb assist is re-established by action of the user, such as pulling on the cable. In further embodiments, a fall arrest system is integrated into the climb assist system.
Referring to
The tension adjusting assembly 104 includes a housing 105 that is attached to the ladder 101 with brackets 110. Similar to the extension member 106, the housing 105 includes a ladder hook 112 used to position the housing 105 on the ladder 101 while attaching brackets 110 are engaged. The motor assembly 102 is coupled to the tension adjusting assembly 104. The motor assembly 102 provides pulling force on the looped cable 120 as is further described below. As
Further illustrated in
Referring to
The drive sheave 210 is coupled to the drive shaft 410 of the motor 402 via slip clutch 502. A third guard cover 420 is coupled to the retaining plate 412 to cover the looped cable 120 in a V-shaped groove of the drive sheave 210. The third guard cover 420 includes a first cable notch 421 and a second cable notch 423 that provides a path for the looped cable 120 to and from the drive sheave 210. The ring catch 304 is coupled to the third guard cover 420 as illustrated. A first and second drive sheave covers 404 and 422 are coupled to the ring catch 304 to cover the front of the drive sheave 210.
Referring to
The drive sheave 210 is further illustrated in
Referring to
Fall arrest system 550 in this example includes two pawls 302A and 302B. It will be understood that the one or more pawls could be used and that the present invention is not limited to two pawls. Each of the pawls 302A and 302B has a first end that is pivotally coupled to a side plate 210a of a rotational drum such as drive sheave 210. The drive sheave 210 is in a rotational connection with the lifeline such as the loop cable 120 as discussed above. Around the pivot connection 570 is the elastic bushing 532. Proximate another end of each of the pawls 302A and 302B, biasing members 530 are coupled between connecting apertures 556 in the respective pawls 302A and 302B and screws 558. As discussed above, the biasing members 530 bias the pawls 302 away from the inner protrusions 306 of the ring catch 304 until enough centrifugal force is created by the speed of the drive sheave 210 to counter the force of the biasing members 530, thus allowing the pawls to pivot outward.
In use, bushing 532 associated with pawl 302A deforms which absorbs some of the energy generated during the impact of the surface 552 of pawl 302A on surface 554 of the inner protrusion 306. The energy is absorbed instead of being released back (rebound) as is typical for a rigid contact system (for example metal on metal). In addition to this energy absorption aspect, the deformation of the bushing 532 allows a slight rotation of the sheave in the opposite direction of the fall before the pawl disengages. This is because it takes a few degrees of sheave rotation for the bushing to go back to its original non-deformed shape. The play (differing radial lengths) provided by the elastic bushing 532 during the few degrees of the sheave rotation is enough to help prevent disengagement between pawl 302A and the inner protrusion 306 of the ring catch 304 (ratchet wheel). Hence, even if the system rebounds a couple of degrees, the deformation provided by the elastic bushings 532 allows the system to catch up with the rebound without disengaging the pawl 302A from the inner protrusion 306. Accordingly, the use of elastic bushings 532 prevents ratcheting. Although only one pawl 302A is illustrated in
A control panel 600 of one embodiment is illustrated in
Referring to
Referring back to 8B, the tension adjusting assembly 104 includes an adjustment member 108 and a moving support 803. When the adjusting member 108 is rotated, the moving support 803 is moved down to adjust the tension in the cable 120. The moving support 803 includes the attaching member 208 as discussed above. The moving support 803 further includes a biasing member 808, a washer 806, shaft 252 and bearings 812A and 812B. The shaft 252 fits through openings 825 in the attaching member 208. The bearings 812A and 812B fit on the shaft 252 proximate respective ends of the shaft 252. In particular, respective retaining rings 816A and 816B are positioned between the bearings 812A and 812B and an outer surface of the attaching member 208. The retaining rings 816A and 816B ensure the attaching tube 208 stays in a middle portion of the housing 105 which is square in one embodiment. The bearings 812A and 812B guide the attaching member 208 in the openings 206 in opposite sides of the housing 105 of the tension adjusting assembly 104. This is illustrated in regard to bearing 812B in opening 206 in
An upper sheave assembly 1004 is coupled to the adjustment plate 1014. The upper sheave assembly 1004 includes an upper sheave 1010 that is rotationally coupled to the adjustment plate 1014 via fastener 1040, washers 1042 and nut 1046. A bearing 1044 is positioned between a surface of fastener 1040 and a portion of the upper sheave 1010 that defines a central aperture 1060 passing through the upper sheave 1010. An upper guard cover 1012 covers a portion of cable 120 (not shown) received in the upper sheave 1010. The upper guard cover 1012 has a first opening 1062 and second opening 1064 that allow the cable 120 (not shown) to enter into and exit out of the upper sheave 1010. A front upper cover 1016 is used to cover the front of the sheave 1010. The front upper cover 1016 and the upper guard cover 1012 are coupled to the adjustment plate 1014 via fasteners 1038. The adjustment plate 1014 includes upper and lower slots 1030A and 1030B. The adjustment plate 1014 is slidably coupled to the extension member 1002 via bolts 1024A and 1024B that pass through the upper and lower slots 1030A and 1030B and through apertures 1032A and 1032B in the extension member 1002. Nuts 1036A and 1036B retain the bolts 1024A and 1024B in the upper and lower slots 1030A and 1030B of the adjustment plate 1014 and the apertures 1032A and 1032B of the extension member 1002. As also illustrated in
Referring to
An upper sheave assembly 1104 is coupled to an adjustment plate 1114. The upper sheave assembly 1104 includes an upper sheave 1110 that is rotationally coupled to a retaining plate 1170 via fastener 1140, washers 1142 and nut 1148. In particular, fastener 1140 passes through a retaining plate central opening 1170c in the retaining plates and is engaged with nut 1148. A bearing 1144 is positioned between a surface of fastener 1140 and a portion of the upper sheave 1110 that defines a central aperture 1160 passing through the upper sheave 1110. An upper guard cover 1112 covers a portion of cable 120 (not shown) received in the upper sheave 1110. The upper guard cover 1112 has a first opening 1162 and second opening 1164 that allow the cable 120 (not shown) to enter into and exit out of the upper sheave 1110. A front upper cover 1116 is used to cover the front of the sheave 1110. The front upper cover 1116 and the upper guard cover 1112 are coupled to the retaining plate 1070 via fasteners 1138.
The upper cable guide 1100 of this embodiment further includes an adjustment plate 1114. The adjustment plate 1114 includes a first slot 1114C and a second slot 1114D. A connecting third slot 1114E is positioned between the first and second slots 1114C and 1114D. The third slot 1114E has a height that is greater than the height of the first and second slots 1114C and 1114D. The retaining plate 1170 is slidably coupled to the adjustment plate 1114. In particular, fasteners 1172A and 1172B passing through apertures 1170A and 1170B in the retaining plate 1170 and in slots 1114C and 1114D respectfully are retained via washers 1150 and nuts 1146. Nut 1148 coupled to fasteners 1140 is received in the central slot 1114E. To adjust the location of the sheave 1110, nuts 1146 are loosened to allow fasteners 1172A and 1172B to slide in slots 1114C and 1114D of the adjustment plate. When the desired location is achieved, the nuts 1146 are re-tightened. The adjustment plate 1114 is coupled to extension member 1102 via fasters 1124A and 1124B. In particular, fasteners 1124A and 1124B passing through, apertures 1114A and 1114B in the adjustment plate 1114, passages 1132A and 1132B in the extension member 1102 are coupled to the extension member 1102 via nuts 1136A and 1136B. Spacers 1128A and 1128B are used to space the adjustment plate 1114 from the extension member 1102. In one embodiment, the adjustment plate 1114 is not symmetrical and therefore its assembly in the right position is critical. In this embodiment, a notch 1182 is placed in a surface that defines slot 1114E as indicated in the close up view of section 1180 in
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
Claims
1. A fall arrest assembly comprising:
- a rotational drum configured to rotate in response to a movement of a lifeline;
- at least one pawl in rotational communication with the rotational drum, the at least one pawl further configured to pivot about a pivot connection in response to select rotational velocities of the rotational drum;
- a catch, the at least one pawl configured to engage the catch when the at least one pawl pivots in response to the select rotational velocities of the rotational drum to stop the rotation of the rotational drum and movement of the lifeline; and
- an elastic bushing for each pivot connection, each elastic bushing positioned about an associated pivot connection of an associated pawl, wherein each elastic bushing deforms in shape as an associated pawl engages the at least one portion of the catch.
2. The fall arrest assembly of claim 1, further comprising:
- the rotational drum having a side plate, the at least one pawl pivotally coupled to the side plate; and
- a biasing member for each pawl, each biasing member configured to prevent an associated pawl from pivoting until the select rotational velocities of the rotational drum are reached.
3. The fall arrest system of claim 1, wherein the catch further comprises:
- a catch ring, the at least one pawl configured to engage at least one portion of the catch ring when the at least one pawl pivots in response to the select rotational velocities of the rotational drum to stop the rotation of the rotational drum and movement of the lifeline.
4. The fall arrest assembly of claim 3, wherein the at least one portion of the catch ring is at least one interior protrusion, the at least one pawl configured to engage the at least one interior protrusion when the at least one pawl pivots in response to the select rotational velocities of the rotational drum to stop the rotational drum from rotating.
5. The fall arrest assembly of claim 1, further comprising;
- a guard cover positioned around at least a portion of an outer parameter of the rotational drum, the catch coupled to the guard cover.
6. The fall arrest assembly of claim 1, wherein the rotational drum is a sheave in a climb assist assembly.
7. The fall arrest assembly of claim 6, wherein the climb assist assembly further comprises:
- a motorized climb assist system configured to assist a user in using a ladder.
8. The system of claim 7, wherein the motorized climb assist system further comprises:
- a tension adjusting assembly configured to be coupled proximate a first end of the ladder;
- a motor assembly coupled to the tension adjusting assembly, the motor assembly including the fall arrest assembly; and
- an upper guide configured to be coupled proximate a second end of the ladder, the motor assembly and the upper guide configured to movably engage a looped belt therebetween, the looped belt coupled to the lifeline.
9. A fall arrest assembly comprising:
- a sheave in rotational communication with a lifeline;
- a cover positioned around at least a portion of an outer perimeter of the sheave;
- a ring catch coupled to the cover, the ring catch including inner protrusions;
- at least one pawl pivotally coupled to the sheave, the at least one pawl configured to engage at least one inner protrusion of the ring catch during a fall event to prevent the sheave from rotating thereby preventing the lifeline from paying out; and
- an elastic bushing for each pawl, each elastic bushing positioned about a pivot connection that pivotally couples an associated pawl to the sheave, wherein each elastic busing deforms when its associated pawl engages an associated inner protrusion of the ring catch to help prevent ratcheting of the fall arrest assembly.
10. The fall arrest system of claim 9, further comprising:
- a biasing member for each pawl, each biasing member configured to assert a select force on its respective pawl to position its respective pawl away from the at least one inner protrusion of the catch ring during normal operation and allow its respective pawl to engage one of the at least one inner protrusion during a fall event.
11. The fall arrest system of claim 10, wherein the each biasing member is coupled to a side plate of the sheave.
12. The fall arrest assembly of claim 9, further comprising:
- a motorized climb assist system configured to assist a user in using a ladder, the sheave integrated in the climb assist system.
13. The system of claim 12, wherein the motorized climb assist system further comprises:
- a tension adjusting assembly configured to be coupled proximate a first end of the ladder;
- a motor assembly coupled to the tension adjusting assembly, the motor assembly including the fall arrest assembly; and
- an upper guide configured to be coupled proximate a second end of the ladder, the motor assembly and the upper guide configured to movably engage a looped belt therebetween, the looped belt coupled the lifeline.
14. The system of claim 13, wherein the motor assembly further comprises:
- a motor having a drive shaft, the sheave coupled to the drive shaft;
- a retaining plate coupled to the motor; and
- at least one routing sheave rotationally coupled to the retaining plate, the at least one routing sheave configured to route the looped belt around the drive sheave and to the upper guide.
15. A fall arrest assembly comprising:
- a rotational drum configured to rotate in response to a movement of a lifeline;
- at least one pawl pivotally coupled to the rotational drum;
- a biasing member for each for each pawl, each biasing member coupled to each associated pawl to assert a biasing force on its associated pawl to prevent its associated pawl from pivoting about its pivot connection to the rotational drum;
- a catch ring, the at least one pawl configured to pivot and engage at least a portion of the catch ring when rotational velocities of the rotational drum create centrifugal forces greater than the biasing force of an associated biasing member; and
- an elastic bushing for each pivot connection, each elastic bushing positioned about an associated pivot connection of an associated pawl, wherein each elastic bushing deforms in shape as an associated pawl engages the at least one portion of the catch ring.
16. The fall arrest assembly of claim 15, further comprising:
- the rotational drum having a side plate, the at least one pawl pivotally coupled to the attaching side plate; and
- each biasing member coupled to the side plate.
17. The fall arrest assembly of claim 15, wherein the at least a portion of the catch ring is at least one interior protrusion, the at least one pawl configured to engage the at least one interior protrusion when rotational velocities of the rotational drum creates centrifugal forces greater than the biasing force of an associated biasing member.
18. The fall arrest assembly of claim 15, further comprising;
- a guard cover positioned around an outer parameter of the rotational drum, the catch ring coupled to the guard cover.
19. The fall arrest assembly of claim 15, wherein the rotational drum is a sheave in a climb assist assembly for a ladder.
20. The fall arrest assembly of claim 19, wherein the climb assist assembly further comprises:
- a looped belt;
- an attaching member coupled to the looped belt configured to attach a safety harness thereto;
- a motor assembly including, a motor having a drive shaft, and the rotational drum coupled to the drive shaft, the rotational drum in contact with the looped belt;
- a tension adjusting assembly coupled proximate a first end of the ladder, the tension adjusting assembly further coupled to the motor assembly, the tension adjusting assembly configured to adjust a tension in the looped belt around the rotational drum;
- an upper guide having a first end coupled to the ladder a select distance from the first end of the ladder; and
- an upper sheave coupled proximate a second end of the upper guide, the looped belt engaged with the upper sheave.
Type: Application
Filed: Jan 26, 2010
Publication Date: Sep 2, 2010
Applicant:
Inventor: Vincent G. Meillet (Cannes la Bocca)
Application Number: 12/694,086
International Classification: E06C 7/18 (20060101); A62B 35/00 (20060101); A62B 1/08 (20060101);