GB1560254A

GB1560254A - Headgear catches for pit cages

Info

Publication number: GB1560254A
Application number: GB707377A
Authority: GB
Original assignee: Rowell A S
Current assignee: Rowell A S
Priority date: 1978-02-09
Filing date: 1978-02-09
Publication date: 1980-01-30

Description

(54) IMPROVEMENTS RELATING TO HEADGEAR CATCHES FOR PIT CAGES (71) I, ARTHUR SURTEES ROWELL, a British Subject, of 3 Lambert Drive, Leeds LS8 1NL, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a method of and apparatus for catching an upwardly moving object and limiting its subsequent fall, particularly but not exclusively where the object is a pit cage.

In raising a pit cage up a mine shaft the danger exists of the cage being lifted far above ground level and indeed of being raised as far as the pit head gear with consequential damage to cage and gear and at least serious injury to any occupants of the cage. The winding rope by which the cage is raised is conventionally coupled to a block from which the cage hangs on chains, and the precaution has been taken hereto of providing means, known as a detaching bell, for releasing the rope from the block when the cage has over-shot the ground level and similtaneously attaching the block to a secure anchorage. However, accidents have been known to happen even with the use of this equipment as a result of the cage's continuing to move upwardly, after the relese of the rope, because of its momentum, and then falling freely to the full extent of the chains.The resultant stress on the chains could even cause the chains to break allowing the cage to fall to the bottom of the shaft.

The object of the invention is to minimize the aforementioned hazard.

According to one aspect of the invention there is provided a method of catching an upwardly moving object and limiting its subsequent fall comprising displacing at least one first means by the upward movement of the object, moving a second means to a position under the object as a result of the said displacement of the or each first means, and restricting downward movement of said second means so as to limit the fall of the object; Preferably the displacement of the first means is vertically upwardly and the movement of the second means is inclinedly upwardly.

According to a further aspect of the invention there is provided apparatus for catching an upwardly moving object and limiting its subsequent fall comprising at least one first means for location in the path of and displaceable by the upwardly moving object, a second means operatively associated with the or each first means whereby it is moved to a position under the object by the displacement of said first means, and means for restricting downward movement of said second means so as to limit the fall of the object.

Preferably the apparatus further comprises means for guiding said first means vertically upwardly during the displacement thereof and for guiding said second means inclinedly upwardly during the movement thereof.

Preferably the guide means comprises means defining a track having a vertical upper portion and an inclined lower portion for guiding the or each first means and the associated second means.

The means for restricting downward movement of the second means may comprise at least one pawl pivotally mounted on the second means and a vertically mounted rack engageable by the pawl with the second means located under the object. Preferably the second means mounts two pawls in staggered relationship with the teeth of the rack. Preferably the rack is resiliently mounted on a fixed support.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings of which: Fig. 1 is a vertical section of a lower part of an apparatus according to the invention taken on line I-I of Fig. 4 and showing a catch shoe in parked position; Fig. 2 is a vertical section of an upper part of the apparatus as in Fig. 1 showing the same catch shoe in cage-supporting position; Fig. 3 is a vertical section of the lower part of the apparatus taken on line 11-11 of Fig. 4: and Fig. 4 is a horizontal section taken on line 111-111 of Fig. 2.

In the figures a vertically disposed elongated robust box-sectioned assembly 36, comprising an opposed pair of channel-sectioned members 1, a back flange plate 2 and a front right flange plate 2A is resiliently supported by compression spring 4 on the lower of a pair of horizontal beams 5 which constitute part of the pit head gear and which prevent lateral movement of the assembly.

The front flange plate 2A is apertured and accommodates a vertically disposed ratchettoothed rack or catch stick 6, the forward toothed edge of which projects through the aperture of plate 2A as shown in Fig. 2. The catch stick is secured to a plurality of guide blocks 9 (only one shown in Fig. 2 for simplicity) each being arranged between sides 9A so that the catch stick can be drawn further into the assembly 36, to lessen the protrusion of the teeth, by nut-and-bolt assembly 8. The catch stick may be secured in its forward position by bolts extending through holes 7 and through corresponding holes in the main members 1.

A pair of elongated vertical plates 16 are mounted perpendicularly to the forward flange plate 2A and extra support is given thereto by stiffeners 15. A pair of guide rails 14 is secured to the face of each plate 16 which faces the other plate; the guide rails 14 extend for the major part of the length of each plate 16 and define between them a vertical track, but towards the bottom of the assembly 36 guide rail portions 14A and 14B incline inwardly with different degrees of slope so as to define between them a track which converges as it extends upwardly and to the right as shown in Fig. 3. At the lower end of guide rail portion 14A is a stop 17.

As shown particularly in Figures 1 and 2 the apparatus further comprises a guide shoe 10 which is provided with a pair of vertically elongated guide blocks 34 for sliding in the vertical track between the guide rails 14. This shoe projects forwardly of the plates 16 and indeed projects beyond the line 30 which represents the line of movement of the edge of a structural component of the pit cage closest to the assembly 36. The lower edge 31 of shoe 10 is horizontal for firm engagement with the structural component of the rising cage.

The shoe 10 is pivotally connected to a catch shoe 11 which comprises a pair of spaced side plates 24 each of which is provided on its outer surface with an upper guide block 28 and a lower guide block 26.

With the catch shoe 11 in its "parked" position shown in Fig. 1, the guide block 26 is supported against stop 17.

Each of the side plates 24 has a fowardly projecting portion 32 which does not, when when the shoe is in the parked position, project as far as the line 30 of the extreme edge of the rising cage. However, with the shoes 10 and 11 in an elevated position, such as is shown in Figure 2, the catch shoe adopts a vertical orientation, with guide blocks 26 in the track defined between the guide rails 14 and the guide block 28 located between the rearward guide rail 14 and the forward flange plate 2A. In this orientation the forward projection 32, of which the upper surface 33 is horizontal, projects beyond the line of the rising cage.

A pair of pawls 12 are pivotally mounted between the side plates 24 for engaging with the teeth of the catch stick 6. The spacing of the two pawls is such that when one is engaged in the teeth of a catch stick the other is in a position midway between a pair of teeth thereof. The pawls are urged into engagement with the catch stick by maintenance-free torsion units 13, but in other embodiments may be simply spring loaded or urged into engagement by gravity.

In the fully engaged position the pawls are supported by supporting blocks 35. In use of the apparatus the assembly 36 is mounted around horizontal headgear beams 5 in such a position that the underside 31 of catch shoe 10 will be struck by the nearest structural member of a pit cage which has overshot the ground level and the vertical distance between the face 31 of shoe 10 and surface 33 of shoe 11 is such as to accommodate therebetween the said structural member which advantageously is the top hoop member of the cage.

Thus when the cage overshoots, the upper surface of the top hoop member strikes the underside 31 of guide shoe 10 and moves the shoe upwardly guided by the block 34 in the track defined by the rails 14, and the catch shoe is dragged along after it. Initially, the projection 32 of the catch shoe is out of the line of the top hoop member, but as the catch shoe is drawn upwardly it also pivots in an anticlockwise direction as shown in Fig. 1 about pivot 37 as the guide block 26 runs upwardly along the guide rail 14A, which movement causes the projection 32 to move under the top hoop member. As the guide shoe continues to move upwardly, the guide block 26 enters the vertical track between the guide rails 14 and the upper guide block 28 enters the channel between the rearward guide rail 14 and the forward flange plate 2A.

The assembly 36 and in particular the catch stick 6 is arranged to extend as high as the cage is likely to ascend after the winding rope has been released by the action of the detaching bell referred to above. Thus the situation shown in Figure 2 represents about the highest position that the shoes are likely to reach and in the majority of cases the shoes will reach a position intermediate between those shown in Figs. 1 and 2 when the cage reaches its highest point after having been released from the winding rope.

Immediately after that moment in time the cage begins to descend under gravity but the lower edge of the top hoop member then engages upwardly facing surface 33 or projection 32 of shoe 11 and urges shoe 11 downwardly with it. The shoe 11 can move downwardly only by a maximum of half of the pitch of the catch stick before one or other of the catches 12 engages in the teeth of the catch stick. The catch stick as has already been mentioned is secured to the assembly 36 by bolts passing through the holes 7 and by the slide assembly 9, 9A.

Thus the weight of the cage is taken by the whole assembly 36 and thus is transferred to the beam 5 of the pithead gear through the compression spring 4. A movement of the projection 32 under the top hoop of the cage allows for a close fit of the surfaces 31 and 33 with the hoop so that there is little free fall of the cage before projection 32 is engaged; the pitch of the catch stick can be arranged as fine as possible consistant with the engagement thereof with the catches 12 having adequate strength so that the total free fall of the cage before the spring 4 is engaged is minimal. The spring 4 brings the assembly and cage to rest in a relatively gentle manner and in practice. though this is not part of the invention, an emergency escape platform will be provided for the occupants of the cage at several levels above ground level but below the detaching beam of the head gear.

After the cage has been brought to a standstill and the occupants have escaped, the winding rope will be secured again to the block from which the cage normally hangs on chains and the weight of the cage will then be taken up by the winding gear.

The assembly 36 will then rise on the compressions spring 4 and the top hoop of the cage will engage with surface 31 of shoe 10 so as to remove any load on the teeth of the catch stick 6. The catch stick can then be drawn by means of nut-and-bolt assembly 8 along the slide devices 9, 9A to the left as shown in Figs. 1 and 2 until the teeth of the catch stick are completely out of engagement with the catches 12 at which point the cage can be lowered to the ground level, the shoes 10 and 11 lowering with the cage until the guide block 26 engages the stop 17 at which point the projection 32 is out of line of the cage. The catch stick 6 can then be moved forwardly. the bolt passing through the holes 7 which had to be removed for the withdrawing of the catch stick and be reinserted and the apparatus is ready for further use.

An aperture 39 is provided at the lower end of the back flange plate 2 to give access to the catches 12 of the shoe 11 so that a check on the operation of the catches can be undertaken. It will be noted that the supporting blocks 35 support the catches 12 when they are engaged with the catch stick so that the load of the cage is not borne solely on the pivot of the catches.

In another embodiment of the invention the shoe 11 would not be provided with catches 12 but with rearward projections or ribs each of which would, as the shoe was pulled upwardly by the rising cage, in turn lift one or more of a series of catches mounted in the assembly 36 and after the passage of the projections these catches would fall back either on the gravity or by other contrived forces such as springs or resilient mountings into engagement with a co-operating member also secured to the assembly 36. These catches would be arranged in two rows of staggered pitches so that together with the correct spacing of the two ribs on the shoe would ensure that when the cage ceased its upward movement it could not only fall back a minimal distance until held by one of the catches preventing further downward movement of the trailing shoe.Normal known methods of testing the effective free operation of the catches would be applied and these means would allow the cage to be freed from the catches on re-connection of the normal suspension gear. The cage then being lowered would allow the shoes to disengage when they reach their normal position of rest.

It will be appreciated that if the cage is not provided with a top hoop or other suitable outwardly projecting constructional member such a member will be provided of suitable dimensions for being accommodated between the surfaces 31 and 33 and of course being sufficiently integral with the cage as to secure the cage when the member itself is secured.

The inference has been made in the specification that the normal elevation for stopping the pit cage to allow the occupants to get out is at ground level, but sometimes the normal position for this purpose is at a decking level elevated above the actual ground level, and the specification should be interpreted accordingly.

WHAT I CLAIM IS: 1. A method of catching an upwardly moving object and limiting its subsequent

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The assembly 36 and in particular the catch stick 6 is arranged to extend as high as the cage is likely to ascend after the winding rope has been released by the action of the detaching bell referred to above. Thus the situation shown in Figure 2 represents about the highest position that the shoes are likely to reach and in the majority of cases the shoes will reach a position intermediate between those shown in Figs. 1 and 2 when the cage reaches its highest point after having been released from the winding rope. Immediately after that moment in time the cage begins to descend under gravity but the lower edge of the top hoop member then engages upwardly facing surface 33 or projection 32 of shoe 11 and urges shoe 11 downwardly with it. The shoe 11 can move downwardly only by a maximum of half of the pitch of the catch stick before one or other of the catches 12 engages in the teeth of the catch stick. The catch stick as has already been mentioned is secured to the assembly 36 by bolts passing through the holes 7 and by the slide assembly 9, 9A. Thus the weight of the cage is taken by the whole assembly 36 and thus is transferred to the beam 5 of the pithead gear through the compression spring 4. A movement of the projection 32 under the top hoop of the cage allows for a close fit of the surfaces 31 and 33 with the hoop so that there is little free fall of the cage before projection 32 is engaged; the pitch of the catch stick can be arranged as fine as possible consistant with the engagement thereof with the catches 12 having adequate strength so that the total free fall of the cage before the spring 4 is engaged is minimal. The spring 4 brings the assembly and cage to rest in a relatively gentle manner and in practice. though this is not part of the invention, an emergency escape platform will be provided for the occupants of the cage at several levels above ground level but below the detaching beam of the head gear. After the cage has been brought to a standstill and the occupants have escaped, the winding rope will be secured again to the block from which the cage normally hangs on chains and the weight of the cage will then be taken up by the winding gear. The assembly 36 will then rise on the compressions spring 4 and the top hoop of the cage will engage with surface 31 of shoe 10 so as to remove any load on the teeth of the catch stick 6. The catch stick can then be drawn by means of nut-and-bolt assembly 8 along the slide devices 9, 9A to the left as shown in Figs. 1 and 2 until the teeth of the catch stick are completely out of engagement with the catches 12 at which point the cage can be lowered to the ground level, the shoes 10 and 11 lowering with the cage until the guide block 26 engages the stop 17 at which point the projection 32 is out of line of the cage. The catch stick 6 can then be moved forwardly. the bolt passing through the holes 7 which had to be removed for the withdrawing of the catch stick and be reinserted and the apparatus is ready for further use. An aperture 39 is provided at the lower end of the back flange plate 2 to give access to the catches 12 of the shoe 11 so that a check on the operation of the catches can be undertaken. It will be noted that the supporting blocks 35 support the catches 12 when they are engaged with the catch stick so that the load of the cage is not borne solely on the pivot of the catches. In another embodiment of the invention the shoe 11 would not be provided with catches 12 but with rearward projections or ribs each of which would, as the shoe was pulled upwardly by the rising cage, in turn lift one or more of a series of catches mounted in the assembly 36 and after the passage of the projections these catches would fall back either on the gravity or by other contrived forces such as springs or resilient mountings into engagement with a co-operating member also secured to the assembly 36. These catches would be arranged in two rows of staggered pitches so that together with the correct spacing of the two ribs on the shoe would ensure that when the cage ceased its upward movement it could not only fall back a minimal distance until held by one of the catches preventing further downward movement of the trailing shoe.Normal known methods of testing the effective free operation of the catches would be applied and these means would allow the cage to be freed from the catches on re-connection of the normal suspension gear. The cage then being lowered would allow the shoes to disengage when they reach their normal position of rest. It will be appreciated that if the cage is not provided with a top hoop or other suitable outwardly projecting constructional member such a member will be provided of suitable dimensions for being accommodated between the surfaces 31 and 33 and of course being sufficiently integral with the cage as to secure the cage when the member itself is secured. The inference has been made in the specification that the normal elevation for stopping the pit cage to allow the occupants to get out is at ground level, but sometimes the normal position for this purpose is at a decking level elevated above the actual ground level, and the specification should be interpreted accordingly. WHAT I CLAIM IS:

1. A method of catching an upwardly moving object and limiting its subsequent

fall comprising displacing at least one first means by the upward movement of the object, moving a second means to a position under the object as a result of the said displacment of the or each first means, and restricting downward movement of said second means so as to limit the fall of the object.

2. A method as claimed in Claim 1 wherein the displacement of the first means is vertically upwardly.

3. A method as claimed in Claim 1 or Claim 2 wherein the movement of the second means is inclinedly upwardly.

4. A method as claimed in any one of the preceding Claims wherein the object is a structural component of an overwound pit.

cage.

5. A method as claimed in Claim 5 wherein the downward movement follows a release of a winding rope from said cage.

6. A method of catching an upwardly moving object and limiting its subsequent fall substantially as described with reference to the drawings.

7. Apparatus for catching an upwardly moving object and limiting is subsequent fall comprising at least one first means for location in the path of and displaceable by the upwardly moving object, a second means operative associated with the or each first means whereby it is moved to a position under the object by the displacement of said first means, and means for restricting downard movement of said second means so as to limit the fall of the object.

8. Apparatus as claimed in Claim 7 further comprising means for guiding said first means vertically upwardly during the displacement thereof.

9. Apparatus as claimed in Claim 7 or Claim 8 further comprises means for guiding said second means inclinedly upwardly during the movement thereof.

10. Apparatus as claimed in Claim 8 or Claim 9 further comprising means defining a track having a vertical upper portion and inclined lower portion for guiding the or each first means and the assoicated second means.

ii. Apparatus as claimed in any one of Claims 7 to 10 wherein the means for restricting downward movement of the second means comprises at least one pawl pivotally mounted on the second means and a vertically mounted rack engageable by the pawl with the second means located under the object.

12. Apparatus as claimed in Claim 11 wherien the second means mounts two pawls in staggered relationship with the teeth of the rack.

13. Apparatus as claimed in Claim 11 or Claim 12 wherein the rack is resiliently mounted on a fixed support.

14. Apparatus as claimed in any one of Claims 1 to 13 wherein the means for restricting downward movement of the second means comprises a resilient member.

15. Apparatus for catching an upwardly moving object and limiting its subsequent fall substantially as described with reference to the drawings.

16. An installation comprising at least one apparatus as described in any one of Claims 9 to 15 mounted on a pit head gear.

17. An installation as claimed in Claim 16 further comprising a pit cage comprising a structural component adapted to displace said at least one first means upon overwinding and of such dimensions that the second means is movable to a position thereunder.

18. An installation for catching an upwardly moving overwound pit cage and limiting its subsequent fall substantially as described with reference to the drawings.