Note: Descriptions are shown in the official language in which they were submitted.
590
DESCRIPTION
SCRAPER ELEVATOR DRIVE MO~NTING
This invention relates in general to
conveyor systems and, in particular, to a heavy duty
conveyor system such as used as an elevator on a
carry-type scraper wherein the elevator is used to
move material into the scraper bowl.
More specifically, but without restriction
to the particular use which is shown and described,
this invention relates to a mounting for a conveyor
or elevator drive to prevent elevator sprocket shaft
load-initiated deformation or deflection, and torsional
vibration, from causing undue stress on the drive
mechanism and particularly on the gear reduction
output shaft and bearings contained therein.
Proper alignment between the drive mechanism
and an elevator sprocket shaft driven therefrom is
particularly important in heavy duty conveyor systems.
Rigid mounting of the gear housi~g, which contains
drive reduction gears and an output shaft for coupling
to the sprocket shaft, has been found to be undesirable.
The sprocket shaft, being relatively long, must be
supported for rotation at both laterally positioned
ends and be close coupled at one end to the geared
driveshaft. Such a shaft and gear reduction housing
combination is frequently subjected to misalignment
stresses caused by both manufacturing variations
when the parts are produced and operational induced
loading. Further misalignment is caused by bending
loads imposed on the elevator frame and the sprocket
shaft. These induced stresses occur along with
torsional vibrations which occur when the elevator
moving material into the scraper bowl strikes rocks
or other such material and frequently results in
damage to the elevator system.
Scrapers generally include a box~type
structure, referred to as a "bowl, n open at its
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forward end with the bottom or floor of the bowl
having an adjustable forward cutting edge adapted to
cut a predetermined amount from the upper surface of
the ground. The bowl is normally open at its forward
end so that the material cut by the cutting edge as
it moves through the ground will pass into the bowl.
However, as the material is cut it accumulates
adjacent to the cutting edge and does not spread
uniformly throughout the scraper bowl. Therefore, a
conveyor or flight-type elevator must be carried
within the bowl and positioned above and to the rear
of the cutting edge to receive the material as it is
passed into the forward portion of the bowl to move
it both rearwardly and upwardly for more complete
filling.
These elevators generally comprise a pair
of rigidly joined side frame members extending the
full length of the elevator and carrying idler
wheels at the lower forward end and sprockets at the
upper rear end which engage endless link-type chains
of a flight-type elevator. Such elevators are
normally provided with a mounting frame structure
carried on the scraper bowl which permits floating
action of the elevator over dirt or material entering
the bowl to prevent damage to the elevator or cutting
edge when a large stone or other object is hit by
the scraper. However, while such structure prevents
damage by permitting the elevator to float when
large stones or hard material is hit repeatedly,
hitting these stones causes torsional vibrations in
the drive system frequently damaging the elevator
flights because of the rotating inertia of the drive
mechanism. Also sprocket shaft deflection, caused by
the same action that causes toxsional vibration, as
well as the occasional trapping of rocks or stones
between the sprocket shaft and one or more of the
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elevator flights, causes deflection of the shaft and
misalignment resulting in severe loading of bearings
located between the driving mechanism and the driven
sprocket shaft.
Other prior art elevator drive mechanisms
are resiliently supported on the elevator frame
which, to some extent, overcomes some of the adverse
effects of the aforementioned sprocket shaft deflection.
For example, U.S. Patent No. 3,543,915 discloses a
pivot connection mounting of the drive mechanism on
the elevator frame and U.S. Patent No. 3,046,859
discloses a similar mounting structure.
Another attempt to provide a solution to
these problems is disclosed in U.S. Patent No.
3,738,031 wherein a drive mechanism is pivoted for
rocking movement about the elevator drive shaft,
and includes a spring positioned between the drive
mechanism housing and a frame to permit limited
rocking in response to reaction torque which is
incurred when shock loads are encountered by the
elevator.
While the prior art has provided improved
structures to solve the problems of misalignment
and torsional vibration, the present invention
solves the problem to a greater extent by a simple
rugged structure. While this invention is believed
to have general applications to all types of
conveyor systems, for convenience of illustration,
a preferred embodiment will be described with0 reference to its use in the elevator of a scraper.
SUMMARY OF THE INVENTION
It is, therefore, an object of this
invention to improve scraper elevator systems.
Another object of this invention is to
improve the torsional vibration damping means of
scraper elevator systems.
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A further object of this invention is to improve
the mounting of the elevator drive mechanism of scraper
elevator systems so that misalignment between drive and
driven members of the system is prevented.
These and other objects are obtained in accordance
with the present invention wherein there is provided an
elevator drive mounting for a scraper elevator system which
absorbs torsional vibrations generated by the elevator
material loading function and, coincident therewith, main-
tains axial alignment between the driving and driven members
of the drive mechanism.
According to the above objects, from a broad
aspect, the present invention provides a mounting for drive
gear assembly operatively connected to a drive sprocket
assembly of a flight-type elevator for isolating torsional
stresses incurred during loading of material comprising a
material loading elevator means including an elevator frame
and a plurality of material conveying flights supported
thereon for movement in a predetermined endless path of
movement for loading materials, said plurality of material
conveying flights being supported by said elevator frame
upon a rotatable drive sprocket assembly and rotatable idler
wheels carried by said elevator frame, said drive sprocket
assembly having a driven and operatively connected to a
drive gear assembly for rotating said drive sprocket assembly
to move said plurality of material conveying flights in an
endless path of movement, a cantilevered support arm carried
by said elevator frame for supporting said drive means, said
cantilevered support arm being supported by mounting means
upon said elevator frame to effect movement in a plane
transverse to the rotational axis of said drive sprocket
assembly in response to a predetermined force being applied
to one of said plurality of material conveying flights
during loading of material, said mounting means comprising
a bushing block which torsionally rotates about a longitu-
dinal axis through a resilient bushing.
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DESCRIPTION OF THE DRAWI~GS
Further objects of the invention, together
with additional features contributing thereto and advan-
tages accruing therefrom, will be apparent from the
following description of one embodiment of the invention
when read in conjunction with the accompanying drawings
wherein:
FIG. 1 is a horizontal planar view of a portion
of a scraper elevator to illustrate the drive mounting
system,
FIG. 2 is an enlarged profile view of a portion
of the apparatus shown in FIG. 1 to better illustrate the
drive torque reaction connection to the elevator frame;
FIG. 3 is an enlarged horizontal planar view of
a portion of the drive mounting of FIG. 1 to better illus-
trate the mounting thereof,
FIG. 4 is an enlarged view of a portion of the
resilient connection shown in FIGS. 2 and 3 which provides
damping of torsional vibrations, and
FIG. 5 is a sectional view along the line 5-5 of
FIG. 3 to better illustrate the axially aligned drive
mounting and coupling.
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DESCRIPTION OF A PREFERRED EMBODIMENT
Although this invention may be used in
many conveying systems for varying applications, for
convenience of illustration the preferred embodiment
is described with reference to its use with a scraper
elevator. While the scraper does not form any part
of this invention it is believed that a general
description of an earthmoving scraper will assist in
a better understanding of this invention.
A scraper generally comprises a pair of
vertical side walls spaced one from the other by a
bottom and a rear wall to define a bowl having an
open front end. The scraper bowl is supported at
its rear end by a pair of wheels, and at its front
end by a connection to a draft vehicle, such as a
tractor, which pulls the scraper over the ground.
The scraper bowl includes a cutting edge at the
front end of the bottom which excavates a predetermined
amount of material as the tractor pulls the scraper
over the ground.
The amount of material removed from the
ground as the scraper passes thereover is controlled
by raising or lowering the cutting edge carried at
the front end of the bowl. The excavated material
will thereafter pass into the scraper bowl as the
scraper is pulled forwardly. Since the excavated
material has a tendency to pile up and accumulate in
the forward portion of the bowl, an endless conveyor
or elevator mechanism 100, shown in FIG. 1 and
incorporating the subject of this invention, is
carried within the bowl adjacent the front end and
cutting edge. During excavation, an endless chain
conveyor 150 of the conveyor mechanism 100 moves the
excavated material upwardly and rearwardly into the
bowl to obtain more complete filling and uniform
material distribution.
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As best shown in FIG. 1, the conveyor
elevator 100 includes drive sprocket and idler wheel
assemblies 120 and 140, respectively, rotatably
journaled between two spaced parallel frame members
101 and 102 to define the run length of the conveyor.
The two spaced parallel frame members 101 and 102
form a frame which is supported between the side
walls of the scraper bowl. The endless chain conveyor
150 extends about the drive sprocket and idler wheel
assemblies and includes a plurality of drag bars or
flights 151 which are appropriately secured to
conveyor chains 152.
The idler wheel assembly 140 is rotatably
supported between the frame members 101 and 102 at
the lowermost end of the conveyor by means of suitably
sealed bearings. A pair of idler wheels 141 are
secured to an idler spool 142 to be freely rotatable
in unison with the idler spool 142 in response to
movement of the endless chain conveyor 150 through
the excavated material.
The drive sprocket assembly 120 includes a
pair of sprockets 121 secured to a rotatable hollow
sprocket shaft 122 for driving the endless chain
conveyor 150. The drive sprocket assembly 120 is
supported from the uppermost end of the elevator and
is driven by a drive gear assembly 110 operatively
connected thereto which transmits the power from a
drive motor, not shown, to the drive sprocket assembly
120 for moving the endless chain conveyor 150 in its
endless path of movement through the excavated
material. One end of the drive sprocket assembly
120 is in driven engagement with the drive gear
assembly 110, hereinafter referred to as the driven
end.
As best shown in FIGS. 2, 3, and 5, the
drive gear assembly 110 is pivotally supported by a
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support bracket 117 and retainer cap 118 from frame
members 101 by means of a collar or quill 119 fixed
to a troque arm 125. The opposite or free end of
the drive sprocket assembly 120 i5 supported on
frame member 102 by means of a self-aligning bearing
assembly 123. The bearing assembly 123 functions
with the torque arm collar 119, connected to the
frame member 101, to permit the drive sprocket
assembly 120 to properly track the endless chain
conveyor 150.
The drive gear assembly 110 has an output
shaft 116 (seen in FIG. 5) operatively coupled by a
spline connection to the driven end of the drive
sprocket assembly 120, and is carried by the frame
member 101 on the torque arm 125 to which the drive
gear assembly 110 is secured. Torque arm 125 is
constrained for limited movement with relation to
the frame member 101 to absorb torsional vibrations
by a resilient connection or anchor, generally
indicated by reference numeral 130, which functions
to resist the torque reaction and to absorb torsional
vibrations generated by the flights 151 strikinq
rocks and other highly resistant material. An
outwardly extending flange 126 carried at the lower
end of the torque arm 125 (best seen in FIG. 2) is
releasably secured to a bushing block 131 of the
resilient connector 130 for ease of initial assembly
and servicing.
The resilient connector 130 is secured to
the conveyor frame member 101 by means of a base
plate 132 and a generally U-shaped support member or
plate 133. Both the base plate 132 and the support
member 133 are formed with apertures therethrough to
receive a coupling pin 135 which functions to operatively
join the bushing block 131 with the conveyor frame
101 .
~131~0
In order to restrain the torque arm 125
and thereby absorb the torsional vibrations, the
coupling pin 135 is joined to the bushing block 131
by a bushing 136 of resilient material. The bushing
136 is press-fit into an internal bore of the bushing
block 131 and the bushing 135 has an internal bore
137 for slidably engaging the coupling pin 135
thereby providing a resilient anchor for the torque
arm 125. The pin 135 is formed with a head 138
having an aperture through which a bolt 139 passes
to secure the pin 135 to the support plate 133.
While the torque arm 125 and the resilient
anchor will permit the drive gear assembly 110 to
rock sufficiently to compensate for torsional vibrations
generated by the endless chain conveyor 150 within
the limits of resiliency of the bushing 136, a stop
lug 104 is secured to the elevator frame 103 to
define positive limits of movement of the torque arm
125. The stop lug 104 is positioned on the frame
103 to extend within a notch 124 formed in the
torque arm 125. In this manner, the maximum movement
of the torque arm is limited by the clearance distance
between the lug 104 and the notch 124. In addition,
the stop lug 104 and the notch 124 are effective as
locators when assemblying the drive ~procket assembly
and the drive gear assembly 110, with its associated
drive motor, to the frame members 101 and 102. It is
then a simple maneuver to connect the flange 126 of
the torque arm 125 to the bushing block 131.
While the invention has been described
with reference to a preferred embodiment, it will be
understood by those skilled in the art that various
changes may be made and equivalents may be substituted
for elements thereof without departing from the
scope of the invention. In addition, many modifications
may be made to adapt a particular situation or
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material to the teachings of the invention without
departing from the essential scope thereof. Therefore,
it is intended that the invention not be limited to
the particular embodiment disclosed as the best mode
contemplated for carrying out this invention, but
that the invention will include all embodiments
falling within the scope of the appended claims.
