Note: Descriptions are shown in the official language in which they were submitted.
~37~7
The present inv~ntion re~-ltes to a drilling boom assembly
secured on a drilliny carriage or on a drilling riy and use-l
in driving mine openings and in stoping.
A known drilling boom assembly comprises a telescopic
boom with an ac~uating hydraulic cylinder, said boom being
hinged with its one end to a pivot mounted on a bearlng plate.
The boom can turn round its own axis. Hinged to a free end
of the telescopic boom is-a feed bar with a drifter, said feed
bar being provided with a hydraulic cylinder. Rigidly fixed
to this free end of the telescopic boom is a head carrying
hydraulic cylinders for til-ting and swivelling the feed bar
in a horizontal plane as well as a rotational mechanism to
turn the feed bar round the axis of -the rotational mechanism
' which axis is parallel to that of the feed bar.
Change of the angle of inclination of the telescopic boom
in a vertical plane is accomplished by means of a hydraulic
cylinder whose rod free end is hinged to the boom, while its
body is articulated to the pivot.
Turning the telescopic boom in a horizon-tal plane is
accomplished by means of a hydraulic cylinder whose rod free
; end is articulated to the bearing plate.
A disadvantage of the known drilling boom is that lifting
or turning of the boom causes the distance between the feed
~ar and a rock face to vary. Also, the horizontal angle and
.
the vertiGal angle of the feed bar with respect to the rock face
become altered.
This occurs when lifting the telescopic boom in a vertical
plane and turning the boom in a horizontal plane.
Alignment of the working end of the feed bar with the
hole is a rather laborious and time-consuming operation.
It is an object of the present invention to provlde a
drilling boom assembly that automatically compensates for
'~
~37~
cleviation o~ the end of ~he manipu].ator fron~ the face, ~hile
~- swinginy the telescopic manipulator.
According to the present invention, there is provided
~: a drilling boom assembly comprising, a telescopic boom, the boom
being expandable and contractable in lenyth and having a first
end and a second end, the first end being hinged to a pivot
mounted on a bearing plate, the pivot and the boom being pivotal
relative to the bearing plate about a vertical axis, a first :
hydraulic cylinder assembly forming part of the boom for control- -
~j 10 ling the length thereof, a feed bar hinged to the second end of ~ . :
``¦ the boom, the feed bar being provided with a drifter and having :
' a working end, the feed bar being axially movable forwards and
~' backwards relative to the second end of the boom by means of a
second hydraulic cylinder assembly, the second hydraulic cylinder
q
~ assembly being mounted on the second end of the boom, a third
:, hydraulic cylinder assembly for tilting the feed bar in a vertical
j plane, the third hydraulic cylinder assembly also being mounted
on the second end of the boom, a fourth hydraulic cylinder
assembly for turning the feed bar in a horizontal plane, the
fourth hydraulic cylinder assembly also being mounted on the second
. end of the boom, a mechanism for rotating the feed bar about an
~ axis parallel to the axis of the feed bar, a fifth hydraulic
cylinder assembly for lifting the boom, one end of the fifth
. hydraulic cylinder assembly being hinged to the boom, the other
end of the fifth hydraulic cylinder assembly being hinged to the
pivot, a sixth hydraulic cylinder assembly for turning the tele-
~ ~:
: scopic boom in a horizontal plane, one end of the sixth hydraulic
cylinder assembly being hinged to the bearing plate, the other end
` of the sixth hydraulic cylinder assembly bein~ hinged to the boom,
- 30 a servomechanism for controlling operation of either the first or
~ alternatively the second hydraulic cylinder assembly, the cylinder
assembly controlled by the servomechanism hereinafter being
,. .
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.
. ~' . '
. . .
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referred to as the controlled cylinder assembly, the servo-
mechanism comprising a support rod, a seventh hydraulic cylinder
assembly and a servovalve, one end of the seventh hydraulic
cylinder assembly being connected to the pivot and the other end
thereof being connected to the support rod each of the afore-
mentioned hydraulic cylinder assemblies comprising a respective
cylinder accommodating a piston defining a first variable volume
space and a second variable volume space in the cylinder, the
first variable volume space of the seventh hydraulic cylinder
being in communication with the first variable volume space of
. .
the cylinder of the controlled cylinder assembly, said communic-
ating spaces being equal in volume at any one time, the servovalve
comprising a body and a plunger accommodated in the body and
attached to the rod, the body having a first duct for supply of
working fluid to the servovalve, a second duct communicating with
the second variable volume space of the controlled cylinder for
supplying working fluid to that space and a third duct communic-
ating with the second variable volume space of the seventh hydra-
ulic cylinder for return of working fluid from that space, the
plunger controlling communication ~etween the ducts, and a connec-
ting means coupling the rod with the boom which causes the seventh
hydraulic cylinder assembly and the body of the servovalve to
displace with respect to the plunger, thus bringing the first duct
into communication via the second duct with the second variable
volume space of the controlled hydraulic cylinder assembly, thus `
either extending or retracting the controlled hydraulic cylinder
assembly and compensating to maintain the working end of the feed
bar in a desired vertical plane, when either (i) the controlled
cylinder assembly is the first hydraulic cylinder assembly and
the boom turns in a vertical plane or (ii) the controlled cylinder
assembly is the second hydraulic cylinder assembly and the boom
turns in a horizontal plane.
3 _
..
371~7
It is expedient that the servomechanism drive be
secured on the boom, with the piston-end space or rod-end space
of the boom actuating hydraulic cylinder communicating
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with the respect:ive rod-end s~!~ce or piston-end space of the
servomechanism clrive hydraulic cylinder, and that thc
connecting means include a slide block. tn this case vertical
lifting of the boom will cause the slide block to move along
the guideways to displace -the body of the servomechanism drive
hydraullc cylinder.
It is also preferable that the servomechanism drive
be secured on the bearin~ plate, with the piston-end space or
rod-end space of the feed hydraulic cylinder communicating
with the respective space of the servomechanism drive hydraulic
cylinder. Preferably, the connecting means is provided with -
; a tie rod hinged to the servomechanism drive hydraulic cylinder
body, said connecting means being secured on a pivot by means
.~ - .
of an arm. In this case horizontal turning of the boom
causes the tie rod to move with respec-t to the axis of the
pivot to displace the body of the servomechanism drive
hydraulic cylinder.
drilling boom assembly embodying the invention is
described below with reference to the accompanying drawings,
wherein:
~ Figure 1 is a general schematic side view of the
,! drilling boom assembly, in a horizontal position (I)l in a
lifted position (II) and in a lowered position (III).
I Figure 2 is a plan view of the drilling boom assembly
of Figure 1,
Figure 3 is a vertical elevation of a bearing plate
carrying a pivot, a boom actuating hydraulic cylinder and
a servomechanism drive;
Figure 4 is a longitudinaI, partly sectional, view
3Q of a boom of the drilling boom assembly of Figures 1 and 2;
Figure 5 is a cross-section taken along line V-V
in Figure 4;
. .,
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, . . . .::
7~7
Figur~ 6 is a lonc~itllclinal sec-tional view of a
hydraulic cylinder ~or controll:ing the lenc3th of ~he boom
shown in Figure 4;
Figur~ 7 is a longitudinal sectional view of a
hydraulic cylinder for lifting the boom through a vertical
plane
Figure 8 is a longitudinal sectional view of a drive
of a servomechanism;
Figure 9 is a longitudinal sectional view of a valve
of the servomechanism drive; and
Figure 10 is a schematic representation of the drill-
ing boom assembly of Figure 1.
The drilling boom assembly shown in the drawings
icomprises a telescopic boom 1 (Figure 1). One end of the boom ~ -
is secured on a pivot 2 which is mounted on a bearing plate 3
so that the pivo-t 2 together with the boom 1 may turn about a
ver-tical axis l. A feed bar 4 is hinged to the end of the
boom remote from the pivot 2, i.e. the free end of the boom.
The feed bar 4 is provided with a dr:ifter 5. The feed bar 4
- comprises a hydraulic cylinder 6 and i5 connected to a head 7
which is rigidly fixed to the free end of the boom. The boom 1
accommodates an actuating hydraulic cylinder 8. The head 7 is
provided with a hydraulic cylinder 9 for tilting the feed bar
4 through a vertical plane and a hydraulic cylinder 10 ~Figure
.~ 2) for turning the feed bar 4 through a horizontal plane. The ;~
head also carries a rotational mechanism 11 ~Figure 1) for
rotating the feed bar 4 through an angle of up to 180 about
an axis 23 parallel to the axis of the feed bar. Provision -~
of the rotational mechanism 11 makes it possible to carry out
drilling operations to produce parallel holes in a rock face
at a small distance from the rock walls and roof of a mine
opening and, moreover, almost fully excludes a 'dead zone' on ~-
. ~ .
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thc ~ace whe~ein drillillg is iml~ossible. ~ hydraulic cylinder
1.2 ~or :liEting !:he tc:l.escoE~ic boom through a vertical r~Lane is
hinyed at one end to said boom. The other end of the hydraulic
; cylinder 12 is secured on the pivot 2 by means of a joint 13.
The drilling boom assembly also comprises a hydraulic cylinder
14 (Figure 2) for turning the telescopic boom in a horizontal
plane.
The drilling boom assembly is provided with a
servomechanism 15 for controlling operation of the hydraulic
actuating cylinder 8 of -the boom. The servomechanism 15
comprises a drive 15a secured on the telescopic boom 1 and a
- connecting means 16.
.:: The drilling boom assembly also carries a servo- .
mechanism 17 (Figure 3) which is similar.in design to the
servomechanism 15 and is for controlling operation of the
hydraulic cylinder 6 of the feed bar 4. The servomechanism 17
comprises a drive 17a secured on the bearing plate 3 and a
connecting means 18 for connecting servomechanism 17 to pivot 2.
The telescopic boom 1 (Figure 4) is provided with an
~l 20 eye 19 and a groove "a" (Figure 1). The guideway 20 is rigidly
.~ fixed to the pivot 2 and.forms part of the connecting means 16
l of the servomechanism 15. The guideway 20 slidingly supports
:' ! a slide block 21 which is rigidly fixed to the hydraulic
cylinder of the servomechanism and forms part of the connecting
means 16. The telescopic boom comprises a body 22 (Figure 4).
The actuating hydraulic cylinder 8 incorporates bronze bushes
.-' 23 and bronze liners 24 (Figures 4 and-5). A rod 25 of the -
actuating hydraulic cylinder 8 is connected with the body 22
of the telescopic boom 1. The body 22 of the telescopic boom
is coupled with a rod 26. The rod 25 is held against rotation
about its own axi.s by means of keys 27 and 28 housed in grooves
"b" and "c" of the body 22. The body 22 is provided with
~: - 6 -
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as~embly ports "cl" (Figure 4) -lncl "e" tFigure 5) normally
closed with cov~rs 29 (I~'icJure 4) and 30 (Figure 5).
The actuating hydraulic cylinder 8 comprises a body
8a. The body 8a (Fiyure 6) accommodates the rod 26. ~ piston
31 is fixed to the rod 26. A support 32 provided with an eye
; 32a is welded to the rod 26. A support 33 provided with an
eye 33a is welded to the body 8a. Working fluid is fed to a
piston-end space "f" of the cylinder and to a rod-end space "g"
-through respective inlets 34 and 35 provided in the support 32.
The working fluid is oil. Sealing of working spaces "f" and
"g" is effected by means of collars 36, 37 and 38. The piston
31 on the rod 26 is sealed by means of rubber rings 39 and 40.
i From the inlet 34-the working fluid flows to the space "f" via
-, a pipe 41 sealed with rubber rings 42 and 43. A bush 44 is
held in the body 8a with the help of a rubber ring 46. Mud
removers 47 and 48 are secured by means of a cover 49 and
cotter pins 50 and 51.
The servomechanism 15 and 17 can be used in drilling
boom assemblies of any type and, particularly, on drilling boom
assemblies adap-ted to maintain paral:Lelism of the feed motion
, and operating on the principle of hydraulic parallelogram.
As shown in Figure 7, the hydraulic cylinder 12
:1 !
comprises a pilot cylinder 52 employed in a hydraulic parallel-
ogram circuit and a hydraulic cylinder 53 for lifting the
telescopic boom-in a vertical plane. Rods 54 and 55 of
hydraulic cylindars 52 and 53 are interconnected by means of nut
56 fixed on the rod 55 with a cotter pin 57 retaining said nut
against spontaneous unscrewing. Pistons 58 and 59 are secured
on the rods 54 and 55. Sealing of the spaces of the hydraulic
cylinder 52 is effected by means of collars 60 to 66 and
rubber rings 67 -to 73. A bush 74 is held in a body 75 by means
; of a snap ring 76. Mud removers 77 and 78 are retained with a
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,
3~ 7
cove~r 79 and cotter pins 80 an~l 81. A bush 82 is secured
between thc body 75 and a body 83 which are interconnecte~ h
bolts ~4 and ~5. Rod-end and piston-end spaces of the pilot
cylinder 52 are hydraulically intercommunicated through
connections 86 and 87 with the respective spaces of the hydra-
ulic cylinder 9 (Figure 1) for tilting through a vertical plane
the feed bar 4 and are equal in volume with the spaces of the
hydraulic cylinder 9.
The hydraulic cy]inder 12 for lifting the telescopic
boom 1 and the hydraulic cylinder 9 for tilting the feed bar 4
thus operate in unison. Thus, the inclination of the feed bar
4 always remains the same, irrespective of the inclination of
the boom 1 to the vertical, i.e. said cylinders ensure operation
of a "hydraulic parallelogram."
The drive 15a of the servomechanism 15 is secured on
the body 22 of the telescopic boom 1 by means of brackets 88
~' .
and 89 (Figure 8). The drive 15a comprises a hydraulic cylinder
90 having a body 91 connected with tlle slide block 21 (Figure 1)
through a dowel pin 92. A piston-end space "h" and a rod-end
space "i" are defined within the hydraulic cylinder 90. The
~ rod end space "i"isin-ommunication with the rod-end space "g" ~ -
i (Figure 6) of the actuating hydraulic cylinder 8 of the tele- ~
;, : ,
scopic boom 1. The rod-end space "i" of the hydraulic cylinder
90 and the rod-end space "g" of the hydraulic cylinder 8 are
equal in volume at any one time. A servo-valve 95 has a body
:. ~.
94 secured on the free end of a rod 93 (Figure 8) of the
hydraulic cylinder 90. The body 91 of the hydraulic cylinder
90 accommodates a piston 96 provided with rings 97 and 98 and
secured on the rod 93 by a nut 99. A cover 100 of the -
hydraulic cylinder 90 is fixed in the body 91 by means of a
snap ring 101, a washer 102, and bolts 103 and 104. Sealing
of the spaces along the rod 93 is effected by means of collars
- 8 -
A
.
376i'7
I05 to 10~ and rubber rings ll() to 112. Mud removers 113 ancl
114 are secured in the body 91 by means of a cover 115 and
cotter pins 116 and 117. Mud removers 118 and 119 are secured
in the body 91 hy means of the cover 100 and the washer 102.
The hydraulic cylinder 90 comprises connections 120 and 121.
cover 122 of the servo-valve 95 accommodates a collar 123
and mud removers 124 and 125 fixed by means of a cover 126 and
cotter pins 127 and 128. The body 94 of the servo-valve 95 is
sealed by means of rubber rings 129 and 130, said body being
~ 10 provided wi-th a connection 131 for feeding the working fluid
; into the servo-valve. The servo-valve 95 comprises a ~lunger
132 mounted on a rod 133.
`~ The body 94 (Figure 9) is provided with a duct 134 -
to feed working fluid into the piston-end space "h" (Figure 8)
of the hydraulic cylinder 90 of the drive 15_ of the servo-
mechanism 15, a duct 135 (Figure 9) to feed the working fluid
, into the rod-end space "f" (Figure 10) of the actuating
hydraulic cylinder 8, ducts 136 and 137 (Figure 9) to return
the working fluid Erom said spaces "h" and "f" respectively and -~
` 20 a duct 138 to feed the working fluid into the servo-valve 95.
The plunger 132 has a shoulder 139 which together with springs
: .
~ 140 and 141 and washers 142 and 143 retain the plunger 132 in
j ! a fixed position with respect to the rod 133. The washers 142and 143 bear against a shoulder 144 of a bush 145 coupling
together two rods 146 and 147 housed-in the rod 133 (Figures 8
and 9).
The servome-chanism 17 (Figure 3) is intended to
maintain constant the horizontal distance of the feed bar 4
(Figure 2) rock from the vertical rock face when turning the
telescopic boom 1 and feed bar 4 in a horizontal plane. The
servomechanism 17 is connected with the extending hydraulic
cylinder 6. The drive 17a (Figure 3) of the servomechanism 17 ~
~ 9~ ' ~;
:. .
.
~3~7i~7
is secured on the bearin~ plat~ 3 not shown, by means of
brackets 148 and 149 and is provided with a rod 150, coaxially
mounted on which are a servo-valve 151 and a hydraulic cylinder
152 having a body 153 connected with a tie rod 155 of the
connectinc~ means 18 through a hinged joint 154. The -tie rod
155 is pivotally connected through a joint 156 with an arm 157
rigidly secured on the pivot 2. The body 153 is held against
rotation around its longitudinal axis with the help of a roller
158 mounted on the bearing plate 3 and located in a groove "j"
of the body 153.
The rod-end space of the hydraulic cylinder 152 of
the drive 17a communicates with the rod-end space of the
; extending hydraulic cylinder 6 (Figure 1) of the feed bar 4
and is equal in volume at any one time with the rod-end space
of cylinder 6.
The drilling boom assembly is associated with a
control desk (not shown) having distributors 159, 162 and 163
(Figure 10). The distributors 159, 162 and 163 are connected
; to a working fluid line (not shown).
The drilling boom assembly shown in the drawings
operates as follows.
When opera-ting in a mode which allows for automatic
maintainance of the distance of the feed bar 4 from a vertical
rock face despite lifting of the boom, the distributor 163 is
put into operation. If the duct 138 is closed by the plunger
132 and cannot communicate with ducts 134, 135 (Figure 9)
working fluid cannot flow into the hydraulic cylinder 8 of the
telescopic boom 1.
` To make the telescopic boom 1 move vertically, the
; 30 distributor 159 (Figure 10) is operated with the distributor
163 turned on. Working fluid from a working fluid line (not
shown) is fed through the distributor 159 into the piston-
- 10 -
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~ c "k" or in~o thc r~l-cnd sE)~ce "I" o~ Wle hy~raulic cyLinder 12.
Upon fe~in~J tlle ~rking flui.d into ~he piston-end space "k" of the hydrauli.c
cylinder 12, the rod 55 is displaced and turns the telescopic boom anti-
clockwise wlth resp~ct to the bearinc3 plate 3. ~s a result, the slide
block 21 of the connecting means 16 of the servcmechanism 15, sliding up
along the guideway 20, displaces the hydraulic cylinder 90 and, due to the
fluid trapped in spaces "h" and "i", the body 94 (Figure 8) of the servo-
valve 95 relative to the plunger 132 towards the bracket 89. Consequently
working fluid from the working fluid line flows along the duct 138 into
. 10 the duct 135 communicated with the piston-end space "f" oE the hydraulic
cylinder 8, thus extending the latter and increasing the leng-th of the
telescopic boom 1. Slmultaneously, -the space "h" of the hydraulic cylinder
90 comes into cGmmunication through the duct 134 with the duct 136 which i.s
in communication with a return line through a pipeline 161. As the - :
hydraulic cylinder 8 extends, the working fluid expelled from the rod-end
space "g" of the hydraulic cylinder 8 flows into the rod-end space "i" of
the hydraulic cylinder 90 along the pipeline 160 and displaces the
cylinder rod 93 (Figure 8~ which is connec-tecl to the body 34 of the servo-
valve 95, relative to the plunger 132, towards the bracket 88. As a
20. result, the plunger 132 returns to the position shown in Figure 9 and the
duct 138 and becornes closed once again. Thus, working fluid ceases flowing
. to the duct 135 and to the piston-end space "f" of the hydraulic cylinder -;
8. Consequently, the telescopic boom is extended a length enough to
co~ensate for the horizontal deviation of the end of the boom 1 away from
the rock face due to the anti-clockwise moverrent of the boom; which makes
it possible to drill holes whose ends are located in the s~r.e vertical
plane.
. The inclination of the feed bar to the vertical is
retained by rneans of the hydraulic cylinder 9 which operates together
with cylinder 12 in a hydraulic parallelogram (Figure
' ~;
,
6~
10). Ul~on Eeeding the workinc~ fluid into the rod-piston space
"1" of the hydraulic cylinder 12, the telescopic bcom 1 ~urns
clockwise and c3ets shorter correspondingly.
When operating at a rock face, conditions may arise
which require not only automatic but also independent control
of the boom length and its vertical swivel. An example is
found under conditions which require the change of the length
of the telescopic boom without altering its angle of elevation,
or vertical swivel of the drilling boom assembly with the
telescopic boom length unchanged.
Provision of independent control of both the length of
the telescopic boom and its vertical swivel is attained in
the drilling boom assembly by virtue of servo-valves available
on the con-trol desk and the springs 140 and 141 in the servo- -~ ;
valve 95, due to which the plunger displacement is relatively ~;
inconsiderable during lengthy displacement of the servopiston
~ body.
; Such independent control can occur only when the
servo-valve of the servomechanism dr:ive 15a controlling the
length of the boom is disconnected from -the oil line. In order
to operate in an independent control mode, the distributor 163
` (loca-ted on the control desk) for feeding the working fiuid
to the servo-valve 95 of the servomechanism drive 15a is ~ ~
turned off. When the servo-valve 95 is disconnected from the ~-
oil line, vertical lifting of the telescopic boom l causes -the
servo-valve 95 to displace with respect to-the plunger 132,
and thus the telescopic boom remains retracted. With the
drilling boom assembly operating in an independent control
mode, the telescopic boom may be lifted by means of the dis-
tributor 159 located on the control desk.
The working rluid is fed to piston-end space "k"
of the hydraulic cylinder 12 by means of the distributor 1~9.
- 12 -
'
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~37~
~; a r~n~uLt, th~! rod 55 eY~en~s and causes the telescopic
boom 1 to turn counter-clockwise with respect to the p;vot 2.
The slide block 21 moves up the guideway 20 and displaces the
cylinder 90 together with the body 94 of the servor-valve
95 with respect to the plunger 132 till the butt end of the
plunger 132 comes in contact with -the butt end of the rod 93
(see Figure 9). Then the body 94 of ~he servo-valve 95 con-
tinues to displace towards the bracket 89 together with the
plunger 132 whose collar 139 also displaces the washer 143
towards the bracket 89, thereby compressing the spring 141.
Upon feeding the working fluid into the rod-end
space "1" of the hydraulic cylinder 12 (Figure 10), the tele-
` scopic boom 1 turns clockwise.
~ ~ When operating in an independent control mode, the
`~ telescopic boom 1 may be extended by actuating the distributor
162 (Figure 10) located on the control desk. As a result, the
working fluid is fed through the distirbutor into the piston-
., :
i end space "f" of the hydraulic cylinder 8 whose rod 25 ge-ts
e~tended, thus increasing the length of the telescopic boom 1.
The working fluid expelled from the rod-end space "g" is fed
` through the hydraulic pipeline 160 into the rod-end space "i"
of the hydraulic cylinder 90 and urges the rod 93 together
with the body 94 of the servo-valve 95 and the plunger 132 to
displace towards the bracket 88, thus compressing the left-hand
spring 140 (Figùre 9)-. As a result, the space "h" of the
hydraulic cylinder 90 (Figure 10) of the servomechanism 15a
is communicated with the return line through the distributor
i62.
Upon retracting the telescopic boom the working
fluid is fed through -the distributor 162 into the piston-end
space "h" of the hydraulic cylinder 90. As a result, the rod
93 together with the body 94 of the servo-valve 95 and the
- 13 -
,.~
.. ... . .
37~;'7
ngcr 1.32 are displaced tow~r.cls the bracket 89, thus com-
pressing the ri.cJht-hand spring 1~1 (Figure 9). The workiny
~luid e~pelled from the rod-end space "i" is fed through the
hydraulic cylinder 160 into the rod-end space "g" of the
hydraulic cylinder 8. As a result, the rod 25 retracts into
the hydraulic cylinder 8, thus decreasing the length of the
telescopic boom 1.
When changing over from an independent control of
operation to an automatic one, working fluid is fed through
10 -the distributor 163, and the servo-valve 95 of the servo-
mechanism drive 15a into the actuating cylinder 8. ~s a result,
the springs 140 and 141 of the servo-valve 95 are set to the
initial position (see Figure 9). ~:
~ The drive 15_ of the servomechanism 15 coupled w.ith
the actuating hydraulic cylinder ~ o:E the telescopic bo.om 1
; and the drive 17a of the servomechanism 17 coupled with the
hydraulic cylinder 6 of the feed bar 4 are similar in design,
therefore when discussing the operation of the servomechanism
17, reference is directed to the constructional units as shown
in Figures ~ and 9 and to the reference numerals in the
accompanying drawings.
The o~eration of the servomechanism 17 is entire
! analogous.to the mode of operation of the servomechanism 15,
which has already been described. However, whilst the
servomechanism I5 controls the degree of extension of tele~
scopic boom 1 in response to lifting of the boom in a vertical
~ plane, the servo-mechanism 17 controls the degree of extension
of the telescopic boom 1 in response to tuning of the boom i.n
a horizontal plane. Just as the servomechanism 15 could
: 30 alternatively be used to control axial movement of the feed
'1
bar 4 by means of the second hydraulic cylinder 6, so as to
maintain the working end of the feed bar at a constant
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7~7
l1stance ~rom a vertical rock ~ace, so the servomechanism 17
may also alternatively control the second hydraulic cy]inder 6.
As the boom 1 attached to pivot 2 booms in a
horizontal plane, the hydraulic cylinder 152 is moved by the
connecting means 1~ along the rod 150. The rod 150 is rigidly
fixed by means of brackets 148 and 149 to bearing plate 3.
Thus, for example, anticlockwise turning of the pivot 2
(considered from above in Figure 3) is converted by means of
arm 157 on the pivot 2, tie tod 155 and hin~ed join-t 54 into
axial movement of hydraulic cylinder along the rod towards the
right hand side in Figure 3.
The construction of hydraulic cylinder 152 and
, servovalve 151 (Figure 3) is converted by means of arm 157 on
the,pivot 2, tie rod 155 and hinged joint 154 into axial
!movement of hydrualic cylinder along the rod towards the right
hand side in Figure 3.
The construction of hydrau:Lic cylinder 152 and servo-
valve 151 (Figure 3) is substantially identical to the con-
struction of hydraulic cylinder 90 and servovalve 95,
respectively, shown in Figures 8 and 9. The hydraulic cylinder
152 will therefore be considered to have a piston-end space ~
"L" and a rod-end space "i", and the same reference numerals ~ -
, . .
` used in connection with hydraulic cylinder 90 and servovalve
95 will be used also in connection with hydraulic cylinder 152
and servovalve 151.
We shall consider the case when servomechanism 17
controls extension of the boom. Rod end space "i" of hydraulic ~;
~` cylinder 152 is connected to rod-end space "~" of hydraulic
cylinder 8 which controls extension of the telescopic boom 1.
Duct 135 is connected to piston-end space "f" of cylinder 8
and duct 134 is connected to piston-end space "L" of hydraulic
cylinder 152.
:
- 15 -
.
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3~
~ s p~eviously descr;bed, anticlockwise turninc3 o~ the
pivot 2 and boom 1 causes hydraulic cylinder 152 to mov~ to the
riyht (in Figure 3) along rod 150.
Servovalve 151 is in the position shown in Figure 9,
so that ducts 134 and 135 in comrnunication with spaces "L" and
:.
"f", respectively, are closed so that working fluid is trapped
in spaces "L" and "f". Thus, movement of the hydraulic
cylinder 152 to the riyh-t is transmitted, by way of the working ~`
fluid trappedfluid trapped in space "L", to piston 96 and
causes rod 93 attached to body 94 of servovalve 95 (i.e.
servovalve 151) to also move to the right. As a result of the ~ -
movement of body 94 relative to plunger 132, duct 138 becomes
connected to duct 135 and working fluid fed into servovalve
g5 ~i.e. servovalve 156) through duct 138 flows into piston
end space "f" of boom extending the con-trolled hydraulic
cylinder 8 via duct 135. The telescopic boom 1 thus becomes
extended.
As fluid flows into piston-end space "f" of cylinder
8, working fluid is forced out of rocl-end space "g" into rod-
end space "i" of hydraulic cylinder 90 (i.e. hydrauliccylinder 152). Consequently piston 96 is moved to the left
:~ . .
(in Figure 3 or 8) and restored to its initial position
- (~igure 9).
`` When fluid is passing into rod-end space "i", fluid
is forced out of piston-end space "L" along duct 134 and into
the return duct 136, which has become connected to duct 134
. . -:
by the movement towards the right relative to plunger 132 of
the body 94 of servovalve 35 (i.e. servovalve 151).
;
In the same way, clockwise movement of the boom and
pivot Z causes movement of body 94 of the left relative to
plunger 132 (in Figure 8 or 9), the connection of duct 138 to
duct 134 to supply working fluid to piston-end space "L" and
- 16 -
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, ~ , , : ' , , ,:. ' '
~3767
tl)e c:onnection of cl~lct 135 to duct 137 Eor return of working
fluid from piston-elld space "f" of the controlled hydraulic
cylinder 8 as the telescopic boom 1 contracts in lenyth.
Preferably, servomechanism 15 controls the extension
of the telescopic boom by means of hydraulic cylinder 8 in
response to lifting of the boom in a vertical planej whilst
servomechanism 17 controls the axial extension of the feed bar
by means of hydraulic cylinder 6 in response to turning of the
boom in a horizontal plane.
It will be appreciated from the above description
that the drilling boom assembly shown in the drawings may be
operated both on an automatic cycle and in an independent
control mode. This considerably extends the capabillties of
the'drilling boom assembly.
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