Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Field of the Invention
This invention relates to a surface mining shovel
having a highly effective crowd mechanism, a high digging
force and a long digging reach. More particularly, the
invention relates to a mining shovel having a handle
mounted on a boom and pivotally moved by a rope hoist and
a hydraulic crowd mechanism which moves the boom to
provide crowd movement for the handle.
Background of the Invention
Surface mining shovels, particularly larger shovels,
utilize wire rope hoists for pivoting the handle on which
the dipper is supported and lifting the dipper. Such
hoists are reliable and have low maintenance. They can
be supported on sheaves at the upper end point o~ a long
boom to provide a long digging reach for the shovel.
Because of the long boom in combination with the rope
hoist, a high cutting force is produced when digging into
high earth banks. Also, the wire rope hoist provides a
high degree of shock absorption during digging compared
to other attachment methods. It further minimizes the
amount of structural weight which must be lifted with
each digging stroke compared to other methods. The crowd
mechanism is typically of a rack and pinion type in which
a bifurcated handle straddling the boom is moved by the
crowd mechanism in the direction of the length of the
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handle outward from the boom. Because of this type of
crowd movement, it has proven to be difficult to provide
a practical method to enable tilting of the dipper
assembly. Consequently, the dipper is fixed in its
position on the end of the handle so that it cannot be
provided with varying pitch positions to optimize the
pitch for different positions in the bank. As a result,
when the handle and dipper are pivoted to a downward
position on the floor of the digging area, the pitch of
the dipper cannot be adjusted to keep the tooth direction
in line with the direction of dipper movement or enab]e
greater dipper movement ability in a linear direction.
Thus, the ability to make an extended cut at floor level
is limited. The lack of dipper pitch adjustment also
limits the shovel in its flexibility to carry out a
number of other digging movements, such as prying
material loose.
During application of crowd force, as the dipper is
moved into the earth material being dug, the opposing
force of the earth material is transmitted back to the
boom. In response, the boom, which is pivotally mounted
on the frame of the shovel, pivots back or "jacks". This
movement of the boom, depending on operator skill, can
limit the amount of crowd force that can be applied and
also causes stressing of the boom support ropes. The
rack and pinion crowd, besides permitting boom jacking,
is a very expensive structure to build and requires some
degree of maintenance skill.
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summary of the Invention
It is general object of this invention to provide
crowd means for a surface mining shovel which prevents
boom jacking when crowd force is applied to the dipper of
the shovel. It is a further object of the invention to
provide a surface mining shovel crowd means which readily
permits the extending of hydraulic fluid lines to the
dipper of the shovel mounted on the handle for
controlling the pitch of the dipper. It is also an
object of the invention to provide a surface mining
shovel with a handle operated by a wire rope hoist which
provides a high digging force and also combines with the
crowd means of the shovel to provide high digging force
adjacent to the floor of the digging area.
The invention is accomplished by providing a surface
mining shovel with a frame including a working end and a
boom extending upward from and pivotally mounted on the
frame adjacent the working end. A handle is pivotally
mounted on the boom and a dipper is mounted on the handle
at a position enabling engagement of the dipper with the
earth material as the handle pivots. Hoist means is
connected to the handle for pivoting it to engage the
dipper with the earth material and lift the dipper.
Crowd means is connected between the frame and the boom
for pivoting the boom and moving the dipper on the handle
into the earth material whereby the earth material enters
the dipper and can be lifted with the dipper as the
handle is pivoted by the hoist means.
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The crowd means is preferably of a hydraulic type
having a cylinder and a piston which is hydraulically
extended from and retracted into the cylinder. The frame
may include a gantry support extending upward and the
crowd means, in such case, is connected to the gantry
support. The hoist means may be connected to the handle
at a location generally above the boom and preferably
comprises a wire rope hoist for pivoting the handle on
the boom. The handle may include an upper section
normally extending a distance above the boom and the
hoist is connected at or adjacent to the outward end of
the upper section of the handle.
During digging movement of the dipper, the boom is
braced by the crowd means against the frame to prevent
jacking movement of the boom in a direction generally
opposite to the digging direction of the dipper and
toward the frame. At the same time, the handle may be
pivoted by the hoist means to move the dipper to dig into
the earth material to provide a high digging force
resulting from the application of both crowd force and
handle pivoting force.
Brief De~cription of the Drawin~
Further objects and advantages of the invention will
appear when taken into conjunction with the accompanying
drawings in which:
FIG. 1 is a perspective view of a surface mining
shovel incorporating the present invention;
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FIG. 2 is a side elevation view of the surface
mining shovel shown in FIG. 1 and illustrating various
positions of the shovel as it moves through digging and
lifting operations;
FIG. 3 is a side elevation view of a surface mining
shovel incorporating an alternate embodiment of the
invention;
FIG. 4 is a plan view of the shovel shown in FIG. 2
with portions of the shovel broken away;
FIG. 5 is a cross-sectional view, with portions
broken away, taken along lines 5-5 of FIG. 2;
FIG. 6 is a cross-sectional view taken along lines
6-6 of FIG. 2; and
FIG. 7 is a cross-sectional view, with portions
broken away, taken along lines 7-7 of FIG. 3.
Detailed Description of the Invention
Referring generally to Figures 1 and 2, a surface
mining shovel is illustrated as having a revolving frame
2 including a base 4, a gantry 6 extending upward from
the base 4, a machinery house 8 mounted on the frame 2,
an operator's cab 10 mounted on the machinery house 8, a
hydraulic supply system 11, and a crawler frame 12 on
which the frame 2 is revolvingly supported. The crawler
frame 12 includes a car body 14, side frames (only one of
which is shown), and an upwardly projecting slewing ring
18. The ring 18 is surrounded by and engages a
downwardly projecting slewing ring 20 which is part of
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the frame 2 to thereby support the frame 2. The frame 2
is revolving driven on the crawler frame 12 by a pair of
electric swing motors and gear drives 22 which engage
teeth along the periphery of the ring 20. The side
frames extend laterally from opposite sides of the car
body 14. A crawler track 24a is supported for continuous
movement on the tumbler of a propel drive 28 and on
rollers 26 mounted on the side frame 16 shown in Figs. 1
and 2. A crawler track 24b is supported on rollers (not
shown) similar to rollers 26 mounted on a side frame
similar to the shown side frame 16 and on a propel drive
(not shown) similar to propel drive 28. Each of the
propel drives comprises an electric motor driven
transmission gear for driving the crawler tracks and
moving the shovel along the ground.
With reference to FIG. 1, 2 and 4, the gantry 6 has
an aft leg 82 affixed to the base 4 and a pair of front
legs 84 and 86 affixed to the base 4 adjacent to a
working or front end 34 of the base. The aft leg 82 has
an upper head 88 to which the front legs are also
affixed.
With reference to FIGS. 1, 2 and 4-6, the surface
mining shovel further includes a boom 30 pivotally
mounted on the base 4 by pins 32 adjacent to the front
end 34 of the base of frame 2, an elongated handle 36
having upper and lower oppositely extending sections 37
and 39 respectively including opposite upper and lower
ends 38 and 40, the handle being pivotally mounted by
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pins 42 on the boom 30 intermediate the ends, and a
dipper 44 pivotally affixed to the lower end 40 of the
handle for digging into and lifting earth material 90. A
hoist 46 is mounted on the frame 2 within the machinery
house 8 and includes an electric motor 48, a rotatable
drum 50 driven by the motor, a pair of hoist ropes 52
connected to the drum 50 and to the end 38 of the handle
by an equalizer 54. The drum 50 is rotated by the motor
to pay the ropes out so that the handle pivots downward
about the boom due to the weight of the handle and dipper
to thereby lower the dipper, i.e., to swing the dipper
counterclockwise relative to the view of FIG. 2. The
drum is also rotatable by the motor to wind the ropes in
or on to the drum to rotate the handle to swing the
dipper clockwise and upward relative to the view of FIG.
2. The dipper 44 comprises a front 56 and a back 58
pivotally connected to the handle 36 at pins 60. The
dipper front 56 is pivotally connected to the back S8 at
pins 62 to allow the back and front to pivotally move
apart about pins 62 and dump any load in the dipper. A
pair of hydraulic cylinders 64, only one of which is
shown, are connected between the back and the front of
the dipper for opening and closing the front and back. A
pair of hydraulic cylinders 66a and 66b are pivotally
connected by pins 68 to handle 36 and by pins 70 to the
back 58 of the dipper. The cylinders 66a and 66b control
the pitch of the dipper to provide it with the desired
angular attitude when the dipper is at a low or
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intermediate height position for digging into earth
material 90, at an intermediate or high height position
for lifting earth material, or at a dumping position. A
pair of hydraulic cylinders 72a and 72b are pivotally
connected to the gantry by pins 78 at the head 88 and
include pistons 74a and 74b pivotally connected by pins
76 to the boom 30. The cylinders 72a and 72b provide
crowd movement for the dipper 44 by pivoting the boom
about pins 32 away from the frame 2 so that the handle
and the dipper on the end 40 of the handle move downward
and away from the frame. The dipper 44 thereby moves
along a path into the earth material 90 to dig into it so
that the earth material enters the dipper. The cylinders
72a and 72b are positioned between the gantry 6 and boom
30 to brace the boom from movement toward the frame and
apply force opposing the force on the dipper from the
earth material in the direction of the boom as the dipper
moves into the earth material. The boom is thus held
firmly by the cylinders 72a and 72b so that it will not
pivot or "jack" bac~ward due to force on the dipper
opposing the crowd movement.
The hydraulic supply system 11 includes at least one
pump such as pump 80 for supplying hydraulic fluid to the
hydraulic cylinders 64, 66a, 66b, 72a and 72b for their
operation. The hydraulic supply system 11 includes hoses
and piping 92 and 94, shown schematically in FIG. 2, from
the pump to the cylinders 64, 64b, 66a, 66b, 72a and 72b.
The system 11 also includes valves, filters, additional
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piping, at least one fluid reservoir, and other devices
required to supply pressurized hydraulic fluid, which are
well-known in the art and are not shown in the drawings.
In the operation of the shovel, with reference to
FIG. 2, the drum 50 is rotated to pay out the hoist
ropes 52 so that the dipper 44 rotates and drops with the
handle 36 about the boom. In conjunction with the paying
out of the ropes 52 to permit the dipper to drop, the
pistons 74a and 74b are retracted into the crowd
cylinders 72a and 72b so that the handle 36 and dipper 44
are in the position a shown in phantom lines in FIG. 2.
The drum 50 may then be rotated to take in the ropes 52
so that the dipper 44 moves along a path from position a
into engagement with the earth material 90 at position b
of the dipper. At the same time, the hydraulic pitch
cylinders 66a and 66b may be operated to adjust the
attitude of the dipper so that the dipper teeth 126
engage the earth material at the desired angular
position, e.g., in a horizontal position. The crowd
cylinders 72a and 72b are then operated to move pistons
74a and 74b outward so that the boom 30 pivots away from
the frame 2. Thereby the handle 36 and dipper 44 also
move away from the frame 2 and the dipper continues
movement along the path from position b into the earth
material to position c shown in phantom lines in FIG. 2
so that the earth material 90 enters into the dipper.
During the crowd movement of the dipper by the boom, the
handle may be held stationary relative to the boom.
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However, if desired, t~e drum 50 may be further rotated
to take in the ropes 52 and pivot the handle and thereby
the dipper 44 about the boom simultaneously with the
operation of the crowd cylinders to increase the force of
the dipper digging into the earth material.
The upper section 37 and lower section 39 of the
handle together have a length greater than that of the
boom 30. Thus, substantial leverage is possible through
the length of the handle from the hoist attachment
location at handle end 38 to the dipper at handle end 40.
Also, the handle can be designed with a length that
provides, with the hoist, a selected dipper digging
force. During the crowd movement of the dipper and also
during the handle pivoting movement of the dipper into
the earth material 90, the resisting force of the earth
material against the dipper will push against the dipper
and handle and thereby the boom to attempt to pivot the
boom or "jack" it toward the frame 2. However, the force
of the crowd cylinders 72a and 72b in a direction
opposing jacking movement of the boom toward the frame
and the bracing of the crowd cylinder against the frame
will prevent the boom from such movement.
After sufficient earth material enters the dipper
44, the drum 50 is further rotated to pivot the handle
about the boom and the hydraulic pitch cylinders 64a and
64b are further operated to tilt the dipper upward to
retain the earth material in the dipper as it is lifted
by the rotation of the drum and pivoting of the handle to
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position d shown in phantom lines in FIG. 2. The dipper
is then lifted further to position e where the revolving
frame 2 then may be swung on the crawler frame 12 by
operation of the swing motors and drive gears 22 to move
the boom, handle and shovel to a dumping location where
the hydraulic cylinders 64a and 64b are operated to open
the dipper and cause the earth material to be dropped
from the dipper.
An alternate embodiment of the invention
incorporated in a surface mining shovel shown in FIG. 3.
In the embodiment of FIG. 3, the components of the shovel
which operate in the same way as the components shown in
FIG. 2 carry the same identifying numerals. Components
of the shovel in FIG. 3 which differ in operation from
those in FIG. 2 are identified with different numerals.
In FIG. 3, a gantry 100 has an aft leg 102 affixed to the
base 4 of the frame 2, and front legs 104 and 106 affixed
to a support 108 adjacent to the front end 34 of the base
4. A boom 110 is pivotally mounted by pins 112 on the
base 4 adjacent to the end 34 and is also pivotally
connected by pins 114 to the handle 36 intermediate the
opposite ends 38 and 40 of the handle. A pair of crowd
cylinders 116a and 116b are pivotally mounted on the head
118 of the gantry 100 and include pistons 120a and 120b
pivotally mounted by pins 122 to the boom 110 adjacent
and end 124 of the boom. The hydraulic crowd cylinders
116a and 116b and their pistons 120a and 120b operate in
substantially the same manner as the hydraulic crowd
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cylinders 72a and 72b and their pistons 74a and 74b shown
in FIG. 2. Thus, the hoist 46 and crowd cylinders 116a
and 116b cooperate to move the dipper 44 to positions a
and b, as shown in FIG. 3. The crowd cylinders 116a and
116b extend the pistons 120a and 120b to pivot the boom
110 away from the frame 2 to thereby move the dipper 44
into the earth material 90 and the hoist 46 pivots the
handle and dipper to positions d and e prior to dumping
the earth material from the dipper.
The reacting force of material 90 against the dipper
44 attempts to jack the boom 110 about the pins 112
toward the frame 2 during digging of the dipper into the
earth material. However, the force of the cylinders 116a
and 116b in the direction of the reactive force caused by
the material 90 resists and prevents the jacking movement
of the boom 110. The connection of the pistons 120a and
120b adjacent the end 124 of the boom, at a location
relatively close to the pivot pins 42 at which the handle
is mounted on the boom, decreases the amount of bending
stress on the boom 110 as compared to the amount of the
stress on the boom 30 in the embodiment of the invention
illustrated in FIG. 2. Also, the attachment of the
gantry 100 adjacent the end 34 of the base 4 simplifies
the machinery house structure because the gantry does not
project through the machinery house. Further,
positioning the gantry at the working end 34 of the base
permits shorter length crowd cylinders 116a and 116b.
This results in relatively greater rigidity of the crowd
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and boom structure, particularly when the crowd pistons
are extended, and permits a lower volume and lower
pressure hydraulic fluid system.
The invention described herein provides a highly
effective apparatus and method for preventing boom
jacking of a surface mining shovel. The crowd mechanism
is further arranged to provide a particularly high level
of crowd force. The crowd mechanism according to the
invention eliminates the common prior art rack and pinion
crowd mechanism and, as a consequence, permits hydraulic
fluid connections between the machinery house of the
shovel and the handle so that hydraulic pitch adjustment
is available for the dipper of the shovel. The invention
also includes a wire rope hoist arrangement in which the
rope is attached directly to an end of the handle to
provide a long lever arm and high digging and lifting
force for the dipper. The durability of the hoist ropes
is enhanced by the elimination of boom jacking by the
crowd mechanism to thereby correspondingly eliminate
hoist rope shock due to the jacking movement.
It will be understood that the foregoing description
of the present invention is for purposes of illustration
only and that the invention is susceptible to a number of
modifications or changes, none of which entail any
departure from the spirit and scope of the present
invention as defined in the hereto appended claims.
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