Note: Descriptions are shown in the official language in which they were submitted.
~118~6
BACKGROUND OF THE INVENTION
1~ Field of the Invention
This invention relates to a material handling vehicle
for use in undergound mining operations and more particularly
to a self-propelled mine vehicle having a telescoping boom
member that is arranged to position a material handling device
secured to the end of the boom member in a preselected lateral
and vertical position for performing material handling opera-
tions in a ~,ine.
,, ,
~2. Description of the Prior Art
In underground mining operations it is the customary
practice to move equipment and materials into and out of the
mine by conventionally known methods using devices such as
~chain5, pulleys, hoists and the like. Particularly in the as-
sembly and disassembly of longwall mining systems various com-
ponents such as pans, cribbing, roof supports and conveyors
must be transported into the mine entry and maneuvered into
position adjacent the mine face. This requires a number of
material handling operations which require the coordinated
effort of the erection crew. In a mine where the working area is
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1~ 06
limited and the visibility is restricted, substantial pre-
cautions must be taken in coordinating the movement of men and
materials in order to prevent serious injury to operating
personnel. Such is the case when material and equipment are
towed into position by conventional block and tackle means
extending a considerable distance in the mine where the con-
ditions make it difficult for the operator of the prime mover
to make certain that the entry is clear before the equipment is
moved. Consequently, due to the disadvantages of conventional
known material handling devices and methods that are utilized
in the mine, serious injuries to operating personnel have
occurred while moving equipment in the mine.
Therefore, there is need for a multipurpose, self-
propelled material handling device that i5 maneuverable in a
mine to safely and efficiently perform a variety of material
handling operations.
~18~6
SUMMARY OF THE INVENTION
In accordance with the present invention there
is provided a material handling vehicle for use in an
underground mine that includes a mobile body and a boom
assembly that extends from the mobile body. The boom
assembly has a first end portion positioned adjacent the
mobile body and a second end portion spaced from the first
end portion and extending from the mobile body. A pivot
pin is secured to the mobile body and extends upwardly
therefrom. The boom first end portion is pivotally
connected to the upwardly extending pivot pin. A first
actuating device is mounted on the mobile body and is
connected to the pivot pin for pivoting the boom assembly
laterally relative to the mobile body. First connecting
apparatus is provided to secure the boom assembly first
end portion to the mobile body to permit upward and
downward movement of the boom assembly relative to the
mobile body. A second actuating device is connected at
one end to the upwardly extending pivot pin and is con-
nected at the other end to the boom assembly first end
portion for raising and lowering the boom assembly to
effect upward and downward movement of the boom assembly
18;~6
independent of the pivotal movement of the boom assembly.
A material engaging device is connected to the boom
assembly second end portion for engaging material to be
lifted and moved by the boom assembly. The material
engaging device includes a hook member having an elongated
shank and a hooked end portion. A retainer is pivotally
connected to the boom assembly second end portion for
upward and downward pivotal movement about a horizontal
axis. The retainer has a socket for rotatably receiving
the hook member shank. The hook member is supported by
the retainer for rotational movement about the elongated
axis of the shank. Second connecting apparatus connects
the retainer to the boom member second end portion. The
second connecting apparatus i8 secured to the boom member
~econd end portion. Extensible means is provided for
extending and retracting the boom assembly second end
portion relative to the boom assembly first end portion.
The extensible means has an end portion secured to the
second connecting apparatus.
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A
~i~18-~J6
The boom assembly first end portion is formed by an
elongated channel-shaped member that is pivotally secured by
the connecting apparatus to the pivot arrangement~ The channel-
shaped member is pivotal through a vertical plane about a
horizontal axis formed by the pivot arrangement~ The boom
channel-shaped first end portion has an open end opposite the
end that is pivotally connected to the pivot arrangement~ The
boom assembly second end portion extends through this open end
in a manner to permit slidable movement of the boom assembly
second end portion relative to the boom assembly first end
portion~
The boom assembly second end portion also has an
elongated channel-shaped configuration similar to the boom
assembly first end portion~ The cross sectional area of the
boom assembly first end portion is greater than that of the
boom assembly second end portion to permit extension and
retraction of the second end portion relative to the first end
portion~ A piston cylinder assembly is disposed within the
boom assembly second end portion and is secured ~t its end
portions to the respective portions of the boom assembly~ With
836
this arrangement actuation of the piston cylinder assembly is
operable to move the boom assembly second end portion in a
telescoping manner relative to the boom assembly first end
portion and thereby change the effective length of the boom
member.
The material engaging device is securely engaged to
the outer end portion of the boom assembly second end portion.
Preferably, the device includes a hook member rotatably posi-
tioned within a socket that is pivotally connected to a bracket
member secured to the end of the boom assembly. The hook
member is operable to assist in performing a number of lifting
and moving operations in a more efficient manner than presently
available with conventional apparatus and methods now used in
underground mining operations.
The pivot arrangement includes a pin member that is
preferably secured to a frame member that projects forwardly
of the mobile body. A pivot housing surrounds the pin member
and includes outwardly extending portions that are connected to
a pair of piston cylinder assemblies that are pivotally mounted
on the mobile body. The boom assembly first end portion is
connected for pivotal movement about a horizontal axis to the
pivot housing~ Upon the coordinated extension and retraction
of the pair of piston cylinder assemblies, the pivot housing is
pivoted about the vertical axis of pin member to, in turn,
pivot the boom assembly about the vertical axis of the pin
member~ This arrangement permits the boom assembly to be
swung laterally about the pin member at the forward end portion
of the mobile body~
The swinging movement of the boom assembly is
,
accomplished independently of the upward and downward movement
of the boom assembly~ Upward and downward movement of the boom
assembly is accomplished by operation of the second actuating
device which preferably includes a piston cylinder assembly
connected at one end to the pin member of the pivot arrangement
and at the opposite end to the boom assembly first end portion~
Extension and retraction of the second act~ating device effects
upward and downward movement of the entire boom assembly~ By
extending the boom assembly a preselected length, the material
engaging device at the end of the boom assembly is moved to a
preselected height relative to the mobile body~ This movement
~ili8~6
is coordinated with the lateral swinging movement of the boom
assembly to position the material engaging device at a pre-
selected vertical and lateral position at the front of the
mobile body~
The mobile body is propelled by ground traction
devices which are driven by a suitable prime mover~ An
operator's station provided on the mobile body safely positions
an operator for controlling tramming of the vehicle and the
lateral and upward and downward movement of the boom assembly
to perform a number of material handling operations
Accordingly, the principal object of the present
invention is to provide a material handling vehicle operable
in underground mining operations and including a boom assembly
that is positioned for upward and downward and lateral swinging
movement on a mobile body to facilitate efficient handling of
material and equipment in an underground mine~
Another object of the present invention is to provide
a self-propelled mine vehicle that is maneuverable to a pre-
selected location in an underground mine and is operable by a tele-
scoping-type boom member to perform material handling operations
by laterally swinging and raising and lowering the boom member~
806
;
A further object of the present invention is to
provide a self-propelled mine recovery vehicle in which an
operator is safely positioned on the vehicle to operate a
telescoping-type boom member arranged to move a material
handling device horizontally and vertically to preselected
positions in performing material handling operations in the
mine.
These and other objects of the present invention will
be more completely disclosed and described in the following
specification, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRA~INGS
Figure 1 is a top plan view of a self-propelled
; vehicle for use in underground mining operations for performing
material handling operations, illustrating a telescoping boom
assembly having a material engaging device secured to the end
psrtion thereof and movable upwardly and downwardly and lat-
erally on the vehicle~
~ Figure 2 is a view in side elevation of ~he material
; handling vehicle shown in Figure 1, illustrating the boom
assembly in a retracted position and extending substantially
horizontally and fowardly of the vehicle.
i:
llil8~)6
Figure 3 is a fragmentary plan view, partially in
section taken along line 3-3 of Figure 2, illustrating a piston
cylinder assembly housed within the boom assembly and operable
to extend and retract the boom assembly to position the mat-
erial engaging means a preselected distance from the vehicle~
Figure 4 is a fragmentary view in side elevation of
the front end of the material handling vehicle, illustrating in
phantom the piston cylinder assembly for extending the boom
assembly and the piston cylinder assembly for raising and
lowering the boom assembly~
Figure 5 is a fragmentary top plan view of the front
end of the material handling vehicle, illustrating the boom
~
assembly pivoted laterally in a retracted position from a
position illustrated in phantom~
Figure 6 is a fragmentary view in side elevation of
the boom assembly, illustrating the boom assembly in a re-
tracted position and a hook member which comprises the material
engaging device and is secured to the end of the boom assembly~
Figure 7 is a fragmentary end view of the boom
assembly shown in Figure 6, illustratîng the arrangement for
pivotally and rotatably connecting the hook member to the end
of the boom assembly~
--10--
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, and particularly to
Figures 1 and 2, there is illustrated a material handling
vehicle generally designated by the numeral 10 for use in
underground mining operations or in any type of underground
excavation work. The material handling vehicle 10 includes a
mobile body portion 12 having a longitudinally extending frame
14. The frame 14 has a front end 16 and a rearward end 18~
The frame 14 of the mobile body 12 is mounted on ground en-
gaging traction devices 20, such as a pair of propelling
endless tracks 22 and 24~ Each of the tracks 22 and 24 are
reeved about a drive sprocket 26 and an idler sprocket 28 with
idler rollers 30 supported by a frame 32 that extends between
and is connected to the sprockets 26 and 28. The idler rollers
30 support the upper and lower reaches of the endless track as
it turns in a preselected direction upon rotation of the driven
sprocket 26~
The drive sprocket 26 for each endless track 22 and
24 is drivingly connected, in a manner not shown, to a suitable
prime mover 34, such as an electric motor which is secured to
vehicle frame 14. Electrical power is supplied to the motor 34
,~
through an electrical cable 36 wound upon a cable reel 38 by a
spooling device 40. The cable reel 38 is mounted on the
rearward end 18 of the frame 14 adjacent an operator's station
generally designated by the numeral 42. The operator's station
includes an overhead canopy 44 that is raised and lowered by
piston cylinder assemblies 46 as determined by the overhead
clearance provided between the top of the vehicle lO and the
mine roof. The operator's station is provided with controls
for propelling and steering the vehicle, as well as for carry-
ing out the material handling operations performed by the
vehicle lO in accordance with the present invention.
The motor 34 is also employed for operating a fluid
pump 48 that supplies fluid under pressure to the various fluid
operated devices on the vehicle l~, such as the fluid actuated
piston cylinder assemblies provided on the mobile body 12 and
to be described later in detail. The fluid pump 48 supplies
fluid, such as hydraulic oil, from a tank 50 mounted on the
frame 12 through conventional hydraulic conduits ~not shown) to
the various fluid operating devices. The controls for supplying
fluid to the fluid operated devices are provided at the
operator's station 42, together with the electrical controls by
which the speed and direction of movement of the vehicle 10 is
controlled..
A telescoping boom assembly, generally designated by
the numeral 52, extends forwardly from the front end 16 of
frame 14 and is supported thereon by a pivot arrangement 54 for
carrying out lateral swinging movement of the boom assembly 52.
The boom assembly 52 includes a first portion 56 that is
secured to the pivot arrangement 54 by connecting apparatus ~8
in a manner to facilitate upward and downward movement of the
entire boom assembly 52~. A second end portion 60 of the boom
assembly 52 is extensible out of and into the boom first end
portion 56 and includes at its outer end portion a material
engaging device, generally designated by the numeral 62. As
will be described in greater detail, material engaging device
62 is utilized to perform a number of material handling opera-
tions encountered in underground mining,.
The material handling device 62 is moved by boom
assembly 52 relative to the mobile body 12. Lateral movement
of the boom assembly 52 is accomplished through the pivot
1~118~6
,,
arrangement 54 by operation of a pair of fluid actuated de-
vices, such as piston cylinder assemblies 64 and 66~ Each of
the assemblies 64 and 66 includes a cylinder portion 68~ The
cylinder portion 68 includes a connecting end portion 70 having
a lug 72 extending upwardly therefrom, in which the lug is
received within a longitudinal slot 74 of a bracket number 76~
The bracket member 76 is securely mounted to the vehicle frame
14~ This arrangement provides for pivotal movement of the
cylinder portion 68 during its operation~ The opposite end
portion of each of the assemblies 64 and 66 includes a piston
rod 78 that is extensible from the cylinder portion 68 and is
secured at its outer end portion to the pivot arrangement
54~
The piston cylinder assemblies 64 and 66 are operable
in pairs to effect lateral swinging movement of the boom assem-
bly 52 at the front end 16 of frame 14~ Thus in a manner to be
explained further in greater detail to swing the boom assembly
52 laterally in a clockwise direction on the frame 14, assembly
66 is actuated to extend its piston rod 78 from the cylinder
68; while the piston rod 78 associated with assembly 64 is re-
tracted into the cylinder portion 68~ Preferably, a single
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8~6
',
control is operable to effect the coordinated extension and
retraction of the piston rods of the assemblies 64 and 66~
Conversely, to swing the boom assembly 52 laterally in a
counterclockwise direction the piston rod of assembly 64 is
extended and the piston rod of assembly 66 is simultaneously
retracted.
Independently of the laterally swinging movement of
the boom assembly 52, the boom assembly is also operable to
move upwardly and downwardly to position the material gathering ,
device 62 at a preselected elevation relative to the frame 14
or relative to the mine floor and roof~ Upward and downward
movement of the boom assembly 52 is accomplished by a fluid
actuated device, such as piston cylinder assembly 80 having a
cylinder portion 82 and a piston rod 84 movable into and out of
the cylinder portion 82~ The cylinder portion 82 is pivotally
connected at its end portion 86 by a clevis-type connection 88
to the pivot arrangement 54~ The outer end of the piston rod
84 is also connected by a clevis-type connection 81 to the boom
assembly 52 and more specifically to the outer end of the boom
assembly first end portion 56~ ~ith this arrangement extension
and retraction of the piston rod 84 is operable to move the boom
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8~6
assembly 52 together with the material handling device 62
upwardly and downwardly as the end portion of the boom assembly
52 adjacent the pivot arrangement 54 pivots about the connect-
ing apparatus 58 that connects the boom assembly 52 to the
pivot arrangement 54~ Thus the boom assembly 52 is movable
both vertically and laterally in an arcuate path at the front
end of the mobile body 12~
Referring to Figures 3 and 4 there is illustrated in
greater detail the construction of the boom assembly 52 and the
manner in which the boom assembly is extended and retracted~
As stated hereinabove, the boom assembly first end portion 56
has a channel configuration formed by laterally spaced side
plates 90 and 92 which are suitably connected to a top plate 94
and a bottom plate 96. The top plate 94 has been removed in
Figure 3 for purposes of illustration~ This arrangement forms
a rectangular shaped channel for receiving the boGm assembly
second end portion 6a~ The second end portion 60 has laterally
spaced side plates 98 and 100 connected to laterally spaced top
and bottom plates 102 and 104 respectively~ The plates 98-104
thus form a rectangular shaped channel having a cross-sectional
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11118Q6
i~
!
area which is less than the cross-sectional area formed by the
~plates of the boom assembly first end portion 56. This permits
¦slidable movement of the boom assembly second end portion 60
¦relative to the boom assembly first end portion 56 to provide
the telescoping feature of the boom assembly 52~
In Figure 3, the boom assembly second end portion 60
i6 shown retracted within the boom assembly first end portion
56 and the top plates 94 and 102 removed to illustrate a fluid
actuated device, such as piston cylinder assembly 106. The
assembly 106 is operable upon actuation to extend and retract
¦the second end portion 60 relative to the first end portion 56
and thereby change the effective length of the boom assembly
I52. The assembly 106 includes a piston cylinder 108 and an
¦~extensible piston rod 110~ The cylinder 108 has an end portion
112 with a bore therethrough, and the end portion 112 is
aligned with a pair of coaxially positioned bosses 114. The
bosses 114 are secured to the inner surfaces of side plates 90
and 92. A pin member 116 extends through aligned bores of the
side plates 90 and 92, the bosses 114 and the ènd portion 112.
¦¦With this arrangement the end portion of the piston cylinder
¦~assembly 106 is secured for moYement with the boom assembly
first end portion 56.
,i .
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.
,
It is to be noted, as illustrated in Figure 4, that
the ends of side plates 98 and 100 of the boom assembly second
end portion 60 are provided with arcuate recesses 118. With
this arrangement the recesses 118 permit the boom second enæ
portion 60 to be fully retracted within the boom first end
portion 56 ~ithout interference by the pin 116 at the inner end
of the boom second end portion 60.
The outer end of the piston rod 110 of assembly 106
'includes an enlarged end portion 120 having a bore there-
through, which is aligned with bores extending through a pair
of ears 122. The ears 122 are secured to the boom second end
portion 60~ A pin 124, illustrated in Figure 4, extends
through aligned bores of rod end portion 120 and ears 122 to
secure the piston rod llO to the boom second end portion 60.
~Thus upon actuation of the piston cylinder assembly 106,
extension of the piston rod 110 from the cylinder 108 extends
the boom second end pGrtion 60 relative to the boom first end
portion 56. Accordingly, retraction of the piston rod 110 into
~the cylinder 108 retracts the boom second end portion 60 into
the boom first end portion 56~ In this manner the boom assem-
~bly 52 is adjustable to a preselected length.
.~
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111~6
~ As illustrated in Figures 3 and 4 and in greater
;detail in Figures 6 and 7, the material handling device 62 is
secured to the outer end of the boom assembly second end
portion 60. The outer end of the boom assem~ly second end
portion 60 includes a plate member 126 that is suitably secured
to the side plates 98 and 100 and the top and bottom plates 102
and 104. A plate 128 is secured by bolts 130 to the plate 126.
The pair of ears 122 extend through aligned slots cut in plates
126 and 128 and are suitable welded thereto to secure the pair
of ears 122 to the plates 126 and 128. The end portion of the
ears 122 that extends beyond the plate 128 is connected to the
material handling device 62.
The material handling device 62, as illustrated in
Figures 6 and 7, includes a hook member 132 having a shank por-
tion 134 extending upwardly from the hooked end with an enlarged
end portion 136 at the upper end of the shank 134~ The shank
portion 134 extends through a bore of a retainer 138 having a
socket 140 for receiving the end portion 136 so that the end
portion 136 is rotatably positioned ~ithin the socket 140 to
permit 360~ rotation of the hook 132. The upper portion of the
11118~6
retainer 138 is pivotally connected by a pin 142 to the outer
end of the pair of ears 122~ The pin 142 extends through the
bore of the retainer 138 and the bores of the ears 122 that
extend beyond the plate member 128.
The hook member 132 may be swung upwardly and down-
wardly about the horizontal axis formed by the pin 142, as well
as rotated about the axis of the shank 134~ This arrangement
provides a versatile means by which a number of lifting,
pulling and other material handling operations may be per-
formed~ It should be understood, however, that the hook member
132 is only an illustration of one type of material handling
device that may be incorporated in the present invention, and
other suitable devices may be utilized with the present inven-
tion to perform various material handling operation encountered
in underground mining operations~
As illustrated in greater detail in Figures 6 and 7,
the piston rod 84 of piston cylinder assembly ~0 is connected
as above discussed to the outer end of the boom assembly first
end portion 56 by the clevis-type connection 89~ The connection
89 includes an enlarged end portion 143 of the end of piston
- 20 -
rod 84. A flange 144 extends around the end of the boom
assemb1y first end portion 56 and includes an upper end portion
with a pair of laterally spaced projections 146 having aligned
bores therethrough. The piston rod end portion 143 includes a
bore which is axially aligned with the bores of projections 146
so as to permit a pin 148 to be extended through the aligned
bores to thereby secure the piston rod end portion 143 to the
projections 146 and thereby connect the end of the piston
cylinder assembly 80 to the boom assembly 52.
The cylinder portion 82 of the assembly 80 is con- :
nected by the clevis-type connection 88 to the pivot arrange-
ment 54. The pivot arrangement 54 includes a vertically extend-
ing pin 14B that is secured at its lower end portion to the front
end 16 of mobile body frame 14. The connection 88 includes a
collar 150 that is positioned in surrounding relation with the
upper end portion of pin 148 and rotatable relative thereto.
A pair of ears 152 of the collar 150 extend forwardly from the
pin and the end 86 of cylinder portion 82 is positioned between
the ears 152 so that bores extending through the ears and cy-
linder end portion 86 are aligned to receive a pivot pin 154. In
8~6
this manner the cylinder portion 82 is connected to the collar
150, and the collar 150 is arranged to pivot about the pin 148
to permit the piston cylinder assembly 80 to move laterally
with the boom assembly 52 upon actuation of the piston cylinder
assemblies 64 and 66.
The pivot pin 148 is securely mounted to the front
end 16 of mobile body frame 14 by a pair of brace members 156
and 158~ One end of each brace member 156 and 158 is secured
to the frame 14 and the opposite end portion is suitably
secured to a plate member 160 that is secured as by welding to
the pin member 148 and extends rearwardly therefrom. The end
portions of the brace members 156 and 158 may be secured to the
plates 160 by bolting~ With this arrangement the pivot pin 148
iæ securely supported in a vertical position on the front end
16 of the mobile body frame 14.
A swivel housing 162 surrounds the lower end portion
of the pivot pin 148 and includes a base member 164 that is
movably positioned on the frame 14 to permit pivoting of the
housing 162 about the pivot pin 148. The base member 164
includes outwardly extending end portions 166 and 168~ The
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end portions 166 and 168 are connected to the end portions of
piston rods 78 of the piston cylinder assemblies 64 and 66
respectively,
Each of the base member portions 166 and 168 includes
an elongated slot 170 arranged to receive a pin 172 that is
secured to and extends upwardly from the end portion of each of
the piston rods 78. With this arrangement the pins 172 are
ovable in the slots 170 to permit the piston cylinder assem-
blies 64 and 66 to pivot relative to the base member portions
166 and 16~ as the assemblies are extended and retracted to
pivot the base member 164 and swing the boom assembly 52
laterally on the frame 14~
~ he lateral swinging movement of the boom assembly 52
by operation of the pivot arrangement 54 is illustrated in
greater detail in Figure 5 where the boom assembly 52 is
illustrated in phantom extending forwardly from the frame 14 in
a position aligned with the longitudinal axis of the frame 14.
Actuation of the piston cylinder assemblies 6~ and 66 pivots
the boom assembly 52 in a clockwise direction from the position
illustrated in phantom by extension of the piston rod of assembly
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~1`18~
.
,,
66 and retraction of the piston rod of assembly 64. Extension
and retraction of the respective assemblies takes place simul-
taneously. The cylinder portions 68 of each assembly pivot
about their connections to the mounting brackets 76 as the
piston rods 78 are extended and retracted and the housing 162
pivots about the pivot pin 148~ As the boom assembly 52 pivots
about the vertical axis formed by pivot pin 148, the piston
cylinder assembly 80 connected at one end to the boom assembly
52 pivots at its opposite end about the pivot pin 148~
The boom assembly 52 is also arranged for upward and
downward pivotal movement about a horizontal pivotal axis
formed by the connection of the boom assembly 52 to the pivot
arrangement 54. This connection is illustrated in detail in
Figures 3 and 4. The end of the boom assembly first end
portion 56 adjacent the vertical pivot pin 148 includes a pair
of rearwardly projecting portions 174 that are received within
slots formed by a conventional clevis 176. The clevis 176
extends forwardly from the pivot housing 162~ The projection
portions 174 and clevis 176 have aligned bores for receiving a
pivot pin 178 that is securely retained within the aligned
bores in a conventional manner. With this arrangement the boom
assembly first end portion 56 is arranged to pivot about the
horizontal axis formed by the pivot pin 17g ~pon actuation of
the piston cylinder assembly 80~
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~1118~6
As illustrated in Figure 4, retraction of the piston
rod 84 into the cylinder portion 82 pivots the entire boom
assembly 52 upwardly about the pivot pin 178 to thereby raise
the hook member 132 at the end of the boom assembly second end
portion 60~ Lowering the boom to the position illustrated in
Figure 2 is accomplished by extending the piston rod 84 from
the cylinder portion 82~ As discussed hereinabove the upward
and downward pivotal movement cf the boom assembly 52 is
accomplished independently of the lateral swinging movement of
the boom assembly 52. In this manner the hook member 132 is
selectively positioned at a preselected elevation and at a
preselected lateral position relative to the mobile body frame
14~
Thus, in operation for example in moving the compo-
nents of a longwall mining system into position at the mine face,
the boom assembly 52 is safely and efficiently operated to posi-
tion the hook member 132 for engaging the piece of equipment to
be moved. Movement of the equipment is accomplished by tramming
of the vehicle 10 where the vehicle operator has a clear view of
the equipment to control its movement in a safe manner through
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111~6
.~ `
the mine. At all times movement of the boom assembly 52 and
the vehicle 10 is controlled by the operator from the protected
operator's station 52. This arrangement substantially reduces
the hazards encountered with conventional material handling
devices and techniques used in the past in underground mining
operations.
According to the provisions of the Patent Statutes,
we have explained the principle, preferred construction and
mode of operation of our invention and have illustrated and
described what we now consider to represent its best embodi-
ments. However, it should be understood that, within the scope
of the appended claims, the invention may be practiced other-
wise than as speciiically illustrated and described.
.,
,
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