U.S. patent number 3,563,364 [Application Number 04/797,647] was granted by the patent office on 1971-02-16 for portable conveyor.
This patent grant is currently assigned to Harsco Corporation. Invention is credited to Charles J. Arndt, Roy F. Lo Presti.
United States Patent |
3,563,364 |
Arndt , et al. |
February 16, 1971 |
PORTABLE CONVEYOR
Abstract
In an improved conveyor of the type including an elongated
conveyor-carrying boom pivotally mounted at one end to a wheeled
supporting frame, with the other end of the boom being supported by
an arm pivotally mounted adjacent the other end of the frame, with
a sheave-carrying arm pivotally mounted adjacent the said other end
of the support frame, and with a cable passing over the sheave and
connected at one end to the support arm and at its other end to an
hydraulic cylinder, the sheave arm and support arm are positioned
such that the ratio of the reaction force acting on the support arm
to the moment arm lying between the support arm pivot point and the
point the cable passes over the sheave remains substantially equal
for any given position of the conveyor boom. Such a conveyor
additionally preferably includes means for adjusting the length of
the aforesaid moment arm such that the same structural elements may
be employed for booms of varying length.
Inventors: |
Arndt; Charles J. (Valley View,
Glen Ellyn, IL), Lo Presti; Roy F. (Chicago, IL) |
Assignee: |
Harsco Corporation (Harrisburg,
PA)
|
Family
ID: |
25171427 |
Appl.
No.: |
04/797,647 |
Filed: |
February 7, 1969 |
Current U.S.
Class: |
198/316.1;
198/304; 198/825; D34/29; 198/306 |
Current CPC
Class: |
B65G
41/002 (20130101) |
Current International
Class: |
B65G
41/00 (20060101); B65g 021/02 () |
Field of
Search: |
;198/120.5,121,122,99,233 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sroka; Edward A.
Claims
We claim:
1. Supporting apparatus for a conveyor for concrete mix and the
like comprising:
a support frame;
a conveyor support boom pivotally mounted on the support frame
adjacent one end thereof, the other end of the boom being free;
a support arm pivotally mounted at one end adjacent the other end
of the support frame, the other end of the support arm being
adapted to support the free end of the conveyor support boom;
a sheave arm pivotally mounted o at one end about a pivot point
adjacent the other end of the support frame;
a sheave pivotally mounted at the other end of the sheave arm;
and
cable means fixed at one end to the support arm and at the other
end to means for moving the cable means, with the cable means being
passed over the sheave;
the sheave arm and support arm being relatively positioned such
that the ratio of the reaction force acting on the support arm to
the moment arm lying between the point at which the cable passes
over the sheave and the pivot point of the support arm is
substantially equal for any given pivotal position of the conveyor
support boom.
2. Supporting apparatus, as claimed in claim 1, wherein the
conveyor support boom comprises a main section and a tail section,
with the sections being telescopically mounted end-to-end whereby
to adjust the tension of a conveyor belt carried by said boom.
3. Supporting apparatus, as claimed in claim 2, wherein the length
of the conveyor support boom is increased by the provision of at
least one extension section interposed between the main section and
the tail section.
4. Supporting apparatus, as claimed in claim 3, wherein the length
of the support frame is increased by the provision of a support
frame extension member for each boom extension section in excess of
one.
5. Supporting apparatus, as claimed in claim 4, wherein the
position of the pivot point for the sheave arm is adjustable in
order to lengthen the said moment arm whereby, for a conveyor
support boom of a given length, the ratio of the said reaction
force to the said moment arm remains substantially equal for any
given pivotal position of the conveyor support boom.
6. Supporting apparatus, as claimed in claim 1, and further
comprising antifriction means provided at the other end of the
support arm on which the conveyor support boom rests.
7. Supporting apparatus, as claimed in claim 1, wherein the support
frame comprises:
a plurality of rotatably mounted wheels, with at least one of the
wheels being driven by a chain driven by an hydraulic motor;
and
an adjustable telescopic mounting for the hydraulic motor for
adjusting the tension of the chain drive by varying the relative
position between the hydraulic motor and the wheel.
8. Supporting apparatus, as claimed in claim 1, and further
comprising cradle means pivotally mounted on the support frame
adjacent the said other end thereof and adapted to provide a
support for the conveyor support boom when the conveyor support
boom is disposed in a lowered, rest position, the said cradle means
including at least one longitudinally disposed V-shaped angle
generally positioned beneath the conveyor support boom, with at
least one generally cylindrical member being mounted beneath the
conveyor support boom and generally in longitudinal alignment with
a corresponding V-shaped angle, whereby when the conveyor support
boom is pivoted downwardly toward its rest position, each
cylindrical member cooperates with the corresponding V-shaped angle
to self-center the conveyor support boom on the cradle means.
9. Supporting apparatus, as claimed in claim 8, wherein the cradle
means comprises a pair of V-shaped angles.
10. Supporting apparatus, as claimed in claim 8, wherein the
pivotal mounting for the cradle means is adjustable whereby the
cradle means may be disposed in different positions for conveyor
support booms of different lengths.
11. Supporting apparatus, as claimed in claim 1, wherein the
conveyor support boom comprises:
a power-driven drive roller disposed at one end of the conveyor
support boom;
a main idler roller disposed at the other end of the conveyor
support boom;
a plurality of upper V-shaped idler roller assemblies removably
mounted on the conveyor support boom;
a plurality of lower idler roller assemblies mounted on the
conveyor support boom; and
an endless conveyor belt disposed about the main idler roller and
the drive roller;
with the upper train of the belt being supported by the V-shaped
idler roller assemblies, and the lower train thereof being
supported by the lower idler roller assemblies.
12. In a supporting apparatus for a conveyor comprising a support
frame; a conveyor support boom pivotally mounted adjacent one end
of the support frame, with the other end of the boom being free; a
support arm pivotally mounted adjacent the other end of the support
frame; a sheave arm pivotally mounted at one end about a pivot
point adjacent the other end of the support frame; a sheave
pivotally mounted on the other end of the sheave arm; and a cable
fixed at one end to the support arm and at the other end to means
for moving the cable, with the cable being passed over the sheave,
the improvement comprising the pivot point for the support arm
being positioned relative to the pivot point for the sheave arm
such that the ratio of the reaction force acting on the support arm
to the moment arm lying between the point at which the cable passes
over the sheave and the pivot point of the support arm is
substantially equal for any given potential position of the
conveyor support boom.
13. The improvement, as claimed in claim 12, wherein the conveyor
support boom comprises a main section and a tail section, with the
sections being telescopically mounted end-to-end whereby to adjust
the tension of a conveyor belt carried a by said boom.
14. The improvement, claimed in claim 13, wherein the length of the
conveyor support boom is increased by the provision of at least one
extension section interposed between the main section and the tail
section.
15. An improvement, as claimed in claim 14, wherein the length of
the support frame is increased by the provision of a support frame
extension member for each boom extension section in excess of
one.
16. An improvement, as claimed in claim 15, wherein the position of
the pivot point for the sheave arm is adjustable in order to
lengthen the said moment arm whereby, for a conveyor support boom
of a given length, the ratio of the said reaction force to the said
moment arm remains substantially equal for any given pivotal
position of the conveyor support boom.
Description
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to conveyors and more particularly to
a power-driven elevator-type conveyor especially designed for use
with concrete mix or the like.
2. Description of the Prior Art
While portable boom-type conveyors of the elevator type, in which a
conveyor supporting boom is pivoted at one end of a portable frame
with the other end of the boom being supported by a pivotal support
arm, have long been known in the art, problems have been
encountered with reference to the particular manner in which the
position of the support arm (and hence of the conveyor-supporting
boom) is adjusted or maintained in static equilibrium. In
particular, problems have been encountered where the position of
the support arm is maintained by a cable passing over a sheave
arrangement to a cable drive arrangement. Because of the geometry
of the prior art systems, as the conveyor was elevated hydraulic
pressure increased, thereby increasing the tension in the cable.
Likewise, the prior structures have not been usable with
conveyor-supporting booms of varying length. It has been necessary
to provide completely different support frame structures for booms
of different lengths.
A further difficulty encountered with prior art devices is that the
preferred endless conveyor belts have not been usable because of
the configuration booms involved. With such prior structures, it
has been necessary to use a spliced conveyor belt which is much
less desirable.
Furthermore, such devices have been unsatisfactory in the manner in
which the conveyor boom is supported in a lowered, rest position in
that the exact centering of the conveyor on a supporting cradle
structure has been achieved only with careful manual manipulation.
Yet a further difficulty has been the manner in which the wheels on
the supporting structure have been driven.
SUMMARY OF THE INVENTION
The foregoing and other difficulties encountered with prior
power-driven elevator-type conveyors have been overcome in
accordance with the conveyor supporting apparatus of the present
invention, which comprises: a support frame; a conveyor support
boom pivotally mounted on the support frame adjacent one end
thereof, the other end of the boom being free; a support arm
pivotally mounted at one of its ends adjacent the other end of the
support frame; antifriction means provided at the other end of the
support arm, with the antifriction means adapted to support the
free end of the conveyor support boom; a sheave arm pivotally
mounted at one of its ends adjacent the other end of the support
frame; A sheave pivotally mounted at the other end of the sheave
arm; cable means fixed at one end to the support arm, with the
cable being passed over the sheave; the other end of the cable
means being secured to means for tensioning and adjusting the
length of the cable means; the sheave arm and support arm being
located such that the ratio of the reaction force acting on the
antifriction means to the moment arm between the point at which the
cable passes over the sheave and the pivot point of the support arm
is substantially equal for any given position of the conveyor
support boom.
In addition, the device preferably includes auxiliary mounting
means for the sheave arm such that by merely varying its mounting
point, the aforesaid equilibrium conditions can be maintained for
conveyor support booms of varying length. In addition, means are
preferably provided for supporting the conveyor boom in its lowered
or rest position, including automatic centering means for locating
the boom in its rest position.
As a result, a primary object of the present invention is to
provide a portable elevator conveyor of the character described in
which stresses within the system are equalized irrespective of the
exact position of the conveyor boom.
A related object is to provide a conveyor support structure of the
character described which is fully portable and which is fully
power operated.
Yet another object is to provide a structure of the character
described in which an endless conveyor belt may be quickly and
conveniently and removably positioned in operative relation.
A further object is to provide a structure of the character
described using interchangeable parts and the same basic supporting
structure for conveyor booms of varying length.
A still further object is to provide a device of the character
described in which improved means are provided for tensioning the
conveyor belt supported by the boom.
DETAILED DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, advantages, and features of the
present invention will hereinafter appear, and, for purposes of
illustration will but not of limitation, exemplary embodiments of
the present invention are shown in the accompanying drawings, in
which:
FIG. 1 is a perspective view of the device produced in accordance
with the present invention;
FIG. 2 is a side elevational view thereof;
FIG. 3 is a plan view of the support frame portion thereof;
FIG. 4 is a fragmentary view, partially in section, taken
substantially along line 4-4 in FIG. 2;
FIG. 5 is an elongated fragmentary perspective view of the forward
end of the support frame structure;
FIG. 6 is a sectional view taken substantially along line- 6 in
FIG. 2;
FIG. 7 is a sectional view taken substantially along line 7-7 in
FIG. 2;
FIG. 8 is a top plan view of the head section of the conveyor;
FIG. 9 is a top plan view of the tail section of the conveyor with
the feeding hopper removed; and
FIG. 10 is a sectional view taken substantially along line 10-10 in
FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 and 2 show a portable elevator-type conveyor 20 comprising a
support frame assembly 22, a boom sa assembly 24, and a power
assembly 26. As will hereinafter be described in detail, boom
assembly 24 is pivotable between a lowered or rest position shown
in full lines in FIG. 1 and a raised position shown in broken lines
in FIG. 1.
As best shown in FIGS. 2 and 6--9, boom assembly 24 comprises a
main section 30, an extension section 32 (see FIG. 2), and an
adjustable tail section 34 mounted on extension section 32 in a
manner and for a purpose to be described in detail hereinafter.
Main section 30 and extension section 32 are of the same general
configuration and structure and differ only in size and position.
Sections 30, 32 are bolted together in a manner that will
hereinafter be described in detail.
As best shown in FIG. 6, conveyor extension section 32 comprises
four longitudinally spaced angles 38, 40, 42, 44 arranged in a
generally rectangular cross-sectional form (see FIG. 6). REspective
pairs of angles 38, 40 and 42, 44 are fixed in position by a
plurality of diagonally positioned spacer bars 46 (see FIG. 2), the
ends of which are welded to the respective angle pairs. In
additional vertical spacer angle 48, 50 (see FIG. 6) is welded in
place at one end of section 32 and a similar angle (not shown) is
welded in position at the other end thereof.
Main boom section 30 is of the same basic overall construction with
longitudinal angles 50, 52 forming one side of the boom and
longitudinal angles 53, 54 forming the other side of the conveyor
section. A plurality of bars 56 are welded in position between
angles 50, 52 and a plurality of similar bars 57 (see FIG. 5) are
welded between angles 53, 54 in order to stabilize them in
position. A pair of vertically disposed end angles 58, 60 (see FIG.
2) further serve to stabilize relative positions of the respective
pairs of side angles.
As best shown in FIG. 9 the respective sides of boom secton 30 are
stabilized in position by a plurality of bars 62, the ends of which
are welded to the opposite lower angles of section 30. Similar
crossbars (not shown) are provided between the bottom angles 40, 42
of section 32. In addition, generally horizontal angles are welded
between the respective longitudinal side angles in order to further
stabilize the positions of the longitudinal angles forming the
general configuration of the respective boom sections. Thus, a
cross angle 64 is provided between angles 50, 54 of boom section 30
and a similar cross angle 66 (see FIG. 1) is provided between
angles 52 and 53.
As a result, the boom sections of the device of the present
invention are strongly and stably formed by the four longitudinal
angles maintained in position by welded crossbars and angles.
In order that a problem experienced with portable prior art
conveyors at the point of interconnection of adjacent boom sections
may be avoided, as best shown in FIG. 6, a bushing 450 is welded in
position behind the face of vertical angles (e.g., angles 48, 50)
provided at abutting ends of the adjacent boom sections, and bolts
460 are passed through respective pairs of bushing located behind
such adjacent spaces in order to solidly bolt the adjacent boom
sections together.
In order to support a movable conveyor belt on the boom assembly
24, a plurality of upper idler roller assemblies 70 are provided
between angles 50, 54 of section 30 and an additional upper idler
assembly 72 (see FIG. 8 is provided between upper angles 38, 44 of
section 32. Similarly, a plurality of lower idler roller assemblies
74 are provided between lower angles 52, 53 of section 30 and lower
idler roller assembly may also be provided for section 32 if
desired.
As best shown in FIG. 6, the lower idler roller assembly 74
comprises a pair of opposed brackets 76 projecting inwardly from
angles 40,4 40, 42, respectively. A pair of upstanding ears 78 are
bolted to brackets 76, and ears 78 contain pockets in which the
ends of a shaft 80, on which is rotatably carried a lower idler
roller 82, are rotatably received. The other lower idler roller
assemblies 74 are of similar configuration.
Each of the upper idler roller assemblies 70, 72 (which are best
shown in FIGS. 6, 8, and 10) are removable for a purpose that will
best hereinafter appear. As best shown in FIGS. 6 and 8, assembly
72 comprises a pair of opposed angle brackets 84, each of which is
secured respectively to one of the longitudinal angles 38, 44 as by
the use of a plurality of bolts 83. A pair of V-shaped bars 86 are
welded between angle brackets 84 (see especially FIG. 8) and bars
86 serve to further strengthen extension section 32. An additional
V-shaped bar 88 passes through a pair of openings in angle brackets
86, with the end being secured in position by retaining pins 90
(see FIG. 6). A pair of upper idler rollers 92 are disposed on the
opposed legs of V-shaped shaft 88. Because the ends of V-shaped rod
or shaft 88 pass through openings in angle brackets 84, the rollers
92 may be removed and/or changed without removing brackets 84 from
the positions in which they are bolted. The upper idler roller
assemblies 70 which are removably positioned on main boom section
30 are identical to upper idler section 72.
As previously described, a tail section 34 is provided at the end
of boom extension section 32. As shown in FIG. 8, section 34
comprises a pair of upper longitudinal angles 94, 96 and a similar
pair of lower longitudinal angles 98, 99 (see FIGS. 2 and 7). the
bottom longitudinal angles are braced in position by welded
crossbars 100 (see FIG. 7), and upper longitudinal angles 94, 96
are retained in their desired configuration by a pair of upper
idler roller assemblies 102, each of which corresponds in structure
and in function to the previously described upper idler roller
assembly 72. Provision is made for slidable movement of section 34
with respect to section 32, by means of the telescoping
interrelation between the longitudinal angles of the section 32 and
the longitudinal angles of section 34, for a purpose that will
hereinafter appear.
A drive roller 106 is journaled for rotation at the forwardmost end
of section 34 (see FIGS. 7 and 8, especially). A pair of vertical
channels 108 are fixed in position between the respective pairs of
upper and lower longitudinal channels (e.g., channels 94, 99 shown
in FIG. 7), and a pair of bearing assemblies 110 are mounted on
angles 108. A shaft 112, on which drive roller 106 is mounted, is
journaled for rotation in the two bearing assemblies 110. In
addition, a drive sprocket 114 is mounted adjacent one end of
roller 106 and a drive chain 116 shown in broken lines in FIG. 2
passes over sprocket 114 and a sprocket 118 of an hydraulic drive
motor 119 (see FIG. 7). Suitable hydraulic connections are provided
between hydraulic motor 119 and power assembly 26, which includes
selective controls for effecting the driving of drive roller 106
via motor 119, chain 116, and sprockets 114, 118. A stabilizing
hoop 120 is welded in position between longitudinal angles 94, 96
in order to further stabilize the end of the tail section 34.
As best shown in FIG. 2, at the lower end of main section 30, a
large end idler roller 122 is journaled for rotation, the mounting
of idler roller 122 being similar to the mounting of previously
described drive roller 106 except that a power drive connection is
not provided.
A conveyor belt B is passed over the rollers 106, 122 disposed at
opposite ends of the boom assembly 24, and the upper train of the
belt B (shown in broken lines in FIG. 6) passes over the top of the
idler rollers 92 provided in the various series of upper idler
roller assemblies 70, 72 and 102. The lower train of belt B passes
over the upper surfaces of the rollers 82 provided in the lower
idler roller assemblies 74 provided along the bottom of boom
assembly 74.
In order to properly adjust the tension of the conveyor belt B
between the drive roller 106 and the opposite end idler roller 122,
the exact position of extension tail section 98 with respect to
extension section 32 may be adjusted by telescoping the section 34
in the previously described manner and then locking the respective
overlapping longitudinal angles in the desired position, in
accordance with the belt-tensioning system described and claimed in
J.F. Oury, U.S. Pat. No. 3,203,538.
A hopper 130 is mounted over the lower end of the boom 24 at the
lower end of main section 32 in order to provide a means of
funneling concrete mix or the like onto the belt B, and a discharge
chute assembly 132 is preferably provided at the discharge end of
section 34. Briefly, chute assembly 132 comprises a hood section
134 fixed to hoop 120 and a pivotal underlying chute 136 into which
the hood 134 directs concrete mix. As noted, chute 136 is pivotable
in order to move it from a withdrawn transport position (as shown
in FIG. 2) to any desired pouring configuration, as will be obvious
to those skilled in the art.
A belt scraper holder 470 (see FIG. 9) is mounted at the receiving
end of boom section 30, and a scraper blade 472 is fixed to support
frame 470 so as to contact the underside of belt B as it passes
over idler roller 122 at the receiving end of boom section 30,
thereby to clean the surface of belt B prior to its passing under
the hopper 130 directing fresh concrete mix or the like onto the
moving surface of belt B.
As previously noted, the actual length of boom assembly 24 may be
varied by incorporating additional extension sections (similar to
section 32 shown the drawings). An especially suitable arrangement
for the device of the character described embodies a basic main
boom section 30 32 feet long with extension sections 32 in
additional 8 foot increments up to a total of 32 additional feet,
thereby providing a boom assembly 24 of up to 64 feet in
length.
As best shown in FIG. 3, support assembly 22 comprises a generally
T-shaped frame formed by a main longitudinal member 150 (shown in
cross section in FIG. 10) and a transverse member 152 fixed thereto
at its forward end. A pivot bar 154 is fixed to longitudinal member
150 at one end, and a pair of pivot pins 156 project outwardly from
the end of member 154 and are adapted to pass through suitable
openings in the opposed lower longitudinal channels 52, 53 of main
boom section 30 in order to provide for the pivotal mounting of
boom assembly 24 with reference to support assembly 22.
A rear wheel 160 is suitably journaled in a wheel mounting yoke 162
(see FIG. 2), which is in turn mounted on a shaft 164 (see FIG. 3)
which passes rotatably through the rearward end of member 150. A
sprocket 166 is mounted on the upper end of shaft 164. A chain 168
passes about sprocket 166 (see FIG. 3) and about a smaller sprocket
170 provided on a shaft 172 (see FIG. 2) journaled for rotation in
a sidewardly projecting beam 174 (see FIG. 3) which is welded to
longitudinal member 160. A crank arm 176 (see FIGS. 2 and 3)
permits a shaft 172 to be rotated via sprockets 164, 170 and chain
168, and thus yoke 162 and the wheel 160 may be rotated about a
vertical axis thereby serving to steer the conveyor 20 when it is
moved. A seat 180 mounted on a seat support 182 is provided on
sidewardly projecting beam 174 in order to provide a convenient
location for an operator to sit.
A pair of sidewardly projecting beams 190, 192 (see FIG. 3) provide
a base for a suitable engine or motor 194 which in turn provides a
source of energy for the conveyor 20 and the operation of the
hydraulic power source 196 which provides the motive force for the
operation of the conveyor belt B and the other power features
embodied in the conveyor 20.
An upstanding ear 200 is welded in position on the top edge of
longitudinal member 150, and ear 200 has an opening therein. A pair
of complementary ears 202 are provided on the end of an hydraulic
cylinder 204, and a pivot pin (not shown) passes through ears 200,
202 in order to provide a pivotal mounting for hydraulic cylinder
204 for a purpose that will hereinafter appear. Cylinder 204 is
provided with an actuating arm 206 which extends from the forward
end thereof, and, in response to operation, may be extended or
withdrawn under hydraulic pressure. Arm 206 terminates in a yoke
208 adapted to receive pivotally a cable mounting bracket 210 fixed
in position at the end of a cable C provided for a purpose that
will hereinafter appear.
As best shown in FIG. 3, a pair of diagonal angle braces 220 are
welded between longitudinal member 150 and transverse member 152 in
order to lend stability to the forward end of the support frame
assembly 22. A pair of forwardly projecting ears 222 are provided
at one side on member 152 and a similar pair of forwardly
projecting ears 224 are provided at a similar location at the
opposite side of member 152. A pair of upwardly projecting support
arms 226, 228 are pivotally mounted between the respective ear
pairs 222, 224 by means of pivot pins 230, 232 (see FIG. 3).
Support arms 226, 228 are fixed together by three crossbars 234,
236, 238 (see FIGS. 1 and 5) such that arms 226, 228 pivotally move
with reference to the member 152 as a single unit which will be
referred to hereinafter as the arm assembly 240.
A roller 242 (see FIGS. 1 and 2) is journaled for rotation between
the ends of arms 226, 228, and the ends of roller 242 preferably
comprise upstanding flanges whereby the center portion of roller
242 provides an antifriction support surface on which boom assembly
24 may be supported as shown in FIGS. 1 and 2. Because roller 242
functions as an antifriction support, as the support arm assembly
240 is pivoted the angle of elevation of boom assembly 24 varies,
with the respective extreme positions of support arm assembly 240
and boom assembly 24 being shown in full and broken lines in FIG.
1.
The forward (see of cable C is fixed to a turnbuckle 250 (see FIG.
2) which is in turn pivotally attached to the upper end of support
arm assembly 240 by a pivotal link 252. As a result, when hydraulic
cylinder 204 is properly actuated and the actuating arm 206 thereof
is hydraulically moved, cable C is either advanced toward the right
(whereby under the influence of gravity support arm assembly 240
may pivot downwardly) or toward the left. Support arm assembly 204
is pulled upwardly so as to move boom assembly 204 toward its
broken line raised position (shown in FIG. 1).
A sheave assembly 260 is provided in order to guide the cable C
intermediate its linking with the arm 206 and the support arm
assembly 240. As best shown in FIGS. 5 and 10, the sheave assembly
260 comprises an upwardly projecting plate 262 which is welded to
member 150 and which is provided with a pair of reinforcing angles
264 (see FIGS. 3 and 5). Four openings 266, 268, 270, 272 are
provided in one side of plate 262, the precise location of which
holes is determined in a manner that will hereinafter be described
in detail. A pair of sheave arms 274 are pivotally mounted about a
pivot shaft 276 which passes through one of the openings 266, 268,
270, 272. The particular opening through which bottom portion of
sheave arms 274 are pivotally mounted will be determined in the
manner hereinafter described in detail. A sheave 280 is pivotally
mounted between the upper ends of arms 274, with shaft 282 passing
through openings in the end of each arm 274 and with sheave 280
pivoting thereabout. A groove 284 is provided in the periphery of
sheave 280 and provides a channel through which cable C passes.
Because sheave arms 274 are free to pivot about shaft 276, sheave
arms 274 and sheave 280 will thus be free to assume the natural
position to which it is urged by the cable C depending upon the
precise angle at which support arm assembly 240 is disposed.
Normally, sheave arms 274 will substantially bisect the angle
formed by cable C.
A cradle assembly 290 (see FIGS. 2, 3, and 5) is provided in order
to provide a framework for boom assembly 24 upon which to rest in
its lowered or rest position as shown in FIG. 1. Cradle assembly
290 comprises a pair of side legs 292 formed of metal bar or
tubular material which project upwardly and then angle inwardly as
best shown in FIG. 5. At the upper end of each side leg 292 is
provided V-shapd angle 294 disposed in a longitudinal direction as
shown in FIG. 5. A pair of tubular braces 296, 298 link the
respective ends of V-angles 294 and side legs 292 in order to
stabilize each side of the cradle assembly 290. In addition, a pair
of crossbars 300 serve to solidly stabilize the respective sides of
the assembly 290. A series of openings 302, 304, 306, 308 are
provided in the lower end of each side leg 292 (opening 306 is not
per se shown in the drawings because a pivot bolt 310 which passes
through a pair of ears 312 and through opening 306 serves to
provide a pivot point about which the cradle assembly 290 may
pivot). A similar pivotal mounting arrangement is provided for the
opposite leg 292.
In order to brace cradle assembly 290 in a given angular position,
a pair of braces 320 are pivotally attached to a lug 322 on cross
brace 300 by means of a pivot rod 324, the other ends of braces 320
pivotally mounted on plate 262 by means of a pin 326 which passes
through one of a series of openings 330, 332, 334, 336 (opening 332
being obscured in the drawing). When it is desired to use boom
assemblies 24 of greater length or when it is desired that the rest
position (as shown in FIG. 1) of boom assembly 24 be higher or
lower, the pivotal mounting of legs 292 through one of the series
of four holes therein may be varied and likewise the lower mounting
point of braces 320 may be varied in its similar select series of
four holes provided in plate 262 may likewise be varied.
In 5), and with the present invention, an especially desirable
feature of cradle assembly 290 is the provision of the V-shaped
supporting angles 294 (best shown in FIG. 5). A longitudinally
positioned anchoring member 340 (which preferably takes the form of
a metal tube) welded beneath the lower longitudinal angle 52 of
boom section 30 (see FIGS. 2 and 5), and a similar tube 344 is
provided beneath longitudinal angle 53. As best shown in FIG. 5,
members 340, 344 are respectively carried in V-shaped angles 294
when the boom assembly 24 is disposed in its rest position.
However, in order that precise centering of the boom assembly 24 on
the cradle assembly 290 need not be accomplished in lowering the
boom assembly 24 to its rest position, the provision of the
outwardly projecting sides of V-shaped angles 294 cooperate with
the tubular cross section of members 340, 344 to provide for an
automatic centering as the boom assembly 24 is lowered. Thus,
precise centering need not be accomplished, with the angularly
disposed sides of angles 294 accomplishing this purpose
automatically.
As shown in FIGS. 1--5, a pair of wheels 350 are provided at the
respective ends of transverse member 152. The detailed construction
and manner in which wheels 350 are driven and mounted on transverse
member 152 are best shown in FIGS. 4 and 5. Each tire 350 is
mounted on a wheel 351, which in turn is mounted on a hub 352. Hub
352 is mounted on an axle 354, on which is provided a drum 356
having a plurality of sprocket teeth 358 disposed thereon. Hub 352
is adapted to rotate with respect to axle 354, with hub 352 being
fixed to drum 356 so as to rotate therewith. Axle 354 is welded to
a U-shaped bracket 360 having projecting side legs 362, and bracket
360 is bolted to transverse member 152 by a bolt 364 and nut 366
which pass through legs 362 of U-shaped bracket 360 and through
transverse member 152. As best shown in FIG. 3, legs 362 of bracket
360 comprise a plurality of radially positioned openings (e.g.,
openings 363), and bolt 364 may be removably passed through
different pairs of openings 363 in order that wheels 350 may be
disposed at any desired angle.
Wheel 350 is driven by an hydraulic motor 370 which drives a shaft
372 on which is mounted for rotation therewith a sprocket 374. A
chain 376 passes about sprocket 374 and sprocket teeth 358.
Hydraulic motor 370 is mounted on an angle bracket 380 and bracket
380 is in turn mounted on a tube 382 which is slidably fitted
within a sleeve 384 for vertical movement. A bushing 386 is welded
in the lower end of tube 382, and an adjustment bolt 388 is
threaded in bushing 386 for a purpose that will hereinafter appear.
Bolt 388 is journaled for rotation in a sleeve 390, and a ratchet
connection 392 and a ratchet handle 394 are provided at the lower
end of bolt 388 in order to rotate the same. By rotating bolt 388
bushing 386 and hence tube 382 may be adjusted vertically so as to
adjust the vertical position of hydraulic motor 370. As a result,
the tension on drive chain 376 may be precisely adjusted merely by
operating ratchet handle 394 in order to quickly and conveniently
provide the desired degree of chain tension. Sleeve 390 is likewise
bolted in position within a sleeve 400 welded to the end of
transverse member 152. An identical hydraulic drive system and
chain adjustment arrangement is provided for the other of the
wheels 350.
Suitable hydraulic hose connections for pressurized hydraulic fluid
are provided between the power assembly 26 and hydraulic motors
370, hydraulic motor 119, and hydraulic cylinder 204. A control
panel 410 (see FIG. 1) may be provided in order to give the
operator convenient control of all of the power options provided on
the device.
In order that appropriate support is given to the elongated boom
assemblies (i.e., a boom assembly to which additional extension
sections, such as section 32, have been added), additional insert
sections in the longitudinal member 150 may desirably be provided.
The minimum length is shown in FIG. 2 in which member 150 comprises
a main section 150' and an extension section 150" bolted together
at a joint 151. FIG. 1 shows a conveyor in which an additional
extension section 150'" has been interposed between sections 150'
and 150". In general, where an extension section (such as section
32) is added to boom assembly 24, it is unnecessary to add any
extension sections to member 150. However, for each successive
extension section added to the boom assembly 24, an additional
extension section (such as extension 150'") should be interposed as
a part of member 150.
In operation, once the appropriate configurations of the boom
assemblies 24 and the member 150 have been satisfactorily chosen
and the correct mounting positions for the cradle mounting assembly
290 and the sheave assembly 260 have been ascertained, in
accordance with the hereinafter to be described principles of
operation, an operator sitting in the seat 180 can by manipulating
appropriate hydraulic controls on the control panel 410 cause the
boom assembly 24 to move either upwardly or downwardly between its
extreme positions (as shown in FIG. 1) and likewise by operating
hydraulic motors 370 may cause the portable conveyor to advance
either forwardly or rearwardly, with steering being accomplished by
manipulating handle 176, all as previously described in detail.
Because of the geometric relationship between the support arm
assembly 240 and the sheave assembly 260, stresses throughout the
portable conveyor and particularly throughout cable C are
maintained substantially uniform. More particularly, the geometry
of the arrangement is such that the ratio of the reaction force
acting on antifriction roller 242 to the moment arm between the
point at which cable C passes over sheave 280 and the pivot point
for support arm assembly 240 (i.e., the perpendicular distance
between the point denoted by the lead arrow from reference
character X and a line passing through the pivot points identified
by the reference character y as shown in FIG. 3) is maintained
substantially equal for differing angular positions of boom
assembly 24. Thus for all positions of boom assembly 24, the
apparatus satisfies the expression
where F is the reaction force acting on roller 242; where M is the
perpendicular distance between a line passing through points Y and
a parallel line passing through point X; and where K is
substantially constant.
In other words, as boom assembly 24 changes its position and the
reaction force on roller 242 changes, the pivot of sheave arms 274
about pivot point 276 results in a change in the aforesaid moment
arm such that the substantially constant ratio is maintained.
Because of the differences in the reaction forces acting on the
antifriction roller means 242 with boom assemblies 24 of differing
lengths, the moment arm distance must likewise be changed, and this
is achieved by positioning pivot point 276 through a different one
of the openings 266, 268, 270, 272 in order to vary the desired
moment arm distance and so that the equilibrium expression may be
obtained for various angular positions of boom assembly 24. Also,
the length of member 150 is appropriately adjusted. In this manner,
stresses within cable C are equalized and the likelihood of
operational failures due to unbalanced stresses within the cable C
are absolutely minimized.
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