US3362169A

US3362169A - Roof supporting systems for mine workings

Info

Publication number: US3362169A
Application number: US419647A
Authority: US
Inventors: Karl Maria Groetschel
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-12-21
Filing date: 1964-12-21
Publication date: 1968-01-09
Anticipated expiration: 1985-01-09
Also published as: DE1236451B; BE657425A; GB1091312A; ES307315A1

Description

Jan. 9, 1968 K. M. GROETSCHEL 3,362,159

- ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS l0 Sheets-Sheet 1 Filed Dec. 21, 1964 m" m wt m mm a V OI.

Jan. 9, 1968 K. M. GROETSCHEL 3,362,169

ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 Sheets-Sheet 2 INVENTOR:

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ROQF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 Sheets-Sheet 3 \HVENTOR: L mum. Groeasd2eL 3 b ow E45! fittornets Jan. 9, 1968 K. M. GROETSCHEL 3,362,169

7 ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 Sheets-Sheet 4 \NVENTOR KarL mam, G'roetscl'zaL s= 6PM W QtLorn e5 Jan. 9, 1968 K. M. GROETSCHEL ,3

ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 Q l0 Sheets-Sheet 5 Fife KcurL mam GroetsciyeL 3 fipmwz #A nttorn e 55 Jan. 9, 1968 K. M.'GROETSCHEL 3,362,169

ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 She'et$Sheet 6 ,c K 2o| 2031 7 b b b 208 205 20 202 9 I /K 2n Fig.

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ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 Sheets-Sheet 7 b 4|5 113 1114 40g 405 4022 401 O 4G0 40s? 48 484 F ll a 1 n 4l8 8 40l 4O INVENTOR. KourL mm GvoatscbeL mu: 4; i 38- QttOrne S Jan. 9, 1968 K. M. GROETSCHEL 3,

ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 Sheets-Sheet 8 502 sov soa 50s 50o 503 G06 627 600 c.35c s35 (535 INVENTOR:

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ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 10 Sheets-Sheet 9 702b /7OG 705 7o2 ll 55525523 iNVENTOR; KourL maria. GroetscbeL Jan. 9, 1968 K. M. GROETSCHEL 3,362,159

ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Filed Dec. 21, 1964 1O Sheets-Sheet 10 Fag.

INVENTOR'.

K L maria. Groetsdzd Httome5$ United States Patent 3,362,169 ROOF SUPPORTING SYSTEMS FOR MINE WORKINGS Karl Maria Groetschel, 44 Stolzestrasse, 463 Bochum, Westphalia, Germany Filed Dec. 21, 1964, Ser. No. 419,647 Claims priority, application Germany, Dec. 21, 1963, G 39,458; Great Britain, May 14, 1964, 20,054/64 29 Claims. (CI. 61-45) ABSTRACT OF THE DISCLOSURE A guiding device is provided for use between opposed side faces of adjacent self-advancing mine roof supports in mine workings where the floor of the mine working is laterally inclined with respect to the'direction of advancement. The guiding device comprises laterally spaced side members of which at least one has a contact face approximately as long as the base of one of the self-advancing roof supports, the lateral separation of the side members being controlled by a hydraulic piston and cylinder unit connected pivotally at opposite ends to the side members respectively, while longitudinal rigidity of the guiding device is maintained by a stay member connected between longitudinally offset positions on the two side members respectively. Optionally, a similar structure can be provided between adjacent superstructures of two adjacent self-advancing mine roof supports and can be carried at the requisite elevation above the lower unit by an extensible post. The guiding device is preferably pivotally connected to an anchorage member extending laterally of a row of self-advancing roof supports in front of the supports.

This invention is concerned with roof supporting systems for supporting the roofs of mine Workings and including self-advancing roof supports, herein referred to as being of the kind specified, and each comprising a base, a plurality of power-operated props thereon, a roof-engaging superstructure carried by the props at their upper ends, and traction means for advancing the support. Supports of the kind specified may be either of two types. The first of these is one wherein the base comprises a single base element upon which all of the props are mounted, in this case the base element having a part movable relatively to the remainder of the base element in the direction of advancement by the traction means, such part being adapted for connection to a conveyor or other member forming an anchorage and normally disposed at the forward end of the support when the latter is in use. The second type incorporates a base comprising a forward base element and a rearward base element each carrying certain of the props and respectively carrying fore and rear parts of the superstructure, the traction means being operatively connected between these base elements so that when the props of the rear base element are extended and the rear part of the superstructure under load, the rear part of the support as a whole forms an anchorage with respect to which the traction means can advance the fore part of the superstructure as a whole, the props thereof being then temporarily contracted to lower the fore part of the superstructure, whilst the functions of the two parts are reversed for a second stage of movement in which the fore part forms an anchorage whilst the rear part is drawn up to it by the traction means.

Self-advancing roof supports of the kind specified employed in a system of coal mining known as long wall mining wherein a plurality of the supports are disposed at positions spaced apart laterally from each other along the length of the coal face, and a conveyor and coal-getting machinery is advanced periodically towards the new- 1y exposed portions of the coal face as coal is extracted therefrom, the traction means of the supports being operated to move these in succession towards the coal face.

In many mines the floor (and roof) of the mine working is inclined to the horizontal in a direction from one end of the coal face towards the other and there is often a tendency for an individual roof support to become displaced out of its proper laterally spaced relationship with the adjacent roof supports on each side of it, or for the whole groups of successive roof supports to slide in a downward direction in which the floor of the mine working slopes.

In my copending applications 20,046/64 and 20,047/ 64 I have disclosed self-advancing roof supports of the kind specified in which the direction of advancement is determined by the provision of guide means incorporated in the support itself, such guide means being arranged to permit of angular adjustment in a horizontal, or approximately horizontal, plane of the direction in which a forwardly projected part adapted for attachment to the conveyor or other anchorage is projected by the traction means, or the direction in which the forward base element of a two-part support is advanced relatively to the rear base element.

Supports incorporating guide means as referred to in the preceding paragraph, although advantageous in comparison with roof supports which do not provide any facilities for steering or controlling the direction of advancement, do not invariably permit of ready correction of deviations from their correct lateral positions when used under conditions in which the floor of the mine working has a steep inclination, for example exceeding about 20. Moreover many self-advancing roof supports of the kind specified already in service do not even incorporate such guiding means.

One of the objects of the present invention is to provide for satisfactory operation of a roof supporting system under conditions in which the floor of the mine working may have a steep inclination in the longitudinal direction of the coal face and irrespective of whether the self advancing roof supports employed do or do not incorporate guiding means as disclosed in my previously mentioned copending applications.

With this object in view there is provided in accordance with the present invention a guiding device for use between laterally spaced self-advancing roof supports, such device being in the form of a unit which is separate structurally from the roof supports themselves and comprising laterally spaced side members for engagement with opposed side faces of the roof supports, one at least of such side members affording a guide face of effective length sufficient to control the direction of advancement of that one of said supports in contact therewith, and power-operated bracing means extending between the side members and serving to control their lateral separation and inclination.

The power-operated bracing means may comprise a piston and cylinder unit adapted to be energised by fluid under pressure and disposed between said side members, and a stay structure connected operatively between the side members and resisting relative longitudinal move ment thereof while permitting of relative lateral movement toward and away from each other. In this case it is preferred that the piston and cylinder unit be pivotally connected at its ends to the side members respectively, and the stay structure comprises a stay bar forming with the piston and cylinder unit, and at least part of one of the side members, a generally triangular structure.

Whilst it would be within the scope of the invention for the guiding device as herein defined to consist of a single unit which in use is disposed between the bases of adjacent roof supports, a further feature of the present invention is the provision of a guiding device in which both upper and lower units, as aforesaid, are provided for interposition respectively between the bases and the superstructures of adjacent roof supports, the upper unit being supported from the lower unit by at least one upwardly extending post. Such post is preferably adjustable in length to enable the height at which the upper unit is situated to be varied.

Further, in acordance with the invention, the guiding of laterally spaced self-advancing roof supports is effected by the provision of the combination of a guiding device, as herein defined, with a laterally extending anchorage member situated at the leading end of the guiding device having regard to the direction of advancement of the roof supports, and means for effecting connection between the anchorage member and the guiding device at any of a number of positions along the length of the anchorage member.

The anchorage member may be constituted by a conveyor extending along the coal face, such conveyor being normally present for the purpose of receiving and conveying away coal extracted from the face by a coalgetting machine movable along, and usually guided by, rails provided on the conveyor. Alternatively, however, an anchorage member specifically for the purpose of controlling the relative lateral positions of the guiding devices at their leading ends may be provided. Such anchorage member may be a cable (which expression is to be deemed to include any form of rope, chain or other elongated, flexible or articulated member), such cable being mounted on or attached to the conveyor.

In a form of the guiding device incorporating lower and upper units as aforesaid the conveyor may be provided with both lower and upper cables.

The connecting means may be formed or constructed to provide a limited elastic displacement of the guiding device lengthwise of the anchorage member at the point of connection.

A support system for the roof of the mine working in accordance with the invention comprises the combination of laterally spaced self-advancing roof supports and at least one guiding device, as herein defined, intervening between such supports, and wherein the side member affording said guide face has a length at least equal to the base of the supports associated therewith. When the roof supports are of the two-part kind herein specified the side member affording said guide face may comprise two sections connected at adjacent ends in such a manner as to permit of relative angular movement parallel to the plane of the floor, each such section being associated with a separately operable part of the power-operated bracing means.

In a roof support system the traction means by which the supports are advanced may each comprise a traction piston and cylinder unit and the piston and cylinder units of the bracing means and of the traction means may be connected in a supply and control system for pressure fluid including valve means adapted to coordinate operation of the bracing and traction means. Thus, the bracing means of the guiding device, or each of same, may be supplied with fluid to extend the bracing means concurrently with the supply of fluid to the traction piston and cylinder unit of the support which is guided during its advancement by such guiding device.

The invention will now be described, by way of example, with reference to the accompanying drawings wherein:

FIGURE 1 is a view in front elevation of one embodiment of guiding device incorporating both a lower and upper unit;

FIGURE 2 is a plan view of the embodiment of FIGURE 1;

FIGURE 3 is a plan view of the embodiment of FIG- URE l in cross-section on the line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary view in cross-section on the line 4--4 of FIGURE 1;

FIGURE 5 is a fragmentary view in cross-section on line 5-5 of FIGURE 1; I

FIGURE 6 is a fragmentary view in vertical crosssection showing a modification of the post supporting the upper unit of the guiding device;

FIGURE 7 is a view in plan illustrating a roof supporting system incorporating guiding devices in accordance with an alternative embodiment of the invention wherein the guiding device comprises a single lower unit between the bases of adjacent roof supports;

FIGURE 8 is a view in rear elevation of the system illustrated in FIGURE 7;

FIGURE 9 is a view similar to FIGURE 7 illustrating a further embodiment of the invention;

FIGURE 10 is a view similar to FIGURE 7 illustrating a portion of a modification of the embodiment of FIG- URE 7;

FIGURE 11 is a view similar to FIGURE 7 illustrating a further embodiment of the invention;

FIGURE 12 is a View in side elevation of the embodiment shown in FIGURE 11;

FIGURE 13 is a view in rear elevation of the embodiments shown in FIGURES 11 and 12;

FIGURE 14 is a view similar to FIGURE 7 of a further embodiment of the invention;

FIGURE 15 is a view similar to FIGURE 7 illustrating a further embodiment;

FIGURE 16 is a view in plan of a further embodiment of the invention incorporating an auxiliary prop which is trailed with the guiding device;

FIGURE 17 is a fragmentary view in rear elevation showing the supporting means,

FIGURE 18 is a hydraulic circuit diagram applicable to any of the embodiments above referred to; and

FIGURE 19 is a plan view of an attachment for connecting a non-parallel sided base or superstructure to one presenting parallel sides.

Referring firstly to the embodiment of the guiding device in accordance with the invention, as illustrated constructionally in FIGURES 1 to 5, the device comprises a lower unit 20 and an upper unit 21 for disposition respectively between opposed lateral faces of the bases of adjacent roof supports (not shown in FIGURE 1) and opposed lateral faces of the superstructure of such supports. In each case the

units

20 and 21 are structurally separate from the supports themselves so as to be capable of being inserted in, or removed from, their proper positions in between adjacent roof supports without the necessity for providing on the latter end special brackets or other attachment formations for connection to the units.

The upper unit 21 is supported at the required height above the floor 22 of the mine working by means of an upwardly extending support in the form of a post 23, and the guiding device as a whole is adapted for connect1on to a conveyor extending along the coal face or other anchorage member, as hereinafter described, by an attachment means 25 (FIGURES 2 and 3).

Referring specifically to the construction of the lower unit 20 as seen in FIGURES 1 and 3, this comprises two laterally spaced

side members

26 and 27. The side member 26 has a length which ordinarily will be approximately equal to the length of the side face of the base of the roof support with which the outer side face 28 of this side member is in contact during use.

The side member 27, may, as illustrated, be shorter in length and typically would have a length of about one quarter to one sixth of the side face of the base of the roof support with which its outer side face 29 is in contact during use.

The side member 26 may be formed of a length of steel rail which throughout most of its length has 9. laterally projecting web or stem 30 so that it is of T section, the rearward end portion 31 of both the vertical flange of the rail and the web being inclined inwardly of the device as viewed in plan.

The side member 27 may also be in the form of a length of steel rail of T section having an inwardly extending web 32 and in this case both

end portions

33 and 34 are inclined inwardly.

Extending between the

side members

26 and 27 is a power-operated bracing means for resisting inward movement of the side members towards each other, such bracing means comprising a piston and cylinder unit 35 adapted to be energised by fluid under pressure, preferably hydraulic fluid, and further comprising a stay structure in the form of a stay bar 36 connected between the forward end of the side member 27 and a point on the side member 26 near its forward end.

The piston and cylinder unit 35 may for the most part be of conventional form and preferably a double-acting piston and cylinder unit is employed. At one end of the unit the cylinder has a pair of vertically spaced lugs 37 welded or otherwise secured to the adjacent end wall of the cylinder and between these extends a vertical pivot pin 38 passing through a hole in the web 32 of the side member 27 to eflect pivotal connection between the piston and cylinder unit and this side member about a vertical axis.

At the opposite end the piston rod 39 of the piston and cylinder unit terminates in a fork 4!}, between the limbs of which extends a further pivot pin 41 extending through a hole in the web 30 of the side member 26 to effect pivotal connection about a vertical axis between the side member and the piston and cylinder unit.

The stay bar 36 is pivotally connected at its rearward end by means of a pivot pin 42 to the assembly of the piston and cylinder unit and side member 27 conveniently to a lug 43 provided on the latter at its leading end. The opposite end of the stay bar 36 is pivotally connected to the side member 26 through the intermediary of a lug 44 projecting inwardly from the web 30 at the forward end of this member. The side member 26, stay bar 36, a portion of the side member 27, and the piston and cylinder unit form a generally triangular structure as viewed in plan, the stay bar serving to prevent any undesirable lateral forces being applied to the piston and cylinder unit such as might cause bending of the piston rod or other damage to this unit.

Movement of the

side members

26 and 27 away from each other is determined by the provision of stop means. Such stop means are preferably formed or constructed to provide for adjustment of the maximum separation between the side members, and a particularly simple and convenient form is that illustrated and which comprises two lengths of chain 45 connected respectively between the opposite ends of the side member 27 on the one hand and corresponding longitudinally spaced points on the side member 26 on the other hand.

For this purpose the vertical flange of the side member 27 may have welded to each of its end portions a pair of vertically spaced, inwardly projecting, lugs 46 (FIGURE 5) which in turn are welded at their inner edges to the web 32. Anchor pins 47 extending between the lugs pass through respective terminal links of the lengths of chain 45. These anchor pins may be in the form of bolts and nuts as illustrated so that each can be readily removed to be inserted through any selected link of each length of chain, thereby enabling the effective length of chain utilised to be varied and so adjust the maximum separation of the side members from each other.

Connection of the lengths of chain 45 to the side member 26 is in a like manner effected by the provision of two pairs of vertically spaced lugs, of which one is seen at 48 and its associated anchor pin at 49 (FIGURE 3).

The

side members

26 and 27 are supported at the required height above the floor 22 of the mine working to engage with their respectively associated bases of the supports on each side of the guiding device by

skid members

50 and 51 each comprising a length of strip metal bent into U-shape as seen for the skid member 51 (FIG- URE 5), the upward extremities of the limbs of the skid member being welded to the associated web of the side member.

The connection means 25 is adapted to provide for limited displacement, against resilient means, of the guiding device in a direction extending longitudinally of the conveyor or anchor member to which the guiding device is attached. One suitable connecting means as illustrated thus comprises a generally box-like housing 52 secured by welding or otherwise to the web 30' of the side member 26 at its forward end.

This housing 52 has top and bottom walls each formed with a laterally extending slot, as seen at 53, through which passes the vertical pivot pin 54 of a short connecting link 55 having an aperture 56 at its forward end for connecting to the anchor member.

Movement of the pivot pin 54 along the slots, such as 53, may be controlled by the provision of resilient members such as blocks of rubber 57 disposed in the housing above and below the link 55 so that there is a gap between these blocks within which the link can move laterally, whilst the upper and lower end portions of the pin 54 extend through holes in the rubber blocks and are restrained against movement longitudinally of the slots 53.

If it is desired to prevent or adjust the limit of possible movement in either direction, stop members such as threaded bolts 58 passing through nuts 59 welded to the housing at its inner side, can be screwed in so that their inner ends positively engage the opposing side face of the link 55 in the region of the pivot pin.

Referring now to the upper unit 21, this is of the same general form as the lower unit 20 except that in this case the side member 60 is substantially shorter in length than the corresponding side member 26 above which it is disposed and typically is about twice as long as the opposite shorter side member 61. These side members are again formed as steel rails and have respective webs 62, 63 pivotally connected to opposite ends of an upper piston and cylinder unit 64 by

pins

65, 66. Maximum separation of the

side members

60 and 61 is limited by lengths of chain 67 connected to the side members by removable I pins 68 and 69 respectively, the webs 62 and 63 being welded to vertically spaced lugs or

plates

70 and 71 between the pins extend.

The upper chains 67 and lower chains 45 may be adusted to provide different effective lengths between the side members of the upper and lower units in any case Where it is required to correct lateral tilt of the props of an associated support. In some cases the props of an associated support may be given a tilt deliberately relatively to the base of the support.

The upper unit is supported from the lower unit by a post 23 which the lower section 72 is of tubular form and preferably of non-circular shape in cross-section, for example square section as shown and of which the upper section 23 is of corresponding shape in cross-section and slides telescopically in the lower section. The upper section is formed with a plurality of vertically spaced holes 74, and a retaining pin can be passed through holes in the lower section and any selected pair of holes 74 to adjust the height of the post.

The pin 75 is retained against inadvertent withdrawal by means of a cotter pin 76 itself held captive by a length of chain 77 to the lower section of the post.

The lower section of the post is supported from a base plate 78 welded, to the upper edge of the vertical flange of the side member 26 and welded also to a further upwardly projecting flange 79 at the inner side of the vertical flange of the rail and connected thereto at its lower, end by a horizontal flange 80. The base plate 78 is stiflened by means of a rib 81, the inner section 82 of which is welded to the outer section 72 of the post.

At its underside the base plate 78 rests on one of the end flanges 83 of the piston and cylinder unit, this being of fiat plane form at its upper side to provide a supporting surface of substantial area contacting the underside of the base plate 78.

The upper section 73 of the post is welded to a carrier plate 84 which in turn is welded at its outer end to the vertical flange of the side member 60 and which at its opposite end carries two upstanding cradle plates 85 (FIGURE 4) between which the cylinder of the upper piston and cylinder unit 64 is received.

At their lower ends the cradle plates 85 are formed with outwardly extending slots 86 forming the lateral margins of a guideway, further defined by the upper surface of the carrier plate 84 and in which is disposed a slide plate 87.

The slide plate at its outer end is welded to the vertical flange of the side member 61.

Constraint afforded by the contacting surfaces of the slide plate 87 and the guide structure formed by the carrier plate 84 and cradle plates 85 prevent any undesirable lateral forces being applied to the upper piston and cylinder unit and maintain the

side members

60 and 61 in parallel, or approximately parallel, relation with each other.

The piston and cylinder units of the upper and lower units may be connected to some of the hydraulic fluid under pressure throgh valve means co-ordinating their operation. Usually these units would be pressurised to expand concurrently and contract concurrently.

A modification is illustrated in FIGURE 6 in which parts corresponding to those already described bear like numerals of reference. In this modification the upper section 73 of the post can be raised and lowered by a piston and cylinder unit 23a, the piston rod 23b of which is engaged at its upper end in a recess formed in a pad 84a fixed to the underside of the carrier plate 84. The piston and cylinder unit is supported by means of a block 72a fixed in the interior of the lower section 72 of the post. The piston and cylinder unit may be energised by fluid under pressure, preferably hydraulic fluid, and need only have a relatively short stroke, e.g. approximately six inches.

The upper and lower sections of the post are normally held in the desired relation by means of a clamping ring 75a embracing the upper section 73, such clamping ring being split at one position around its circumference and tightened by a screw element 75b operable by a handle 75c. This arrangement has the advantage that if excessive downward pressure is exerted on the guiding device, the upper section 73 of the post can move downwardly relatively to the lower section 72 when the frictional grip exerted between the collar 75a and the upper section is exceeded by the downward thrust on the latter, the clamp itself abutting the upper end of the lower section 72.

Referring now to the embodiment illustrated in FIG- URES 7 and 8 in more diagrammatic form, such embodiment comprises only a lower unit in each guiding device of a form generally similar to that already described. Parts of this lower unit corresponding to those already described are thus designated by like numerals of reference.

The laterally spaced supports in the roof supporting system illustrated in FIGURE 7 are indicated generally at 1a, 1b, 1c, 1d and have respective bases such as that indicated at 10b on which are supported rear props 2b and a forward prop 3b. The base 10b includes a forwardly projected part 4b carried by a guide bar 5b sliding in a guide structure 6b in the base b, the part 4b being projected by means of a double-acting piston and cylinder unit 7b forming the traction means and energised by fluid under pressure, preferably hydraulic fluid. As indicated the piston rod 8b is connected to the part 4b. Means controlling the direction in which the part 4b is projected relatively to a longitudinally reference axis of the base 10b is not illustrated but may comprise means as disclosed in my previously mentioned copending applications.

Each support includes a superstructure such as those shown at 9b, 9c, FIGURE 8, these being omitted for clarity from FIGURE 7. It will be noted that the support 10 differs somewhat from the support 1b, in that it includes two forward props and a different arrangement of guide means 50, 6c and traction means 70.

The supports are respectively connected to an anchorage member, indicated diagrammatically at 9, and which may be the conveyor previously mentioned, or may be a cable which is either secured to the conveyor or possibly independently anchored to the floor of the mine working.

The forwardly projected parts such as 4b of the supports are connected to the anchorage member, preferably through the intermediary of connecting means, such as 1112, providing for limited movement of the part 4b longitudinally of the anchorage member 9 against elastic resistance at the point of connection. Such connecting means may be of the form already described and illustrated at 25 in FIGURES 2 and 3.

The operation of the roof supporting system, as illustrated in FIGURES 7 and 8, is as follows.

The section of the conveyor 9 or other anchorage member illustrated in FIGURE 7 has already been advanced towards a newly exposed coal face, as have also the roof supports 1d and 10. It will be understood that during advance of the conveyor or other anchorage member 9 the piston and cylinder units 35 of the guiding devices are caused or permitted to contract by appropriate exhaust of hydraulic fluid on one side of the piston and if of double-acting form a supply of hydraulic fluid under pressure to the other side of the piston, so that the longer side member 26 on the higher side of each guiding device takes place up the post shown in full lines for the guiding device between the

supports

10, 1d, thereby avoiding any significant constraint to advancement of the conveyor or other anchorage member 9.

In respect of a support not yet advanced, such as the support 1b as seen in FIGURE 7, the guiding device at the lower side is rendered operative by extension of its piston and cylinder unit by appropriate supply of hydraulic fluid to move the

side members

26 and 27 apart to the maximum extent, as determined by the chains 45. The guiding device at the higher side of the support 1b remains in its inoperative state in which the piston and cylinder unit 35 is contracted as previously mentioned.

The piston and cylinder unit 7b forming the traction means is then appropriately pressurised by hydraulic fluid to draw the support 7b forwardly towards the anchorage member, during which operation the lower side face of the base 10b is in contact with the outer side face of the side member 26 and moves along a path determined by this member. It will be understood that at this time the props 2b, 2c are contracted to lower the superstructure 9b, as seen in FIGURE 8, whereas the props 2c and 3c of the support 10 are extended so that the superstructure 9c is in roof-supporting relation and the base 10c of this support forms an abutment against which the side member 27 of the guiding device engages.

The lateral position of any given support such as lb, or of a group of supports such as Ia to M, can be corrected, if such supports have become mispositioned by sliding down the incline, by temporarily detaching the guiding device at the lower side of the support concerned from the anchorage member and re-connecting its connecting means, such as 25a, 25b, 250 to the anchorage member at a position spaced laterally on the higher side of that at which such means were formerly connected to the anchorage member. It is contemplated that this would be necessary only in extreme cases since ordinarily the presence and proper operation of the guiding devices would serve to prevent any undesirable lateral displacement of any of the supports from its proper position.

Smaller correction could be achieved without disconnection of the connecting means 25 by utilisation of the stop members 58 positively to displace the pin and associated link 55 lengthwise of the slot 53, in this case the connection at the aperture 53 to the anchorage member preferably being non-rotatable.

FIGURES 7 and 8 illustrate two possible modifications of the lower unit. In the first of these the stay bar 36, instead of being connected directly to the side member 26, is connected indirectly thereto through the intermediary of the anchorage member, as indicated in chain lines at 36b.

In the second modification illustrated in FIGURE 8, the lower unit 20, as shown in chain lines at 20b, is raised so that its side members engage with corresponding side faces of the bases b and 100 at a higher level, this being achieved by the use of higher skid members such as 50 and 51, or possibly skid members of which the height is adjustable. For example, such skid members may each comprise a bottom rail for engaging with the floor and an X-shaped cruciform structure intervening between this rail and the associated side member of the lower unit, connections at one end of the cruciform structure being pivotal to both the bottom rail and side member and by pin and slot assemblies at the other end of the cruciform structure, clamping means being provided to lock the cruciform structure in any of a number of positions providing for height adjustment.

In the embodiment illustrated in FIGURE 9 parts corresponding to those already described are designated by like numerals of reference with the prefix 2.

In this construction the piston and cylinder unit 235 of the lower unit is arranged longitudinally of the side member 226, and the two

side members

226 and 227 are connected with each other through the intermediary of a toggle mechanism 290 and a stay bar 236 which in this case is connected between the rearward end of the side member 226 and a point on the side member 227 adjacent to one end of the toggle mechanism.

The piston and cylinder unit 235 is connected between the central or knee joint of the toggle mechanism and a lbracket 291 on the side member 226. One of the advantages of this arrangement is that the guiding device may be made of particularly compact lateral dimensions. Further, the diameter of the piston and cylinder unit 235 can be reduced to a minimum since the toggle mechanism provides a high velocity ratio at its straightened or nearly straightened position corresponding to maximum separation of the side members.

In the modification illustrated in FIGURE 10 parts corresponding to those already described are designated by like numerals of reference with the prefix 3. In this modification the longer of the side members 326 is bent laterally at its forward end and is pivotally connected to a bracket 326a for movement relatively thereto about a vertical axis. The bracket is itself connected, preferably detachably, to the base 31Gb of one of the supports. The stay bar 336 is also pivotally connected at its forward end to the bracket 326a for movement about a vertical axis. The guiding device may be otherwise as already described with reference to FIGURES 7 and 8.

This modification may be adopted in respect of the lower unit, or both the upper and lower units, in a guiding device incorporating same.

In the embodiment illustrated in FIGURES 11, 12 and 13 parts corresponding to those already described are designated by like numerals of reference with the prefix 4.

The guiding device in this case incorporates a lower unit 420 and an upper unit 421, the latter being carried by an upwardly extending support 423.

The

side members

426 and 427 of the lower unit are of equal length, each somewhat exceeding the length of the associated base 41017 and 410c of the supports on either side of the guiding device.

The bracing means of the lower unit comprises two piston and cylinder units 435 and a stay bar 436 extending obliquely with respect to the side members as viewed in plan, and connected between lugs 444 and 444a at a position in between the two piston and cylinder units.

The upper unit 421 comprises laterally spaced

side members

460 and 461 which are substantially longer than the upper side members of the unit 20' illustrated in the embodiment of FIGURES l to 5. Each of these members has a length approximately equal to the side face of the superstructure 412k and 412c which it is required to guide.

Since such superstructures project forwardly of the associated bases 41% and 4100 and also because it may be required to connect the side members of the upper unit to an anchorage member at their forward ends, these project forwardly beyond the corresponding side members of the lower unit, the forwardly projecting portions preferably being lightened, for example, by being made of longitudinally tapering form as seen in side elevation at 461a (FIGURE 12).

The bracing means of the upper unit includes two longitudinally spaced piston and cylinder units 464 with which are associated guide structures comprising in each case a carrier 484 serving to support the piston and cylinder unit concerned and afford a guideway extending transversely of the guiding appliance as a whole, and a slide plate 487.

The support 423 may be formed by a hydraulic prop, the lower section 472 of which is contained in a socketlike base member 498 connected to the side member 426 by a strap or clamping structure 499.

The upper section 473 of the prop carries a collar 473a upon which the carrier 484 of the rearward guide structure associated with the rearward piston and cylinder unit 464 is supported. The upper section 473 of the prop extends through an opening in the carrier (the prop being off-set rearwardly from the centre line of the rearward piston and cylinder unit 464) and carries a roof-engaging member 473b for engaging and supporting the roof 419 of the mine working.

The side members of the lower unit are connected to an anchorage member, such as the conveyor 409, by means, such as the connection means 25 described with reference to the embodiments of FIGURES 1 to 5. The upper unit may also be connected to an upper anchorage member 409a which may be in the form of a cable spaced vertically above the lower anchorage member and supported therefrom by a post 40% comprising telescopically assembled upper and lower sections 4090 and 409d which can be held in any of a plurality of different positions of relative extension, according to the height at which the upper unit is required to be situated, by means of a locking pin 409a passing through holes in the lower section and through a selected pair of holes in a vertically spaced series in the upper section. A rod or rope 409i extending medially of the upper unit may serve to connect the cable 409a directly tothe upper end of prop 423 and to the rearward ends of the

side members

460, 461 through the

parts

484, 487.

It will be noted that each of the supports 401b and 4010 has its respective superstructure 41% and 4120 supported by three props, these comprising the two rearward laterally spaced props 402k and 4020 and a single forwardly disposed prop 403b and 4030. This arrangement of props is especially advantageous in that, not only does it provide a laterally extending manway between the rearward and forward props whereby personnel can move in a direction generally parallel to the coal face, but also provides good access in a direction fore-and-aft of each support because of the substantial lateral clearances existing between the forward props 40312 and 4030 of adjacent supports. At the same time the supports are adapted for effective cooperation with the guiding devices by utilising bases 410i; and 4100 which are of substantially rectangular form, as viewed in plan, whilst the superstructures employed, which in each case comprise openwork structures composed of roof bars or girders, also present a generally rectangular form or at least two parallel side faces spaced apart by a distance approximately equal to that which separates the side faces of the corresponding base.

Thus, it will be noted that the support 4011) has a superstructure comprising laterally spaced roof bars or girders 413b carried at their rearward ends on the props 40212 and at their forward ends on a transversely extending yoke 414b of the forward prop 403b. The roof structure further comprises a long roof bar or girders 415b supported in roof-engaging relationship at a single point approximately mid-way along its length by the prop 4031). Such prop may be a multi-section prop having a plurality of sections slidable telescopically within each other and adapted to carry respective roof-engaging elements, one of which is the yoke 41412 and another of which is a cap or socket for supporting the central roof bar or girder 415k. Alternatively the yoke or girder 4141) may be so constructed as simultaneously to carry the roof bars or girders 413b and the inner roof bar or girder 41511.

In either case the latter roof bar or girder is temporarily supported when the prop 403b is lowered by means of a transverse connecting member 416b extending between the rearward ends of the laterally spaced roof bars or girders 41311 and cranked downwardly between them to provide a depressed cradle upon which the rearward end of the roof bar or girder 415b can rest.

The roofengaging superstructure 4120 of the other roof support differs, in that pair of laterally spaced roof bars or girders 4130 are connected at their forward and rearward ends by transversely extending connecting members 4170 and 4160 of which the former is supported by the single central prop 4030. The forward ends of the roof bars or girders 4130 carry pivotally connected cantilever bars 4180 adapted to be pivotally raised and lowered about transverse horizontal axes at their rearward ends by hydraulic piston and cylinder means and intervening wedge-inclined plane slide or the like mechanisms.

It will thus be noted that in both the supports the requisite side faces are presented by the bases and superstructures for cooperation with the intervening guiding device. The relatively small gap existing between the central roof bar or girder 415b and the laterally spaced roof bars or girders 4131) prevents any excessive angular displacement of the former due to inclination of the floor. If, however, desired auxiliary guiding means could be provided in these spaces to prevent any angular displacement of the central roof bar or girder 415b in a plane parallel to the floor and relatively to the outer roof or girders 413b,

In FIGURE 14 parts corresponding to those already described are designated by like numerals of reference with the prefix 5.

Referring to the alternative embodiment of guiding device illustrated in FIGURE 14 in the roof-supporting system, such guiding device is designed primarily for use with roof supports 501b and 5010 which are of two-part construction as generally referred to herein, and which thus comprise forward base elements 500b, 5000 and rearward base elements 5101) and 5100. It will be understood that the superstructure is also sub-divided into a fore part carried by a prop 503b, 5030, whereas the rear part of the superstructure is carried upon three

props

502b, 5020.

In the associated guiding device the side member on the higher side comprises a

forward portion

526a and 526b which are pivotally connected to each other at 5260 for angular movement about an axis at right angles to the plane of the fioor. The other side member 527 is a single member rigid throughout its length.

The power-operated bracing means comprises two piston and cylinder units 535a and 535b connected respectively between the side member 527 and the forward and rearward portions 526a, 5261) of the opposing side member. Further, a stay bar 536 is pivotally connected at one end to the forward end of the side member 527 and at its forward end to the connecting means 525 by which the forward portion 526a is connected to the anchorage member 509.

The operation of this system is similar to that already described with reference to FIGURES 7 and 8 insofar as the piston and cylinder units 535:: and 53517 are both contracted during advancement of the anchored member 509 to allow each of the guiding devices to be drawn forwardly.

The supports themselves are advanced in two stages, the forward prop 50317 associated with the forward base element 5001) together with the associated fore part of the superstructure being lowered first and the forward base element 50% projected forwardly by the associated traction means 5071). Thereafter in the second stage the forward prop 5031; is extended to engage the fore part of the superstructure with the roof and the rear props 502b are contracted to lower the rear part of the superstructure, whereupon the rear base element 510b is drawn forwardly by the traction means 5071;.

In the first stage of movement the forward piston and cylinder element 535a is extended to the limit of separation of the side members of the guiding device, as determined by the adjustable stop means such as the chains as previously described. At this time the forward section 526a is effective to guide the forward base element 500]).

During the second stage of advancement the rearward piston and cylinder unit 5351; is extended to the limit of separation of the side members as determined by the adjustable stop means, and serves to guide the rear base element 510b, The stop means associated with the two piston and cylinder elements 535a and 5351) need not be adjusted to provide the same separations. It will be appreciated that the forward base element 500!) may be projected forwardly relatively to the rear base element 501i: at an angle which is oblique to the longitudinal centre line of the latter base element by virtue of the setting of the guide means 5050, 506b of the rearward base element and in such a case the angle between the two sections 526a and 52Gb of the side member of the guiding device may be set to a value corresponding to that at which the forward base element 50% is projected relative to said longitudinal centre line.

The supports in this case are not connected to the anchorage member 509.

If desired separate guiding devices of shorter length than those illustrated in FIGURE 14, but otherwise similarly constructed, may be provided between the two rear parts of the supports and the two fore parts of the supports. In such a case the guiding device for the rear part of the support may include upper and lower units respectively engaging the bases and superstructures, and similarly upper and lower units may be incorporated in the guiding device for the fore part of the support to engage with forward base element and fore part of the superstructure.

Referring to the embodiment illustrated in FIGURE 15, parts corresponding to those already described are designated by like numerals of reference with the prefix 6.

This embodiment is a simplified form of the invention intended for use primarily in conjunction with supports as illustrated, sub-divided into a rear part and a fore part each incorporating its own rear base element 610 and forward base element 600. These base elements are themselves operatively connected by piston and cylinder units 607 spaced apart laterally of, and mounted in, the rear base element, whilst each base element is provided with respective cooperating guide members 605 on the forward base element and 606 on the rear base element.

The guide members 605 have some lateral clearance with respect to the guide members 606 and admission of fluid under pressure, for example hydraulic fluid, to the piston and cylinder units 607 differentially provides some measure of self-steering for the support so that the duty required to be performed by the associated guiding device is less severe in cases where no steering facilities are provided.

The

side members

626 and 627 of the guiding devices are cranked inwardly at their ends and are secured to the anchorage member 609 through the intermediary of connection means 625 providing for limited displacement against resilient means in a direction longitudinally of the anchorage member 609 and, if desired, to some extent in a direction at right angles thereto in a horizontal plane.

The

side members

626 and 625 are connected with each other by manually adjustable bracing means 635. Such bracing means may comprise a laterally projecting bar fixed to the side member 626, as indicated at 635a, engaging in each case in a tubular member 63511 fixed to the other side member 627, means being provided to hold the parts 635:: and 635!) in any desired position of longitudinal extension with respect to each other. For example, each bar 635a may have a series of longitudinally spaced holes, any one of which can be brought selectively into register with a hole in the associated tubular member 635b, the two parts being retained in the desired position by a cotter pin passed through the aligned holes. Such pin is indicated at 635c.

In certain cases it is desirable to provide additional roof support in the space or passageway extending foreand-aft of the direction of advancement of the supports and in between successive roof supports, such as a, 10b, 10c illustrated in FIGURES 7 and 8. I A further embodiment of the guiding device in which such support is provided is shown in FIGURES 16 and 17 wherein parts corresponding to those already described are designated by like numerals of reference with the prefix 7.

For this purpose in this embodiment a prop 786 is provided. This prop may be of the kind embodying two telescopically assembled prop sections defining a chamber between them for the reception of hydraulic fluid.

The lower of the prop sections is preferably enclosed by a mounting member 786a in the form of a box or frame open at its top and bottom and which may be secured to the associated side-member 726, preferably in such a manner as to permit of adjustment longitudinally of the side member.

Clearance is left between the inner surface of the box or frame and the prop section encircled thereby so as to provide for both free vertical movement of the prop and some angular deflection of the prop in vertical planes extending both fore-and-aft of the guiding device and transversely thereof. The clearance space may, if desired, be filled with, or contain, resilient elements of material such as rubber or synthetic rubber.

The lower section of the prop rests on the floor of the mine working by'means of a base element 786b and hence does not transmit any roof load to, or through, the remaining parts of the guiding device. At its upper end the upper section of the prop is equipped with any suitable roof-engaging superstructure 7860, such as a short length of roof bar or a plate or pad preferably provided at its underside with a domed concave seating which engages in an upwardly presented covex termination at the upper end of the upper prop section, as seen particularly in FIGURE 17.

As illustrated the auxiliary prop 786 is disposed in a region approximately midway between the forward and rearward ends of the side member' 726 and adjacent thereto. In certain cases, however, it may be located in a position about midway between the side members of the guiding device but preferably, in any event, rather nearer to the forward end of the guiding device than to its rearward end.

This enables support to the roof to be furnished immediately adjacent to the conveyor or other anchorage member on the side thereof remote from the coal face where it is frequently necessary for personnel to work.

If desired the box or frame 786a may serve as an intermediary connection for the stay bar 736, in which case the boX or frame would be provided at its side remote from the side member 726 with a lug by means of which pivot-a1 connection to the stay bar may be effected through a pivot pin.

In any of the constructions of guiding device as hereinbefore described and which comprise lower and upper units, the latter together with the upper part of the post may be made of materials which are lighter in weight than those performing corresponding functions in the lower unit and lower part of the support. This ensures that the centre of gravity of the device as a whole is kept to as low a level as possible. It is contemplated that suitable lightweight materials which may be employed include synthetic resins especially polyester resins reinforced by glass fibre and compressed materials made from synthetic resin and metal constituents and aluminium alloys.

In any of the foregoing embodiments operation of the piston and cylinder unit, such as 35, FIGURES 7 and 8, forming part of the power-operated bracing means, may be coordinated with operation of the piston and cylinder unit, such as 7b, forming the traction means of a support guided by the device.

FIGURE 18 illustrates a hydraulic circuit diagram suitable for this purpose. In this diagram parts corresponding to those already shown and described with reference to FIGURES 7 and 8 are designated by like numerals of reference.

The piston and cylinder unit 7b is a double-acting unit having ports 712 and 7b communicating with the interior spaces of the cylinder on opposite sides of the piston, whilst the piston and cylinder unit 35 is a single acting unit having a port 35a.

A source of hydraulic fluid under pressure is connected to a supply pipe while an exhaust pipe 91 provides re turn flow to this source, e.g. a hydraulic pump.

A manually settable control valve 93 has four fixed ports connected respectively to the

pipes

90 and 91 and to two

further pipes

94 and 95, of which the former is connected to the port 712 and the latter has to branches 95a, 95b connected respectively to the ports 7b and 35a. The control valve has a rotatable valve member formed with ducts 93a, 93b which in the position shown connect the supply pipe 90 concurrently to the two ports 7b and 35a and the ports 7b to the exhaust pipe 91. The poweroperated bracing means is thus expanded to move the side members of the guiding device apart whilst the piston and cylinder unit 7b is energised in such a manner that the cylinder is drawn to the right, as seen in FIGURE 18, to advance the associated support.

Rotation of the rotatable element of the valve 93 through 90 serves to place the pipe 95 in communication with the exhaust pipe 91 and to pressurise the pipe 94 from the supply pipe 90 so that the piston rod 8b is again moved to the position illustrated in FIGURE 18 concurrently with contraction of the piston and cylinder unit 35. This relaxes lateral pressure between adjacent supports and allows the conveyor or other anchorage member, such as 9, to which the piston rod 8b is indirectly attached as shown in FIGURE 7, to be moved forwardly towards the coal face.

Although in the foregoing description and drawings the bases and superstructures of the supports have been disclosed as having parallel side faces engaged by the side members of the guiding device, the latter may be used with supports which have side faces which are convergent with respect to each other in a direction fore-and-aft of the support or have some other nonparallel relationship in this direction.

For this purpose, and as illustrated in FIGURE 19, adaptors may be provided which, when attached to the base or the superstructure as the case may be of the support in question, present the requisite parallel side faces for engagement by an associated guiding device in accordance with any of the foregoing embodiments.

As shown in FIGURE 19 the base or superstructure shown diagrammatically in outline at 810 is of generally trapezium shape as viewed in plan with its opposite side faces 810a convergent with respect to each other in the forward direction, that is to say in the direction of advancement.

The adaptor comprises two units each including a side member 896 in the form of a metal plate of sufficient thickness to provide the required strength and rigidity, or, if desired, formed with stitfening ribs extending longitudinally as indicated at 896a.

At each end the side member has brackets 896b and 8950 fixed to it and formed with vertical bearing openings through which extend hinge pins 896d and 396a.

On the base element or superstructure as the case may be the adaptor further comprises

attachment members

897 and 898, of which the former is pivotally connected to the bracket 8261) by the pin 8966, Whilst the latter is connected to the bracket 8960 pivotally at the pin 896d by means of a link 899.

The attachment member 898 is formed with a plurality of longitudinally spaced holes as indicated at 898a, thereby permitting the link to be selectively connected to the attachment member at any position along its length and varying the angular relation between the side member 896 and the side of the base element or superstructure so that a single design of adaptor may be applied to a number of different designs of support in which the side faces 310:: have different angles of convergence without the necessity for any structural modifications in the adaptor.

The

pins

896d, 896a and a connecting pin 89% may all be in the form a bolts so as to be removable and the attachment members 897 may be detachably connected to the side face 816a by bolts or by other suitable means.

What I claim then is:

1. A guiding device for use between opposed side faces of adjacent self-advancing roof supports for guiding same along a predetermined direction of advancement, said guiding device comprising, in combination:

(a) laterally spaced side members having respectively outwardly presented contact faces extending longitudinally of said direction of advancement;

(b) bracing means extending between said side members for controlling the lateral separation thereof, said bracing means including relatively movable bracing members and means for holding said bracing members in a predetermined relative position corresponding toa predetermined lateral separation of said side members;

(c) stay means connected between said side members for preventing relative longitudinal movement thereof but affording freedom for said side members to move towards and away from each other to a lateral separation determined by said bracing means, said stay means being connected to said side members at respective positions thereon spaced apart from each other longitudinally of said side members; and

(d) means for connecting said device to a member which is stationary with respect to one of said roof supports during advancement of the other of said roof supports to hold said guiding device against movement in said direction of advancement.

2. A device as claimed in claim 1 wherein said stay means comprises:

(a) a stay bar extending obliquely with respect to each of said side members;

(b) means pivotally connecting said stay bar to said side members for movement relative thereto in a plane generally parallel to a floor of the working over which said roof supports are to be advanced.

3. A device as claimed in claim 1 wherein:

(a) said bracing means comprises hydraulic piston and cylinder means; and wherein (b) said stay means comprises a stay bar and means pivotally connecting the stay bar to said side members for relative angular movement in a plane generally parallel to a floor of the working over which said roof supports are to be advanced.

4. A device as claimed in claim 3 wherein:

(a) said hydraulic piston and cylinder means is pivotally connected at its opposite ends respectivel to said side members for angular movement parallel to said plane; and wherein (b) said piston and cylinder unit, said stay bar, and

at least part of one of said side members are connected together to form a generally triangular structure.

5. A device as claimed in claim 4 wherein:

(a) one of said side members is longer than the other;

(b) said piston and cylinder means is connected between said longer side member and said other side member at a position adjacent to corresponding ends of the side members; and wherein (c) said stay bar is connected to said longer side member at a position adjacent to the end thereof remote from said piston and cylinder means.

6. A device as claimed in claim 2, wherein:

(a) said bracing means comprises piston and cylinder units extending between said side members at respective positions spaced apart longitudinally of said side members; and wherein (b) said stay means comprises a stay bar connected operatively at its opposite ends with said side members respectively and extending obliquely between said side members intermediate of said longitudinally spaced piston and cylinder units.

7: A device as claimed in claim 1 for use between opposed side faces of adjacent self-advancing roof supports each of which includes a base, a plurality of props thereon, and a roof-engaging superstructure carried by said props, wherein:

(a) said laterally spaced side members include two lower side members and two upper side members:

(b) said bracing means includes a lower piston and cylinder means extending between and controlling the lateral separation of said two lower side members. and an upper piston and cylinder means extending between and controlling separation of said two upper side members;

(c) said stay means extends between and connects at least said two lower side members; and further comprising (d) support means extending upwardly from said assembly of lower side members, lower piston and cylinder means, and stay means for supporting the upper unit formed by said upper side members and said upper piston and cylinder means.

8. A device as claimed in claim 7 and further comprising:

(a) a guide structure carried by one of said upper side members and forming a guideway extending transversely of said side members between the latter; and

(b) a slide member carried by the other of said upper side members and movable in said guide structure whereby said upper piston and cylinder means is at least partly relieved from lateral stress due to any tendency to relative longitudinal movement between 17 one of said upper side members and the other of said upper side members.

9. A device as claimed in claim 8 wherein:

(a) the cylinder of said piston and cylinder means is pivotally connected to one of said lower side members and the piston thereof is pivotally connected to the other of said lower side members;

(b) said stay means comprises a draw bar; and wherein (c) said stay bar, piston and cylinder means and at least part of one of said lower side members are connected together to form a generally triangular structure.

10. A device as claimed in claim 8 wherein:

(a) said upper piston and cylinder means extends between said upper side members at respective positions spaced apart longitudinally thereof; and wherein (b) said upper unit includes stay means for resisting relative longitudinal movement of said upper side member while permitting relative lateral movement thereof toward and away from each other.

11. A device as claimed in claim 3 and further comprising:

(a) a toggle mechanism arranged between said side members and including pivotally connected toggle arms disposed in at least approximately straight relation when said side members have said required lateral separation; and

(b) means pivotally connecting said piston and cylinder means to said toggle mechanism and to at least one of said side members for driving said toggle mechanism towards its straightened configuration.

12. A device as claimed in claim 3 and further comprising adjustable stop meansfor limiting lateral separation of said side members with respect to each other.

13. A device as claimed in claim 12 wherein said stop means comprises:

(a) at least one length of chain;

(b) means for connecting said length of chain to one of side members; and

(c) releasable connecting means for connecting said length of chain at another position along its length to the other of said side members, the last-mentioned connecting means being engageable selectively with any links of said chain.

14. A device as claimed in claim 1 wherein:

(a) said laterally spaced side members include two upper side members and two lower side members;

(b) said bracing means includes upper power-operated bracing means extending between said upper side members for controlling the lateral separation thereof and lower power-operated bracing means extending between said lower side members for controlling the lateral separation thereof;

(c) said stay means includes at least a lower stay bar connected at opposite ends to said lower side members at respective positions spaced apart longitudinally of said side members; and further comprismg (d) a power-operated extensible prop having atbase and a root-engaging member,

(e) means connecting said prop operatively with a lower unit comprising the assembly of said lower side members, lower power-operated bracing means, and lower stay bar so that said prop is moved with said lower unit during advancement of said guiding device; and

(f) said prop extending upwardly from said lower unit and supporting an upper unit comprising said two upper side members and said upper power-operated bracing means.

15. Guide means for guiding adacent self-advancing roof supports along a predetermined direction of advancement, comprising, in combination:

(a) a guiding device including:

(1) laterally spaced side members having respective outwardly presented contact faces extending longitudinally of said direction of advancement;

(2) bracing means extending between the side members for controlling the lateral separation thereof, said bracing means including relatively movable bracing members; and

(3) means for holding said bracing members in a predetermined relative position corresponding to a predetermined lateral separation of said side members;

(b) a laterally extending anchorage member positioned at the forward end of said guiding device; and (c) means for pivotally connecting said anchorage member and said guiding device at any of a number of positions along the length of said anchorage member for angular movement of said guiding device in a plane generally parallel to a floor surface on which said roof support rests.

16. The combination claimed in claim 15 wherein said 25 connecting means further comprises:

(a) elastic means. affording freedom for displacement against elastic constraint of said guiding device longitudinally of said anchorage member relative to the latter at said connection; and

(b) stop means for positively limiting the extent of said elastic displacement.

17. The combination claimed in claim 15 wherein:

(a) said anchorage member includes a cable; and

wherein (b) said anchorage means includes means for holding said cable against displacement in the direction of the length of said cable with respect to a floor surface on which said roof supports rest.

18. The combination claimed in claim 15 wherein:

(a) said bracing means comprises a hydraulic piston and cylinder means; and

(b) said laterally spaced side members are connected at positions spaced apart longitudinally by stay means for resisting relative longitudinal movement of said side members while affording freedom for relative lateral movement of said side members towards and away from each other.

19. A support system for the roof of a mine working comprising, in combination:

(a) laterally spaced self-advancing roof supports each including a base, a plurality of props thereon, and a roof-engaging superstructure carried by the upper ends of said props;

(b) at least one guiding device intervening between said supports for guiding the supports along a predetermined direction of advancement, said guiding device comprising:

(1) laterally spaced side members structurally separate from said roof supports, at least one of said side members being at least as long as the base of the adjacent roof support, said side members having respective outwardly presented contact faces extending longitudinally of said direction of advancement for engaging contact faces on said bases of said supports;

(2) bracing means extending between said side members for controlling the lateral separation thereof, said bracing means including relatively movable bracing members and means for holding said bracing members in a predetermined relative position corresponding to a predetermined lateral separation of said side members; and

(3) stay means for preventing relative longitudinal movement between the said side members while affording freedom for said side members to move towards and away from each other under the control of said bracing means.

20. A support system as claimed in claim 19 wherein:

(a) said bracing means comprises hydraulic piston and cylinder means;

(b) said stay means includes a stay bar extending obliquely between said side members; and wherein (c) said piston and cylinder means and said stay bar form a generally triangular structure.

21. A support system as claimed in claim 19 wherein:

(a) at least two of said roof supports each includes as its base a forward base element and a rearward base element, and further includes as its superstructure a fore part and a rear part supported by certain of said props associated respectively with said forward base element and said rearward base element, said base elements being connected with each other by traction means for advancing them alternately step by step;

(b) the guiding device disposed between said two supports has at least one of its side members formed in two sections, and means for connecting said sections at adjacent ends permitting relative angular movement parallel to the floor surface on which said supports rest; and

() each such side member section being associated with a separately operable part of said bracing means.

22. A support system as claimed in claim 19 wherein:

(a) at least one of said roof supports includes traction means comprising hydraulic piston and cylinder means;

(b) said bracing means comprises hydraulic piston and cylinder means; and further comprising (c) a hydraulic fluid supply system coupled to the hydraulic cylinders of said traction means and said bracing means for applying a fluid under pressure thereto to coordinate the operation thereof.

23. A support system as claimed in claim 22 wherein said hydraulic fluid supply system comprises:

(a) a source of fluid under pressure;

(b) pipe means for connecting said source to said cylinder means;

(c) valve means operatively connected in said pipe means for simultaneously supplying fluid to both of said cylinder means for extending said bracing means to move said side members into a predetermined lateral separation relative to each other and to simultaneously advance at least part of said support via said traction means.

24. A guiding device for use between opposed side faces of adjacent self-advancing roof supports for guiding the roof supports along a predetermined direction of advancement, each including a base, a plurality of props thereon, and a roof-engaging superstructure carried by said props, the guiding device comprising:

(21) upper and lower guiding units each including laterally spaced side members having respective outwardly presented contact faces extending longitudinally of said direction of advancement, and power-operated bracing means for controlling the lateral separation of said side members and extending between them, the bracing means of said upper guiding unit comprising:

(1) piston and cylinder means adapted to be energized by fluid under pressure and operatively connected between said side members of said upper guiding unit;

(2) a guide structure carried by one of said side members of said upper guiding unit and affording a guideway extending transversely of said side members between the latter; and

(3) a slide member carried by the other of said side members of said upper guiding unit and movable in said guide structure, whereby said piston and cylinder means is at least partly relieved from lateral stress due to any tendency to longitudinal movement of said side members of said upper guiding unit; and

(b) support means extending upwardly from said lower unit for supporting said upper unit.

25. A device as claimed in claim 24 wherein said bracing means of said lower guiding unit comprises:

(a) a piston and cylinder unit, means pivotally connecting the cylinder thereof at one end of said unit to one of said side members, means pivotally connecting the piston thereof at the opposite end of said unit to the other of said side members,

(b) the stay means comprises a stay bar,

(c) said stay bar, piston and cylinder unit, and at least part of one of said side members forming a generally triangular structure as viewed in plan.

26. A device according to claim 24 wherein said bracing means and said upper guiding unit comprises:

(a) piston and cylinder units extending between said side members at respective positions spaced apart longitudinally thereof,

(b) stay means for resisting relative longitudinal movement of said side members whilst permitting of relative lateral movement thereof toward and away from each other.

27. A guiding device for use between opposed side faces of adjacent self-advancing roof supports for guiding the roof supports along a predetermined direction of 30 advancement, said guiding device comprising:

(a) laterally spaced side members having respective outwardly presented contact faces extending longitudinally of said direction of advancement;

(b) power-operated bracing means for controlling the lateral separation of said side members and extending between them, said power-operated bracing means comprising a piston and cylinder means adapted to be energized by fluid under pressure; and

(0) means operatively connected between said piston and cylinder means and said side members for increasing the thrust applied to the latter to hold same in predetermined lateral separation against inward pressure from said inward roof supports relatively to said thrust as is provided by said piston and cylinder means itself, said means for increasing said thrust comprising a toggle mechanism arranged between said side members, said toggle mechanism including pivotally connected toggle arms in at least approximately straight relation when said side members have the required lateral separation.

28. A guiding device for use between opposed side faces of adjacent self-advancing roof supports for guiding the supports along a predetermined direction of advancement, said guiding device comprising:

(a) laterally spaced pairs of upper and lower side members having respective outwardly presented contact faces extending longitudinally of said direction of advancement;

(b) upper and lower power-operated bracing means for controlling the lateral separation of said upper and lower side members and extending between corresponding pairs of side members, said bracing means including relatively movable members and means for holding said members in a predetermined relative position corresponding to a predetermined lateral separation of the corresponding side members;

(c) a power-operated extensible prop having a base and a roof-engaging member, said prop extending upwardly from a lower unit comprising said lower side members and lower bracing means and supporting an upper unit comprising said upper side members and said upper bracing means; and

(d) means connecting said prop operatively with the assembly of said side members and said bracing