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(11) |
EP 0 034 134 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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30.05.1984 Bulletin 1984/22 |
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Date of filing: 03.02.1981 |
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International Patent Classification (IPC)3: E21D 20/00 |
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Rock bolting apparatus
Maschine zum Setzen von Gebirgsankern
Machine pour installer des boulons d'ancrage
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Designated Contracting States: |
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AT CH DE FR GB IT LI |
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Priority: |
08.02.1980 SE 8001018
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Date of publication of application: |
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19.08.1981 Bulletin 1981/33 |
| (71) |
Applicant: Atlas Copco Aktiebolag |
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S-105 23 Stockholm (SE) |
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| (72) |
Inventor: |
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- Ägren, Nils Axel
S-191 46 Sollentuna (SE)
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| (74) |
Representative: Molin, Alexis et al |
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c/o Atlas Copco Aktiebolag
Patent Department S-105 23 Stockholm S-105 23 Stockholm (SE) |
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| |
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| Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
|
[0001] This invention relates to a rock bolting apparatus including a rock drill and a bolt
setting machine, and more particularly to an apparatus wherein drilling, bolting and,
if desired, resin insertion, can be accurately and quickly carried out in succession.
[0002] Such a rock bolting apparatus is previously known from German Patent Specification
No 22 22 646. This known apparatus has a feed bar which is common to the rock drill
and the bolt setting machine, the rock drill and the bolt setting machine being situated
on two opposite sides of the common feed bar. The drill rod and the rock bolt are
guided by respective supports located at the end of the feed bar which is directed
towards the rock surface. To achieve an effective guidance, at least the drill rod
support should abut against the rock surface. However, rock bolting often takes place
in tunnels with a rough surface or else the bolting could be needed obliquely to the
surface. When using this prior art apparatus under such circumstances, the bolt support
will often hit projecting rock parts before the drill support has gotten sufficient
abutment against the rock surface. Correspondingly, the drill support often hits projecting
or other rock parts when the swingable unit is turned to the position for inserting
resin cartridges or bolts. As a result of these disadvantages, the drill hole will
not always be as required because of adjoining rock irregularities or because the
bolt will not be inserted sufficiently deep in the drill hole.
[0003] It is an object of this invention to provide a rock bolting apparatus avoiding the
disadvantages of the kind mentioned above and which apparatus will make it possible
to insert rock bolts by machine power even if the rock surface is uneven or inclined.
[0004] In accordance with the invention, a rock bolting apparatus includes at least a rock
drill and a bolt setting machine both of which are carried by a swingable unit connected
to a boom, the swingable unit being laterally swingable relative to the boom about
an axis; power means for power displacing the rock drill and the bolt setting machine
laterally into and out of a working position by means of controlled swinging of the
swingable unit about said axis; and clamping means for clamping the swingable unit
between a rock surface and the boom, the clamping means including a jack arranged
on the swingable unit and being extensible in alignment with said axis. A bolting
apparatus of this type is known from beforementioned DE-C-22 22 646. The improvement
of the invention resides in that the swingable unit comprises a first feed bar movably
mounted thereon and carrying the rock drill for feeding and guiding the rock drill;
a second feed bar (27) movably mounted thereon and carrying the bolt setting machine;
and power displacing means coupled to the feed bars for powder displacing the two
feed bars independently of each other relative to the swingable unit in the longitudinal
direction of the feed bars.
[0005] In a preferred arrangement, the first and second feed bars are mounted relative to
said axis such that on swinging movement of the swingable unit about said axis, both
said rock drill and said bolt setting machine are in alignment with the hole being
drilled.
In the drawings
[0006]
Fig. 1 is a side view of a rock bolting apparatus according to the invention;
Fig. 2 is a view seen as indicated by the arrows 2-2 in Fig. 1;
Fig. 3 is a view seen from above as indicated by the arrows 3-3 in Fig. 1 but on an
enlarged scale;
Fig. 4 is a cross-section along the line 4-4 in Fig. 3 but on a somewhat reduced scale;
and
Fig. 5 is a fragmentary cross-section along the line 5-5 in Fig. 3 but on an enlarged
scale.
[0007] In Fig. 1 there is shown a boom 11 mounted to a suitable transportable chassis 12
by a universal joint 13. The boom 11 is laterally swingable by means of a hydraulic
cylinder 14 arranged between the chassis 12 and the joint 13 while vertical movement
of the boom 11 is achieved by a pair of cylinders 15 arranged between the joint 13
and the arm 11. A vertically swingable supporting means 16 is attached to the free
end of the boom 11. The swinging motion of supporting means 16 is achieved by a hydraulic
cylinder 17 arranged between the boom 11 and the supporting means 16. A swingable
unit 18 is in turn attached to the supporting means 16 by two bearings 19 and 20 and
is laterally swingable relative to the arm 11 about an axis 21 by means of a pair
of cylinders 22 arranged between the supporting means 16 and the swingable unit 18.
[0008] The two cylinders 22 are arranged in some suitable way in order to give their piston
rods 23 three distinct mechanical stop positions whereby the swingable unit 18 is
given three defined working positions. In Figs. 1-3 the unit 18 is shown in its second
working position in which the piston rods 23 are projected to half their length against
a middle stop position.
[0009] As seen in Figs. 2 and 4, the swingable unit 18 has a central box-shaped supporting
frame 24 with brackets 25 arranged thereon, the brackets 25 holding a first 26 and
a second 27 feed bar on two opposite sides of the frame 24. The feed bars 26 and 27
are displaceable relative to the frame 24 by the operation of hydraulic cylinders
28 and 29 (Figs. 4), each of which is connected to a respective feed bar 26 and 27.
The cylinders 28 and 29 are arranged side by side in a plane through the axis 21 as
seen in Fig. 3. In Fig. 4 the cylinders are, for clarity, shown side by side in a
plane perpendicular to said first plane. They may take other positions. The cylinders
28 and 29 are located in the frame 24 having their piston rods 30 and 31 protruding
from the upper part of said frame 24 and being attached to respective brackets 32
and 33 on the respective feed bar 26, 27. The feed bars 26 and 27 are displaceable
by means of cylinders 28 and 29 in a direction parallel to the axis 21. During such
motion the feed bars 26, 27 are guided by tracks 34 mounted on two opposite sides
of the feed bars and being adapted to run in corresponding notches in the brackets
25.
[0010] The feed bars 26 and 27 may each be constructed as the feed bar disclosed in German
Patent Specification No 28 20 325, but also other feed bars can be suitable.
[0011] As seen in Figs. 1-4, an impact rock drill 40 is arranged on a cradle which is feedable
in a conventional way along the first bar 26. A drill rod 42 connected to the rock
drill 40 goes through a hole in a drill support 43 arranged at the upper end of the
feed bar 26. The support 43 includes a cushion 44 of an elastic material which is
adapted to abut against the rock surface 45 and having a hole 46 therein whose diameter
is adapted to the drill bit to enable the drill bit to be at least partly drawn into
the cushion 44 and to be guided by the same when collaring a hew hole. The support
43 includes further an elastic sleeve 47 whose hole is equal to the diameter of the
drill rod 42 and is adapted for guiding said drill rod 42. A bowl-shaped part 48 is
located between the cushion 44 and the sleeve 47 and is arranged for collecting the
flushing water mixed with cuttings flowing out of the drill hole 49.
[0012] A machine 50 for setting bolts 51 is arranged on the second feed bar 27. The machine
50 comprises a nut running tool with fluid-pressure drive mounted on a cradle 52 movable
along the feed bar 27. The head of the bolt 51 is receivable in a rotatable socket
53 also carrying a washer 54 threaded on the bolt 51. A support 55 for the bolt 51
is arranged at the upper part of the feed bar 27 and includes an arm 56 which is turnable
aside. The arm 56 has a gripping means 57 adapted for gripping and guiding the bolt
51. When the washer abuts the arm 56, the arm 56 and gripping means 57 are swung upwardly
about pivot 61 (Fig. 3) so that the gripping of the bolt 51 is released and the washer
may pass upwardly past the arm 56 and gripping means 57.
[0013] A charging tube 58 for resin cartridges is carried by the supporting frame 24 and
is axially displaceable by an hydraulic motor 59. The lower end 60 of the tube 58
is connectable to a hose (not shown) in which the resin cartridges are inserted and
pneumatically transported to the drill hole 49.
[0014] The unit 18 further includes an upwardly protruding frame part 62 having an hydraulic
jack 63 disposed therein. Jack 63 whose upper part is shown in Fig. 5 comprises an
hydraulic cylinder 64 mounted to the upper end surface of the frame part 62. A piston
rod 65 is extensible from the cylinder 64, said rod 65 having a bearing sleeve 66
screwed on the free end thereof. The bearing sleeve 66 carries a clamping head 67
journalled on the sleeve by a radial bearing race 68 and an axial bearing race 69.
As a'result of the bearing shape, rotation of the clamping head 67 is allowed without
any declination in relation to the piston rod. The clamping head 67 is adapted to
abut against the rock surface when the apparatus is used and has therefore a cushion
70 of elastic material for providing a favorable grip against the rock. The rotation
axis of the clamping head 67 is arranged to coincide with the longitudinal axis 71
of the hydraulic cylinder 64, said axis 71 in turn coinciding with the axis 21. The
drill rod 42, the charging tube 58 and the bolts 51 are so disposed that they are
in parallel to the axis 21 and are located the same distance from axis 21. At the
swinging movement of the swingable unit 18, these devices 42, 58, 51 will therefore
describe a motion along one and the same arc 72 as indicated by the chain-dotted line
in Fig. 3.
[0015] The operation of the rock bolting apparatus will now be further described. First
the apparatus is set in the drilling position by displacing the piston rods 23, Fig.
3, to their full length so they will reach their external stop position. The unit
18 is thus turned 45° to the first working position in which the drill rod 42 will
coincide with the charging tube 58 position shown in Fig. 3. Then the first feed bar
26 is positioned so that the drill rod 42 will point at the desired drilling position
for the bolt. Then, the bar 26 is displaced towards the rock surface 45, causing the
drill support 43 to abut thereagainst as seen in Fig. 4. Then the hydraulic cylinder
64, Fig. 5, is activated to press the clamping head 67 towards the rock to thus clamp
the unit 18 between the rock and the arm or boom 11. To increase the clamping force,
the feed bar 26 is further pressed against the rock by the hydraulic cylinder 28.
Fig. 4, enabling the clamping head 67 to be fed in succession thereto and to thereby
protrude still another bit to increase the clamping effect. Thereafter the feed bar
26 is somewhat withdrawn while the hydraulic cylinder 64 is kept in its extended position
by means of a suitable hydraulic lock (not shown). By the described cooperation between
the hydraulic cylinders 28 and 64 the effective clamping force will be greater than
if only the hydraulic cylinder 64 of the clamping head 67 should have been used, thus
enabling the indexing to be accurately done about one carefully fixed axis 21. During
the setting of the unit 18 against the rock, both the feed bar 27 for the bolts 51
and the charging tube 58 are displaced backwards so that they will not knock against
irregularities in the rock surface.
[0016] When the unit is satisfactorily clamped against the rock the drilling is started.
During the collaring the drill bit is guided by the hole 46 in the cushion 44 while
the drill rod throughout the complete drilling operation is guided by the sleeve 47.
When the required hole depth has been reached the drilling machine 40 with the drill
rod 42 is fed backwards and the feed bar 26 is displaced from the rock by the hydraulic
cylinder 28. Then the piston rods 23 are drawn back into cylinders 22 to their middle
stop position making the unit 18 turn 45° about the axis 21 while the clamping head
67 is maintained in immovable abutment against the rock. The unit 18 will now be in
the second working position which is that position shown in Fig. 3 with the charging
tube 58 located in alignment with the drill hole 49. The charging tube 58 is fed up
into the hole by the hydraulic motor 59 and resin cartridges are inserted in a suitable
way. When the charging operation has been completed the charging tube 58 is drawn
back from the hole and the unit 18 is turned another 45° to the third working position
in which the bolt 51 will be aligned with the drill hole 49. The third position will
be defined by drawing back the piston rods 23 into cylinders 22 to their inner stop
position. The feed bar 27 for the bolt setting machine 50 is now positioned a suitable
distance from the rock surface so the bolt 51 can be inserted to a sufficient depth
by means of the bolt setting machine 50. During insertion, the bolt 51 is guided by
the gripping means 57 until the bolt has gone so far into the hole as the washer 54
must pass the arm 56. The gripping means 57 will at that time release the guiding
grip about the bolt and is folded upwards, thus enabling the washer 54 and the machine
50 to be brought to abutment against the rock surface. The bolt 51 is then in a known
way fixed to the rock by hardening of the resin and tightening of the bolt. The bolting
operation is now completed and the clamping head 67 is drawn back so that the unit
18 is set free and is able to be positioned for another bolting operation.
[0017] By virtue of the fact that the bolting apparatus comprising two feed bars 26 and
27 which are displaceable independently of each other, the apparatus can be positioned
so that the one feed bar which is brought to a working position will be situated sufficiently
close to the rock surface to enable satisfactory guidance and feed length to the drill
rod and bolts without being hindered by the other feed bar hitting irregularities
in the rock.
1. In a rock bolting apparatus including at least a rock drill (40) and a bolt setting
machine (50) which are carried by a swingable unit (18) connected to a boom (11),
the unit (18) being laterally swingable relative to the boom (11) about an axis (21);
power means for power displacing said rock drill (40) and said bolt setting machine
(50) laterally into and out of a working position by means of controlled swinging
of the swingable unit (18) about said axis (21); and clamping means for clamping said
swingable unit (18) between a rock surface and the boom (11), said clamping means
including a jack (63) arranged on said swingable unit (18) and being extensible in
alignment with said axis (21); characterized in that said swingable unit (18) comprises:
a first feed bar (26) movably mounted thereon and carrying said rock drill (40) for
feeding and guiding said rock drill (40); a second feed bar (27) movably mounted thereon
and carrying said bolt setting machine (50); and power displacing means (28-33) coupled
to said feed bars (26, 27) for power displacing said two feed bars (26, 27) independently
of each other relative to said swingable unit (18) in the longitudinal direction of
said feed bars.
2. Rock bolting apparatus according to claim 1, characterized in that said swingable
unit (18) comprises a common supporting frame (24) for said feed bars (26, 27), said
common supporting frame (24) comprising guiding means (25, 34) for each one of said
feed bars (26, 27) to permit displacement of said feed bars in their longitudinal
direction relative to said frame (24).
3. Rock bolting apparatus according to claim 2, characterized in that said common
supporting frame (24) carries said power displacing means.
4. Rock bolting apparatus according to claim 3, characterized in: that said common
supporting frame (24) is box-shaped; said power displacing means comprises hydraulic
cylinders (28, 29) arranged inside said common supporting frame (24); and said guiding
means comprises brackets (25) at opposite sides of said common supporting frame (24)
for slidingly holding said feed bars (26, 27).
5. Rock bolting apparatus according to any one of claims 1-4, characterized in that
said first feed bar (26) has a support (43) at one end thereof, said support (43)
being adapted to abut against a rock surface when said first feed bar (26) is pressed
towards the rock surface.
6. Rock bolting apparatus according to claim 5, characterized in that said support
(43) has a hole therethrough for guiding a drill rod connected to the rock drill (40),
and that said support (43) has an elastic cushion (44) on the part thereof adapted
to contact the rock surface.
7. Rock bolting apparatus according to claim 5 or 6, characterized in that the power
displacing means (28) for said first feed bar is arranged to cooperate with said jack
(63) during the clamping of said swingable unit (18) so that their cooperative compressive
force will determine the clamping force.
8. Rock bolting apparatus according to any of the previous claims, characterized by
a clamping head (67) coupled to said jack (63), said clamping head (67) being arranged
to abut against the rock surface and being rotatable with respect to said jack (63).
9. Rock bolting apparatus according to claim 8, characterized in that said clamping
head (67) includes an elastic cushion (70) on the part thereof adapted to contact
the rock surface.
10. Rock bolting apparatus according to claim 8 or 9, characterized in that said clamping
head (67) is connected to the jack (63) by a connection (66) which permits rotary
movement only in a plane perpendicular to the jacking direction of said jack.
1. In einer Maschine zum Setzen von Gebirgsankern mit wenigstens einer Gesteinsbohrmaschine
(40) und einer Ankersetzvorrichtung (50), die von einer an einem Auslager (11) angeschlossenen
Schwenkeinheit (18), welche in seitlicher Richtung zum Ausleger (11) um eine Achse
(21) verschwenkbar ist; Kraftbetätigungsmittel zum seitlichen kraftbetätigten Verlagern
der Gesteinsbohrmaschine (40) und der Ankersetzvorrichtung (50) in und aus einer Arbeitsstellung
durch gesteuertes Verschwenken der Schwenkeinheit (18) um die genannte Achse (21);
und eine Verspanneinrichtung zum Verspannen der Schwenkeinheit (18) zwischen einer
Gesteinsoberfläche und dem Ausleger (11), wobei die Verspanneinrichtung eine an der
Schwenkeinheit (18) angeordnete und in Richtung zu der genannten Achse (21) ausfahrbare
Winde (63) enthält; dadurch gekennzeichnet, daß die Schwenkeinheit umfaßt: eine schwenkbar
daran angeordnete und die Gesteinsbohrmaschine (40) zum Vorschieben und Führen der
Gesteinsbohrmaschine (40) tragende erste Vorschublafette (26); eine zweite schwenkbar
daran angeordnete und die Ankersetzvorrichtung (50) tragende Vorschublafette (27);
und an die Vorschublafette (26, 27) angekuppelte Kraftbetätigumgsmittel (28-33) zum
kraftbetätigen Verlagern der beiden Vorschublafetten (26, 27) unabhängig voneinander
im Verhältnis zur Schwenkeinheit (18) in Längsrichtung der Vorschublafetten.
2. Maschine zum Setzen von Gebirgsankern nach Anspruch 1, dadurch gekennzeichnet,
daß die Schwenkeinheit (18) einen gemeinsamen Stützrahmen (24) für die beiden Vorschublafetten
(26, 27) umfaßt, welcher Führungsmittel (25, 34) für eine jede der Vorschublafetten
(26, 27) aufweist, um eine Verlagerung der Vorschublafetten in ihrer Längsrichtung
im Verhältnis zu dem Stützrahmen (24) zu ermöglichen.
3. Maschine zum Setzen von Gebirgsankern nach Anspruch 2, dadurch gekennzeichnet,
daß der gemeinsame Stützrahmen (24) die genannten Kraftbetätigungsmittel trägt.
4. Maschine zum Setzen von Gebirgsankern nach Anspruch 3, dadurch gekennzeichnet,
daß der genannte Stützrahmen (24) kastenförmig ist; daß die Kraftbetätigungsmittel
zwei Hydraulikzylinder (28, 29) aufweisen, welche innerhalb des gemeinsamen Stützrahmens
(24) angeordnet sind; und daß die Führungsmittel an entgegengesetzten Seiten des gemeinsamen
Stützrahmens (24) Halterungen (25) zum Gleitführen der Vorschublafetten (26, 27) aufweisen.
5. Maschine zum Setzen von Gebirgsankern nach einem der Ansprüche 1 bis 4, dadurch
gekennzeichnet, daß die erste Vorschublafette (26) an ihrem einen Ende einen Bohrhalter
(43) aufweist, der angepaßt ist, gegen eine Gesteinsoberfläche anzuliegen, wenn die
erste Vorschublafette (26) gegen die Gesteinsoberfläche gedrückt wird.
6. Maschine zum Setzen von Gebirgsankern nach Anspruch 5, dadurch gekennzeichnet,
daß der Bohrhalter (43) ein durchgehendes Loch zum Führen einer mit der Gesteinsbohrmaschine
(40) verbundenen Bohrstange hat und daß der Bohrhalter (43) ein elastisches Kissen
(44) an demjenigen Teil von ihm hat, welches angepaßt ist, gegen die Gesteinsoberfläche
anzuliegen.
7. Maschine zum Setzen von Gebirgsankern nach Anspruch 5 oder 6, dadurch gekennzeichnet,
daß das Kraftbetätigungsmittel (48) für die erste Vorschublafette so angeordnet ist,
daß es mit der Winde (63) während des Verspannens der Schwenkeinheit (18) zusammenarbeitet,
so daß deren mitwirkende Druckkraft die Spannkraft bestimmt.
8. Maschine zum Setzen von Gebirgsankern nach einem der vorhergehenden Ansprüche,
gekennzeichnet durch einen mit der Winde (63) gekuppelten Verspannkopf (67), welcher
so angeordnet ist, daß er gegen die Gesteinsoberfläche anliegt und mit Bezug auf die
Winde (63) verdrehbar ist.
9. Maschine zum Setzen von Gebirgsankern nach Anspruch 8, dadurch gekennzeichnet,
daß der Verspannkopf (67) ein elastisches Kissen (70) an demjenigen Teil aufweist,
das dazu bestimmt ist, gegen die Gesteinsoberfläche anzuliegen.
10. Maschine zum Setzen von Gebirgsankern nach Anspruch 8 oder 9, dadurch gekennzeichnet,
daß der Verspannkopf (67) mit der Winde (63) durch eine Verbindung (66) verbunden
ist, die eine Drehbewegung nur in einer Ebene senkrecht zu der Ausfahrrichtung der
Winde gestattet.
1. Machine pour installer des boulons d'ancrage, comprenant au moins une perforatrice
(40) et une machine (50) à fixer des boulons qui sont portées par un ensemble basculent
(18) relié à un affût (11), l'ensemble (18) pouvant pivoter latéralement par rapport
à l'affût (11) autour d'un axe (21 des moyens pour pouvoir déplacer latéralement la
perforatrice (40) précitée et la machine (50) à l'intérieur et à l'extérieur d'une
position de travail au moyen d'un basculement contrôlé de l'ensemble pivotant (18)
autour de l'axe (21) précité, et un dispositif pour serrer l'ensemble pivotant (18)
précité entre une surface rocheuse et l'affût (11), ce dispositif de serrage comprenant
un vérin (63) disposé sur l'ensemble pivotant (18) précité et extensible en alignement
avec l'axe (21 et caractérisée en ce que l'ensemble pivotant précité (18) comprend:
a) une première barre d'avance (26) montée de façon amovible et portant la perforatrice
(40) précitée pour alimenter et guider cette perforatrice; b) une seconde barre d'avance
(27) montée de façon amovible et portant la machine (50) à fixer des boulons; et c)
des dispositifs mobiles (28-33) reliés aux barres d'avance (26, 27) pour les déplacer
mécaniquement indépendamment l'une de l'autre par rapport à l'ensemble pivotant précité
(18) dans le sens longitudinal des barres d'avance précitées.
2. Machine suivant la revendication 1, caractérisée en ce que l'ensemble basculant
précité (18) comprend un cadre porteur commun (24) pour les barres d'avance précitées
(26, 27), ce cadre porteur commun (24) comprenant un système de guidage (25, 34) pour
chacune de ces barres d'avance (26, 27) pour permettre un déplacement des barres d'avance
précitées dans leur sens longitudinal par rapport au cadre (24) précité.
3. Machine suivant la revendication 2, caractérisé en ce que le cadre porteur (24)
porte les dispositifs de déplacement précités.
4. Machine suivant la revendication 3, caractérisée en ce que: a) le cadre porteur
commun (24) est en forme de boite; b) le dispositif de déplacement comprend des cylindres
hydrauliques (28, 29) placés à l'intérieur du cadre porteur commun (24); et c) le
dispositif de guidage comprend des supports (25) sur les côtés latéraux opposés du
cadre porteur commun (24) pour maintenir de façon coulissante les barres d'avance
(26, 27).
5. Machine suivant l'une des revendications 1 à 4, caractérisée en ce que la première
barre d'avance (26) possède à une extrémité un support (43), et que ce support est
capable de buter contre une surface rocheuse quand la première barre d'attente (26)
est appliquée contre la surface rocheuse.
6. Machine suivant la revendication 5, caractérisée en ce que chaque support (43)
est percé d'un trou pour guider une tige de forage reliée à la perforatrice (40),
et en ce que ce support (43) possède un coussin élastique (44) sur la partie capable
de contacter la surface rocheuse.
7. Machine suivant l'une des revendications 5 ou 6, caractérisée en ce que le dispositif
de déplacement (28) pour la première barre d'avance est capable de coopérer avec un
vérin (63) pendant le serrage de l'ensemble pivotant (18) de façon que leur force
coopérative compressive détermine la force de serrage.
8. Machine suivant l'une des revendications précédentes, caractérisée par une tête
de serrage (67) reliée au vérin (63), cette tête de serrage étant disposée de façon
à buter contre la surface rocheuse et pouvant tourner par rapport au vérin (63) précité.
9. Machine suivant la revendication 8, caractérisée en ce que la tête de serrage (67)
précitée comprend un coussin élastique (70) sur la partie capable de contacter la
surface rocheuse.
10. Machine suivant l'une des revendications 8 ou 9, caractérisée en ce que la tête
de serrage (67) est reliée au vérin (63) par une connexion (66) qui permet un mouvement
rotatif seulement dans un plan perpendiculaire à la direction du soulèvement du vérin
précité.