Self-advancing support and control means therefor

A self-advancing support, suitable for use in mines, includes a cantilever which is extendible and retractable with respect to a main portion of the support, and a sprag which is so mounted on said cantilever as to be extendible and retractable with respect thereto. Means are provided for advancing the support with respect to a mineral face and further means are provided for ensuring that during advance of the support the sprag is maintained in an extended, mineral-face-engaging, condition while the main portion is moved with respect to the cantilever in the direction towards the face, thereby reducing cantilever extension.

This invention relates to a self-advancing support and control means 
therefor suitable for use in mines in association with mineral cutting and 
conveyor equipment. 
Hitherto, certain such supports have included a sprag mounted upon the free 
end of a cantilever, the cantilever being extendible and retractable with 
respect to the main part of the support. The sprag can be held against the 
substantially upright wall of the mineral face by suitable means, for 
example an hydraulically-operable ram. When a cutting machine moving on a 
conveyor which extends along the mineral face has passed the respective 
support thereby revealing a new upright wall forming the working face, it 
is necessary in customary manner to release the support from engagement 
with the mine roof and to advance it by suitable means towards the new 
wall. Before such advancing can take place it has been the practice to 
retract both the sprag and the cantilever and subsequently, following 
advancing of the support, to extend the sprag and cantilever respectively 
for engagement with the new upright wall and the adjacent part of the mine 
roof. The cantilever has itself been extended for example by an hydraulic 
ram and has been tilted into engagement with the roof by an 
hydraulically-operable capsule. The sprag has been pivotally-mounted on 
the cantilever and thus upon operation of its ram hinged forwardly into 
engagement with the upright wall. 
This arrangement suffers from the disadvantage that during advance of the 
support the sprag is withdrawn from the face which is therefore left 
unsupported adjacent that support. Further, upon completion of support 
advance it is necessary to re-sequence the rams for effecting extension of 
the cantilever and sprag to their roof and wall supporting positions. 
The invention as claimed is intended to provide a remedy. It solves the 
problem of how to design a self-advancing support suitable for use in 
mines in which there is no need to retract the sprag with respect to the 
cantilever, and the cantilever into the stationary main portion of the 
support, before support advance can take place. 
According to this invention a self-advancing support, suitable for use in 
mines, includes a cantilever which is extendible and retractable with 
respect to a main portion of the support, a sprag which is so mounted on 
said cantilever as to be extendible and retractable with respect thereto, 
means for advancing the support with respect to a mineral face and means 
for ensuring that during advance of the support said sprag is maintained 
in an extended, mineral-face-engaging, condition while said main portion 
is moved with respect to said cantilever in the direction towards said 
face, thereby reducing cantilever extension. 
Preferably, said sprag is pivotally-mounted upon the free end of said 
cantilever and is movable from its retracted to its extended condition, 
and vice versa, by a first fluid-pressure-operable ram suitably connected 
to the sprag and to the cantilever. 
Preferably also, said cantilever is extendible and retractable with respect 
to a mine-roof-engageable canopy, forming part of said main portion, by a 
second fluid-pressure-operable ram housed within said canopy. 
The means for advancing said support may comprise a third 
fluid-pressure-operable ram one element of which is connected to a 
mine-floor-engaging beam, forming another part of said main portion, and 
the other element of which is connected to one end of a relay bar, the 
other end of said relay bar being connected to conveyor equipment 
associated with the support and running along the length of said face. 
Mineral cutting equipment is preferably mounted upon the conveyor 
equipment, so that as it is hauled along the conveyor equipment it can be 
caused to engage said face and to extract mineral material therefrom. 
The first, second and third rams preferably form part of a fluid-pressure 
control circuit for said support, suitable control valve means being 
provided which are so operable that for advance of the support said first 
ram is hydraulically locked in an extended condition thereby to maintain 
said sprag in engagement with said face, the second ram is placed in 
communication with return or with low pressure, and the third ram is 
operable to move said main portion towards said face. 
Preferably also said support includes a fluid-pressure-operable capsule 
operable to tilt said cantilever, when in an extended or extending 
condition, into load-supporting engagement with the mine roof. 
The said canopy may be supported from said floor-engaging beam by a 
plurality of fluid-pressure-operable telescopic props. 
Also according to this invention a support system, suitable for use in 
mines in association with conveyor equipment running along a mineral face, 
includes a series of self-advancing supports arranged in side-by-side 
relationship along the face and each support including a 
mine-floor-engaging beam, fluid-pressure-operable prop means mounted on 
said beam and supporting a roof-engageable canopy, a cantilever which is 
extendible and retractable with respect to the canopy, a sprag engageable 
with said face and so mounted on said cantilever as to be extendible and 
retractable with respect thereto, and an advancing ram connected between 
the support and the conveyor equipment for advancing the support with 
respect to said face, said system also including a source of fluid 
pressure, a fluid-pressure-operable ram for operating said sprag, a 
fluid-pressure-operable ram for operating said cantilever, and control 
valve means in communication with said source and in fluid circuit with 
said rams and said prop means, said control valve means being so operable 
that with said prop means released and thus said canopy released from 
engagement with said roof and with the advancing ram then energised for 
advance of the support towards said face the ram associated with said 
cantilever is so open to return or low pressure as to offer substantially 
no resistance to operation of said advancing ram, while the ram associated 
with said sprag is so energised as to maintain the sprag in an extended, 
mineral-face-engaging, condition. 
The advantages offered by the invention are mainly that the sprag can, 
during advance of the support, remain in load-supporting engagement with 
an upright working face of the mine and as a result the risk of 
inadvertent collapse of that face, for example onto adjacent conveyor 
equipment, is substantially less.

The self-advancing support 10 shown in FIGS. 1 and 2 is of shield type, its 
main portion 11 including a mine-floor-engaging beam 12, two pairs 13, 14 
of hydraulically-operable telescopic props mounted on the beam and a 
mine-roof-engageable canopy 15 supported by the props. A lemniscate 
linkage 16 provided on the rear end portion of the beam 12 supports a goaf 
shield 17 which is itself pivotally-connected at 18 to the rearward end 
portion of the canopy. 
A cantilever 19 is carried by the canopy, being extendible and retractable 
with respect thereto and at its outer, forward, extremity carrying a sprag 
20. The sprag is so pivotally-mounted at 21 upon the cantilever as to be 
extendible and retractable with respect thereto by a first 
hydraulically-operable telescopic ram 22 pivotally-connected at 23 to the 
sprag and at 24 to the cantilever. In its fully-retracted position, that 
is upon full contraction of the ram, the sprag is folded back under the 
cantilever so as to lie substantially parallel therewith. 
The cantilever 19 is itself extendible and retractable with respect to the 
canopy 15 by a second hydraulically-operable telescopic ram 25 suitably 
mounted on the underside of the canopy. 
Means for advancing the support 10 with respect to the mineral face 26 
includes a third hydraulically-operable telescopic ram 27, the cylinder 28 
of which is pivotally-connected at 29 to the beam 12 and the piston rod 30 
of which is pivotally-connected at 31 to the rearward end of a relay bar 
32. The forward end of the relay bar is pivotally-connected at 33 to 
conveyor equipment 34, of scraper-chain type, associated with the support 
10 and running along the length of the mineral face 26. 
Mineral cutting equipment 35 is mounted on the conveyor equipment and is 
arranged to be hauled along the aligned pans 36 of that equipment by 
suitable means (not shown). The cutting equipment includes cutter drums as 
at 37 each carried by an angularly adjustable ranging arm 38 mounted on 
the body 39 of the equipment. 
Two hydraulically-operable capsules, one of which is shown at 40, are 
carried side-by-side on the underside of the forward end portion of the 
canopy 15. When pressurised these capsules tilt the cantilever upwardly 
into load-supporting engagement with the mine roof 41. The self-advancing 
support 10 is one of a series of similar supports arranged in side-by-side 
relationship along the mineral face 26. 
FIG. 3 shows the circuit arrangements associated with the ram 22 for 
operating the sprag 20, with the ram 25 for operating the cantilever 19 
and with the capsules 40 for tilting the cantilever. Two three-position 
control valves 42, 43 are arranged in circuit with the ram 22, each valve 
having fluid-pressure-operator means 44, 45; 46, 47 responsive to 
hydraulic pilot signals transmitted through either the pilot line 48 or 
the pilot line 49 from a suitable rotary selector valve (not shown). 
Whichever of the two lines 48, 49 is not so transmitting a pilot signal is 
open to return. Pressure lines 50, 51 are taken to the centre section of 
the valves 42, 43 and return lines 52, 53 are taken therefrom. A service 
line 54 is taken from the valve 42 to the right-hand side of the ram 22 
and this line incorporates a yield valve 55. A service line 56 is taken 
from the valve 43 to the left-hand side of the ram 22. 
A further three-position control valve 57 is arranged in circuit with the 
capsules 40 and has fluid-pressure-operator means 58, 59 to which pilot 
lines 60, 61 are taken. A pressure line 62 is taken to the centre section 
of this valve and a return line 63 is taken therefrom. A service line 64 
is taken from the valve 57 to the capsules 40. 
Another three-position control valve 65 is arranged in circuit with the ram 
25 for operating the cantilever, this valve having fluid-pressure-operator 
means 66, 67. Hydraulic pilot signals can be transmitted to either of 
these means through lines 68 or 69 in dependence upon the setting of a 
suitable selector (not shown) for controlling operation of the cantilever. 
A pressure line 70 is taken to the centre section of the valve 65 and a 
return line 71 is taken therefrom. A service line 72 which is taken to the 
right-hand side of the ram 25 includes a restrictor 73. 
Although not shown in the drawings suitable control valves and hydraulic 
circuits are provided in association with the advancing ram 27 and with 
the telescopic props 13, 14. 
The hydraulic circuits above described are supplied with liquid under 
pressure adequate for the intended operation of the support from a source 
S comprising suitable pumping and reservoir means. 
In operation, assuming the support 10 to be in the position shown in FIG. 
1, that is with the canopy 15 in load-supporting engagement with the roof 
41, the cantilever 19 fully extended and tilted upwardly against the roof 
by the capsules 40 and the sprag urged by the ram 22 into load-supporting 
engagement with the face 26, the extraction of the mineral material can 
take place along the length of the face by operation of the cutting 
equipment 35, the material extracted being carried away from the face by 
the conveyor equipment 34. In this condition of the support the ram 22 is 
hydraulically locked with the sprag 20 in load-supporting engagement with 
the face 26 and any movement of the sprag such as might be caused by 
movement of mineral material from the face is resisted by the yield valve 
55. The ram 25 is also hydraulically locked on its full area side and any 
rearward movement of the cantilever is received on a suitable relief valve 
(not shown) provided in association with that ram. The capsules 40 are 
similarly held hydraulically locked and a suitable relief valve (also not 
shown) is similarly provided. 
When it is required to advance the support towards the newly cut face 26, 
the control valves (not shown) associated with the props 13, 14 are 
operated as a first step in the support advance sequence so that the 
canopy 15 is lowered away from engagement with the mine roof 41. 
Simultaneously, the valves 42, 43 are caused by suitable operation of the 
rotary selector valve and consequent application of pilot signals to the 
means 45, 47 to move to the left away from their neutral positions so that 
the right-hand side of the ram 22 is placed in communication with return 
by way of lines 54, 52, and so that the left-hand side of that ram is 
placed in communication with return by way of lines 56, 53. This allows 
sprag 20 to fall freely to the vertical position as shown in FIG. 2. 
Simultaneously also, a pilot signal is applied to the means 59 and the 
valve 57 moves to the left away from its neutral position so that the 
capsules 40 are placed in communication with return by way of lines 64, 
63. 
When, as the second step in the support advance sequence, the appropriate 
control valves (not shown) are operated so that the advancing ram 27 is 
energised in its extending direction, a pilot signal is suitably 
transmitted to the means 67 of valve 65. As a result this valve is moved 
to the left so that the right-hand side of ram 25 associated with the 
cantilever 19 is placed in communication by way of the line 72, restrictor 
73 and line 71 with return, or alternatively is placed in communication 
with a source of liquid at a suitable low pressure which, whilst being 
high enough to maintain a useful forward force on the sprag, is 
nevertheless low enough not to impede support advance seriously, and the 
sprag is held in supporting engagement with the face 26. As this occurs 
the rotary selector valve is operated to release the pilot signals applied 
to the means 45, 47 and the valves 42, 43 are spring-centred to the 
neutral positions. Hence the ram 22 is hydraulically locked to maintain 
the sprag in its face-supporting condition. With continued extension of 
the ram 27 the main portion 11 of the support advances towards the face 26 
with the sprag and cantilever stationary and the canopy moving onto the 
cantilever, the amount by which the cantilever projects from the canopy 
thus being at least substantially reduced. 
As the ram 27 reaches it fully extended condition the pilot signal to the 
means 67 is released so that the valve 65 is spring urged back to its 
neutral position and the ram 25 is then held in an hydraulically-locked 
condition. 
During the advancing movement of the support the conveyor equipment is held 
fast with respect to the floor 74 by adjacent supports which are then not 
themselves undergoing advance. Additionally, hydraulically-operable 
staking means may be provided on the conveyor equipment in the vicinity of 
the pivotal connection 33 to provide for positive holding of the conveyor 
with respect to the ground at the forward end of the relay bar 32. 
The third step in the support advance sequence is the setting of the 
telescopic props 13, 14 which is effected by suitable operation of their 
control valves (not shown). This causes re-engagement of the canopy 15 
with the mine roof 41 and simultaneously a pilot signal is suitably 
applied to the means 58 of valve 57 to move that valve to the right so 
that pressure liquid passes through the lines 62, 64 to the capsules 40. 
Consequent extension of the capsules tilts the cantilever 19 so that its 
forward end portion is brought into load-supporting engagement with the 
roof 41. 
When it is necessary to retract the sprag to allow the cutting equipment to 
pass that particular support for extracting mineral material from the face 
26 in the vicinity of the sprag, valve 43 is caused to move to the right 
and valve 42 to the left resulting in contraction of the ram 22. It may be 
desirable to retract the sprag fully so that it folds back into a position 
substantially parallel to the canopy for this purpose. Thereafter, the 
sprag is re-extended by causing the valve 43 to move fully to the left and 
the valve 42 to the right. The cantilever 19 can be extended 
simultaneously by causing valve 65 to move to the right to effect 
extension of ram 25 appropriate to the required new face-supporting 
position of the sprag. The valves 42, 43, 65 are then permitted to return 
to their neutral positions so that the rams 22, 25 are hydraulically 
locked in their new positions. Thus the sprag 20 is removed from 
engagement with the face 26 for the shortest possible time and is then 
rapidly returned to its face-supporting position. 
If operational conditions require it, the sprag can be fully or partially 
retracted whenever necessary simultaneously with suitably controlled full 
or partial retraction of the cantilever, but again can be rapidly returned 
to its supporting position. Also, if with the sprag extended conditions 
are such that adjustment in the setting of the sprag against the face 26 
is necessary this can quickly be effected by suitably operating the valves 
42, 43 for appropriate adjustment of the ram 22. 
In conventional manner, when it is required to advance the conveyor 
equipment 34 the ram 27 is caused to contract and since the support 10 is 
then set fast against the floor 74 and roof 41 this movement is 
accordingly transmitted by the relay bar 32 to the conveyor equipment 34, 
the rams 27 of adjacent supports operating likewise, so that the equipment 
is bodily advanced as required. 
By this invention therefore means are provided to ensure that the sprag 20 
is maintained in positive load-supporting engagement with the face 26 
during the advancing of the support, thus avoiding the undesirable 
situation, as hitherto was the case, of leaving the face unsupported 
during advance and hence susceptible to collapse. This is extremely 
advantageous, especially in mines where the mineral material being 
extracted is of a friable nature, for example where the material is 
lignite.