Cable projectile catcher

A mechanism is provided for attachment to the exit end of a conduit during cable installation through the conduit. The mechanism absorbs the energy from, and captures the projectile and cable assembly exiting from a conduit during cable installation. A clamp is provided to attach the mechanism to the conduit. The clamp can be readily adjusted to fit a variety of conduit sizes.

FIELD OF THE INVENTION

The present invention relates to an energy-absorbing and projectile capturing system, finding utility when installing fiber-optic cable, or other like cable, in a buried conduit.

BACKGROUND ART

Conduits are often laid underground in covered trenches for long distances. Subsequently, fiber-optic cables or the like are installed in these conduits. During installation the cables are propelled from the open installation end of the conduit over a distance to the open exit end of the length of conduit by a combination of mechanical feeding and air pressurization as illustrated in U.S. Pat. No. 6,059,264 by Kaminski, et al.

The leading end of the cable is affixed with a device that allows free movement of the device through the conduit while also providing a seal between the device and the inside diameter of the conduit. This device is often referred to as a “bird”, “parachute”, or projectile, or the like. When the open installation end of the conduit is pressurized the pressure differential across the bird propels the bird and the attached cable along the path of the conduit to the open exit end of the conduit. The bird and attached cable may arrive at this exit end at very high velocity. Bodily injury, such as broken limbs, and, property damage, such as firing the projectile and cable over external power lines, have been reported as a result of the violent exit of the bird and cable from the exit end of the conduit.

U.S. Pat. No. 6,318,411 by Kology addresses these problems by using a receiver at the exit end of a conduit to absorb energy and catch the bird. This prior art describes the proofing of a conduit using only a bird, such as, if the bird can be sent through the conduit and arrive at the exit end, the conduit is assumed to be free of obstruction, and hence, ready for cable installation. Kology describes a three-piece tubular structure with a removable cap, which contains an energy absorbing rubber stop. One section of the tubular structure contains attachment threads for joining the removable cap. The second section contains perforations for allowing air escapement that accumulates in front of the moving bird. The third section is a transition tube that adapts the second section diameter to the conduit by reducing the third section diameter so that the inside diameter of the third section equals the inside diameter of the conduit.

The prior art requires a different size receiver for each different size of conduit. Separate conduit clamps or couplers must be provided to attach the receiver to the conduit.

SUMMARY OF THE INVENTION

The present invention utilizes a single tubular construction. One end of the tube is threaded to receive an end cap. The end cap supports a rubber snubber that provides energy dissipation when struck by the bird and cable being installed. Longitudinal slots are provided in the tube to allow air escapement from inside the tube to atmosphere, but are sized to retain the bird and cable within the tube.

The other end of the tube is fitted with a clamping mechanism, including a hinged pair of coupling halves and a locking swivel toggle bolt for attaching the tube to the conduit. The coupling halves are fitted with easily changeable clamping pads that contain gripping means for securing the tube to the conduit. Only one cable catcher is required to handle cable installation in a variety of conduit sizes by simply using the proper size clamping pads to match the conduit size.

Hence, a reliable and inexpensive mechanism provides safety and convenience for dissipating kinetic energy and capturing projectiles and cables during cable installation in multiple sizes of conduit.

DETAILED DESCRIPTION OF THE INVENTION

InFIG. 1a cable projectile catcher10is shown. One end of tube12is releasably fitted with an end cap14. Tube12is provided with multiple longitudinal slots16. Attached to the other end of tube12is a clamp18.

FIG. 3shows clamp18with hinged half22joined to hinged half24by hinge pin26. Either hinged half22or hinged half24is welded or otherwise joined to tube12. For example, hinged half22is shown joined to tube12by weld28inFIG. 1. Clamp pads30and32are attached to hinged halves22and24respectively by flush mounting screws34. The inside surfaces of clamp pads30and32may be provided with gripping means, such as minute circumferential ribs. Clamp pads30and32can be properly sized to accommodate the conduit40(seeFIG. 2) being used in the present installation.

Tightening wing nut36onto threaded swivel bolt38causes clamp18to securely clamp catcher10to conduit40(seeFIG. 2). Conversely, as shown inFIG. 4, if wing nut36is loosened, threaded swivel bolt38can be swung out of engagement with hinged half24. Hinged half24can then be rotated open to permit removal of catcher10from conduit40.

CONCLUSION

Thus, catcher10offers distinct advantages over prior art. Catcher10provides a convenient means to provide safe and efficient capture of birds and cable exiting from conduit during installation of the cable. Catcher10can accommodate a range of conduit sizes. Catcher10is economical to manufacture using a minimal number of parts. Catcher10is durable and easy to use.

It will be appreciated that while particular embodiments of the invention have been shown and described, modifications may be made. It is intended in the claims to cover all modifications that come within the true spirit and scope of the invention.