GB1562246A

GB1562246A - Mining

Info

Publication number: GB1562246A
Application number: GB4892376A
Authority: GB
Original assignee: Hayden Nilos Conflow Ltd
Current assignee: Hayden Nilos Conflow Ltd
Priority date: 1976-11-24
Filing date: 1976-11-24
Publication date: 1980-03-05

Description

(54) IMPROVEMENTS IN OR RELATING TO MINING (71) We, HAYDEN NO LOWS CON FLOW LIMITED, a British Company, of 18, Darnall Road, Sheffield 9, Yorkshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to mining and is concerned with (a) providing roof support at a ripping lip, (b) providing face support at a ripping lip and (c) facilitating the erection of mine arches at an advancing ripping lip.

Hitherto it has usually been necessary for the crown of a fresh mine arch to be lifted manually into position between the last erected arch and the ripping lip, and for the crown then to be held in place by forepoles, advanced manually from behind the last erected arch, whilst the legs of the arch are brought into position and connected to the crown with fishplates. While scaffolding or staging is usually provided to assist the erectors it affords no added protection against possible falls of roof between the last erected arch and the ripping lip, or against possible falls of the face, and very considerable manual effort is also required in these dangerous conditions to lift the crown into place and bring the legs of the fresh arch into position.

According to one aspect of the present invention, equipment for providing roof support at a ripping lip comprises a rail, brackets for removably securing the rail to the undersides of the crowns of erected mine arches, a carriage movable longitudinally with respect to the rail, forepoles linked to the carriage and arranged to project beyond the last erected arch when the carriage is subjacent the crown of that arch, a double-acting ram acting between the rail and the carriage to advance the carriage with one direction of operation of the ram and a latch on the carriage for automatic hooking engagement with the crown of the last erected arch at the end of the advance of the carriage, whereafter reverse operation of the ram can be effected to cause the rail to slide in the brackets and be advanced beyond the last erected arch.The forepoles are advanced to the ripping lip before ripping out takes place. and after ripping out the rail is advanced. With the forepoles and the rail in the advanced position, the crown of the fresh arch is first attached by a detachable bracket above the projecting end of the rail.

Except in the case where the crown is part of a complete arch, the forepoles are advanced to the ripping lip to afford added protection while legs are added, one to each side of the crown, as by means of fishplates, to complete the arch, whereafter the carriage is again advanced to the ripping lip before the next ripping out takes place.

Each arch is strutted, in the usual manner, to the preceding arch immediately upon completion of erection of the complete arch or after assembly of legs to a fresh crown, so as to ensure the correct spacing and adequate rigidity for supporting the equipment in accordance with the invention and the spaces between the arches and struts and the roof and walls may be packed or filled in any known manner.

When the carriage is again advanced the latch releases itself automatically from the crown of the arch with which it was engaged.

While the carriage may be directly carried by the rail and run therealong, the carriage is preferably carried by a joist suspended from the rail, the rail being formed of rigid lengths equal to the spacing of the arches and loosely linked by horizontal pivots, and the joist being of a length substantially equal to a number (e.g., three) of the rail lengths, with the ends of the joist linked to the respective ends of the group of rail lengths by horizontal pivots, whereby the rail lengths can conform to any usual variation in the levels of the crowns of the arches to which the rail lengths are secured by the brackets at their linkages, with the leading rail length pivoted to a nose portion of the rail rigidly secured to the leading end of the joist, and with double acting ram operated linking means between the leading end of the joist and the leading rail length, whereby the attitude of the nose portion relative to the next rail length can be adjusted to suit the level to which the crown of the next arch is to be raised.

According to another aspect of the present invention, the forepoles for providing roof support at a ripping lip have associated therewith parallel downwardly facing channel members advanceable with the forepoles, face support bars with one end of each carried by a pivot extending between the sides of the forward end of one of the channel members and able to swing between a position within the channel member and a position depending from the pivot, struts with one end of each on a horizontal pivot rearwardly of one of the channel members and with clamping means at the other end for engagement anywhere along the length of the corresponding face support bar, for the purpose of bracing the face support bars against a rip face, and means for releasably retaining the face support bars within the channel members and with the struts extending rearwardly and substantially in alignment therewith.

Thus the forepoles and face support bars afford protection against possible falls of roof and/or face between the last erected arch and the ripping lip for erectors erecting a complete fresh arch or assembling the members of a fresh arch. The face support bars may be provided with lugs or brackets for supporting timbers extending across the face to increase the protection afforded.

The means for releasably retaining the face support bars within the channel members and with the struts extending rearwardly and substantially in alignment therewith may be slide bolts through holes in the sides of the rearward ends of the channel members, and by which bolts both the face support bars and the struts are supported when in the aforesaid positions.

According to a further aspect of the present invention which is especially advantageous, equipment for providing roof support at a ripping lip as aforesaid preferably also facilitates the erection of mine arches at an advancing ripping lip by further comprising a hoist carried by the rail and for lifting a fresh crown and bracket into position between the forward ends of the forepoles in first advanced position and the ripping lip, the hoist comprising a lever arm extending from a transverse pivot on a trolley movable longitudinally with respect to the rail, a ram for raising the hoist, drive means for moving the trolley, and a cradle at the free end of the lever arm for supporting a crown of an arm which is located centrally by the bracket, the cradle being mounted on transverse trunions so that it can swing to enable a crown of an arch to remain in a vertical plane as it is lifted into position. The ram for the hoist is preferably provided with a throttled exhaust so that the hoist can only descend slowly when released. The lever arm of the hoist preferably includes an overload yield device, which causes a portion of the lever arm carrying the cradle to drop about a pivot if the cradle becomes overloaded, thereby giving a visual warning. The hydraulics for the hoist preferably include an overcentre control valve, whereby any obstruction of the hoist results in immobilisation of the hoist. The drive means for moving the trolley of the hoist preferably comprises a rack secured longitudinally with respect to the rail and a pinion on the trolley driven by a hydraulic motor through a gearbox.

The trolley of the hoist is preferably carried by the rearward end of the joist carrying the carriage for the forepoles, with further joists linked by horizontal pivots one to the leading joist and one to the next joist (and so on if more than two further joists are provided), whereby the hoist can be moved by its trolley to where arches or arch members can lie in waiting well away from the area below the carriage (which area is thus clear for a ripping machine), and each further joist has its ends linked by horizontal pivots to the respect ends of further groups of rail lengths pivotally linked together as aforesaid and similarly to each adjacent group of rail lengths.

According to yet another feature of the invention, the cradle on the hoist for facilitating the erection of mine arches is provided with freely pivoted catches in mutually opposed pairs at both sides of the cradle, whereby a crown of an arch can be simply dropped on to the cradle and removed merely by lifting it vertically or by merely lowering the cradle away from a crown supported in a vertical plane, but if the cradle is tilted the catches swing into jamming positions which prevent the crown of the arch leaving (e.g. falling from) the cradle.

The cradle is preferably mounted on its trunnions on a lever bracket on the lever arm, with a ram acting between the lever arm and the lever bracket to raise the cradle farther after raising of the lever arm, whereby a crown of an arch carried by the cradle can be brought close up to the roof, after the lever arm has been advanced to a predetermined stop position, with the crown on the cradle very precisely spaced from the last erected arch (e.g. to within 1 mm. of the desired spacing).

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures I (a) and I (b) together form a side elevation of equipment for providing roof and face support at a ripping lip and for facilitating the erection of mine arches at an advancing ripping lip; Figure 2 is a plan of the cradle at the right-hand end of Figure 1:: Figure 3 is an elevation of the right-hand side of Figure 2; Figure 4 is an elevation of the cradle showing (in section) the crown of an arch in the cradle; Figure 5 is a plan of Figures l(a) and l(b), to a smaller scale, but with the cradle omitted from the right-hand end; Figure 6 is a section (on the line 66 of Figure 7) of one of the brackets for securing the rail to the undersides of the crowns of erected mine arches; Figure 7 is half elevation half section (on the line 7-7 of Figure 6) of the bracket; Figure 8 is a fragmentary elevation of part of Figure l(b) with the face support bar in an operative position; Figure 9 is a small scale elevation from the right-hand end of Figure 5, but with the hoist and cradle omitted;; Figures 10 and 11 are fragmentary diagrams illustrating how the rail and joist combination is advanced; Figures 12 to 14 are similar diagrams illustrating how the attitude of the leading joist is controlled; and Figures 15 to 17 are diagrams illustrating various stages in the operation of the equipment.

The equipment shown in the drawings comprises joists 1A, 1B, IC suspended from groups 2A, 2B, 2C (see particularly Figures 12 to 14) of rail lengths 2, which equal the spacing of mine arches 3 (except for the leading rail length 2X in the leading group 2A) and are loosely linked by horizontal pivots 4 (see Figures l(a), I(b)), the joists being of a length equal to three rail lengths, i.e., equal to the length of each group of rail lengths (except for the leading group 2A in which the difference is made up by a nose portion 5 rigidly secured to the leading end of the joist 1A and linked by a horizontal pivot 4X - see Figures l(b) and 5), and the joists being linked by horizontal pivots 6 to each other and by horizontal pivots 7 to the respective ends of the groups of rail lengths.

The middle rail lengths in the groups 2A, 2B, 2C are held captive to the respective joists IA, 1B, IC by chains 8. The mine arches 3 do not form part of the equipment according to the invention, but the equipment does comprise brackets 9 (see particularly Figures 6 and 7) by means of which the rail lengths 2 are removably secured to the undersides of the crowns of erected mine arches, and double-acting ram operated linking means 10 between the leading end of the leading joist 1A and the leading rail length 2X enables the attitude of the nose portion 5 relative to the next rail length 2 to be adjusted to suit the level to which the crown of the next arch 3X (see particularly Figures 12 to 14) is to be raised.

The means 10 (see particularly Figures l(b) and 5) consists of a pair of double-acting rams 11 secured one on each side of the nose portion 5 with their piston rods connected by a link 12 to a cam lever 13, which is pivotable about a pivot 14 on the joist IA and has a profiled edge 15 engaging over a roller 16 on an axle between two angle irons forming the leading rail length 2X, the angular disposition of the cam lever 13 about the pivot 14 (as determined by operation of the rams 11 to move the link 12) causing relative movement between the joist IA and the leading rail length 2X.

The leading joist 1A carries a carriage 17 (see particularly Figures l(b), 5 and 9 to 11) with laterally projecting "wings" 18 supporting downwardly facing channel members 19 from the leading ends of which extend lateral plates 20 with eye-bolts 21 and shackles 22 linked to forepoles 23, and the forepoles are removably secured to the mine arches 3 by clamps 24 of conventional form. A double-acting ram 25 (Figures l(a) and 5) between channel-sections forming the joist IA serves to advance the carriage 17 with one direction of operation of the ram, and a pair of latch hooks 26 on pivots 27 on the carriage are spring-loaded upwardly (by springs not shown) and have lever arms 28 with lateral bars 29 for engagement with ramps 30 to cause the latch hooks to pass under the last erected arch 3X.When the lateral bars 29 drop off the ends 31 of the ramps the latch hooks 26 automatically engage the last erected arch 3X at the end of advance of the carriage 17 (see Figure 10). Reverse operation of the ram 25 causes the joist 1A to be advanced and, because of its connection with the leading rail length 2X through the nose portion 5 and the pivot 4X, the rail lengths 2 slide in the brackets 9 and the leading rail length 2X is advanced beyond the last erected arch 3X (see Figure 11).

Simultaneously, of course, the forepoles 23 are advanced and slide in the clamps 24.

The lateral bars 29 are swung about pivots 29X upon engagement of the bars 29 by the advancing ends 31 of the ramps 30 on the joist IA, and when the ramps have passed the bars 29 return under the urge of springs (not shown) to the positions shown in Figure 5.

Each of a pair of support bars 32 have one end carried by a pivot 33 extending between the sides of the forward end of one of the channel members 19 and so able to swing between a position within the channel member (Figures l(b), 5 and 11) and a position depending from the pivot (Figures 8 and 9), and each of a pair of struts 34 has one end on a horizontal pivot 35 rearwardly of one of the channel members 19 and has clamping means 36 at the other end for engagement anywhere along the length of the corresponding face support bar 32, for the purpose of bracing the face support bars against a rip face 37 (Figures 15 and 17).

Bolts 38 slidable in holes in the sides of the rearward ends of the channel members 19 support the face support bars 32 (and the struts 34) in the position within the channel members, as aforesaid. The face support bars are provided with brackets 39 for supporting timbers 40 across the face to increase the protection afforded.

The full sequence of operations, starting with the position shown in Figure 15, will be described presently, after the remainder of the equipment has been described.

Each bracket 9 (Figures 6 and 7) has a pair of fixed jaws 41 through which a flange 42 on a rail 2 or the nose portion 5 is freely slidable, and a pair of separable jaws 43 for clamping on the lower flange 44 of a mine arch 3 by means of a bolt 45 and an elongate nut 46. A pair of shoes 47 extend along the fixed jaws 41 and have downwardly inclined ends 48 to assist entry of the nose portion 5 (which has a slight taper at its leading end) whichever way round the bracket 9 may be used.

The pivots 6 connecting the pairs of adjacent ends of the joists 1A, 1B, 1C also connect lengths of rack 49 secured by brackets 50 (only one shown in Figure 1(a)) between the channel members forming the joists, and the rack is engaged by a pinion 51 which is driven by a hydraulic motor 52 through a gearbox 53 on a trolley 54 of a hoist (Figures l(a) and l(b)) carried by the joist 1A behind the carriage 17 or by the joist 1B or joist 1C.The hoist also comprises a lever arm 55 extending from a transverse pivot 56 on the trolley 54, a ram 57 for raising the hoist, and a cradle 58 (see also Figures 2 to 4) at the free end of the lever arm for supporting a crown of an arch 3X which is located centrally by a bracket 9 fitting between the sides 59 of the cradle, the cradle being supported on transverse trunnions 60 so that it can swing to enable the crown to remain in a vertical plane as it is lifted into position. The cradle is provided with freely pivoted catches 61 in mutually opposed pairs on both sides 59, which catches allow a crown of an arch to be dropped on to the cradle and to be removed by lifting it vertically or by merely lowering the cradle away from a crown supported in a vertical plane, but if the cradle is tilted the catches swing into jamming positions which prevent the crown of the arch leaving (e.g.

falling from) the cradle. The cradle 58 is mounted on its trunnions 60 on a lever bracket 62 on the lever arm 55, with a ram 63 acting between the lever arm and the lever bracket to raise the cradle further after raising of the lever arm (see Figures 16 and 17), whereby the crown of the arch carried by the cradle can be brought close up to the roof 64 after the lever arm has been advanced to a predetermined stop position, with the crown on the cradle very precisely spaced from the last erected arch 3X (e.g., to within 1 mm. of the desired spacing).

The lever arm 55 is provided with an overload yield device 64, which causes a portion 55X of the lever arm to drop about a pivot 65 if the cradle 58 becomes overloaded, and thereby gives a visual warning.

The cycle of operations will now be described with reference to Figures 15 to 17.

In Figures 16 and 17 an operative is shown working a lever operated valve control unit 65 suspended from the trolley 54, which unit provides for control of all the rams as well as the motor 52, so that the ram 25 for advancing the carriage 17 (and the forepoles 23, which are not shown in Figures 15 to 17, so that the channel members 19 and face support bars 32 are visible) can be operated remotely, as will be apparent in Figure 15 where the trolley 54 and control unit 65 are off the sheet.

Starting with Figure 15, the forepole carriage 17 is advanced (by operation of the ram 25) to the ripping lip 66, so that the forepoles provide roof support (if needed), the face support bars 32 are swung down to the face 37, timbers 40 are placed in the brackets 39, and the bars 32 are braced by the struts 34, so that the bars 32 and timbers 40 provide face support (if needed). With the hoist 55, lever bracket 62 and cradle 58 in its raised and retracted position shown, there is ample space below the equipment for a ripping machine (not shown) to advance over the floor 67 and rip out beyond the bars 32 and timbers 40 to an extent approximately equal to the spacing of the arches 3. After ripping out the timbers 40 are removed and the bars 32 and struts 34 are swung up into the channel members 19, where they are secured by the bolts 38. The carriage 17 is advanced slightly (if need be) to enable the latch hooks 26 to engage with the last erected arch 3X, and the ram 25 is operated in reverse direction to cause the joists 1A, 1B, lCto be advanced along with the rail lengths 2X, 2 which slide through the brackets 9 (not shown in Figures 15 to 17) on the arches 3, 3X.

Following on from this position in Figure 16, the ripping machine having been withdrawn, the hoist 55 is lowered to enable a fresh crown 3Y to be placed on the cradle 58, the hoist advanced with the trolley 54 (by operation of the motor 52) until the latter is immediately behind the carriage 17, the hoist is raised (by operation of the ram 57), and the lever bracket 62 is swung upwards (by operation of the ram 63) to bring the crown 3Y above the nose 5 with its bracket 9Y (see Figure 3) engaged therewith.

Following on from this position in Figure 17, the forepole carriage 17 is again advanced (by operation of the ram 25) to afford protection to erectors assembling legs (not shown) on to the crown 3Y, but before this happens the lever bracket 62 is swung down to remove the cradle 58 from the crown 3Y, to allow the linking means 10 between the leading end of the joist IA and the leading rail length 2X to be operated) (by operation of the rams 11 (see Figures l(b) and 5) for adjustment of the level of the crown 3Y by adjustment of the attitude of the nose portion 5 relative to the next rail length 2 (as described previously with reference to Figures 12 to 14).The hoist 55, lever bracket 62 and cradle 58 are lowered (by allowing controlled exhausting of the ram 57) and then withdrawn (by reverse operation of the motor 52), and the face support bars 32 are swung down to the new face 37A, provided with timbers 40 and braced by the struts 34, to provide face support (if needed) at the advanced ripping lip 66A, whereafter the cycle of operations is repeated, starting again as from Figure 15.

WHAT WE CLAIM IS: 1. Equipment for providing roof support at a ripping lip comprising a rail, brackets for removably securing the rail to the undersides of the crowns of erected mine arches, a carriage movable longitudinally with respect to the rail, forepoles linked to the carriage and arranged to project beyond the last erected arch when the carriage is subiacent the crown of that arch, a doubleacting ram acting between the rail and the carriage to advance the carriage with one direction of operation of the ram and a latch on the carriage for automatic hooking engagement with the crown of the last erected arch at the end of the advance of the carriage, whereafter reverse operation of the ram can be effected to cause the rail to slide in the brackets and be advanced beyond the last erected arch.

2. Equipment as in Claim 1, wherein the carriage is directly carried by the rail and runs therealong.

3. Equipment as in Claim 1, wherein the carriage is carried by ajoist suspended from the rail, the rail being formed of rigid lengths equal to the spacing of the arches and loosely linked by horizontal pivots, and the joist being of a length substantially equal to a number of the rail lengths, with the ends of the joist linked to the respective ends of the group of rail lengths by horizontal pivots, whereby the rail lengths can conform to any usual variation in the levels of the crowns of the arches to which the rail lengths are secured by the brackets at their linkages, with the leading rail length pivoted to a nose portion of the rail rigidly secured to the leading end of the joist, and with double-acting ram operated linking means between the leading end of the joist and the leading rail length, whereby the attitude of the nose portion relative to the next rail length can be adjusted to suit the level to which the crown of the next arch is to be raised.

4. Equipment as in any one of the preceding claims, wherein the forepoles for providing roof support at a ripping lip have associated therewith parallel downwardly facing channel members advanceable with the forepoles, face support bars with one end of each carried by a pivot extending between the sides of the forward end of one of the channel members and able to swing between a position within the channel member and a position depending from the pivot, struts with one end of each on a horizontal pivot rearwardly of one of the channel members and with clamping means at the other end for engagement anywhere along the length of the corresponding face support bar, for the purpose of bracing the face support bars against a rip face, and means for releasably retaining the face support bars within the channel members and with the struts extending rearwardly and substantially in alignment therewith.

5. Equipment as in Claim 4, wherein the face support bars are provided with lugs or brackets for supporting timbers extending across the face to increase the protection afforded.

6. Equipment as in Claim 4 or Claim 5, wherein the means for releasably retaining the face support bars within the channel members and with the struts extending rearwardly and substantially in alignment therewith comprises slide bolts through holes in the sides of the rearward ends of the channel members and by which bolts both the face support bars and the struts are supported when in the aforesaid positions.

7. Equipment as in any one of Claims 1 to 3, or as in any one of Claims 4 to 6 in combination with any one of Claims 1 to 3, further comprising a hoist carried by the rail and for lifting a fresh crown and bracket into position between the forward ends of the forepoles in first advanced position and the ripping lip, the hoist comprising a lever

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 16, the ripping machine having been withdrawn, the hoist 55 is lowered to enable a fresh crown 3Y to be placed on the cradle 58, the hoist advanced with the trolley 54 (by operation of the motor 52) until the latter is immediately behind the carriage 17, the hoist is raised (by operation of the ram 57), and the lever bracket 62 is swung upwards (by operation of the ram 63) to bring the crown 3Y above the nose 5 with its bracket 9Y (see Figure 3) engaged therewith. Following on from this position in Figure 17, the forepole carriage 17 is again advanced (by operation of the ram 25) to afford protection to erectors assembling legs (not shown) on to the crown 3Y, but before this happens the lever bracket 62 is swung down to remove the cradle 58 from the crown 3Y, to allow the linking means 10 between the leading end of the joist IA and the leading rail length 2X to be operated) (by operation of the rams 11 (see Figures l(b) and 5) for adjustment of the level of the crown 3Y by adjustment of the attitude of the nose portion 5 relative to the next rail length 2 (as described previously with reference to Figures 12 to 14).The hoist 55, lever bracket 62 and cradle 58 are lowered (by allowing controlled exhausting of the ram 57) and then withdrawn (by reverse operation of the motor 52), and the face support bars 32 are swung down to the new face 37A, provided with timbers 40 and braced by the struts 34, to provide face support (if needed) at the advanced ripping lip 66A, whereafter the cycle of operations is repeated, starting again as from Figure 15. WHAT WE CLAIM IS:

1. Equipment for providing roof support at a ripping lip comprising a rail, brackets for removably securing the rail to the undersides of the crowns of erected mine arches, a carriage movable longitudinally with respect to the rail, forepoles linked to the carriage and arranged to project beyond the last erected arch when the carriage is subiacent the crown of that arch, a doubleacting ram acting between the rail and the carriage to advance the carriage with one direction of operation of the ram and a latch on the carriage for automatic hooking engagement with the crown of the last erected arch at the end of the advance of the carriage, whereafter reverse operation of the ram can be effected to cause the rail to slide in the brackets and be advanced beyond the last erected arch.

arm extending from a transverse pivot on a trolley movable longitudinally with respect to the rail, a ram for raising the hoist, drive means for moving the trolley, and a cradle at the free end of the lever arm for supporting a crown of an arch which is located centrally by the bracket, the cradle being mounted on transverse trunnions so that it can swing to enable a crown of an arch to remain in a vertical plane as it is lifted into position.

8. Equipment as in Claim 7, wherein the ram for the hoist is provided with a throttled exhaust so that the hoist can only descend slowly when released.

9. Equipment as in Claim 7 or Claim 8, wherein the lever arm of the hoist includes an overload yield device, which causes a portion of the lever arm carrying the cradle to drop about a pivot if the cradle becomes overloaded, thereby giving a visual warning.

10. Equipment as in any one of Claims 7 to 9, wherein the hydraulics for the hoist include an overcentre control valve, whereby any obstruction of the hoist results in immobilisation of the hoist.

11. Equipment as in any one of Claims 7 to 10, wherein the drive means for moving the trolley of the hoist comprises a rack secured longitudinally with respect to the rail and a pinion on the trolley driven by a hydraulic motor through a gearbox.

12. Equipment as in any one Claims 7 to 10 in combination with Claim 3, wherein the trolley of the hoist is carried by the rearward end of the joist carrying the carriage for the forepoles, with further joists linked by horizontal pivots one to the leading joist and one to the next joist, whereby the hoist can be moved by its trolley to where arches or arch members can lie in waiting well away from the area below the carriage, and each further joist has its ends linked by horizontal pivots to the respective ends of further groups of rail lengths pivotally linked together as aforesaid and similarly to each adjacent group of rail lengths.

13. Equipment as in any one of Claims 7 to 12, wherein the cradle on the hoist for facilitating the erection of mine arches is provided with freely pivoted catches in mutually opposed pairs at both sides of the cradle, whereby a crown of an arch can be simply dropped on to the cradle and removed merely by lifting it vertically or by merely lowering the cradle away from a crown supported in a vertical plane, but if the cradle is tilted the catches swing into jamming positions which prevent the crown of the arch leaving (e.g. falling from) the cradle.

14. Equipment as in Claim 13 in combination with any one of Claims 7 to 12, wherein the cradle is mounted on its trunnions on a lever bracket on the lever arm, with a ram acting between the lever arm and the lever bracket to raise the cradle farther after raising the lever arm, whereby a crown of an arch carried by the cradle can be brought close up to the roof, after the lever arm has been advanced to a predetermined stop position, with the crown on the cradle very precisely spaced from the last erected arch.

15. Equipment for providing roof support at a ripping lip substantially as hereinbefore described with reference to Figures l(b) and 5 of the accompanying drawings.

16. Equipment for providing face support at a ripping lip substantially as hereinbefore described with reference to Figures l(b), 5 and 8 of the accompanying drawings.

17. Equipment for providing roof support and face support at a ripping lip substantially as hereinbefore described with reference to Figures l(b), 5 and 8 of the accompanying drawings.

18. Equipment for providing roof support and face support at a ripping lip and facilitating the erection of mine arches at an advancing ripping lip, substantially as hereinbefore described with reference to the accompanying drawings.

19. A cradle on a hoist for facilitating the erection of mine arches substantially as hereinbefore described with reference to Figures l(b) and 2 to 4 of the accompanying drawings.