Conveyor shifting apparatus and process

A shifting conveyor apparatus with a belt conveyor laterally shiftable, by flexibly mounted flexible rails therealong, towards a progressive excavation, including a travelling varingly-curving rail-engaging guide array for carrying and drawing the conveyor laterally by the rails, keeping the rails and the conveyor belt in safely controlled and guided distributed travelling curvature.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to long bulk conveyors and to the cooperative 
combination of flexibly shiftable belt conveyors and travelling shifting 
apparatus for lateral shifting of such conveyors by guided distributed 
travelling curvature, the shifting being to maintain convenient proximity 
to a progressive excavation of a bulk deposit such as lignite for 
convenient removal of the excavated bulk by the conveyor. More 
particularly, this invention relates to a belt conveyor comprising a 
framework comprising a flexible continuous rail or rails, a sequence of 
relatively rigid roller-carrier frames, and a set of pivotal, slidable, or 
rigid connections, the rails and frames being assembled by the connections 
into a flexibly continuous shiftable and accessible whole, the flexible 
continuity being largely due to the flexibility of the rails with the 
connections, and not largely due to the roller-carrier frames. This 
invention further relates to a travelling hoisting, shifting, and guiding 
vehicle with an adjustably curving rail-engaging guide roller array 
wherein the vehicle continuously powers and urges the guide array along 
the rails, and meanwhile powers, urges, holds, and adjusts the guide array 
in lateral and vertical position and in attitude, orientation, and 
curvature so as to shift the conveyor through a good distance by keeping 
the rails in controlled distributed travelling curvature. This invention 
also relates to an elongate guide carrier beam assembly for carrying a 
plurality of rail-engaging roller assemblies into linear and varyingly 
curvilinear engagement with the conveyor rail or rails, all for carrying 
and drawing the conveyor laterally by the rails while keeping the rails in 
safely controlled and guided distributed travelling curvature. 
2. Description of the Prior Art 
At a very early date in the development of open cast mining of lignite 
desposits it became apparent that sophisticated and heavy equipment would 
be necessary to remove the lignite in small chunks and pieces and 
transport it from the point of mining to a pick-up or storage location in 
economically feasible quantities. Since the mining apparatus which was 
developed to meet this goal is complex, bulky and heavy, and is designed 
to successively remove the lignite deposits farther and farther from the 
pick-up or storage location, it became necessary to develop successively 
longer conveyors for transporting the lignite to a point of loading or 
storage. These conveyor systems were designed in sections to facilitate 
periodic adjustment of the conveyor line to new positions closer to the 
lignite deposits. As the piecemeal-shiftable conveyor systems became more 
complex and greater in length, it became increasingly difficult to move 
the continuous conveyor sections from one location to another site which 
is closer to the point of mining of the lignite. Accordingly, special 
track lifting mechanisms were introduced into open cast lignite sites, and 
the weight of such apparatus has ranged up to 100 tons, and frequently had 
to be pulled by locomotives. This equipment was sometimes provided with 
traversing crawlers for quicker cross-travel between the conveyor lines 
which had to be shifted, and the cost of the conveyor-shifting operation 
became increasingly prohibitive as the conveyor lengths increased. 
Perhaps the most widely used steerable, non-railbound, shifting device is a 
machine developed in 1953 by Rheinische Braunkohlen A.G., a German Company 
which introduced several innovations into the conveyor shifting procedure. 
A high shifting rate was achieved using the new apparatus, and the machine 
provided good maneuverability on rough and uneven terrain. Other 
advantages consisting of low maintenance and space requirements and 
independence of rail mounting, as well as reduced costs, were also 
realized. The steerable, non-railbound track shifting machine is small and 
compact, but requires the use of a bulldozer or tractor to provide the 
motive force required in the shifting technique. The German shifting 
apparatus includes a roller unit which is characterized by a welded casing 
fitted with two sets of rollers, one roller in each pair being fixed and 
the other pivotable on side arms, the pivotable roller designed to bias 
against the shiftable conveyor railbulb of one of the rails by an 
adjusting mechanism. Buffer springs in the apparatus serve to compensate 
for unequal rail head dimensions, and the device is provided with arms for 
connection to the tractor or bulldozer. The tractor must be provided with 
a side boom, which is attached to the top of the shifting apparatus after 
the apparatus is connected to one of the rails of the shiftable conveyor. 
The side arms extending from the roller unit are supported against one 
side of the tractor. The roller unit is designed to traverse one rail of 
the shiftable conveyor as the tractor is driven forward and at an angle 
with respect to the shiftable conveyor line. When the roller unit of the 
shifting apparatus is mounted on one of the rails of the shiftable 
conveyor, the roller with the rail attached is then raised by the boom 
mounted on the tractor, until one end of the track sleepers is clear of 
the ground. The tractor is then moved forward along the conveyor, pulling 
the conveyor sections in the shiftable conveyor into sequential alignment 
from a first linear position to a second linear position closer to the 
lignite deposits. If sliding of the tractor occurs, during the shifting or 
realignment process the tractor must be steered at a slight angle away 
from the conveyor string in order to provide the proper tractive force and 
direction to realign the conveyor sections. The distance over which the 
rail is drawn sideways in one passage is sometimes called a "shifting 
step", and is represented to be up to two meters on dry and level ground. 
However, in the first passage, the designers of the German shifting 
apparatus recommend that the rail and sleepers be loosened from the 
original linear position, particularly in the case of frozen ground, and 
the second pass is then utilized to actually displace the conveyor 
sections from one position to the other. The designers further emphasize 
that the successive shifting steps ought to be small, rather than large, 
in order to minimize damage to the rail and the tractor and to achieve a 
fair tractor travel speed. Counterweights must also be used on the 
tractor, especially when the ground is soft, in order to better regulate 
traction. 
In the steerable, non-railbound, German shifting machine, great stress is 
placed on the shiftable conveyor rail resulting from the shifting, lifting 
and forward motion of the tractor, to great disadvantage. For shiftable 
conveyor rails with wider rail gauges, the stress and load increases 
considerably, particularly if the module sleepers must be pulled from a 
clay or loam base, which sometimes create a suction effect. Such high 
loads and stresses frequently cause damage to the conveyor rail, and in 
many cases require replacement of the rail due to severe rail distortion, 
which prevents subsequent traversal of the rail by the roller unit of the 
shifting apparatus. Furthermore, the shifting procedure using this 
equipment is slow and requires multiple passes in order to be effective, 
particular under circumstances where the lateral displacement of the 
shiftable conveyor must be extensive. 
Many disadvantages are found in the side-boom tractor with two roller pairs 
as found in the prior art. Firstly, the lateral force on the rail must be 
of the same order of magnitude as the vertical force, or even exceed it, 
since the coefficient of sliding friction between the sleepers and the 
ground will certainly sometimes exceed 1, and the shifting is obtained by 
dragging one end of the nearby sleepers or cross-ties across the ground, 
and both ends of some nearby ones. This by itself is very hard on the 
rails and connections, but this drag has the additional penalties next 
discussed. Secondly, the offset resulting from any s-shaped or reflex 
curve in a structural member depends largely on two causes, namely the 
curvature, and the length over which the curvature is obtained. As is well 
known in structural mechanics, bending stress is directly proportional to 
curvature (i.e., inversely proportional to radius of curvature), and since 
stress is limited by consideration of the material to some allowable 
stress, then curvature is likewise limited to some peak allowable. It is 
therefore desirable to have the peak value obtain over a length. But in 
the prior art, the curvature will be maximum nowhere but within the roller 
assembly, and the drag forces aforementioned will diminish the length of 
curvature obtained, thereby diminishing the shifting step. Thirdly, there 
being only two roller points, and, two points being insufficient to define 
a curve, the curvature is not defined nor limited by the design of the 
machine, but rather by the actions of the operator as governed by 
information, judgement, and attention, which may vary, unfortunately. 
Fourthly, since the drag forces are suddenly and unpredictably variable, 
with only the two roller pairs lifting only one side of the conveyor while 
dragging the other and while breaking adhesion of the ties to the ground, 
the maximum offset safely obtainable is likewise unpredictable. There 
might be some safe limit, but since the limit would only occasionally 
apply, the temptation would build to take too long a step, and then to 
cause damage. Fifthly, the lifting of one side of the conveyor while 
dragging the conveyor introduces torsional stresses into the rails; such 
stresses are simultaneous with the stresses due to lateral curvature, and 
must be reckoned into the total and thus reduce the allowable lateral 
curvature. These stresses also tend to break the connections between the 
rails and the roller-carrier frames. Sixthly, the lifting effects are 
maximum at precisely the point where the lateral bending and torsional 
effects are maximum, and therefore further limit the lateral curvature 
allowable. 
These and other disadvantages of the side-boom apparatus of the prior art 
find expression in frequent breaking of the rails and connections, and in 
long periods of down-time during conveyor shifts. More detailed discussion 
and structural analysis of such shifting structures will further 
illuminate the prior art, and serve to illuminate this invention as well, 
and such discussion follows. 
In the lateral shifting of flexibly shiftable conveyors, it is necessary to 
bring a travelling interval of the conveyor into a travelling s-shaped or 
reflex curve, or into some approximation of such a curve. Analysis and 
understanding of such structures and their deflection curves is usually 
best accomplished by a progression of idealizations from a first simplest 
idealization to other more complicated and accurate approximations such as 
follow. 
For a first illumination and a first approximation, consider some conveyor 
framework as if it were an initially straight beam brought into horizontal 
bending; such idealizations are sometimes usefully applied to triangulated 
trusses using the moment of inertia of the chords alone in beam-theory to 
approximate stresses, then using the rule-of-thumb that calculation will 
underestimate deflections by 15%, more or less. Such calculation will show 
that no useful flexible shifting can be obtained in fully triangulated 
structures of such proportions as are found in strip mining, since even a 
hundred tons of lateral force on the rails would defect such structures 
only a few inches, even with a hundred feet of curvature. Such forces and 
lengths would destroy the conveyor, rather than bring it into useful 
curvature. This is, of course, one of the reasons that such structures are 
not fully triangulated, but rather comprise triangulated panels and 
rectangular panels in alternating sequence. Nevertheless, useful insight 
can be obtained from the idealization, as follows. The idealization shows 
that deflection will depend on the magnitude of the curvature everywhere, 
not just at one point, and that the greatest offset is obtained in a given 
length by having the absolute value of the curvature be maximum 
everywhere. To have curvature be maximum everywhere is to have a pair of 
equal opposite tangent circular arcs, the radius of curvature for maximum 
safe offset being determined by the depth of the beam (i.e., the width of 
the conveyor) and the material of the beam, and only by those things. In 
the art, the material is rail steel, and the tolerable radius of curvature 
will be a thousand or so times the beam depth. Now, in the prior art here 
considered, the reflex curve is obtained by application of a shear at the 
end of the curve, so the curvature resulting varies linearly rather than 
remaining constant, i.e., the moment diagram is a pair of 
antisymmetrically disposed triangles, resembling a skewed bow tie. 
Engineer's beam theory will show the resultant deflection to be two-thirds 
of that obtained by the stepped rectangular diagram of constant (i.e. 
circular) positive and negative curvature; therefore the prior art method 
stresses the structure to a maximum while obtaining only about two-thirds 
of the maximum ideal or theoretical offset. The conclusion is tentative, 
pending a more refined model. The ideal for the beam-like truss is 
obtained by the application of three moments, a first one at the center of 
the reflex curve, and two others of opposite sense, each half the 
magniture of the first, at the two ends. Such a system is in equilibrium, 
and requires no imposition of shears whatever. No lateral force need be 
applied. 
As a second and closer approximation to the shiftable conveyors of the 
prior art, it is useful to analyze the conveyor frame as approximately a 
Vierendeel frame in the horizontal plane, i.e. as a bending member having 
rails as the two chords and having the sequence of roller-carrier frames 
as the sequence of posts of the well-known Vierendeel frame, and having 
the four rail-to-frame connectors at the four corners of each frame as the 
moment connectors between posts and chords which characterize the 
Vierendeel frame. In such frames, overall shear is resisted by s-shaped or 
reflex bending of the chords between the posts, and such reflex bending is 
by far the largest contributor to the overall deflection in case the posts 
and moment connectors are stiff, and such is the case in the conveyors of 
the prior art. Seen otherwise, the principal deflections here are panel 
deflections or shear deflections; deflections due to overall flexure are a 
very small part of the whole. Therefore the maximum safe deflection in 
such conveyors is not found when the overall curvature approximates the 
s-shaped curve composed of two semicircles, but is obtained by having 
constant maximum panel shear, the overall curve approaching the 
cross-section of a terraced lawn of constant step height and constant step 
width, with the individual step-connecting slopes corresponding to the 
s-shaped curve of the first approximation. The overall average curvature 
during maximum safe deflection would approximate a ramp more than it would 
approach the two semicircles of the first approximation. 
Even if a complete degree of rotary freedom were introduced into each of 
the four rail-to-frame connections at every roller-carrier frame (i.e., by 
making the connections pinned, rather than fixed as in the prior art), the 
action of the whole would still correspond to a Vierendeel frame with 
significant flexibility in the posts, since the points of entry of the 
rails into the post region would be slanted rather than level. The rails 
would be in curvature everywhere, with inflection points not only at the 
midpoints of the open shear panels, but also at the midpoints of the 
triangulated roller-carrier frames. The curve of the rails would then 
resemble a tilted corrugation, more than a sequence of terraces. The 
average overall curvature for maximum safe deflection would still 
approximate a ramp (albeit a corrugated ramp) more than it would 
approximate the two semicircles of the first overall approximation. 
However, the safe allowable deflection would be approximately doubled, as 
can be seen from strain-energy considerations, thus: Suppose, for simple 
example, that the open panels and triangulated panels were equal in width. 
Then the portion of the rails within the two types of panels would be 
equal in length and curvature, and would be twice that of the rails of the 
prior art, thus the strain energy will be twice as great, the maximum 
allowable rail curvature would have remained unchanged and, the shear 
unchanged. Therefore, the lateral load would be the same at lateral safe 
deflection, the external work must equal the strain energy and the lateral 
load must deflect twice as far. 
OBJECTS OF THE INVENTION 
Accordingly, it is an object of this invention to provide a new and 
improved shiftable belt conveyor wherein the rails are attached to the 
roller-carrier frames with a degree of freedom, thereby allowing an 
improved and greater safe shifting step. 
Another object of this invention is to provide a new and improved shiftable 
belt conveyor wherein the rails are attached to the roller-carrier frames 
with a rotary degree of freedom, thereby allowing an improved and 
approximately doubled safe-shifting step. 
Another object of this invention is to provide a new and improved shiftable 
belt conveyor wherein the rails have a sliding degree of freedom, thereby 
allowing the overall curvature of the conveyor to be arcuate, thereby 
providing a maximum shifting step. 
Another object of this invention is to provide relief from stress 
concentration in conveyor rails by providing a degree of freedom in the 
connection of the rails to the roller-carrier frames. 
Another object of this invention is to provide travelling spaced lifting 
and shifting machinery for conveyor lifting and shifting, so that stresses 
due to the one are not added to stresses to the other. 
Another object of this invention is to provide travelling conveyor hoisting 
machinery for hoisting conveyors in translation without torsion, thereby 
avoiding stresses due to torsion of the conveyor rails and frame. 
Another object of this invention is to provide conveyor hoisting and 
shifting machinery with means to hoist, shift, and lower a conveyor in 
separate travelling progression, thereby distributing and reducing various 
peak stresses, and thereby assuring that every point on the rails is 
subject to a stress always less than the sum of the peak values due to 
various effects such as the following: 
(1) vertical bending in breaking adhesion with the ground, 
(2) vertical bending in curvature of the ground, 
(3) vertical bending in lifting the conveyor off of the ground, 
(4) lateral bending due to dragging the conveyor across the ground, 
(5) lateral bending due to shifting curvature, 
(6) longitudinal stresses due to warping and torsion of the whole conveyor, 
(7) longitudinal stresses due to local torsion of the rail due to high 
lateral forces at the bulb of the rail, and 
(8) connection stresses due to oveturning of the rail due to high lateral 
forces at the bulb of the rail; 
(9) connection stresses due to overturning of the rail due to high lateral 
forces at the bulb of the rail, the assurance coming from the distribution 
of the peaks. 
Yet another object of this invention is to provide an adjustable 
rail-engaging roller array sufficient to define safe vertical and lateral 
curvature of the rails during hoisting and shifting of a flexibly 
shiftable belt conveyor. 
Another object of this invention is to provide a long rail-engaging 
curvature-defining array providing a long shifting step by defining a long 
interval of substantially constant maximum curvature or slope. 
Another object of this invention is to provide an elongate beam means 
providing a long shifting step by providing a substantial length of 
support of the rail free of a substantial length of ground, thus enabling 
a long support rail-engaging curvature and/or slope. 
Another object of this invention is to provide a controlled-curvature 
rail-engaging array with a laterally straight rail entry to insure against 
lateral bending stresses other than those resulting from controlled 
curvature and slope. 
Another object of this invention is to provide a conveyor-shifting vehicle 
having an elongate articulate beam string for variably defining curvature 
in a rail-engaging array, with steering and beam-adjusting means to 
support the array in such orientation, attitude, and position as to cause 
straight rail entry into and exit from said array over varying terrain 
while variably defining curvature and slope. 
Another object of this invention is to provide releasable couple between a 
conveyor-shifting vehicle and a conveyor shifting rail-engaging array to 
allow for alternative uses of the vehicle, and housing, maintenance, and 
spares for the array. 
Yet another object of this invention is to provide, in shifting conveyors, 
a set of three rail-engaging roller arrays for imparting three moments to 
a rail for reflex curvature, the three comprising a central moment of a 
first sense and magnitude, and two equal other moments of the second sense 
and half of the first magnitude, for defining two adjacent intervals of 
equal and opposite constant circular curvature in rails. 
Yet another object of this invention is to provide, in shifting conveyors, 
a first lifting rail-engaging roller array having lateral freedom, and a 
second laterally-urging rail engaging array having vertical freedom, for 
independent definition of vertical curvature and horizontal curvature of 
the rails. 
And another object of this invention is to provide, in shifting conveyors, 
a beam carrying an adjustable rail-engaging roller array which will adjust 
to provide maximum safe deflections either for conveyors with maximum safe 
deflection curves approximating constant curvature or for those with 
maximum safe curvature approximating constant slope. 
Accordingly, furthermore, it is an object of this invention to provide a 
new and improved conveyor shifting apparatus for moving a shiftable 
conveyor from a first linear position to a second position, which 
apparatus includes a pair of shifting beam strings spanning the conveyor 
and slidably cooperating with both rails in the conveyor to progressively 
shift the conveyor sections into the second position. 
Another object of this invention is to provide a new and improved conveyor 
shifting apparatus of the steerable non-railbound and shifting design, 
which includes a pair of shifting beam strings defined by an articulated 
shifting beam or beams provided with rail engaging assemblies containing 
roller mechanisms for engaging the rails of a shiftable conveyor and 
displacing the conveyor sections in the shiftable conveyor from a first 
linear position to a second linear position displaced a selected distance 
from the first linear position. 
Another object of the invention is to provide a new and improved conveyor 
shifting apparatus which includes a pair of shifting beam strings formed 
by multiple shifting beams in end-to-end articulated relationship, and 
positioned on either side of a set of shiftable conveyor sections and in 
engagement with the rails of the shiftable conveyor sections by means of 
at least one roller mechanism in each shifting beam, with respectively 
opposed ones of the shifting beams in the shifting beam strings maintained 
in substantially parallel relationship as the shifting beam strings 
articulate responsive to the movement of a supporting straddle crane or 
lifting device along the shiftable conveyor, to displace the shiftable 
conveyor sections a selected distance from a first linear position to a 
second linear position. 
Yet another object of the invention is to provide a conveyor shifting 
apparatus which is used in cooperation with a straddle crane or 
alternative lifting and forward-moving device having a supporting gantry 
frame and tracks or wheels in cooperation with the gantry frame to effect 
forward movement, the conveyor shifting apparatus including a first group 
of shifting beams fastened end-to-end in linear, articulated relationship 
and supported on each side of the shiftable conveyor by lift frames 
attached to the straddle crane, and multiple roller mechanisms extending 
downwardly from each of the shifting beams and in engagement with the 
rails of the shiftable conveyor sections, for traversing the rails and 
successively urging the shiftable conveyor sections and the shiftable 
conveyor from a first linear position to a second linear position 
displaced from the first position, responsive to the forward motion of the 
straddle crane and the lateral pressure applied to the conveyor sections 
by means of the shifting beams and the roller mechanisms. 
A still further object of this invention is to provide a new and improved 
conveyor shifting apparatus which is supported and operated by a novel 
straddle crane and includes a pair of shifting beam strings which contain 
multiple shifting beams positioned in end-to-end relationship and fitted 
with articulated joints, the shifting beam strings spaced in substantially 
parallel relationship on each side of several of the shiftable conveyor 
sections and attached to the rails of the shiftable conveyor sections by 
means of roller mechanisms which engage and traverse the rails joining the 
conveyor sections responsive to forward movement of the supporting 
straddle crane, to successively urge the rails and the shiftable conveyor 
sections from a first linear position displaced a selected distance from 
the first position, in order to move the shiftable conveyor closer to the 
point of mining. 
SUMMARY OF THE INVENTION 
These and other objects of the invention are provided in a laterally 
travelling conveyor system comprising a flexibly shiftable conveyor having 
a sequence of roller-carrier frames and a pair of rails tied together with 
connections having a degree of freedom, and further comprising a steerable 
hoisting and guiding vehicle carrying an elongated beam carrying an 
adjustable rail-engaging guide array for carrying the conveyor laterally 
by the rails in safely controlled and guided distributed curvature.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1 of the drawings, the conveyor shifting apparatus of 
this invention is generally illustrated by reference numeral 1, and is 
illustrated in functional configuration on a shiftable conveyor 15 of the 
invention. The straddle crane 2 of the invention serves to provide the 
linear and lateral motive forces necessary to achieve lateral shifting of 
the conveyor sections 16 in the shiftable conveyor 15, and operates by 
means of drive tracks 7, mounted on columns 5 in gantry frames 3, which 
are spaced by spacer beams 6 and are positioned astride the shiftable 
conveyor 15 by means of trolley beams 4. Trolleys 8 are relatively movable 
on the trolley beams 4 by means of trolley cables 12 and the cooperating 
cable rollers 12a, responsive to the trolley winch drive 13. Operation of 
the winch drive 13 serves to position the trolley hydraulic rams 9, 
attached to the trolleys 8, and the sawhorse-shaped lift frames 11, 
positioned on the piston end of the trolley hydraulic rams 9, in proper 
vertical orientation on the trolley beams 4. A cab 10 is positioned 
between the forward ones of the trolley hydraulic rams 9 and the lift 
frames 11 to provide a control module from which the drive tracks 7 can be 
steered to facilitate proper re-alignment of the shiftable conveyor 15, as 
hereinafter described. Steps 14, located in the forward one of lift frames 
11, serve to provide access to the cab 10. 
The conveyor shifting apparatus 1 includes a rail-engaging array 30 
comprising shifting beam strings 31, which in this preferred embodiment 
are generally square or rectangular in cross section, and are articulated 
in end-to-end relationship. The shifting beam strings 31 are suspended 
from the lift frames 11 by removable or permanent attachment between the 
bottom ends of the lift frames 11 and two of the shifting beams 38 in each 
of the shifting beam strings 31, respectively, as illustrated. In this 
preferred embodiment of the invention five such shifting beams 38 are 
utilized in each of the shifting beam strings 31, and the second one of 
shifting beams 38 in each of the shifting beam strings 31 from each end 
are connected to the lift frames 11. As further illustrated in FIG. 1, the 
shifting beam strings 31 are disposed in approximately parallel, spaced 
relationship on each side of the shiftable conveyor 15, and the shifting 
beams 38 are joined to each other in pivotal adjustable articulating 
relationship by means of a pair of powered shifting hinges 43. Multiple 
rail-engaging suspender assemblies 92 are suspended in spaced array from 
the shifting beams 38, and engage the rails 39 of the shiftable conveyor 
15, to facilitate traversal of the rails 39 and progressive lifting and 
guiding of the respective conveyor sections 16 in travelling curvature 
responsive to the forward progress of the straddle crane 2 along the 
shiftable conveyor 15, defining a curvature as hereinafter described. 
Referring now to FIGS. 1-4, and to FIG. 2 in particular, a flexibly 
shiftable conveyor 15 is illustrated, with head station 41 at one end, a 
tail station 42 at the opposite end, and the apparatus 1 comprising a 
straddle crane 2 astride the shiftable conveyor 15. As further illustrated 
in FIG. 3, the rail engaging array 30 is in functional position carried by 
the straddle crane 2, and as the straddle crane 2 moves in the direction 
indicated by the arrow along the shiftable conveyor 15, the conveyor 
sections 16 located between the straddle crane 2 and the tail section 42 
are successively being pulled into alignment with that previously adjusted 
portion of the shiftable conveyor 15 which is located between the straddle 
crane 2 and the head station 41. The mechanics of this adjustment of the 
shifting conveyor 15 from a first linear position illustrated by that 
portion of the shiftable conveyor 15 which is located between the straddle 
crane 2 and the tail station 42, to a position in linear alignment 
illustrated by the segment located between straddle crane 2 and head 
station 41, will be hereinafter described more in detail. As further 
illustrated in FIG. 3, the shifting beam strings 31 permit the articulated 
shifting beams 38 to assume the configuration of those conveyor sections 
16 in shiftable conveyor 15 which are positioned between the shifting beam 
strings 31 and are in the process of being shifted from the first linear 
configuration to the second linear position. Referring now to FIG. 4, the 
rail-engaging array 30 is shown in elevation view, the straddle crane 2 
illustrated in elevation section, and the varying clearance of the module 
sleepers 36a, 36b, and 36c above the ground, upon which the shiftable 
conveyor 15 rests when operating, is illustrated, which clearance 
facilitiates the shifting operation illustrated in FIGS. 1-3. It will be 
appreciated that the general height adjustment above the ground level 115 
of the conveyor sections 16 which are engaged by the rail engaging 
suspender assemblies 92 is achieved by adjustment of the trolley hydraulic 
rams 9, which carry lift frames 11, and that the varying clearance of the 
individual assemblies is otherwise adjusted, as will be explained. Note is 
taken that the rail 39 is in this view of FIG. 4, curved at sleepers 36a, 
straight at sleepers 36b, and curved again at sleepers 36c. 
As further illustrated in FIGS. 1 and 5-9, the shiftable conveyor 15 
includes module sleepers 36, 36a, 36b, and 36c, (generally called 36) 
situated in spaced relationship in each of the conveyor sections 16 along 
the entire length of the shiftable conveyor 15. Stringer supports 17 are 
secured to the module sleepers 36 by means of support mount plates 18, 
with appropriate fasteners. Stringer support braces 34 and module braces 
35 serve to maintain the stringer supports 17 in substantially vertical 
alignment on module sleepers 36, and idler stringers 21 are mounted in 
angular relationship on the stringer supports 17, and connect the stringer 
supports 17 to each other in each one of the conveyor sections 16. 
Referring specifically to FIGS. 5-7, conveyor carrying idlers 19 are 
provided in spaced, rotatable relationship in each of the conveyor 
sections 16, and are each attached to the respective idler stringers 21 by 
means of an end connection 22, secured to an idler shaft 28, on each of 
the conveyor carrying idlers 19 by means of an end connection bolt 29, as 
illustrated in FIGS. 6 and 7. The end connections 22 are also connected to 
a pivot plate 23, which is in turn secured to the idler stringer 21 by 
means of a pivot pin 25. A pivot plate slot 24, and a pivot stop 26, serve 
to facilitate adjustment of the conveyor carrying idlers 19 with respect 
to the stringer support 17. As illustrated in FIGS. 5, 8 and 9, multiple 
belt return idlers 20 are provided beneath the conveyor carrying idlers 19 
in shiftable conveyor 15, and are each provided with an idler shaft 28 and 
end connections 22, for attachment to the stringer supports 17 by means of 
a chain 29a, and a cooperating link slot 33, with a clamp 33a and a lift 
rod 33b. It will be appreciated by those skilled in the art that the 
attachment of the conveyor carrying idlers 19 and the belt return idlers 
20 can be made in a variety of ways, it being necessary only to provide a 
means for flexible support of the conveyor belt 40 in each of the conveyor 
sections 16 of the shiftable conveyor 15. Since the entire length of the 
shiftable conveyor 15 between the head station 41 and the tail station 42 
is shaped by discrete, individual conveyor sections 16, which are 
connected only by the rails 39 and the conveyor belt 40, substantial 
flexibility is built into the conveyor line to facilitate successive 
shifting of the conveyor sections 16. 
Referring now to FIGS. 2 and 13 of the drawings showing a further preferred 
embodiment of another aspect of the invention, each shifting hinge 43 in 
the shifting beam strings 31 includes an outside connector plate 49 and a 
cooperating inside connector plate 52 at the top, and a second outside 
connector plate 49 and companion inside connector plate 52 at the bottom, 
for each shifting hinge 43 which connects the shifting beams 38. 
Accordingly, two pairs of the outside connector plates 49 and inside 
connector plates 52, respectively, are provided as components of each 
shifting hinge 43. As illustrated in FIG. 13, the plate legs 56 of one 
pair of the outside connector plates 49 and inside connector plates 52 are 
attached to a common end of one of the shifting beams 38, while the plate 
legs 56 of the opposite and cooperating pair of the outside connector 
plates 49 and inside connector plates 52 are secured to the adjacent one 
of the shifting beams 38. A shifting beam plate 51 is welded or otherwise 
attached to each of the adjacent shifting beams 38, and is pivotally 
secured between each pair of the outside connector plates 49 and the 
inside connector plates 52, respectively, by means of a connector pin 54. 
This mechanical arrangement permits each of the adjacent shifting beams 38 
in the shifting beam strings 31 to articulate on the connector pins 54, as 
hereinafter described. In a most preferred embodiment of this aspect of 
the invention a shifting beam ram 57 joins the top ones of outside 
connector plates 49 and inside connector plates 52 in each plate 
combination, and includes a cylinder 58 and a cooperating clevis 59, which 
is secured by a connecting pin 63 to the outside connector plate ear 50, 
of the inside connector plate 49. A cooperating ram rod 60 is secured to 
the inside connector plate ear 53 of the inside connector plate 52 at one 
end, by means of another connecting pin 63. The ram rod 60 extends into 
the cylinder 58 and is attached to the piston 61. Accordingly, the 
relative pivot of each shifting beam 38 with respect to the adjacent 
shifting beam 38 in the shifting beam strings 31 is limited and controlled 
by the stroke of the shifting beam rams 57. 
Referring further to FIGS. 10-12, in further disclosure of a preferred 
embodiment of another aspect of the invention, generally 
cylindrically-shaped, hollow spindle housings 44 are mounted in spaced 
relationship in the shifting beams 38, with the top end of each of the 
spindle housings 44 extending from attachment to the shifting beams 38. 
Referring specifically to FIG. 11, a spindle base plate 46 is provided 
with a base plate top 46a, and a pair of base plate flanges 46b extending 
downwardly from the base plate top 46a. A cylindrical spindle 45 extends 
from attachment to the base plate top 46a, and is provided with a spindle 
bore 48. A spindle 45 is designed to register with and project adjustably 
upward through each of the hollow spindle housings 44, as illustrated in 
FIG. 10. Base plate flanges 46b of each spindle base plate 46, are also 
provided with base pin holes 47, as illustrated. 
Referring now to FIGS. 14-17 of the drawings each of the rail-engaging 
suspender assemblies 92 of the conveyor rail engaging array 30 is mounted 
to a spindle base plate 46 by means of a pair of light links 73 and two 
heavy links 77, which are more particularly illustrated in FIGS. 16 and 
17. Each light link 73 is shaped by light link flanges 74 spanning a light 
link body 75, while each heavy link 77 is characterized by somewhat 
thicker heavy link flanges 78 and a thinner heavy link body 79. As 
illustrated in FIGS. 14 and 15, one end of the light links 73 and the 
heavy links 77 are pivotally attached to the base plate flanges 46b of the 
spindle base plate 46 by means of link pins 81, which register with pin 
holes 73a in the light links 73 and the heavy links 77, and with the base 
pin holes 47 in the base plate flanges 46b. Snap rings 55 serve to 
register with grooves provided in the link pins 81 in order to pivotally 
secure the light links 73 and the heavy links 77 to the base plate flanges 
46b. The opposite ends of the light links 73 are attached to the light 
link brackets 85, which extend from an outside roller housing 84 and an 
opposing inside roller housing 94, respectively, as illustrated. 
Furthermore, the opposite ends of the heavy links 77 are attached to heavy 
link brackets 86, also attached to the light link brackets 85 of the 
outside roller housing 84 and inside roller housing 94, respectively. A 
spreader ram 97 is disposed between the outside roller assembly 83, which 
contains the outside roller housing 84, and the inside roller assembly 93, 
which includes the inside roller housing 94, as illustrated in FIG. 14. In 
a preferred embodiment of this aspect of the invention the spreader ram 
cylinder 98 is attached through a mounting eye 62 to the light link 
bracket 85 of the inside roller housing 94, by means of a link pin 81, 
which extends through registering pin holes 73a in the light link bracket 
85 and the mounting eye 62. Snap rings 55 serve to maintain the link pin 
81 in position and to allow pivotal movement of the light link 73 and the 
mounting eye 62 of the spreader ram cylinder 98 with respect to the light 
link bracket 85. The spreader ram piston 99 is provided with a second 
mounting eye 62, which is connected to the opposite light link bracket 85 
positioned on the outside roller housing 84 by means of a second link pin 
81, which link pin 81 also attaches the second connecting light link 73 to 
the light link bracket 85. In a most preferred embodiment, and referring 
again to FIG. 15, a link pin bushing 82 is provided on each of the link 
pins 81 which secure the mounting eyes 62 located on the spreader ram 
cylinder 98 and the spreader ram piston 99, to the light link brackets 85, 
respectively, in order to facilitate positive operation of the spreader 
ram 97, as hereinafter described. 
As heretofore noted, one end of one of the heavy links 77 is attached to a 
heavy link bracket 86, fastened to the inside roller housing 94, while the 
end of the second heavy link 77 is secured a second heavy link bracket 86, 
attached to the outside roller housing 84. Accordingly, referring now to 
FIG. 18, when the spreader ram 97 is activated by appropriate controls 
(not illustrated) to extend the spreader ram piston 99 from the spreader 
ram cylinder 98, the outside roller housing 84 is moved away from the 
inside roller housing 94, in order to facilitate removal of each of the 
rail engaging suspender assemblies 92 from the rails 39. Conversely, 
retraction of the spreader ram piston 99 into the spreader ram cylinder 98 
causes the outside roller housing 84 and the inside roller housing 94 to 
converge, and the outside roller 87 and inside roller 95 to engage the 
outside rail shoulder 104 and inside rail shoulder 105, respectively, as 
illustrated in FIGS. 14 and 18. 
Referring now to FIGS. 14, 15, and 18-21, in a most preferred embodiment of 
another aspect of the invention both the outside roller 87 and the inside 
roller 95 in the outside roller housing 84 and inside roller housing 94, 
respectively, are provided with a roller groove 88, which matches the 
outside rail shoulder 104 and the inside rail shoulder 105 of the rail 39, 
in order to facilitate smooth roller traversal of the rail head 103 as the 
straddle crane traverses the shiftable conveyor 15. 
Referring again to FIGS. 15, 18, 19, 20, and 21, in yet another most 
preferred embodiment of a further aspect of the invention the light link 
brackets 85 in the outside roller housing 84 and inside roller housing 94 
are each characterized by a link pin aperture 76 and a spacer bolt 
aperture 80, spaced from the link pin aperture 76. Furthermore, the heavy 
link bracket housing 86 is welded or otherwise fixedly secured to the 
light link bracket 85 and is provided with a heavy link bracket aperture 
117. Each light link bracket 85 is shaped to define a shaft mount plate 
106, which is provided with an interior space to accommodate a wheel axle 
89, journalled for rotation in the roller shaft aperture 111 and roller 
shaft seat 96. As illustrated in FIG. 19, a wheel axle 89 secures the 
outside roller 87 in the shaft mount plate 106, and in a most preferred 
embodiment, both the outside roller 87 and the inside roller 95 are 
provided with tapered bearing seats 112, and cooperating bearing races 113 
to accommodate bearings 114, in order to facilitate a smooth rotation of 
the outside roller 86 and inside roller 95 on the respective wheel axles 
89. A spacer bolt 90 in inserted in the spacer bolt apertures 80, provided 
in the light link brackets 85, and is secured by the spacer bolt nut 91, 
as illustrated in FIG. 15, in order to secure the wheel axles 89 in the 
roller shaft aperture 111 and roller shaft seat 96, of the outside roller 
housing 84 and the inside roller housing 94, respectively. 
Referring again to FIGS. 14 and 15 of the drawings in a further preferred 
embodiment of the invention each spindle 45, attached to a spindle base 
plate 46 by means of welds 63a, is inserted concentrically inside a 
spindle housing 44, which is welded to the shifting beams 38. Furthermore, 
an adjustable double-acting suspender ram 65, having a suspender cylinder 
68, is attached by means of a ram base 72, to the base plate top 46a of 
each spindle base plate 46, and extends into each spindle 45. Each 
suspender cylinder 68 is further provided with a suspender bore 70, with 
one end of a suspender rod 66 extending through the top of the spindle 
housing 44, and a suspender rod stop 67 at the opposite end of the 
suspender rod 66. A gland 69 is provided at the top of the suspender 
cylinder 68, and the projecting and threaded end of the suspender rod 66 
is secured to the top of the spindle housing 44 by means of suspender 
mount nuts 71. Accordingly, each rail engaging suspender assembly 92 in 
the shifting beams 38 is carried adjustably by a spindle base plate 46, 
which is suspended from a spindle housing 44 and the shifting beams 38, 
and each spindle 45 is permitted and caused to move up and down inside the 
cooperating spindle housing 44 by the action of a suspender ram 65, in 
order to adjustably define the curvature of the rails 39 and the clearance 
of the module sleepers 36 as mentioned hereinbefore, as the rail engaging 
suspender assemblies 92 traverse the rails 39. In a still further 
preferred embodiment of this aspect of the invention, a spindle bushing 64 
is provided between the inside surface of the spindle housing 44 and the 
outside surface of the spindle 45, in order to produce a closer tolerance 
and minimize lateral movement while allowing pivoting of the suspended 
rail engaging suspender assemblies 92 and the spindle base plate 46 with 
respect to the shifting beams 38. 
Referring now to FIGS. 22 and 23, an alternative design of the rail 39 is 
shown in isolated section in FIG. 23 having a threaded pin 108 welded 
thereto, with a cooperating lock nut 108b, having locking means known in 
the art. FIG. 22 shows a section of a hollow module sleeper 119 with a 
slotted hole 108a, receiving the threaded pin 108 locked by a nut 108b 
with some degree of freedom, to wit, in pivoting about the pin 108 and 
also lengthwise of the rail 39 in the oversize design of the slotted hole 
108a. 
FIG. 24 schematically shows the deflected shape 110 of the shiftable 
conveyor 15 components which are supported below the rail-engaging array 
30. Only 4 sets of the outside rollers 87 and inside rollers 95 are shown, 
being those which might have a substantial lateral action in bringing 
about such a shape, as hereinafter explained. The other outside rollers 87 
and inside rollers 95, respectively, are deployed primarily to give 
vertical support to the shiftable conveyor 15, and define the desired 
vertical curvature. The shape is the shape of a Vierendeel Frame with 
relative end translation movements enforced. 
Now that the first preferred major embodiment of the invention has been 
described, another sometimes preferred embodiment will be shown, 
illustrating a differing novel shiftable conveyor and suitable novel 
shifting array. 
Referring now to FIG. 25, which is a schematic plan, a second major shape 
of a conveyor frame 107 of the invention is illustrated, and includes 
conveyor support sections 118, sleepers 119 and rails 120, which are 
similar to the conveyor sections 16, module sleepers 36, and rails 39, 
respectively, of the previous embodiment as illustrated in FIG. 1, 
respectively, with joints 121 and novel telescoping joints 122 and 123 
having a releasable telescoping degree of freedom. The telescoping of 
joints 122 and 123 allows the conveyor as a whole to take on the smoother 
s-shape illustrated by the whole of the FIG. 25, since the conveyor 
support sections 118 are not so constrained, compared to the conveyor 
section 16 of the previous embodiments, to move mainly in translation, but 
can also rotate to a degree, allowing a much larger and safer shifting 
step. 
FIGS. 26 and 27 represent larger and more detailed plans of the conveyor 
frame 107, supporting a conveyor belt 124, comprising a segment of the 
length of the conveyor 125, which also has a head station 41 and a tail 
station 42, as illustrated in FIG. 2. Moreover, the shifter 126, 
comprising a novel steerable straddle frame 127 with a novel shifting 
array 128 is shown. This is all further shown in elevation section 27. 
Further referring to FIGS. 26 and 27, the straddle crane 127 supports 
powered trolleys 130 running on beams 131 supported on columns 132, with 
kingpins 133 steerably housed therein, the king pins 133 mounted on tracks 
134, all by means well known in the art, including tie-beams 135. The 
powered trolleys 130 support double-acting hoist rams 136 from swivels 
137, by means well known in the art. 
Hoist rams 136 have rods 138 with swivel supports 139 adjustably supporting 
the shifting array 128 in service position, all by means well known in the 
art. 
The shifting array 128 comprises a pair of large beams 140, torquing roller 
arrays 141, and lifting suspender drum apparatus 142, with both the 
torquing roller arrays 141 and the lifting suspender apparatus 142 
engaging the rail 120. 
As illustrated in FIGS. 26 and 28 each of the eight lifting suspender drum 
apparatus 142 comprises a drum 143 rotatably mounted in the large beam 140 
and pivoted and powered by a ring gear and motor assembly 144, and bearing 
means 144a, elements which are well known in the art. The drum 143 has a 
spindle housing sleeve 145 mounted eccentrically in the drum 143, to 
selectively carry the spindle housing sleeve 145 to the center or off 
center of the large beam 140 by operation of the ring gear and motor 
assembly 144. FIG. 26 illustrates the spindle housing sleeve means 145 
off-center to accommodate and define the s-shaped curve in the rails 120. 
Suspender 146 is an elongated version of the rail engaging suspender 
assembly 92 illustrated in FIGS. 14, 15 and 18. The greater length of the 
suspender 146 is facilitated because of the lack of lateral sway of the 
suspender 146 as compared to that of the rail engaging suspender assembly 
92. 
Referring again to FIGS. 26 and 27 and additionally to FIG. 29, each 
torquing roller array 141 comprises a cylindrically-shaped rotating 
housing 147 powered in rotation about a vertical axis by a torque, motor, 
and bearing 148 mounted in the large beam 140. Each rotating housing 147 
houses a pair of roller pins 149 mounted in cylindrical bearings 150, the 
roller pins 149 having limited clearance to ride up and down in the 
cylindrical bearings 150. The rollers 151 are mounted to the roller pins 
149 by means of bearings 152 and are vertically positioned to clear the 
rail 120 by hydraulic rams 153 attached thereover; in the alternative, the 
roller pins 149 may be left free-running by leaving the rotating housing 
147 ported. In FIG. 26 the torque motor and bearings 148 are shown to be 
acting to torque the rotating housings 147 in the counter-clockwise 
direction and the center rotating housings 147 in the clockwise direction, 
thereby imparting the traveling s-shaped curve to the rails 120 through 
the rolling contact of rollers 151 on the rail heads 103 of the rails 120. 
The torque of each central torquing roller array 141 is twice that of each 
end torquing roller array 141, thereby imparting equal curvature to four 
intervals of the rails 120 defined by the six torquing roller arrays 141. 
At the same time, lifting suspender drum apparatus 142 hoists the rails 
120 into a smooth even curve. Referring now to FIGS. 30 through 33, which 
illustrate a preferred embodiment of a telescoping joint 123 having an 
automatically releasible degree of freedom, rail segments 120a and 120b of 
rails 120 have feathered ends 154 mating with space therebetween for a 
corrugated frame 155. Feathered ends 154 comprise slanted web slice plates 
156 welded between feathered rail bulbs 120a and 120b and feathered 
flanges 157 and extending into cut-outs 158 in webs 159. Web splice plates 
156 have slotted holes 160, carrying headed keepers 161 insuring against 
excessive separation of the feathered ends 154. The feathered ends 154 
have considerable bending strength imparted by the channel sleeve 162 
comprising a rail segment 163 and slotted fittings 164 welded thereto. 
Slotted fittings 164 are provided with snap lugs 165 in slots 166, adapted 
to snap into snap-recesses 167 in the feathered flanges 157. 
The foregoing two major embodiments and the operation thereof will now be 
further described. 
In operation, and referring again to FIGS. 1-22 of the drawings, when it is 
desired to utilize the conveyor shifting apparatus 1 of this invention, 
the rail engaging array 30 is initially suspended from the straddle crane 
2 which is placed astraddle the shiftable conveyor 15, optionally by 
lifting the whole over, or driving over the tail station 42 or otherwise. 
The lift frames 11 which are attached to selected ones of the shifting 
beams 38 in the shifting beams 31 are attached to the trolley hydraulic 
rams 9, as illustrated in FIG. 1, and each of the spreader rams 97 are 
initially activated by operation of appropriate controls known to those 
skilled in the art, to extend the respective spreader ram pistons 99 and 
open the outside roller housing 84 and inside roller housing 94, as 
illustrated in FIG. 18. This open configuration of the rail engaging 
suspender assemblies 92 is achieved as the opening operation of the 
spreader ram 96 exerts lateral pressure on the link pins 81 joining the 
mounting eyes 62 of the spreader ram piston 99 and the spreader ram 
cylinder 98, to spread the outside roller assembly 83 and the inside 
roller assembly 93. Each of the shifting beam strings 31 are then raised 
by operation of the trolley hydraulic rams 9 to a position over the 
respective rails 39, and the shifting beam strings 31 are are then slowly 
lowered and adjusted by the trolley hydraulic rams 9 until the respective 
ones of the outside roller housings 84 and inside roller housings 94 are 
adjacent to the rail head 103 of each rail 39. When each rail engaging 
suspender assembly 92 is fairly near the proper position the suspender 
rams 65 and shifting beam rams 57 are actuated to bring the apparatus in 
proper relationship to the rails 39 as illustrated in FIG. 18, and the 
spreader rams 97 are again activated by appropriate controls to close the 
outside roller housings 84 and inside roller housings 94 and secure the 
outside rollers 87 and the inside rollers 95 against the outside rail 
shoulder 104 and inside rail shoulder 105, respectively, of the rails 39, 
as illustrated in FIG. 14. 
When each of the rail engaging suspender assemblies 92 are in functional 
position as illustrated in FIG. 14, the trolley hydraulic rams 9 and 
suspender rams 65 are again activated in the required way to lift the 
shifting beams 38 and the attached rail engaging suspender assemblies 92 
and raise the conveyor sections 16 adjacent the shifting beam strings 31 
and the module sleepers 36 beneath the shifting beams 38, off the ground 
to a desired varying degree shown and mentioned in association with FIG. 
2, to define the vertical curvature of the rails 39. This occurs as an 
upward force is applied by the trolley hydraulic rams 9 to the shifting 
beams 38 attached to the lift frames 11, and the shifting beams 38 move 
upwardly, along the suspender rods 66 in the suspender rams 65. Each 
suspender ram 65 provides local adjustment to the outside roller assembly 
83. 
The above described initial lifting sequence is executed with the conveyor 
initially in operation disposition where the rails 39 are substantially 
straight. Also, the conveyor shifting apparatus 1 will be initially 
located immediately adjacent to the head station, 41 (or, if desired, the 
tail station 42). Therefore, the first adjusted supported position of the 
rails 39 will be curved vertically, but straight in plan. Then, by 
employment of means well known in the art, the head station 41 will be 
lifted and shifted slowly through the desired shifting step. 
Simultaneously, the rail engaging array 30 is brought into congruent 
offset curvature by simultaneous operation of the trolley winch drives 13 
and the shifting beam rams 57, resulting in lateral s-shaped curvature, as 
well as the vertical curvature. The shifting step and the s-curvature are 
planned so as to define the curvature of the rails 39 within safe limits. 
The maximum vertical curvature is designed to be some distance from the 
maximum horizontal curvature, thereby providing a diminished total. 
The straddle crane 2 is then moved forward away from the head station 41 in 
the direction of the arrow as illustrated in FIGS. 2 and 3, and the 
lifting and lateral pressure exerted by the rail engaging suspender 
assemblies 92 on the rails 39 causes those conveyor sections 16 which are 
spanned by the shifting beam strings 31, to move laterally from a first 
linear position to a second linear position which is displaced from the 
first position. As the straddle crane 2 continues its forward progress, 
the shifting action continues as the outside rollers 87 and the inside 
rollers 95, mounted in the outside roller housing 84 and the inside roller 
housing 94, respectively, of the rail engaging suspender assemblies 92, 
traverse the rail heads 103. Accordingly, the conveyor shifting apparatus 
1 can be used to shift the entire length of the shiftable conveyor 15 from 
the first position to a displaced second configuration, as illustrated in 
FIG. 2, with the final step of shifting the tail station 42 accomplished, 
just as the head station 41 was shifted, with a simultaneous operation of 
the rail engaging array 30 to maintain congruence. 
A great advantage of the rail engaging array 30 with its great range of 
articulation is that the apparatus can approximate and accommodate a wide 
variety of a s-shaped curves, including the rippled curve of the chords of 
the Vierendeel frame. The local irregularities of the deflected Vierendeel 
frame are accomodated by the partial latent freedom of the rail engaging 
suspender assemblies 92. 
Referring again to FIG. 2, it will be appreciated by those skilled in the 
art that a conventional tractor 116, or equivalent machinery must be used 
to move the head station 41 and similarly the tail station 42, of the 
shiftable conveyor 15, according to the knowledge of those skilled in the 
art. However, it will be further appreciated that the conveyor shifting 
apparatus 1 of this invention can be used to relocate, and more 
particularly, to laterally relocate a shiftable conveyor such as the 
shiftable conveyor 15 of substantially any length or any type, to any 
desired new position which is eigher parallel to or at a selected angle 
with respect to the original conveyor line. This option can be realized by 
guiding the straddle crane 2 or an equivalent conveyor shifting apparatus 
suspension system to whatever degree is necessary in order to achieve a 
specified and desired second conveyor location. 
Now considering the second major embodiment of FIGS. 22-33 the operation of 
the shifter 126 proceeds similarly to that of the conveyor shifting 
apparatus 1. The conveyor 125 is initially straight and empty. The 
straddle crane 127 carries the large beams 140 as far outboard and apart 
as possible, and if possible, drives over the tail station 42 of the 
conveyor 125. Otherwise, the straddle crane 127 is hoisted, by crane 
located at the mine, over the conveyor 125. The lifting suspender drum 
apparatus 142 is revolved to bring the suspenders 146 to the central axis 
of the large beams 140. The rotating housings 147 are then rotated so as 
to maximize the clearance between the pairs of rollers 151. The powered 
trolleys 130 and hoist rams 136 are powered to carry large beams 140 into 
alignment with and well over the rails 120. Hoist rams 136 then operate to 
lower the large beams 140 sufficiently for engagement of the suspenders 
146. Suspenders 146 are engaged after the fashion of the rail engaging 
suspender assemblies 92, already described, thereby gripping the rails 
120. The hoist rams 136 then lift the large beams 140 sufficiently to lift 
the conveyor 125 by the suspenders 146 barely clear of the ground. Means 
of the art are then activated to begin shifting of the tail station 42. 
Hydraulic rams 153 operate to position the rollers 151 at the level of the 
rail bulbs 120a and 120b of the rail 120. The torque motor and bearing 148 
torques the rotating housings 147 to bring the rollers 151 into engagement 
with the rails 120, which forces the rails 120 into flexure. Axial forces 
are induced in the rails 120 which causes the snap lugs 165 to snap out of 
the snap recesses 167, thereby compressing the corrugated springs 155, and 
allowing release and diminution of the axial forces, and facilitating the 
s-shaped curvature illustrated in FIG. 25. 
When the tail station 42 and s-shaped curve approximate the desire safe 
shifting step, the straddle crane 127, which is powered by means 
well-known in the art, drives the shifting array 128 along the conveyor 
125. Conveyor support sections 118 successively pass through the straddle 
crane 127, and be shifted. Telescopic joints 122 and 123 enter the 
torquing roller arrays 141 in sequence, and the major circumference of the 
rollers 151 bear on the web splice plates 156, thereby compressing each 
corrugated spring 155 and releasing the telescoping joints 122 or 123 to 
allow curvature simultaneously with the need for such curvature, all of 
which occurs within the span of the pairs of rollers 151 of the torquing 
roller array 141. The exit procedure and shifting of the head station 41 
is similar to and deducible from the reverse of the aforementioned steps. 
A reversal of the above procedure from the head station 41 to the tail 
station 42 might be undertaken to take another shifting step, optionally. 
The releasibility of the telescoping joints 122 and 123 is preferred, but 
not imperative. This function offers the advantage of additional stiffness 
when shifting is not transpiring, and sufficient flexibility when it is. 
Other embodiments of releasable telescoping might serve, such as a 
non-automatic release, in non-exclusive particular. Likewise, other 
configurations of roller arrays would serve; for example, positioning the 
hydraulic rams 153, while convenient, might be omitted, provided roller 
pins 149 are secured by means in the housings. Other lifting roller arrays 
serving the ends of the suspenders 147 might serve to impart vertical lift 
and curvature, according to methods well-known in the art. Likewise, one 
or two large beams such as the large beams 140 might be carried by one or 
more side-boom tractors and achieve an acceptable shifting result without 
the use of a straddle crane 127. It is also possible for three unconnected 
side-boom tractors to carry three distinct torquing roller arrays such as 
the torquing roller arrays 141, but mounted on special sidebooms instead 
of the large beams 140, to accomplish the distributed curvature disclosed. 
Even so, these variations are all envisioned within the scope of the 
invention. 
The operation and advantage of the equal constant curvature combined with 
the smooth vertical rail deflection is now evidently obtained, especially 
since the sum of stresses in the rails 120 is controlled to a tolerable 
limit. The advantage of the degrees of freedom in the rails 120 is now 
evident in the greater safe shifting step. 
While the preferred embodiments of the invention have been described above, 
it will be recognized and understood that various modifications may be 
made in the invention and the appended claims are intended to cover all 
such modifications which may fall within the spirit and scope of the 
invention.