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| 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)
|
| Appl. No.:
|
04/797,647 |
| Filed:
|
February 7, 1969 |
| Current U.S. Class: |
198/316.1 ; 198/304; 198/306; 198/825; D34/29 |
| 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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