Pass-Through Cable Grab System

Abstract

A pass-through cable grab system which allows a workman wearing a harness to move up and down a ladder on a tower or similar structure while being protected from falling by a vertically extending safety cable attached to the tower. The system includes at least one standoff bracket having a rear end secured to the tower and a forward end secured to the cable. A cable grab assembly includes a housing that can move vertically up and down the cable and further includes a brake mechanism. A lever extends from the housing and is connected to the workman through a lanyard. In the event of a fall, the lever moves downwardly activating the brake mechanism. The housing includes a vertically extending slot which allows the cable grab assembly to pass over the forward end of the standoff bracket as the cable grab assembly moves up and down. The standoff bracket also includes cam surfaces adjacent the top and bottom thereof which engage the housing as it moves toward the bracket to properly align the cable grab assembly so that it can pass over the standoff bracket.

Claims

1. A pass-through cable grab system which allows a workman wearing a harness to move up and down a ladder on a tower or similar structure while being protected from falling by a vertically extending safety cable attached to said tower comprising: a standoff bracket having a rear end adapted to be secured to said tower and a forward end secured to said cable; a cable grab assembly including a housing adapted to move vertically up and down said cable, said housing including a rear wall adjacent said standoff bracket; a brake mechanism located within said housing and adapted to prevent said housing from moving downwardly when said brake mechanism is activated; said cable grab assembly further including a lever extending therefrom and adapted to be connected to said workman, whereby, in the event of a fall by said workman, said lever moves downwardly activating said brake mechanism, and said housing including a vertically extending slot in said rear wall which allows said cable grab assembly to pass over said forward end of said standoff bracket as said cable grab assembly moves up and down said cable.

2. The pass-through cable grab system as claimed in claim 1 wherein said standoff bracket includes a first portion extending directly away from said tower and a second portion connected to said first portion that extends in an angular direction therefrom, the distal end of said second portion being attached to said cable.

3. The pass-through cable grab system as claimed in claim 1 wherein said standoff bracket includes a cam surface adjacent the top thereof which is capable of engaging said housing as it moves downwardly to properly align said cable grab assembly so that it can pass over said forward end of said standoff bracket.

4. The pass-through cable grab system as claimed in claim 1 wherein said standoff bracket includes a cam surface adjacent the bottom thereof which is capable of engaging said housing as it moves upwardly to properly align said cable grab assembly so that it can pass over said forward end of said standoff bracket.

5. The pass-through cable grab system as claimed in claim 4 wherein said standoff bracket includes a cam surface adjacent the top thereof which is capable of engaging said housing as it moves downwardly to properly align said cable grab assembly so that it can pass over said forward end of said standoff bracket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For the purpose of illustrating the invention, there is shown in the accompanying drawings one form which is presently preferred; it being understood that the invention is not intended to be limited to the precise arrangements and instrumentalities shown.

[0015] FIG. 1 is a rear right side perspective view of a pass-through cable grab constructed in accordance with the prior invention as the same is used on a vertically suspended steel safety cable;

[0016] FIG. 2 is a perspective view similar to FIG. 1 with the cable grab detached from the cable;

[0017] FIG. 3 is a perspective view similar to FIG. 2 but with parts broken away to show the inside of the cable grab in its nonbraking condition;

[0018] FIG. 4 is a perspective view similar to FIG. 3 showing the cable grab in its braking condition;

[0019] FIG. 5 is a perspective view similar to the other figures but showing the braking mechanism removed from the housing, and

[0020] FIG. 6 is a top plan view of the pass-through cable grab attached to the cable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] Referring to the drawings in detail wherein like reference numerals have been used throughout the various figures to designate like elements, there is shown in each of the figures a pass-through cable grab system constructed in accordance with the principles of the prior invention and designated generally as 10. In FIG. 1 pass-through cable grab 10 is shown in place on a vertically extending steel safety cable 12. Cable 12 may be only feet long or may be hundreds of feet long. While steel is the material from which most safety cables are made, it is also possible to produce them from other metals and alloys. The cables normally have a diameter of 5/16 to inch, although the thickness of the cable 12 and other specifications concerning the same are regulated by federal regulations and the regulations in several states. Furthermore, the pass-through cable grab 10 is preferably designed to be used with a particular size cable. That is, various different sizes of cable grabs may be made available for different size cables.

[0022] In the environment of the present invention, the cable 12 is secured to a vertical tower (not shown) which may be an antenna or other communications tower or a power line tower or the like. It is not beyond the scope of the present invention, however, to utilize the pass-through cable grab 10 with a cable 12 that is attached to a building or other structure. In any event, the cable 12 is attached to the tower adjacent the top thereof and near the bottom. In addition, a plurality of standoff brackets, such as shown at 14, secure the cable 12 to the tower at intermediate vertical positions along the height thereof. Under current OSHA regulations, the cable 12 must be attached to the tower at least every 40 feet.

[0023] Each bracket 14 includes a rear section 16 that is adapted to be connected to the tower and a forward section 18 that is connected to the cable 12. The connection to the cable is by way of a metal sleeve 20 that is securely crimped about the cable. The forward section 18 of the bracket 14 includes a first portion 22 that extends directly away from the tower (i.e. in the direction of the arrow in the figures) and a second portion 24 connected thereto that extends in an angular direction therefrom. It is the distal end of the second portion 24 that connects to the cable 12 through the sleeve 20.

[0024] Each bracket 14 also includes a plurality of cam surfaces that, as described in more detail below, help guide the pass-through cable grab 10 passed the bracket. These cam surfaces include an upper cam surface 26, an intermediate cam surface 28 and a lower cam surface 30. As can be seen in the figures, the intermediate cam surface 28 is essentially a substantially vertically extending flat surface having a height and a width. The upper cam surface 26 extends upwardly from the intermediate cam surface 28 but is bent backwardly somewhat toward the tower. In a similar manner, the lower cam surface 30 extends downwardly from the intermediate cam surface 28 and is bent backwardly toward the tower.

[0025] As with other known cable grabs, the pass-through cable grab 10 is connected to a worker through the use of a lanyard 32 which may be relatively short or up to 42 inches long in accordance with OSHA requirements. The free end 34 of the lanyard 32 is connected to the worker through a safety belt or harness worn by the worker. The near end 36 of the lanyard is connected to the pass-through cable grab 10 by attaching the same to the first end 38 of the brake lever 40, the details of which will be explained more fully hereinafter.

[0026] The manner in which the pass-through cable grab 10 of the present invention operates to prevent a fall is essentially the same as the cable grab described in prior U.S. Pat. No. 5,924,522, the entire contents of which are hereby incorporated by reference. Accordingly, only a brief description thereof is believed to be necessary.

[0027] The pass-through cable grab 10 is comprised essentially of two parts: a housing 42 and a brake mechanism 44 located within the housing. The cable 12 passes through the housing 42 as shown in FIG. 1. Or, said another way, the housing 42 surrounds the cable 12. In either case, the cable 12 lies between the inside 45 of the rear wall 46 of the housing and the pulley wheel 48. The pulley wheel 48 is mounted on an axle 50 which can ride up and down an elongated slot 52. A forked opening 54 in the second end of the brake lever 40 moves the pulley wheel 48 upwardly toward the inside surface 45 of the wall 46 or downwardly away from the wall 46. A spring 56 biases the pulley wheel 48 upwardly and toward the wall 46 to move the cable 12 toward the inside surface 45 of the wall, i.e. into the braking position.

[0028] As with the cable grab described in Applicant's prior patent, the pass-through cable grab 10 functions as a brake when a workman falls by having the lever 40 move the pulley wheel 48 against the cable 12. This forces the cable against the inside surface 45 of the wall 46. There will, of course, be some slippage which is desirable so as to avoid a sudden shock but after the cable grab 10 moves for several feet along the length of the cable 12, eventually it will function to brake the worker's fall. As is also clear from FIGS. 3 and 4, the cable 12 is guided through the cable grab 10 through the use of the upper roller 58. This helps to maintain the cable grab 10 properly oriented in a vertical position.

[0029] The length of the lanyard 32 allows the worker to move in a horizontal direction to either side of the safety cable 12. As the worker moves higher, the lanyard pulls up on the end 38 of brake lever 40 which, in turn, pulls the entire cable grab 10 upwardly with the worker. As long as the lanyard is above the height of the cable grab 10 and there is some upward force on the lanyard, the weight of the main portion of the cable grab maintains the end 38 of the lever 40 in its upward position so that the entire cable grab can freely move downwardly along the safety cable 12 as the worker descends slowly. Of course, should the worker fall, the end 38 of the lever 16 will move downwardly into its braking position and the cable grab 10 will arrest the fall of the worker.

[0030] The rear wall 46 of the housing 42 includes a vertically extending slot or opening 60. This slot has two primary functions. First, it allows the pass-through cable grab 10 to be attached to the cable 12 at any location along the length of the cable. This is accomplished by removing the pin 61 that secures the brake mechanism 44 to the housing 42 and then removing the brake mechanism from the housing as shown in FIG. 5. The housing 42 is then moved toward the cable 12 allowing the cable to pass-through the slot 60. The cable 12 is then positioned in the larger vertical opening or passageway 62 where it lies in front of the inner surface 45 of the wall 46. Once the cable is in place, the break mechanism 44 is reinserted and the cable now lies between the pulley wheel 48 and the inner surface 45 allowing the cable grab 10 to function as described above. The cable grab 10 cannot be removed from the cable 12 as the cable is held in place and cannot pass-through the space between the projection 64 on the wall 46 and the flange 66 on the wheel 48.

[0031] The second function of the slot 60 is to allow the cable grab 10 to pass the standoff brackets 14 as the cable grab moves vertically up or down along the cable 12. As can be seen best from FIG. 6 the first portion 22 of the bracket 14 simply passes through the slot 60 while the cable 12 or sleeve 20 remain in their proper position in the opening 62. As pointed out above, the cable 12 is essentially locked in place and cannot be dislodged from its proper position between the wheel 48 and the surface 45 of the wall 46.

[0032] As a workman ascends or descends the tower, he may be off to one side of the cable 12. This could cause the cable grab 10 to rotate somewhat about the axis of the cable 12. A small amount of rotation would not cause a problem. However, too much rotation could cause the housing 42 to rotate to the point that one of the top or bottom corners thereof could engage top or bottom of the forward end of the standoff 14. The cam surfaces 26, 28 and 30 described above prevent this from happening. For example, when the cable grab 10 is moving downwardly and if the housing 42 is rotated to one side, the leading corner will engage the surface 26 which will cause the housing to rotate back into its proper position. The essentially flat wall 46 will then engage the cam surface 28 which will keep the cable grab 10 properly aligned as it passes the standoff 14. Obviously, the same will be accomplished by the lower cam surface 30, if necessary, as the cable grab 10 is moving upwardly.

[0033] The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and accordingly reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.