Abstract:
An apparatus and method for advancing extendable ventilation ductwork in an underground facility is disclosed wherein a mechanical cable and pulley system is utilized in conjunction with a support swivel. The support swivel permits support clips to advance without interference from support members. The cable and pulley system comprises a cable, support swivel, head pulley and winding mechanism.

Description:
BACKGROUND OF THE INVENTION 
     A critical problem in underground mining operations has always been the problem of circulating fresh air to a mining location and exhausting polluted and dust-ridden air. In present operations, air is conveyed to and exhausted from a mining location by temporary ductwork. In general, mining operations must be discontinued temporarily while the ventilation system is advanced. 
     As mining operations proceed, the excavation location advances. As a result, the intake for fresh air becomes more and more distant from the excavation site. At times, the ventilation ductwork must be advanced by adding additional sections onto the existing ductwork. In order for ductwork sections to be added safely and without interference, mining operations are stopped temporarily while ventilation ductwork is put in place. Normally, this procedure involves moving in large segments of metal ductwork, bolting them in place and placing some form of gasket around the joint to assure a certain degree of air tightness. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method and apparatus for deploying and retrieving ventilation ductwork in an underground mining operation. An expandable conduit is attached to a continuous cable between an excavation site and a fresh air intake site. A pulley is located at the excavation site and a winch is located at the intake site. A series of hangers are located between the excavation and exhaust sites. Each hanger has two sections, a pulley section and a swivel section. The pulley section is located on the upper part of the hanger and provides a support and a guide for the top portion continuous cable. The swivel section provides support for the bottom portion of the continuous cable while permitting clips attached to an expandable ventilation ductwork to pass by the support without interfering with continuous cable movement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of an expandable ventilation ductwork system. 
     FIG. 2 is a side view of a hanger of FIG. 1. 
     FIG. 3 is a top view of the hanger of FIG. 2. 
     FIG. 4 is a rear view of the hanger of FIG. 2. 
     FIG. 5 is a front view of a swivel portion of a hanger of FIG. 1. 
     FIG. 6 is a sectional view along line 6--6 of FIG. 5. 
     FIG. 7 is a front view of the swivel of FIG. 2 in a second position. 
     FIG. 8 is a sectional view along lines 8--8 of FIG. 7. 
     FIG. 9 is a front view of the swivel of FIG. 2 in a third position. 
     FIG. 10 is a sectional view along lines 10--10 of FIG. 9. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates an expandable ventilation ductwork system 10 having ventilation ductwork 12 connected to a fan housing 14 at an intake site at one end and to a continuous cable 16 by friction clamp 18 through connecting wire 20 at the other end. Ductwork 12 is slidably connected to continuous cable 16 through clips 22 spaced apart and fixed along ductwork 12. 
     Continuous cable 16 extends from winch 24 to pulley 26 running through hangers 28 in a manner that an extended elipse is formed when viewed from the side. Hanger 28 is hung from a mine ceiling 30 by anchors 32 having eye bolts 34 for receiving loops 36 of hangers 28. Hangers 28 have two sections, a support section 38 and a swivel section 40. 
     Referring to FIG. 2, a side view of hanger assembly 28 is illustrated with support section 38 bolted to swivel section 40 by bolts 42. Continuous cable 16 is illustrated as riding on return pulley 44 which rotates on axle 46, which is mounted between walls 48 fixed to top 50. Loop 36 is attached to top 50 so that hanger assembly 28 may be placed on eye bolt 34 of anchor 32 (see FIG. 1). 
     Swivel section 40 comprises a housing section 52 bolted to housing sides 48 with bolts 42. Housing 52 has an offset 54 for mounting swivel 56 on axis 58. 
     FIG. 3 illustrates a top view of the apparatus of FIG. 2 illustrating stubs A, B and C of swivel 56. FIG. 4 illustrates a rear view of the apparatus of FIG. 2, more clearly illustrating housing 52 having swivel 56 mounted thereto. As illustrated, continuous cable 16 runs across pulley 44 mounted on axle 46 traveling in one direction while traveling across swivel 56 in the opposite direction. 
     The operation of swivel 56 mounted on offset 54 of housing 52 is best illustrated in conjunction with FIGS. 5-10. FIG. 5 illustrates swivel 56 with continuous cable 16 riding behind stub A. As friction clamp 18 connected to ventillation duct 12 through connecting wire 20 approaches swivel 56, stubs A, B and C remain motionless. Continuous cable 16 is sliding on the corner of stub A and the body 60 of swivel 56. Body 60 of swivel 56 is configured to contain gearing torque release to hold stub A in position while continuous cable 16 slides thereon. Continuous cable 16 may either be a wire cable or any type of rope currently in use in the art. Furthermore, continuous cable 16 may be greased to permit easier sliding on swivel 56. 
     Referring to FIG. 7, friction clamp 18 along with connecting wire 20 come into contact with stub A of swivel 56. Friction clamp 18 on continuous cable 16 causes torque release of swivel 56 allowing stub A to rotate with stub B picking up continuous cable 16 behind friction clamp 18. Friction clamp 18 does not ride off swivel 56 because of the weight of duct 12 which pulls down via connecting wire 20. Swivel 56 is configured at an angle with horizontal such that connecting wire 20 passes between stub A and stub B while continuous cable 16 rides on the corner formed by stub A and stub B with body 60 of swivel 56. Stubs A, B and C are fixed with respect to each other so that all three rotate in unison. Preferably, stubs A, B and C are configured at 120° apart from each other when viewed facing their axis of rotation. Although three stubs are used for swivel 56, other numbers of stubs may be used as long as swivel 56 remains balanced and there is sufficient room for friction clamp 18 to engage only one stub at a time. 
     Referring to FIG. 9, continuous cable 16 has advanced sufficiently so that friction clamp 18 and connecting wire 20 have advanced ductwork 12 past swivel unit 56. As illustrated in FIG. 10, continuous cable 16 is riding on the corner between body 60 and stub B of swivel 56. Continuous cable 16 will slide on this position until ventilation ductwork 12 is advanced to the point where clip 22 engages stub B causing torque release of swivel 56, allowing stub B to rotate and bring stub C into position for additional contact with a second clip 22. 
     For return of extendable duct, the torque release of swivel 56 is preset lower in the reverse rotation mode, allowing duct 12 to return near fan housing 14. Referring to FIG. 1, ventilation ductwork system 10 advance is accomplished by advancing pulley 26 and adding hanger assemblies 28 as needed to support duct 12. 
     While the preferred embodiment has been described by way of preferred embodiment, it is to be understood that this is for illustration purposes only and should not be limited thereto, but only by the scope of the following claims.