AU660653B2 - Decelerating device - Google Patents

Description

OPI DATI 07/ng/q2 AOJP DATE 15/10/92 APPLN. D 1i?031t q? PCT NUMBER PCT/AIIq2/fnnl2 INTERNi. TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 92/13791 B66B 5/12, 5/22, 5/24 Al B61K 7/18 (43) International Publication Date: 20 August 1992 (20.08.92) (21) International Application Number: PCT/AU92/00032 (81) Designated States: AT (European patent), AU, BE (European patent), CA, CH (European patent), DE (Euro- (22) International Filing Date: 31 January 1992 (31.01.92) pean patent), DK (European patent), ES (European patent), FR (European patent), GB (European patent), GR (European patent), IT (European patent), LU (European Priority data: patent), MC (European patent), NL (European patent), PK 4389 31 January 1991 (31.01.91) AU SE (European patent), US.

(71) Applicant (for all designated States except US): HOISTING Published SYSTEMS PTY. LTD. [AU/AU]; 3 Bennett Street, With international search report.

Perth, W.A. 6000 (AU).

(72) Inventor; and Inventor/Applicant (for US only) ROWE, Peter, G. [AU/ AU]; 3 Bennett Street, Perth, W.A. 6000 (74)Agent: WRAY ASSOCIATES; 239 Adelaide Terrace, Perth, W.A. 6000 (AU).

(54)Title: DECELERATING DEVICE (57) Abstract A decelerating device for moving object such as a cage (11) tra- 15 veiling along steel guides (12) with a mine shaft via a hoisting cable The device comprises clamps (15) mounted to the cage (11) to anchor to the guides (12) when triggered. The ends of arrestor cables (16) are connected to a carrier (09) on the cage (11) and are attached to the clamps Dies (18) mounted to the carrier (69) allow the arrestor cables (16) to pass therethrough and be transversely engaged at an intermediate portion to be radially comoressed and deformed in response to relative ax- -6 I. 12 ial movement between the cables (16) and dies The dies (18) and clamps (15) are initially disposed together so that the free ends of the ar- 12.

restor cables (16) are coiled within compartments on the cage An actuator within an attachment when triggered by a break in the hoisting cable causes the clamps (15) to anchor to the guides (12) 13 whereupon the motive force applied to the carrier (69) causes the relative axial movement between the dies (18) and arrestor cables (16) which is opposed by a retardation force generated by the dies (18) against the arrestor cables WO 92/13791 PCIT AU92/00032 "DECELERATING DEVICE" TECHNICAL FIELD This invention relates to a decelerating device for emergency usage with conveyances or moving objects which develop appreciable momentum such as a mine cage or platform for carrying men or other objects up and down a vertical or inclined shaft, rolling stock, or indeed any other object of significant mass which moves along a predetermined path.

BACKGROUND ART For many years timber guides have been used in vertical mine shafts for the guidance of shaft conveyances, the conveyance being suspended by a single rope on a drum winder. When used on timber guides, it is mandatory in most countries to have a set of grippers on the c-je whioh are spring actuated in the event of loss of tension in the suspension gear such as would occur on rope breakage.

Teeth on the grippers bite into the timber guides and this is intended to arrest the descent of the conveyance, mid shaft. Frequently however, on testing, either the teeth clog with timber or the timber guide surface is weathered and becomes too hard for the teeth to penetrate; in either case the grippers would fail to stop the cage descent. The use of large cages run at higher slord has decreased the likelihood of successful operation of grippers in timber guides, and increased the safety hazard due to the possible inadvertent operation of the grippers without rope failure, and with there being is no control cf the deceleration rate.

Together with the use of larger and higher speed conveyances, steel guides have been introduced in place of timber WO 92/13791 PCT/AU92/00032 2 guides. There is currently no approved system for arresting the descent of a cage in an emergency mid shaft, whilst travelling on steel guides. Likewise there is no approved system to arrest the descent of a cage mid shaft, travelling on rope guides, should the hoisting rope fail.

All past proposals for mid shaft cage arrest rely on the use of clamps attached to the cage. In practice these would either fail to attach to the guides because of the very high forces, or would destroy the guides themselves, as these systems incorporate no means of regulating the deceleration rate of the cage and hence the applied forces.

With regard to rolling stock, railway sidings have employed the use of various means for arresting the progress of a train in an emergency situation, such means ranging from dampened buffers located at the end of the siding to piles of sand or similar material. In the case of buffers, two common types employed are the spring type and the hydraulic cylinder type. With respect to the spring type, these comprise a heavy duty coiled spring which applies a retarding force to an object striking the buffer, which retarding force progressively ii creases with increased compression of the spring. This form of buffer has limited utility and is not suitable for decelerating run away trains or the like where a large momentum is involved, since the maximum retardation force that can be applied by the spring is attained over a relatively short distance determined by the length of the spring with the retardation force of the spring not being applied uniformly to the object striking the buffer.

With respect to the hydraulic cylinder types of buffers, these generally comprise a pair of relatively large and heavy cylinders filled with hydraulic fluid of high viscosity. A relatively small orifice is formed in the cylinder WO 92/13791 PCT/AU92/00032 3 wall which allows the hyqraulic fluid to escape from the confines of the cylinder in a timed manner upon application of a striking force to the buffer, consequently causing the cylinder to apply a relatively constant retardation force to the object striking the buffer as the buffer is displaced by the object striking it. Although these devices are superior to the spring type of buffer in that a relatively constant retardation force is applied, they are still limited in utility by virtue of the retardation force being associated with the length of the cylinder and the possibility of this being exceeded within a relatively short distance by a runaway train. In addition, the hydraulic types of buffers are extremely expensive due to their relative bulkiness and complexity in design.

The aforementioned types of buffers also are used at the ends of mine shafts to arrest over travel of a mine cage, and accordingly suffer from the same disadvantages as outlined in relation to the arresting of moving rolling stock.

Another system employed on a few sites in Australia for arresting the over travel of cages at the ends of mine shafts comprises a transversely extending bar or buffer suspended by a pair of elongated steel plates located at the sides of the mine shaft. The plates are deformed so as to describe an arcuate path around a set of rollers housed within a suspension block fixedly located at the sides of the shaft a short distance above the bar. The plates have a rectilineal extent which projects beyond the suspension blocks which can be progressively deformed by the rollers within the blocks upon the mine cage striking the bar with sufficient momentum creating a force which exceeds the retardation force applied to the deformed section of the plates by the suspension blocks. Consequently, the bar applies a relatively constant retardation force to the cage -4during progressive deformation of the rectilineal extent of each of the plates by the rollers of the suspension blocks. A drawback of this device is that the suspension blocks are very expensive, quite heavy, and are subject to malfunction in time by allowing the ingress of dirt or other foreign materials which can lead to corrosion or clogging of the rollers.

DISCLOSURE OF INVENTION It is an object of this invention to provide a decelerating device which alleviates or overcomes some of the aforementioned disadvantages associated with arresting movement of conveyances or objects in an emergency at a controlled rate of deceleration.

In accordance with one aspect of the present invention, there is provided a decelerating device for decelerating a moving object travelling along a path comprising:anchoring means for anchoring said decelerating device to a fixed reference along the path; a carrier for engaging the moving object; 20 an arrestor cable formed of durtible material and being of substantially constant cross-section, interconnecting said anchoring means and carrier between one end and an intermediate portion of said arrestor cable proximate to said one end such that a free length of said arrestor cable is provided at the other end thereof; compression means for transversely engaging said intermediate portion of said arrestor cable; and said compression means being adapted to radially compress and plastically deform said arrestor cable in response to relative axial movement therebetween; wherein a motive force applied by the moving object to said carrier relative to said anchoring means is transferred by the relative spatial arrangement of said arrestor cable and said compression means with respect to said anchoring means and said carrier to cause relative axial movement between said compression means and said arrestor cable, and said relative axial movement is opposed by a retardation .r WO 92/13791 PCT/AU92/00032 5 force generated by said compression means in response to said relative axial movement.

Preferably, said compression means has associated therewith stop means for stopping conjoint axial movement of said compression means and said arrestor cable, and allowing said relative axial movement.

Preferably, said compression means comprises a die block having a pair of dies defining the sides of a passage extending longitudinally through said die block for engaging said arrestor cable, said passage being tapered to provide a constricted opening at one end relative to the other end of said passage, such that said dies progressively compress said cable along said free length entering the other end of said passage during said relative axial movement.

Preferably, said arrestor cable is fixedly secured at said one end to said anchoring means and said compression means is disposed for positive securement to said carrir,.

Preferably, said arrestor cable is fixedly secured at said one end to said carrier and said compression means is disposed for positive securement to said anchoring means.

BRIEF DESCRIPTION OF DRAWINGS The invention will be better understood in the light of the following description of two specific embodiments thereof.

The description is made with reference to the accompanying drawings, wherein:- Figure 1 is a schematic diagram showing the cage running in a shaft provided with steel guides in accordance with the first embodiment; Figure 2 is a similar view to figure 1 showing the WO 92/13791 PC/AU92/00032 6 cage suspended from the arrestors after failure of the hoist cable; Figure 3 is an elevation of one side of the cable attachment to the cage; Figure 4 is an elevation of another side of the attachment shown at figure 3; Figure 5 is an elevation of the actuator in the closed position; Figure 6 is an elevation of the actuator of figure in an open position; Figure 7 is a fragmentary sectional plan view of the arrestor taken through section 7-7 of figure 8; Figure 8 is a fragmentary.tin elevation of th arrestor taken through section 8-8 of Figure 7; Figure 9 is a side view of the cage showing the arrestor assembly mounted to the top of the cage and the arrestor cables stored within the cage side; Figure 10 is a sectional view taken along section A-A of figure 9; Figure 11 is a cross-sectional view of the compression means; Figure 12 is a schematic plan view of the decelerating device in accordance with the second embodiment, before impact of the carrier; Figure 13 is a similar view to figure 12, but after impact; and Figure 14 is a cross-section view of the compression means.

MODES FOR CARRYING OUT THE INVENTION The first embodiment is directed towards a decelerating device which is fitted to a conveyance in the form of a cage which runs along a vertical mine shaft fitted with steel guides and which is attached to one end of a hoist rope or cable for suspension and hoisting along the shaft by an overhead drum winder.

7 As shown at figure 1 of the drawings a cage 11 runs in a mine shaft fitted with steel guides 12 and is connected to one erd of a hoist rope or cable 13 for suspension and hoisting along the shaft from an overhead drum winder (not shown). Accordingly, the cage 11 moves rectilinearly up or down the saft between the guides 12 by hoisting the cable 1j.

The decelerating device of the present embodiment essentially comprises anchoring means in the form of a pair of arrestor assemblies 15, actuating means housed within an attachment 17 and connected to each of the arrestor assemblies 15, a pair of arrestor cables 16 connected between the arrestor assemblies 15, a carrier being part of the framework of the cage 11, and compression means in the form of a pair of die blocks 18.

The arrestor assemblies 15 are mounted to the top of the cage 11 at each side thereof to respectively slidably engage the corresponding guides 12 at opposite sides of the cage in axial alignment with a pair of vertical channels 22 integrally formed with the framework of the cage to run along the guides, thereby guiding movement of the cage along the guides 12. Each arrestor assembly 15 includes a S"brake comprising a pair of clamping pads 21, a pair of corresponding base plates 19, and a surrounding wedge applicator 23 for housing the clamping pads and base plates.

As shown at figures 7 and 8 of the drawings, the outer face of each base plate 19 is wedge shaped and lies against a matching inner wedge face of the wedge applicator 21 to define an interface 57 at either side of the guide 12 thereof. The corresponding wedge shaped faces 57 of the base plate and wedge applicator at opposite sides of the guide thereof effectively converge from the base of the WO 92/13791 PCI'/AU92/00032 8 arrestor assembly towards the top thereof so as to direct movement of the base plates and clamping pads of a particular arrestor assembly 15 towards the guide 12 in response to independent downward movement of the wedge applicator thereof.

Each base plate 19 is provided with an inner recess which faces the opposing sides of the guide 12 thereof so as to accommodate its corresponding clamping pad 21 for extended and retracted movement of the clamping pad towards or away from the guide. The interface 59 between the confronting faces of the base plate and clamping pad incorporates a series of correspondingly aligned recesses 61 which extend transversely across the interface. These recesses 61 are each provided with compression springs 63 which are in a compressed state when the confronting faces of the clamping pad and base plate are juxtaposed and thus tend to bias the clamping pad from a retracted position to a more extended position.

The attachment 17 comprises an actuator 14 forming part of the actuating means housed within a special slotted suspension link 25, which in turn is connected to a series of links 27 to form a composite linkage assembly connecting the cage 12 to the cable 13. Moreover, the slotted suspension link 25 is pivotally pinned by a bolt and nut assembly 29 to the cage bridle 31 disposed centrally at the top of the cage 12. The suspension link 25 is provided with an elongate slot 33 proximate to its upper end and is pivotally pinned by another nut and bolt assembly 35 to a pair of fish plates 37 which in turn are mutually pinned at their opposite upper ends to one of the serial links 27a by means of a further nut and bolt assembly 41. The serial link 27a is in turn pivotally pinned by another nut and bolt assembly 43 to the bifurcated end of the other serial link 27b which forms the end tie of the cable 13.

WO 92/13791 PCT//U92/80003 9 The actuator 14 is accommodated within the slot 33 so as to space the pin formed by th ut and bolt assembly 35 from the top of the slot 33 causing the opposite ends of the actuator 14 to be compressed when the cable 13 is placed under tension by the suspension of the cage 11 therefrom.

The actuator 14 is formed in two halves 14a and 14b and operates in conjunction with two pairs of control cables 49 in the form of bowden cables, which form the other part of the actuating means. The control cables 49 are arranged so that one pair of control cables interconnect the actuator 14 and one of the arrestor assemblies 15 and the other pair of control cables interconnect the actuator 14 and the other arrestor assembly The two halves of the actuator 14, as shown at figures and 6, are pressed together when there is tension in the suspension links under normal hoisting conditions. The half 14a is provided with an inner recess 45 which houses a compression spring 46 and is adapted to accommodate a spigot end 47 integrally formed with the half 14b. As shown in the drawings, the axial extent of the spigot 47 is less than the corresponding extent of the recess 45 so that when the actuator 14 is in the closed position, as shown at figure 5, the spring 16 is in a compressed state.

Consequently, upon releasing the compressive force applied to the opposing ends of the actuator 14, the spring 16 functions to bias the half 14b away from the half 14a in the open position as shown at figure 6 of the drawings.

The outer sheaths 49a of one end of the one pair of control cables are connected to a corresponding seat provided on the outer side of the actuator half 14a and the inner wires 49b of this same end of the one pair of control cables are respectively threaded through an elongate aperture 44a extending from each seat through the actuator half 14a and WO 92/13791 PCT/AU92/00032 10 through a correspondingly aligned aperture 44b provided in the actuator half 14b adjacent to the spigot 47 to be fixedly attached to the actuator half 14b by flaring the ends of the inner wires 49b behind the aperture of the half 14b.

Similarly, the outer sheaths 49a and inner wires 49b of one end of the other pair of control cables are connected to the other side of the actuator.

The other ends of the control cables 49 are individually connected to corresponding short guide brackets 51 which are disposed in pairs on top and at each side of the cage 11 so that one pair of guide brackets is disposed at either side of a corresponding channel 22 and are surmounted by a corresponding arrestor assembly Moreover, the guide brackets 51 actually form part of the cage 11 and provide a fixture to which the outer sheaths 49a of the control cables may connect proximate to the underside of the arrestor assemblies. The ends of the inner wires 49b at these ends of the control cables are each terminated with a retainer pin rod 53, which situates within a corresponding aperture 54 extending from the guide bracket 51 thereof and through the underside of the corresponding arrestor assembly 15 to associate with a corresponding base plate 19 on one side or the other of the particular arrestor assembly 15 thereof. In the normal position each clamping pad 19 is retained in a retracted position by the retainer pin 55 thereof as a consequence of its fixed attachment to the clamping pad and its locking engagement with the retainer pin rod 53. Moreover, the retainer pin 55 is itself locked by the retainer pin rod 53 when the rod is extended in conjunction with the actuator 14 being closed, thereby retaining the clamping pads 21 in their respective retracted positions as shown figure 8 of the drawings. This locking effected by the retainer pin rod 53 being adapted to intercept with a small hole WO~ 92/13791 PC/AU92/00032 11 provided in a retainer pin 55 associated with each base plate 19 and clamping pad 21 assembly, when the actuator 14 is closed. The corresponding retainer pin 55 is fixedly mounted to the reAr of the corresponding clamping pad 21 and extends outwardly therefrom to be situated within a passage 56 orthogonally disposed in intersecting relationship with the passage 54 so that the retainer pin 55 is transversely disposed with respect to the corresponding retainer pin rod 53. Thus once tension is lost in thl cable 13, the links of the attachment 17 will adopt th open position, as shown in figure 6, in the absence of a tensile force being applied between the links of the attachment 17. Consequently the retainer pin rod 53 is pulled down, releasing the retainer pin 55 and allowing the springs 63 between the clamping pad 21 and the base plate 19 to force the clamping pads on to the opposing sides of each guide rail 12.

The outer face of each clamping pad 21 is provided with a friction liner 65 in the case of the guides 12 being formed of steel, but this may alternatively be provided with serrated edges or teeth if the &aides are formed of wood, so as to achieve the greatest coefficient of f, .ction between the guides and the clamping pads.

The die blocks 18 are mounted at either side of the cage 11 to the carrier 69a which forms part of the main frame work 69 of the cage as shown in figures 9 and 11 of the drawings. Each die block 18 comprises a pair of dies 62 contained within a sleeve housing 64. The dies 62 define the sides of a passage 66 which extends longitudinally through the die block so as to transversely engage a portion of a corresponding arrestor cable 16 which passes therethrough. Both of the dies 62 are wedge shaped so as to provide the passage with a taper defining a constricted opening 66a at one end relative to the other end of the WO 92/13791 PCI/AU92/00032 12 passage. The sleeve housing 64 of the die block is formed with a butt end 64a at the constricted opening end of the die block which is welded or otherwise fixedly secured to the underside of a portion of the carrier 69a so as to form a stop means. The stop means is provided with an opeiling 68 which is coaxially aligned with the passage 66. This opening 68 is of larger size than the constricted opening 66a of the passage and lessor size than the butt end 64a of the die block so as to enable the arrestor cable 16 to pass therethrough but oppose relative axial movement of the die block with respect to the stop means.

The arrestor cables 16 of the sling are each directly connected at one end to one or the other wedge applicator 23 by means of a terminal connector tie 65, pinned to a pendent tab 67 fixedly mounted to the underside of the wedge applicator. As shown at figures 9 and 10 of the drawings, a pair of arrestor cables 16 are associated with each arrestor assembly 13 and have their free length, extending past the respective die block 18 associated therewith at the other end of the cables, stored in a coiled formation within corresponding compartments 70 at the respective opposing sides of the cage.

In the case of relatively large and heavy cages 11, each arrestor cable 16 comprises a wire rope made from a limited number of single wires formed into a large single strand (standard guy wire construction) which has a diameter greater than the constricted opening 66a of each die block 18 so that when the wire rope is pulled through the die, plastic deformation of the wire results. The other end of each arrestor cable 16 is provided with a terminal block fixedly formed with one end thereof to prevent this end of the cable from passing through the passage of the corresponding die block.

WO 92/13791 PC/AU92/00032 13 :n smaller and lighter cages, conventional wire rope coated with PVC or the like may be used for the slings to provide an overall diameter greater than the constricted opening 66a of the die blocks 18, whereby the coating may be stripped off by pulling the wire rope through the die blocks.

In an emergency situation where the hoist rope 13 has failed, as shown at figure 2 of the drawings, the fall off in tension in the serial links of the attachment, as previously described, enables the actuator 14 to open by the spring 46 forcing the two halves of the actuator 14 apart operating the respective control cables 49 by the bottom half 14b of the actuator pulling on the one end of the inner wires 49b. Consequently, the retainer pins 55, are released in the manner previously described.

Subsequently, the clamping pads 59 are extended in response to the action of the compression springs 63 causing the friction liners 14 thereof to engage the opposing sides of each guide 12 resulting in an initial braking action. As the cage 11 descends further down the shaft, the wedge applicators 23 are pulled down by the residual force of the arrestor cables 16 acting against the arrestor assembly, consequently causing the sprinigs 61 to be recompressed until the base plates 21 are hard against the clamping pads 19. In this manner an increased braking force is applied to the clamping pads by the wedging action of the wedge applicator and base plate, where such force applied on the arrestor assemblies is proportional to the downward pull on the wedge applicator and will always be sufficient to present the arrestor assembly slipping on the guide.

Upon further descending movement of the cage, the arrestor cables 16 will be pulled through the respective die blocks 18 associated therewith causing plastic deformation of the WO 92/13791 PC/AU92/00032 14 cables 16. This will apply a known and constant retardation force on the cables which initially causes the wedge applicators to apply great force on to the clamping pads and acting to retard further descent of the cage.

In the present embodiment, the length of the arrestor cables 16 are such that the cage will be brought to rest from full speed at a controlled rate to deceleration of between 0.5g and 1.0g, possibly greater in certain cases, depending on the load in the cage. In this arrangement, the deceleration distance is always designed to be less than the length of the sling, however, in extreme cases, the provision of the terminal blocks 20 on the end of each sling enables final arrest of the descent of the cage.

It should be noted that the plastic deformation of the wires of the arrestor cables provides increased tensile strength and length in the sling than in their undeformed state, thereby producing the multiple effect of not only retarding the descent of the cage, but simultaneously producing slings of greater strength and length to eventually arrest the descent of the case.

The second embodiment is directed towards a decelerating device for use at the end of a railway siding in place of a conventional buffer, in order to decelerate and arrest the movement of rolling stock in an emergency which happens to overrun the end of the siding.

As shown in figures 12 to 14, the decelerating device 71 generally comprises a pair of arrestor cables 73, a pair of compression means 75, an anchorage means in the form of a pair of stop means 77, and a carrier in the form of a bar 79. A corresponding cable 73, compression means 75 and stop means 77 are disposed at either side of the railway line 81 at the end of a siding so that the bar 79 extends WO 92/13791 P~/AU92/00032 15 across the railway line to oppose movement of rolling stock 83 overrunning the siding. In this manner, the pair of cables 73 and bar 79 combine to form a sling which is moveable with respect to the compression means 75 and stop means 77.

The stop means 77 are both fixedly secured to the ground so as to form a pair of abutments which are immoveable. For example, the stop means may be mounted upon a pair of pillars which have a solid foundation within the ground.

In the present embodiment, each stop means 77 comprises a pair of abutment blocks 85 which are spaced apart to define an opening 87 centrally thereof, through which the corresponding cable 73 may pass, as best shown in figure 14 of the drawings.

Each compression means 75 is in the form of a die block comprising a sleeve housing 89 and a pair of dies 91 retainedly disposed therein. The dies are spaced apart to define the sides of a passage 93 which extends longitudinally through the die block in coaxial alignment with the opening 87 of the stop means. Both of the dies 91 are wedge shaped so that the passage 93 is effectively tapered to provide a constricted opening at one end 93a thereof adjacent to the opening 87, relative to the other end 93b of the passage which is opposite to the opening 87, as shown in figure 14. The sleeve housing 89 is for."'.d with a butt end 89a which surrounds the constricted openi 93a of the passage. The butt end 89a is adapted for engaging the abutment blocks 85 of the stop means and consequently the opening 87 is of larger size than the constricted opening 93a and lessor size than the butt end 89a to enable the cable 73 to pass therethrough but to oppose relative axial movement of the compression means with respect to the stop means.

WO 92/13791 P~T/AU921OW322 O'ne end 73a of the cable passes through the compressi.cr means 75 and stop means 77 to be fixedly secured to a corresponding end of the bar 79. The one end 73a of the cable is initially deformed so as to provide a diameter less than or commensurate to the size of the constricted opening 93a so that the one end 73a of the cable exits from the constricted opening 93a and the opening 87 of the stop means for attachment to the bar 79. The other end 73b of the cable is coiled within the housing (not shown) which is disposed adjacent to the compression means 75 at the other end 93b of the passage. The coiled arrangement of the cable is arranged so that the cable can be continuously fed through the compression means during axial movement of the cable relative to the compression means away from the coil.

By adopting this arrangement, the stop means 77 opposes axial movement of the compression means in conjunction with axial movement of the cable away from the coil whilst allowing relative axial movement between the compression means 75 and the cable 73. Furthermore, the compression means 75 by virtue of the dies 91, transversely engages that portion of the cable extending therethrough and by the tapering effect of the passage 93 radially compresses and deforms the cable in a continuous and progressive manner in response to relative axial movement between the cable and compression means when the cable is moved away from the compression means at the constricted opening end 93a of the passage. Consequently, a relatively constant retardation force is applied by the compression means 75 and stop means 77 against the axial movement of the cable which opposes a motive force applied to the bar 79 as would arise from an object such as the rolling stock 83 striking the bar, as shown in figures 11 and 12 of the drawings. In this manner, the sling arrangement of the bar 79 and cables 73 decelerate the rolling stock by the application of the WO 92/13791 PCT/AU92/00032 17 constant retardation force and can bring it to a stop within a prescribed distance depending upon the momentum of the rolling stock and the magnitude of the retardation force applied by the compression means and stop means.

INDUSTRIAL APPLICABILITY The advantages of the emergency braking system described include:- It can save the lives of personnel travelling in a cage should the hoist rope brake or be broken by a falling object, by a surface vehicle hitting the rope, or by partial headframe failure, etc.

It could be set up to be actuated by a high overspeed condition which would occur in the event of a failure of the winder brakes, in which case the cage would be brought safely to rest.

It can be used on steel guides and rope guides for which there is at present no approved emergency cage arrest system.

The wedge action of the clamps ensures that there can be no dangerous clamping applied when the cage is ascending, after any malfunction of the actuator or clamps.

The cage arrestor is comparatively light and will result in zero or negligible loss of payload, particularly if the statutory rope factor of safety can be safely reduced when the cage arrestor is installed.

It applies a controlled rate of deceleration to prevent injury to the cage occupants on application.

WBO 92/13791 PCT/AU92/00032 18 It applies d controlled force onto the shaft guides during cage arrest, either allowing existing shaft guides to be used for this purpose, or with 'he minimum amount of extra support to the guides.

The cage can be periodically drop tested (free fall from a stationary position) on site to prove the system operates satisfactorily, causing only a very short pull-through of the arrestor slings. The slack in the slings after each test can be taken up by providing an adjustable support bracket on the top of the cage from the shaft.

Satisfactory working of the actuator and of the spring clamps can be tested on a regular basis by the mine personnel in a short time and without removing the cage.

It should be appreciated that the scope of the present invention is not limited to the particular embodiments hereinbefore described. In particular, the compression means may comprise pairs of pinching rollers instead of die blocks 18 to deform the arrestor slings and provide a retarding force to the moving object to be arrested. In addition, in the case of a conveyance running on rope guides, as opposed to steel guides, the same principles of the invention can be used but the arrestor assembly may be modified to comprise cone shaped wedges similar to a normal wedge type gland attachment used on rope guides as opposed to the particular arrangement hereinbefore described. In this alternative, a metal scraper disposed beneath the pair of wedges would be provided to remove surplus grease and dirt from the guide rope immediately before application of the wedge.

WO 92/13791 PCT/AU92/00032 19 Furthermore, the principles described herein are not limited to application in connection with the use of conveyances in mine shafts or the arresting of roli.ng stock, but may have equal utility in other areas where an elevator or lifting conveyance is used employing a hoisting mechanism, or where a moving object travels along a predetermined pathway.

Further still, the invention can also be applied to fixed shaft arrestors disposed at the top and bottom of a shaft to bring a cage safely to rest frc- full speed in the case of an overwind. In this particular application, the invention could be suitably applied to both drum and frict ion winder installations.

Claims (3)

1. A decelerating device for decelerating a moving object travelling along a path comprising:- anchoring means for anchoring said decelerating device to a fixed reference along the path; a carrier for engaging the moving object; an arrestor cable formed of ductile material and being of substantially constant cross-section, interconnecting said anchoring means and carrier between one end and an intermediate portion of said arrestor cable proximate to said one end such that a free length of said arrestor cable is provided at the other end thereof; compression means for transversely engaging said intermedi- ate portion of said arrestor cable; and said compression means being adapted to radially compress and plastically deform said arrestor cable in response to relative axial movement therebetween; wherein a motive force applied by the moving object to said carrier relative to said anchoring means is transferred by the relative spatial arrangement of said arrestor cable and said compression means with respect to said anchoring means and said carrier to cause relative axial movement between said compression means and said arrestor cable, and said relative axial movement is opposed by a retardation force generated by said compression means in response to said relative axial movement.

2. A decelerating device as claimed in claim 1, wherein said compression means has associated therewith stop means for stopping conjoint axial movement of said compression means and said arrestor cable, and allowing said relative axial movement. 20a

3. A decelerating device as claimed in claim 1 or 2, wherein said compression means comprises a die block having a pair of dies defining the sides of a passage extending longitudinally through said die block for engaging said arrestor cable, said passage being tapered to provide a constricted opening at one end relative to the other end of S