GB2145388A - High angle conveyor - Google Patents

Abstract

A high angle conveying apparatus including a conveyor belt (12) and a cover belt (14) trained for movement in endless paths of travel. The belts (12,14) are supported for movement by an array of upwardly directed and downwardly directed troughed idler rollers (28,30,56,58) for movement through a material loading zone (24) where the belts are out of operative proximity each with the other, through a material lifting zone (40) where the belts are in operative proximity each to the other whereby material on the conveyor belt will be held in contact between the belts, and then through a material discharge zone (88) where the belts move out of operative proximity each with the other for discharging conveyed material. Pressure devices are provided to maintain predetermined belt speeds and pressures. <IMAGE>

Description

SPECIFICATION High angle conveyor The present invention is concerned with high angle conveyors.

Conventional conveyor belts offer an economical method for transporting bulk material at certain inclined angles ranging from a low of 7" for fine and somewhat lubricious material such as soda ash brickets, that is materials having a relatively low angle of slide, to a high of 30 for cinder concrete and ground phosphate fertilizers.

Typical recommended inclination angles for open-pit mine products such as excavated earth including anthracite coal, bituminous coal, lignite and crushed rock, vary from 15 to 22 while the respective angles of repose for such material vary from 29 to 44 . Typically the angle of repose will exceed the angle of slide for most materials.

The conventional conveyor is often a most economical, reliable and safe means for transporting such bulk materials. There are, however, many instances where an increase in conveying angles is desirable.

In a static case, a material having no interparticulate cohesive forces and placed upon an inclined rubber conveyor belt will begin to slide back down the incline when the incline angle of the belt surface just exceeds the angle of internal friction of the material or exceeds the friction angle or so called angle of slide for the material being conveyed at the interface between the material and the belt surface, whichever is smaller. The angle of internal friction is generally equal to the angle of repose of such materials.

Both the angle of repose and the angle of slide for bulk materials on rubber will vary from one material to the next and will be affected, even for the same type of material, by the maximum lump size, the lump size distribution, the orientation of the conveyor cross-section, and the shape that the particles or lumps take as a result of the reduction process, i.e., blasting and the varying degrees and methods of crushing.

The recommended conveying angles are in general far below the recommended friction angles.

This is due to the dynamics induced in a moving belt conveyor which result in relative motion between adjacent particles or lumps of the bulk material and between the material and carrying surface of the conveyor belt. Such relative motion tends to decrease the angle of slide for the material as conveyed.

Various proposals have been set forth in an effort to convey particular material at relatively high angles. All of these prior art disclosures are directed to solving the problem of conveying bulk material at high or steep angles and elevated volume conveying rates both efficiently and economically. None, however, have received commercial acceptance for one reason or another.

In designing such a system and improving the prior art devices to provide a structure of commercial acceptability, the geometry of conveyor for high angle material transport must provide support extending generally along a straight incline, that is the conveyor belting should not include sags due to support deficiencies. The conveyor surfaces must also lend themselves to facile cleaning and repair.

These past proposals included bucket elevators, flat belts having corrugated rubber sidewalls andl or cross-cleats, and troughed belts having fins. All of these devices function to convey bulk materials along steep inclines. Presently conveyor methods employing these devices are typically expensive, are possessed of limited capacity, and are unable to fully discharge a sticky material where conveyed. Further, the devices tend not to lend themselves to continuous cleaning by belt scrapers or plows, the cleats, fins, and the like interfering with the operation of such cleaning devices.

One proposed solution for such difficulties has been the so-called sandwich belt conveyors consisting of a troughed conveyor belt working in association with a cover or hugging belt. Hugging pressure applied to the conveyor through or by the cover or hugging belt as required to generate friction sufficient between bulk material and the conveyor belt surface whereby the bulk material will not back slide when conveyed at steep angles.

Various methods have been used or suggested to provide the required hugging pressure. These include the use of a heavy, that is weighty, cover belt having a normal component of its linear weight sufficient to provide the necessary hugging force. This proposal is disclosed in U. S. Patent No.

3,618,748 to Suloff.

Employing weighty covers provides an uneconomical solution on conveying angles approaching or exceeding 45". The normal component of the belt weight decreases with increasing conveying angle while at an increased conveying angle the hugging pressure requirement increases. Very weighty belts are therefore required and are expensive to manufacture. Employing such weighty covers, the conveyor support structure also becomes expensive because of the additional loading arising from the heavy cover belt.

Another method for providing the required hugging pressure is in the use of so-called pressing rollers which, when pressed onto an ordinary cover belt, provides the hugging force necessary.

This method is disclosed in USSR Patent No.

502,803 to Usov which describes a concept including two and four rubber tires individually pressing a cover belt to the conveyor belt at each cross-section of the cover belt with wide spacing along the length of the conveyor. These pressing concepts did not distribute the load sufficiently over the cover belt surface and this resulted in load concentrations, localized wear and accelerated breakdowns of conveyor components as well as in the loss of even hugging pressure between the widely spaced rollers along the conveyor length. Material spillage also resulted. Cover belt tension could not be increased to offset these problems typically as a result of the nature of the conveyor loading area.

Yet another proposal for providing hugging pres sure included in the use of two belts each resisting lateral bending as a result of being pressed together at their edges by staggering edge rollers. In this manner the lateral flexural stiffness of the belt must be such that when the conveyed material enters the resulting belt sandwich and pries the belts apart between the edge rollers, resistance to prying providing the hugging pressure necessary to prevent the material from sliding back under gravity. This sandwich conveyor method is described in U. S. Patent No. 3,982,626 to Mehta and German Patent No. 1,259,238 to Pelzer.

This sandwich conveyor method is normally employed for conveying materials vertically only.

Sandwich conveyors have inherent capacity limitations; elevated material transfer volumes At elevated material transfer volumes very wide belts elevated are required. The lateral bending stiffness necessary to provide an adequate prying resistance in wide sandwich conveyors must therefore be very high, such belts must be very thick with many plies of lateral reinforcement making these belts expensive to manufacture. In addition, stiff belts form only with difficulty into a troughed configuration when, at a conveyor loading station where it must behave as an ordinary troughed conveyor.

Practical belt widths typically are limited to approximately 91 centimeters and typically conveying capacity is less than a thousand tons per hour even when conveying very dense material at relatively elevated conveyor velocities.

A further proposal for providing the required hugging pressure to employ two ordinary belts having a low-elastic modulus and to judiciously select a conveyor profile geometry so that one belt is supported by troughing idlers in a convex vertical curve. The other belt provides the hugging pressure necessary by radial pressure resulting from belt tension and the profile geometry when such belts are formed in a C-shaped or snake-like configuration. This proposal is described in U.S. Patent Nos. 2,642,178 and 3,805,946 to Naylor and Yateman, respectively, and the Report "Evolution of Sandwich Belt High Angle Conveyors" by Joseph A. Dos Santos and Earl M. Frizzell.

With this non-elastic belt method, the required hugging pressure is derived by the juidicous selection of a conveying profile geometry which will exploit the inherent belt tension to produce a radial hugging pressure that functions to prevent sliding of the material in the sandwich when conveying at high angles. The nature of the loading area permits the selection of the belt tension in the region which is consistent with the selected conveyor profile and the required radial pressure. The C-shaped loop belt elevator as described in U.S. Patent to Naylor and Yateman, includes structures embodying this method for conveying, which in theory, has no practical capacity limitations. The C-shaped geometry, however, is impractical for conveying material along a straight line path at a predetermined incline.

An extension of the non-elastic belt concept is a snake sandwich conveyor. Such snake sandwich conveyors have solved some of the problems of geometrical conformance by introducing an inflex ion to the conveyor belt. By inflexion it is meant curvature reversal points along the conveyor profile and alternately carrying the top and bottom belts on troughing idlers along a vertical convex curve, with the belt providing the radial pressure by virtue of its belt tension.

The snake sandwich conveyor concept permits conformance to any vertical conveying geometry by the introduction of the inflexion points as required along the length. A correctly conforming geometry with loading and discharging at prespecified locations is determined by trial and error.

Once such a conveyor is installed, the profile geometry cannot be altered appreciably and such a conveyor cannot be extended or shortened. Such conveyors are impractical for applications requiring frequent changes in structural configurations, mobility and/or flexibility.

It is an object of the present invention to provide an improved apparatus for conveying particulate materials at high angles efficiently and economically.

The present invention provides a hugging conveyor having areas or zones where the conveying and cover, or hugging belts move between transition curves and linear paths. In the high angle conveyor of the present invention transitional movement is in part effected by the selection and employment of upwardly directed and downwardly directed troughed idler rollers, and employs an essentially fully equalized hugging pressure device to softly and evenly distribute hugging pressure onto the tensioned cover belt along the straight conveyor profile.The conveyor of the instant invention provides a loading and transition profile for the conveying and cover belts which, when acted upon by pressuring devices, distributes pressure from the devices along the length and across the width of the belts to enhance the lifting performance of the fully equalized hugging pressure device in a sandwich conveyor belt configuration.

The conveyor of the instant invention provies many possible combinations of transition, loading, and discharge zone profiles, making the inventive conveyor especially adaptable to applications requiring a high degree of mobility and flexibility.

In open pit mine applications, a high angle conveying system such as that disclosed herein offers many advantages over a more traditional truck haulage system, including superior energy efficiency. Where trucks must transport their own dead load in addition to the pay load, in the high angle conveyor of the present invention, energy expended functions primarily to elevate material, with only a very small amount being lost to idler bearing friction.

In many applications the presently disclosed system may require less total excavation than where other material hauling systems are employed. High angle conveyors may be supported along any stable slope. Total excavation is, therefore, determined by geotechnical stability considerations and not by the 8% to 27% maximum slope dictates associated with truck haulage ramps or low angle conveyors.

The high angle sandwich belt conveyor of the present invention also offers many advantages such as a simplicity of design approach. The present invention employs conventional conveyor hardware having the advantage of interchangability of components, fast delivery of replacement parts, high availability and relatively low maintenance costs.

The present inventive system is less limited in capacity. The use of conventional conveyor components permits elevated conveying speeds. Available belts and hardware to ten feet or more in width make possible capacities well in excess of 10,000 tons per hour.

High lifts and high conveying angles are also permitted due to the present invention. Lifts to 350 feet are possible with standard fabric belts, and single run lifts to approximately 900 feet are possible with steel cord belts. High angles in excess of 45 are possible without excessive wear in significant part due to a soft, floating, pressing mechanism.

The present invention also permits flexibility in planning and in operation. The sandwich belt conveyor of the present invention lends itself both to a so-called multi-module conveying system using a plurality of self-contained units and to a single run system employing an externally anchored, high angle conveyor. In either case, a conveyor unit may be easily shortened or lengthened or the conveying angle altered according to the requirements of a new location. High angle conveying modules of the present invention may be mounted on rails, rubber tires or crawler type transporters or may be equipped with walking feet for desired mobility.

In the conveyor of the present invention, belts are easily cleaned and quickly repaired. Smooth surfaced belts allow continuous cleaning employing belt scrapers or plows; particularly important in handling wet and/or sticky material. Smooth surfaced belts present reduced obstruction to a quick repair of a damaged belt employing hot or cold vulcanizing techniques, often reducing costly downtime.

Lastly, dust-free operation results from the high angle conveyor of the present invention. During operation, the material is sealed between the conveying and cover belts. Well centered loading and ample belt edge distances result in negligible spillage along the conveyor length. Dust control efforts generally are needed only be at transfer points.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a high angle conveyor constructed in accordance with the teachings of the present invention; Figure 2 is a side elevational view of the curved and straight line portions of the high angle conveyor shown in Fig. 1 and also showing, in phantom lines, the conveyor at different angles of orientation; Figure 3 is a perspective illustration of a transitional portion of the high angle conveyor showing the transition zone of the belt with parts removed for greater clarity.

Figures 4 to 6 are enlarged side elevational views of the top or material discharge zone of preferred embodiments of the invention., Figure 7 is an electrical schematic illustration of a automatic speed/tension proportioning assembly, Figures 8 to 10 are top, side and front elevational views of a fully equalized pressure device shown in Figs. 1, 2 and 4; Figures ii to 13 are perspective views of rollers of Figs. 8 to 10 including a cruciform alternate preferred embodiment of a roller; Figures 14 and 15 are top and side elevational views of an equally preferred variation of the fully equalized pressure device shown in Figs. 8 to 11 employing but a single row of rollers; and Figures 16 to 22 are various elevational views of equally preferred alternate embodiments of fullyequalized hugging pressure devices of Figs. 7 and 15.

General configuration Referring to the drawings, Figs. 1, 2 and 3 depict the general configuration of an embodiment of a sandwich belt high angle conveyor apparatus 10 of the present invention. As shown in Fig. 3, the conveyor 10 includes a lower conveyor belt 12 and a hugging or cover belt 14 cooperatively arranged each in endless configuration to effect the conveying of the material at elevated or high angles.

Referring to .Fig. 2, the lower conveyor belt 12 is supported at extreme ends by an upper drive pulley 16 and by an automatic take-up pulley 18 and suitable or conventional associated take up assembly 20 at its lower end. Support for a lower end on loading zone 24 is provided by a plurality of impact rollers 26, four in the disclosed embodiment, constructed of a plurality of stacked resilient disks 27 configured to present edge surfaces having the capacity to withstand the impact of material dropped onto the belt for conveying.

On opposite sides of the impact rollers 26 are idler assemblies 27 consisting of horizontal-idler rollers 28 to support the central section of the belt with pairs of angled side idler rollers 30 upturned at equal angles, generally of about 35 from the axis of the horizontal rollers. On opposite sides of these rollers, upstream and downstream thereof, are further idler assemblies comprised of horizontal rollers and pairs of side rollers at shallower angles, generally of about 20 . Between these idler assemblies may be additional assemblies at intermediate angles to provide a smoother transition of the belt between the steeper and shallower trough angles as the conveyor belt 12 assumes varying degrees of upwardly troughed configuration as the belt enters and departs the loading zone 24.These idler rollers 28, 30 support the belt and materials loaded therein and hold the conveyor belt 12 at predetermined and varying troughing configuration as it moves along its path of travel.

A curved transitional zone 34 is provided wherein the conveying angle, that is the relative verticle motion of the belt per unit of lateral travel, alters from a relatively flat angle to a lifting zone 40 of relatively steep conveying angle. No supporting idler rollers 28, 30 are provided beneath the conveyor belt 12 in the curved transitional zone 34, the shape of the conveyor belt 12 being dictated by contours of the hugging belt 14 which supports the conveyor belt 12 and the material being conveyed during transition.

Troughed assemblies 38 of idler rollers are provided along the straight line path or lifting zone 40 of the lower conveyor belt to an extent to a point adjacent the upper drive pulley 16 as shown in Fig.

2. These idler roller assemblies 38 are generally equally spaced along the path of conveyor belt 12 travel and are constructed each with a horizontal axis, central idler rollers 28 and angled pairs of side idler rollers 30 extending at about 35 angles as shown in Fig. 3.

On the reverse path of travel of the conveyor belt 12, there are provided a group of idler rollers 44 rotatable around horizontal axes to permit the belt to move readily, out of interfering contact with the lower surface of the upwardly traveling belt 12 portions carrying region of the conveyor belt.

These idler rollers 44 are closely spaced in the curved transitional zone 34 contacting the upper or interior surface of the belt 12. On either side, the return run of the conveyor belt 12 is supported by more distantly spaced idlers 44 on the external or lower surface of the belt.

Referring to Figs. 2 and 3, the upper, hugging or cover belt 14, like the lower or conveyor belt 12, is provided at its opposite ends of travel with pulleys 20, 52, the upper drive pulley 50 being driven and the lower pulley 52, including a suitable or conventional automatic take-up roller assembly 54. The central portion of the belt, in the curved transitional zone 34, includes a group of inverted idler roller assemblies 55 comprising central horizontal idlers 56 and side idlers rollers 58 angled downwardly at about 20 . These idlers 56, 58 tend to curve the upper cover belt 114 into a trapezoidal configuration through its arcuate path of travel through the curved transitional zone 34. When no material is present to be conveyed these downwardly troughed idler rollers 56 and 58 will trough the lower conveyor belt 12 into like configuration.

During a return run, the upper cover belt 14 is held into a position to preclude contact with other portions of the cover belt 14 engaged in a load carrying run by groups of horizontal axis idler rollers 62. These idler rollers 62 are straight, not troughed, and are more closely spaced at the curved zones than at the straight line zones. The idlers 62 guiding the return of the upper cover belt 14, as well as these idlers 44 guiding the return of lower conveyor belt 12, assist in maintaining the proper tension on the belts. All of the idler rollers are maintained in proper relationship each to the other by a plurality of suitable framing members 64.

As shown by the drawings, the framing members 64 are positioned surrounding the conveyor belt 12 and surrounding at least the portion of the cover belt 14 configured to hug the conveyor belt 12 providing a unitary structure with the framing members 64 of the curved transitional zone 34 connected to the framing members of the straight loading zone 24 and the inclined lifting zone 40.

The resulting self-contained supporting framework not only supports the belt load through the idler rollers 26, 27, 28, 30, 36, 38, 42, 44, 55, 56, 58, 62 and rollers 126 but also provides a structure for resisting the belt tension forces in the conveyor belt 12 and cover belt 14 from the one end to the other end through the curved transitional zone 34.

Inflection areas As can be seen in the drawings with particular reference to Figs. 2 and 3, the troughed nature of the idler roller assemblies through the curved transitional zone 34 and immediately prior thereto and immediately therefollowing are of such configuration and design that the lower conveyor belt 12 is upwardly troughed when approaching the transitional zone 34. Conversely, the upper idlers 55 will downwardly trough the upper conver belt 14 at this same area. As a result, the lower conveyor belt 12 when contact with the upper cover belt 14 is initiated will move from being upwardly troughed to being downwardly troughed. This troughing transition is best seen when the belts move through the transitional zone 34 in an unloaded condition but exists to a lesser degree while material is being transported.As a consequence, the lower conveyor belt 12 will go through an inflection area where the straight loading zone 24 meets the curved transitional zone 34.

The forces applied to the belts 12, 14 by rollers 55 at this inflection point provide a transition from a mode where the conveyed material travels in a straight, at most gently sloped path in an essentially conventional manner in approaching the curved transitional zone 34, to a mode where conveying is effected by a sandwich of the belts 12, 14 initiated at the curved transitional zone 34.

A similar type situation occurs at the end of the curved transitional zone 34 wherein the downwardly troughed upper idler roller assemblies 55 cease and the lower upwardly troughed idler rollers 27 again directly support the weight of the belts 12, 14 and conveyed material. Here again it can be seen, with particular reference to the unloaded state, that the lower conveyor belt 12 and, in addition thereto, the upper cover belt 14 jointly pass through a point of inflection from a downwardly troughed configuration to an upwardly troughed configuration, hence creating a second inflection area.

It has been found that the curved transitional zone 34 performs more efficiently in association with the straight zones 24, 40, therebefore and thereafter, if the curved zone 34, in cross section, not be of a constant radius of curvature. Hence, a lower portion of the curved transitional zone 34, adjacent the point of inflection between the zones 24, 34 is preferably at a radius of curvature of about 35 feet and decreases to a radius of curvature of about 30 feet adjacent the inflection point between the zones 34, 40. It has also been found that the lower idler assemblies 27 immediately prior to the curved transitional zone 34 be dropped somewhat below a line established by the preceding straight lined configuration whereby prior to the last three idler assemblies 27 transitional zone 34 establish an effective radius of curvature of about 30 feet.Similarly, the lower idler rollers or assemblies 38 at the beginning of the straight lifting zone 40 following the curved transitional zone 34 have been found to be more effective when following a curve with about a 35 foot radius of curvature. The dropping of these first idler assemblies 27, 28 in the straight loading and lifting zones 24, 40 permits the smooth conformance of the conveyor belt 12 with the curvature of the cover belt 14 at the beginning and end of the curved transitional zone 34. Thus the idler roller assemblies 27, 38 in the straight loading and lifting zones 24, 40 immediately before or after the curved transitional zone 34 trace a curved profile with a center of curvature therebeneath, with respect to a line defined by a tangent to the direction of travel of the conveyor belt 12, while the curved transitional zone 34 has its center of curvature thereabove.

Support & variable angles As can be seen with particular reference to Figs.

1 and 2, the belts 12, 14, idler rollers and assemblies 26-28, 30, 36, 38 and supporting framework 64 are maintained in a desired orientation during operation to provide the desired high-angle conveying. In one preferred embodiment, a pivot head 68 is mounted upon one or more concrete structures and pivotally supports the entire conveying machine 10 through its framing 64. A truss structure 70 spans the conveyor at a central location and it is provided with two upper pulleys 72 which function to support a cable 76. Coupling pulleys 74 are rotationally coupled to framing members 64 of the conveyor and guide the cable between the upper pulleys. One end of the cable 76 is connected to a winch 78. The end of the cable 76 remote from the winch 78 is secured adjacent the pivot head 68.

A winch 78 and a winch driving motor 80 effect any angle variation of the conveyor by shortening or lengthening of the cable. Activation of the winch 78 can reel in or reel out additional cable 76 to raise or lower the upper end of the conveyor through the pulley arrangement. This in turn will increase or decrease the angle of the belts 12, 14 from the horizontal. The particular structure as shown in the primary embodiment is adapted to modify the angle of incline of the lifting zone 40 from about 30 degrees to about 60 degrees. Note the phanthom lines of Fig. 2. It should be noted, however, that the particular configuration and geometry of the conveyor 10 does not appear to offer an effective limitation to the angle that material can be upwardly conveyed up to fully vertical conveying.Further, for many of the same reasons, there is no limit to the length that the linear lifting zone 40 of the conveyor can lift materials in, for example open pit mining sites. It is thought that if any limit exists to the angle or length of such a conveying system, the limiting factor might be the strength or resilience of the belting material em ployed. Alternate suitable or conventional supporting structures and configurations are also contemplated as within the scope of the invention.

There are various reasons for providing the variable angle of a high angle conveyor. In certain open pit mine sites, it is possible for the configurations of the slopes to change with time and as the mining proceeds. As a result, on site variations in conveyor angle might be necessary for optimal utilization at the site. Further, a varying angle permits the high angle conveyor to be utilized as an experimental bread board for determining reactions of the materials and the lifting capabilities of the conveying apparatus to varying configurations of the conveyor. Based upon the results of operation in an experimental mode, idler rollers and assemblies may be adjusted, tensions modified or other parameters varied for carrying out tests and experiments at varying angles which adjustments and alterations may find utility in operating the conveyor during routine operations.

Material recirculation As a further aid to the utilization of the high angle conveyor for experimental purposes the embodiment depicted in Figs. 1 and 2 includes a hopper 84 for discharging material to the lower conveyor belt 12 adjacent the loading zone 24 positioned above the impact idler rollers 26. The hopper 84 typically is utilized in the operation of a mine site for the conveying reception of materials from a power shovel, backhoe, bucket wheel excavator, drag line or other material transferring conveying machine. In the present embodiment, however, the hopper 84 is fed from a fixed return conveyor belt 86 of conventional variety, but angled to convey material from beneath an upper end or discharge zone 88 of the conveyor apparatus to the upper mouth of the hopper 84.

The upper end of the conveyor apparatus 10 is provided with a funnel like member 90 configured to receive the conveyed output from the conveyor belt 12. An enclosed chute 92 connects the funnel through a second hopper 94 at the lower end of the return conveyor belt 86. The chute 92 is preferably closed to minimize environmental contamination from the active downward movement of the materials being conveyed. In this manner, the material being conveyed is discharged at the zone 88 and dropped through the funnel member 90, and the chute 92 to the second hopper 94 whereupon the material is gravity fed to the lower end of the fixed conveyor belt 86 for being conveyed to the hopper 84 positioned above the impact idlers 26 supporting the conveyor belt 12 at the loading zone 24.

Material exit configuration Referring to the drawings, Figs. 4, 5 and 6 depict equally preferred alternate configurations for the discharge zone 88 at the upper portion of the conveying system. In Fig. 4 the upper driven roller or pulley 50 and cover belt 14 extend a distance outwardly of the lower driven conveyor roller or pul ley 16 and the conveyor belt 12 so that the upper cover belt 14 extends for a distance beyond the lower belt 12.

Such an outwardly extension has been found to permit efficient movement of conveyed material to a point generally beyond the point of contact between the conveyor belt 12 and hugging belt 14 expediting gravity movement of the conveyed material from the conveying system. Referring to Fig.

4, scraper elements 98 and 100 are positioned adjacent both the upper and lower belts 12, 14 in close proximity to the zone where the conveyed material is to be gravity dropped. The scraper-elements 98, 100 typically are spring biased members preferably of the type manufactured by Hosch Incorporated of Pittsburgh, PA. The configuration and spring loading orientation is such that substantially no conveyed material should return to the lower portion of the conveyor assembly, but rather that essentially all conveyed material either gravity drops immediately upon passage of the belts 12, 14 over the rollers 16, 50 or after being scraped by the scraper elements 98, 100. Other suitable or conventional scrapers are contemplated as within the scope of the invention.

Referring to the drawings, Figs. 5 and 6 show alternate preferred embodiments of material exit configurations at the discharge zone 88. In the embodiment of Fig. 5, the conveyor belt 12 extends beyond the upper cover belt 14. Additional trough idler rollers 102 support the conveyor belt 12 in a further curved configuration. In this manner, the conveyor belt 12 extending beyond its point of contact with the hugging belt 14 effectively acts as a conventional conveyor belt supported by additional spaced, troughed idlers (not shown) extending to the upper driven conveyor roller 16 positioned at any desired distance from the roller 50. In this manner, the conveyed material may be transported to a location remote from a position immediately atop contours of an excavation necessitating the use of a high angle conveying device where the configuration of the excavation site so warrants.

In the embodiment of Fig. 5, the cover belt 14 should be maintained in supporting contact with the conveyor belt 12 at least until the conveyor belt 12 has achieved a reduced angle of rise, that is, an angle where material may be conveyed in conventional manner such as about a 22 or less rate of rise and preferably about 15 or less.

Referring to the drawings, Fig. 6 depicts an alternate preferred embodiment resembling the configurations of Figs. 4 and 5 in that the lower conveyor belt 12 assumes a curved path beyond the lifting straight line conveying zone 40. Additional troughed idler rollers 104 support the conveyor belt 12 in a curved orientation. Similarly, the hugging or cover belt 14 follows such curve but extends beyond the lower conveyor belt for an additional distance as dictated by the particulars of the excavation site.

In these preferred embodiments the loading zone 24 may be of any desired length. In this manner the impact idlers 26 for the reception of material to be conveyed could be a great distance from the curved transitional zone 34 for greater latitude of apparatus design and to accommodate a wide range of mine site physical configurations.

In any of these embodiments scraper elements 98, 100 preferably are utilized to preclude conveyed material from accompanying the return run of the belts 12, 14 and being upwardly conveyed again.

Automatic take-up roll assembly Referring again to Figs. 1 and 2, the take up roller 18 and lower roller 52 for the conveyor belt 12 and cover belt 14 are mounted at their axial ends with yokes 108 which are in turn mounted on cables 110. The cables reverse direction through idler pulleys 112 fixedly attached to the framing members 64 with the cables 110 being connected to pneumatic cylinders 114.

The cylinders 114 are of conventional variety whereby a pre-set fluid (pneumatic) pressure may be automatically established by the operator at a predetermined setting so that any variations of conditions such as temperature, humidity, or load being carried should not vary the belt tension or strength. Without such an automatic take-up roller assembly the performance of the system 10 would be deleteriously effected through a change in belt tension. Establishing a pre-set pressure in each cylinder 114, one independent from the other, a predetermined tension may be established for each belt 12, 14.

In the event that the tension in a belt 12, 14 would vary, the cylinders 114 automatically function to adjust the corresponding support roller to thereby return the tension of the corresponding belt 12, 14to its predetermined value. The axial ends of each of these pulleys 112 are positioned in slots on the framing members 64 of the support structure of the conveyor for insuring straight line motion of the pulleys when adjustments are automatically made by the cylinders. Other suitable or conventional means for maintaining a predetermined belt tension are contemplated as within the scope of this invention.

Automatic speeditension proportioning assembly An control schematic diagram is shown in Fig. 7 for proportionalizing the torques of the conveyor belt 12 and cover belt 14 and for insuring the conveyor speed of the upper cover belt 14, that is the slave belt, corresponds to the speed of the lower conveyor belt 12, that is the master belt. The optimum condition would be to have the belts and any material being conveyed moving at a constant speed.

Belt speed sensors 118 and 120 are employed having rotatable axes configured to rotate with the two head rollers or pulleys 16 and 50 for independently determining the speed of motion of each belt 12, 14. Speed information is provided to a micro processor of the Ratio Indicator type to integrate the information and determine these speeds both absolutely and as a ratio of one with respect to the other. Where the belt speeds are different the Ratio Indicator sends a signal to a DC controller to change the electrical power being sent through drive circuitry, the electrical controls controlling the speed of motors Ml and M2 which drive the belts through the head driven rollers or idlers 16, 50 in well known manner.

This action functions to increase or decrease the speed of the cover or slave belt 14 to bring its speed into synchronization with the conveyor or master belt 12. A rate indicator is also driven off the Ratio Indicator to give a visual reading of the rate of speed of the conveyor belt with respect to the speed of the drive motor Ml to give an indication of efficiency of speed control synchronization.

Similarly, a visual readout may be provided at the Ratio Indicator of the ratio of the cover belt 14 speed with respect to that of the conveyor belt 12.

Although a 1:1 ratio is desired, a preselected variation may be acceptable. The variation in the acceptable ratio may be modified such as by adjusting a potentiometer in the Ratio Indicator circuitry in well known manner.

Fully equalized pressure devices Appropriate hugging pressure is provided to portions of the upper conveyor hugging belt 14 where required employing a fully equalized hugging or pressure device 124 which distributes hugging pressure to the cover belt and distributes that pressure generally evenly and continuously across a cross-section of the conveyor and along the entire conveyor length. In effective hugging or pressure device 124 distributes the material load, reduces load concentration and provides substantially continuous hugging pressure along the conveyor belt in the lifting zone 40 of high angle operation and enhances tension of the hugging and carrying belts 12, 14 with respect to the conveyed material.

Referring to Figs 8-10, the device 124 includes eight rollers 126. A loading beam 130 supportingly positions the rollers 126 for operation. The rollers 126 each are provided with a rectangular frame like carrier 132, open at the top and bottom. A shaft 134 supports each roller 126 for rolling-rotational motion during operation. The ends of each shaft 134 are supportingly received in apertures provided in the frame like carriers 132. Each frame member of the carrier 132 not supporting the roller shaft 134 integrally includes a shaft 136 received for support in apertures within a primary supporting equalizer bracket 138 permitting rotative motion of the carriers 132 about an axis perpendicular to the axis of rotation of the roller 126.

Two primary supporting equalizer brackets 138 together function to support a pair of rollers 126 carried by the frame like carriers 132 and are supportingly carried in configuration for rotative motion upon a pair of secondary supporting equalizer brackets 140. The brackets 140 are mounted for rotation on the loading beam 130.

One row of rollers 126 supported by a pair of secondary support brackets 140 constitutes a section 142 while a plurality of sections, at least two as disclosed herein, constitute a single module 144. An equal number of rollers 126 are located on either side of the central line of a biasing spring 146 and the support loading beam 130 for applying even and equal pressing forces to the cover belt 14 as shown in Fig. 10. Each section 142 of rollers is arranged and dimensioned to be located centrally along the path of belt movement with respect to the troughing idlers 38 on the opposite side of the conveyor belts as shown in Figs. 9 and 10.

The spacing of the pressing roller sections 142 along the conveyor length is preferably equal to the spacing of the carrying idlers 38 but the location is staggered so that a roller section 142 is located at or near the mid span of the successive carrying idlers 38. Each pressing roller section 142 consists of even numbers, preferably four, fully equalized pressing rollers 126. The number and type of pressing rollers 126 will be determined to the belt width, belt speed, type of materials handled, type of installation, e. g. mines, power plant, transfer terminal, etc.

Support is provided through the framing members 64 of the conveyor immediately above the center of the loading beam 130 through the biasing spring 146 between the frame and the loading beam 130. Other support is through an A-frame or pivot arm support 148, functioning as a pivoting arm rigidly mounted at one end to the loading beam 130 and pivotally mounted at the other or bifurcated end to the frame of the apparatus at a pivot point 150. The pivoting arm support 148 is used to stabilize the entire assembly, both laterally and longitudinally.

Preferably the arm support pivot point 150 from the stand point of a direction of conveyor belt travel is located upstream with respect to the loading beam 130 as shown in Figures 2, 8, 9, 10, 14 and 15 to avoid wedging action between the rollers 126 and cover belt 14.

If a single pressing section 142 is required, then a special single cross-section module as shown in Figs. 14 and 15 may be utilized. The special module is essentially the same as that shown . in Figs.

8, 9 and 10, except that four rollers 126 are mounted directly beneath the pressing spring 140 and the pivot arm support 144 is rigidly attached to the loading beam 130 to avoid knuckling.

The pressing roller 126 in any embodiment preferably consists at least one of a standard steel idler roll, rubber disc impact rollers, special pneumatic or foam-filled rollers, wide rubber tire rollers, and the like supportingly contained in the pivoting bracket 132. Pivoting pins at the pivot point 150 are positioned upon the conveyor framing members 64 to achieve a desired roller load distribution. Typically, but not always, the rollers 126 are at a mid span location with respect to the roller assemblies 38.

As shown in Figs. 12 and 13, special or standard steel rollers, rubber discs, impact rollers, rubber tires, and the like can be arranged on pivoting cruciform axles 152 in lieu of a framed carriers 132.

The pivoting axles 152 are located in this embodiment to the left and right side of the rollers or wheels 126 to achieve a desired load distribution.

An odd number, preferably three, equalizer brackets 138 and 140 are required per section 142 according to the number of pressing rollers in the arrangement, four as shown. The pivoting axle 152 or shaft 136 is located for each roller 126 to achieve a desired load distribution between each adjacent roller 126. Thus each individual roller 126 is freely rotatable about its own shaft 134 mounted in its own framed carrier 132. Each framed carrier 132 in turn is freely rotatable in an axis parallel to the direction of belt movement about its own shaft 136 mounted in a pair of equalizer brackets 138 which in turn is supported by the pair of brackets 140. Therefore, each roller 126 is virtually universally free to move into optimum conformance with the moving cover belt 14 with the equalizer brackets providing the appropriate force distributions thereto.

The pressing or loading beam 130 may typically tie together two sections 142 of the pressing or loading rollers 126 to form one single pressing module 144. The pivoting arm support 148 stabilizes the pressing module 144, both laterally and longitudinally, and provides a seat for the biasing spring 146. The pivot arm support 148 is shown extending from its pivot point 150 on the framing member 64 to a point beneath the spring seat and the pivoting arm support 148 is shown with pivot points at the anchor locations. A pressing device 124, may consist of a biasing spring 146, a fluid powered cylinder unit (not shown) or other means for inhibiting the spring-type response of a linear or non-linear coil spring.The spring 146 is designed or selected with response characteristics that will cause it to increase the load, thus increasing the hugging pressure to the extent required, as the material between the belts forces a separation between the two belts thereby deflecting the loading spring.

The assembly and disassembly of the fully equalized pressing device 124 including the pressing rollers 126 is facilitated by the use of slotted steel bushings 156 throughout to receive the various shafts and with slots to fit snugly into wedgetype receiving slots 157 as shown in Fig. 11. Additional bearings or bushings of self-lubricating materials such as bronze, nylon, polymers of elevated ultra-high molecular weight, graphite, or the like may be used in combination with the steel slotted bushings 156 in well known manner. The faces of the equalizer brackets 138, 140 and the loading beam 130 are shaped with the wedge shaped or convexing slots 157 to accommodate the pivot pin shafts and bushings 56.The slotted bushings 156 may be self-lubricating materials or may be made of steel or other high friction material with an additional bushing or bearing and the like to facilitate easy rotation of any pivot pin.

Shown in Figs. 16 to 18 is an alternative preferred assembly for applying pressure to the rollers 126 of a fully equalized hugging or pressure device 124. This assembly comprises the use of a torsion spring 170, similar to that used in some automotive vehicle suspensions, as for example, the Torsilastic (Registered Trade Mark) spring manufactured by the B. F. Goodrich Company.

A linkage arrangement comprising an upper link 158 and a lower link 159 couple a pair of brackets.

160 on the framing member 64 above the loading beam 130 through. shaft pivots 162, 164. A pivot pin 166 joins the two links 158, 159.

The torsion spring 170, used typically in pairs acting together, resiliently couple the brackets 160 on the framing member 64 to the top of upper link 158. Torsion from the spring 170 is transferred to apply pressure to the top cover belt 14 of the sandwich conveyor through links 158, 159, the loading beam 130, brackets 138, 140 and finally the rollers 126. This arrangement equalizes the pressure applied by the module 144. The arm support 148, pivoted to the framing member 64 of the conveyor 10 and to the loading beam 130 adds stability to the assembly. Superior performance is provided by the shock dampening capabilities of a torsion spring.

Support and pressure are provided to the rollers 126 through the framing member 64 of the conveyor 10 immediately above the center of the loading beam 130. The other point of support is from a remote portion of the arm support 148 through a pivoting arm mounted to the framing member 64 at the pivot point 150. The arm support 148 also fixedly mounts to the loading beam 130.

Shown in Figs. 19 and 20 is an equally preferred specific mode for applying pressure to the rollers 126 of a fully equalized hugging or pressure device 124. This assembly employs a torsion spring, similar to that used in some automotive vehicle suspensions, as for example, the Torsilastic (Registered Trade Mark) spring manufactured by the B. F. Goodrich Company.

A linkage arrangement comprising lower link 171 and an upper link 172 is coupled to a pair of brackets 174 on the framing member 64 above the loading beam 130 employing shafts 176, and 178. A pivot pin 180 joins the two links 171, 172.

A spring 182 resiliently couples the first and second links 171, 172 together to bias the lower link 171 downwardly thereby applying an even pressure to the loading beam 130. Preferably, an additional torsion spring 184, or more accurately, a pair of torsion springs 184 acting together couple the conveyor framing member 64 to the top of the upper link. Torsion from the springs 182 and 184 is thereby transferred to apply pressure to the top cover belt 14 of the sandwich conveyor through link 172, the loading beam 130, brackets and the rollers 126. The A-frame support pivoted to the framing member 64 of the apparatus 10 and to the loading beam 130 adds stability to the assembly.

Superior performance occurs because of the shock dampening capabilities of the torsion springs 182, 184.

In the embodiment disclosed in Figs. 21 and 22, support and pressure are provided to the rollers 126 through the framing members 64 of the conveyor employing a spring driven modified caliper assembly 124. This pressure and support is from a pair of V-frame or wishbone shaped supports 188.

These supports 188 are secured to brackets 190 secured to a framing member 64 of the conveyor ap paratus 10. Pins 192 pivotally secure the upper ends of each support 188 for rotational movement about a common axis. The lower ends of each support 188 converge to an apertured lower end portion for receiving a pin 194, also mounted through a loading beam 130, for creating a pivotable connection.

This apparatus 124 of Figs. 21, 22 contemplates the use of torsion springs 196 and 198 similar to that used in some automotive vehicle suspensions, as for example, the Torsilastic (Registered Trade Mark) spring manufactured by the B. F. Goodrich Company.

The torsion springs 196, 198 couple the upper ends of the respective wishbone shaped supports 188 to urge each support into pressing engagement with the loading beams 130 and, hence, to urge the supported idler rollers 126 toward the cover belt.

Torsion from the springs 196, 198 is therefore transferred to pressure applied on the top cover belt 14 of the sandwich conveyor. This arrangement tends to equalize the pressure applied by the modules 144 in a preferred manner. Superior performance occurs because of the shock dampening capabilities of the torsion spring 196, 198.

The pressing device 124 is thus configured to contact the back side of the cover belt 14 along a line transverse to belt movement as much as possible for maximum pressure equalization. Preferably the majority of such a transverse line should be contacted by the rollers 126.

Environments In utilizing the conveyor device 10 of the instant invention on the job actual support for the conveyor structure is typically supplied at its lower or loading zone 24 end, with a bracing being provided to the side of a hill being mined supporting an upper or discharge zone 88 end. Alternatively, support for the high angle conveyor may be at a discharge station 88 at the upper end of the high angle conveyor with the side of the hill being mined providing support sufficient to secure a lower or loading zone 24 end in an appropriate orientation for receiving ore to be conveyed. Alternatively, both ends of a high angle conveyor may be provided with motion imparting means such as caterpillar tracks or the like for shifting the device 10 at a mining site.Obviously merely one end or the other only could be so provided with such a shifting means depending on the configuration of the mine site.

A plurality of high angle conveyors can be employed in a cascading or modular relationship with a lower high angle conveyor depositing its material output at its upper end to the lower end of a subsequent high angle conveyor. Ridges at the mining sites are normally provided during the mining function whereby pluralitites of such high angle conveyors may be employed in series to convey product from a mine.

Steel cord belts Where stronger, steel cord conveyor belts are needed, steel cord conveyor belts cannot conform to small radii of curvatures as disclosed in the preferred embodiments as set forth. As a result, the radius of curvature at the curved transition zone 34 of the conveyor would be in the nature of 500 to 1000 feet or greater whereas the radius of curvature of the preferred embodiment employing cord belts would typically be 25 to 50 feet or greater.

Claims (30)

1. A high angle conveying apparatus including: (a) a driven conveyor belt trained for movement in a first endless path of travel; (b) a driven cover belt trained for movement in a second endless path of travel; (c) a pulley means defining ends of travel for each.of the belts; (d) a tensioning pressure means in association with at least one of the pulley means to maintain a predetermined tension on the belts;; (e) support means associated with each of the belts to support the belts in a path of travel, the path including a material loading zone where the belts are out of operative proximate contact each with the other, a curved transitional zone and an essentially straight high angle material lifting zone where the belts are in operative proximate contact each to the other whereby material on the conveyor belt is held in lifting contact therewith by the cover belt, and a material discharge zone where the belts are moved out of operative proximate contact each with the other for discharging material therefrom; (f) the support means including upwardly directed troughing idler rollers supporting the lower surface of the conveyor belt in the straight high angle material lifting zone.

(g) the support means further including downwardly directed troughing idler rollers supporting the upper surface of the cover belt in the curved transitional zone, (h) additional pressure means in operative proximity with the non-load contacting surface of the cover belt in the straight zone to apply an essentially fully equalized pressure to the cover belt, and (i) drive means to move the cover belt and the conveyor belt through respective paths of travel whereby material on the conveyor belt is conveyed from the material loading zone, through the curved transitonal zone and up a high angle through the material lifting zone and is discharged from the conveyor belt at the material discharge zone.

2. Apparatus as claimed in claim 1, further including operator controlled means to selectively vary the angle at which the conveying apparatus will convey material through the lifting zone.

3. Apparatus as claimed in claim 1 or 2, wherein the conveyor belt and the cover belt extend both generally perpendicular to a single vertical plane at the discharge zone.

4. Apparatus as claimed in claim 1, 2 or 3, further including motion imparting means beneath at least one of the loading zone and the discharge zone to allow repositioning of the apparatus.

5. Apparatus as claimed in any of claims 1 to 4 wherein the conveyor belt includes steel cables and the curved zone is of an enlarged radius of curvature.

6. A high angle conveying apparatus including: (a) a conveyor belt trained for movement in a first endless path of travel; (b) a cover belt trained for movement in a second endless path of travel; (c) tensioning means in association with at least one of the belts to maintain a predetermined tension on the belts; (d) support means in association with each of the belts to support the belts in a path of travel including: a generally horizon material loading zone where the belts are out of operative proximate contact each with the other, a curved transitonal zone and an essentially straight material lifting zone where the belts are in operative proximate contact each to the other whereby material on the conveyor belt is held in lifting contact therewith by the cover belt, and a material discharge zone where the belts are moved out of operative proximate contact each with the other for discharging material therefrom (e) additional pressure means in operative proximity with the surface of the cover belt obverse to the surface contacting conveyed material in the straight material lifting zone to apply an effectively fully equalized pressure to the cover belt, and (f) drive means to move the cover belt and the conveyor belt through respective paths of travel whereby material on the conveyor belt may be conveyed from the material loading zone through the curved transitional zone and a high angle material lifting zone and then discharged from the conveyor belts at the material discharge zone.

7. A high angle conveying apparatus including: (a) a conveyor belt trained for movement in a first endless path of travel, (b) a cover belt trained for movement in a second endless path of travel, (c) support means associated with each of the belts to support the belts in a path of travel that includes: a material loading zone where the belts are out of operative proximate contact each with the other, a curved transitional zone and an essentially straight material lifting zone where the belts are in operative proximate contact each to the other whereby material on the conveyor belt is held in lifting contact therewith by the cover belt, and a material discharge zone where the belts are moved out of operative proximate contact each with the other for discharging material therefrom; (d) the support means including upwardly directed troughing idler rollers supporting the lower surface of the conveyor belt in the straight material lifting zone; (e) the support means also including downwardly directed troughing idler rollers supporting the upper surface of the cover belt in the curved transitional zone.

(f) drive means to move the cover belt and the conveyor belt through respective paths of travel whereby conveyed material on the conveyor belt may be conveyed from the material loading zone, up a high angle material lifting zone and then discharged from the conveyor belts at the material discharge zone.

8. A curved high angle conveyor apparatus comprising a straight inclined upper lifting zone, a curved transitional zone and a generally horizontal lower loading zone, a lower conveyor belt and an upper cover belt extending through said inclined upper lifting zone, said curved transitional zone and said lower loading zone, and framing members positioned around said conveyor belt and at least a hugging portion of said cover belt providing a self-contained supporting framework to support not only the loaded idlers but also to resist tension forces of said conveyor belt and said cover belt.

9. Apparatus as claimed in claim 8, further including pulley means mounting each end of each of said belts on said framing members, and pressure means in association with at least one of said pulley means to maintain a predetermined tension in said conveyor belt and said cover belt.

10. A high angle conveying apparatus having a conveyor belt and a cover belt trained for movement in endless configurations through a lifting zone where the belts are moved into operative proximate contact each with the other so that material on the conveyor belt is held in contact therewith by the cover belt, pressure means for applying essentially fully equalized pressure to the back surface of the cover belt, said pressure means comprising;; (a) bracket means, (b) at least one row of rollers mounted within the bracket means, the axes of each row of rollers being positioned to contact the surface of the cover belt obverse to the cover belt surface contacting conveyed material along a line transverse to the direction of movement of the cover belt, each of the row of rollers comprising a plurality of freely rotatable individual rollers configured to contact the cover belt across substantially all of the transverse line, each roller being on an individually moveable axis of rotation to permit conformance of each roller to the cover belt independent of its adjacent roller, (c) support means coupled at a first end to the framing member of the conveying apparatus and at a second end to the bracket means, and (d) biasing means to bias the support means, the bracket means and each of the row of rollers into contact with the obverse surface of the cover belt for applying essentially fully equalized pressure thereto.

11. Apparatus as claimed in claim 10, wherein the bracket means supports an even number of rows of rollers and the second end of the support means is pivotally coupled to the bracket means with equal numbers of rows of rollers on either side of the pivotal coupling.

12. Apparatus as claimed in claim 10 or 11, wherein the biasing means is a torsion spring.

13. Apparatus as claimed in claim 12, further including a link means pivotably joining the conveying apparatus and the bracket means, with the torsion spring means coupling an upper end of the link means with the conveying apparatus.

14. Apparatus as claimed in claim 13 wherein the link means includes a pivot point intermediate its ends.

15. Apparatus as claimed in claim 13 or 14 including: (a) a link means coupled at a first end to the framing member of the conveying apparatus and at a second end to the bracket means, the link means including a pivotable joint between the first and second ends; and (b) a torsion spring means coupling the joint to spring bias the link means, and thereby the bracket means and each row of the rollers into contact with the back surface of the cover belt for applying essentially fully equalized pressure thereto.

16. Apparatus as claimed in claim 15, further including a secondary torsion spring means coupling the first end of the link means to the framing member.

17. Apparatus as claimed in claim 10 or 11, including a plurality of support means each coupled at a first end to a pivot point on a framing member of the conveying apparatus and at a second end to one of the bracket means.

18. Apparatus as claimed in claim 17, wherein each bracket means supports an even number of rows of rollers and the second ends of each of the support means is pivotally coupled to one of the bracket means with equal numbers of rows of rollers on either side of the place of pivotal coupling.

19. Apparatus as claimed in claim 19, wherein the resilient means includes torsion spring means coupling the support means with respect to each other.

20. Apparatus as claimed in claim 19, wherein the support means includes two members pivotally coupled at their first ends to the framing members, one member extending upstream and one member extending downstream with respect to the direction of belt movement, one bracket means being coupled to each of the second ends of the support means.

21. Apparatus as claimed in claim 6, in which said curved transitional zone has an input end adjacent said loading zone and an output end adjacent said lifting zone, said curved profile of said curved transitional zone having a radius of curvature greater at said input end than at said output end.

22. Apparatus as claimed in claim 6, further including upwardly directed troughing idler rollers supporting the lower surface of said conveyor belt in said essentially straight upwardly material lifting zone and at least a portion of said upwardly directed troughing idler roller in an inflection area immediately subsequent to said curved transitional zone being dropped and defining a curved profile with its radius of curvature therebeneath.

23. Apparatus as claimed in claim 22, further including pressure means in operative proximate contact with a back surface of said cover belt in said straight upwardly inclined lifting zone to apply an essentially fully equalized pressure to said cover belt.

24. Apparatus as claimed in claim 22, in whioh said radius of curvature thereabove of said curved profile of said curved transitional zone is less than said radius of curvature therebeneath of said curved profile of said upwardly directed troughing idler rollers in said inflection zone.

25. A high angle conveying apparatus includ ing: (a) a conveyor belt trained for movement in a first endless path of travel, (b) a cover belt trained for movement in a second endless path of travel, (c) first pressure means in association with at least one of said belts to maintain a predetermined tension in said belts, (d) support means in association with each of said belts to support said belts in a path of travel including a material loading zone whereat said belts are out of operative proximate contact with each other and also including a material lifting zone whereat said belts are in operative proximate contact with each other whereby material on said conveyor belt will be held in contact therewith by said cover belt and also including a material discharge zone whereat said belts are moved out of operative proximate contact with each other for discharging material therefrom, (e) additional pressure means in operative proximate contact with the obverse surface of said cover belt in said straight material lifting zone to apply an essentially fully equalized pressure to said cover belt, and (f) drive means to move said cover belt and said conveyor belt through their respective paths of travel whereby material on said conveyor belt may be conveyed from said material loading zone, up a high angle through said material lifting zone and then discharged from said conveyor belts at said material discharge zone, (g) said additional pressure means including a plurality of sections of rollers supported at spaced apart positions along said path of travel of said cover belt in said material lifting zone, (h) each of said sections of rollers including a row of rollers positioned to contact the obverse surface of said cover belt along a line transverse to the direction of movement of said cover belt, (i) support means including a framing member and swinging arm supports for said sections pivotally mounted on said framing member at positions lower than said sections, and (j) resilient means to spring bias said sections of rollers into contact with the obverse surface of said cover belt for applying essentially fully equalized pressure thereto.

26. Apparatus as claimed in claim 25, wherein a pair of said sections of rollers are pivotally mounted in a module on one of said swinging arm supports for rotation about a pivot pin extending transversely of said path of travel of said cover belt.

27. Apparatus as claimed in claim 26, wherein one of said sections of rollers is rigidly mounted on one of said swinging arm supports.

28. Apparatus as claimed in claim 26 wherein each said module is mounted separately from adjacent modules and sections for pressing each area of said cover belt independently of the pressing actions on other areas.

29. A fully equalized pressure module for pressing an obverse surface of a cover belt in a high angle conveying apparatus, comprising a first section of rollers and a second section of rollers, each section having a row of rollers parallel to and spaced apart from a row of said other section, each of said rollers being mounted for rotation in a carrier, each said carrier being supported for rotation on equalizer brackets permitting conformance of each of said rollers to the configuration of said cover belt independently of adjacent rollers, and a loading beam pivotally supported between said first section and said second section for rocking support of said brackets of said first section and of said second section and resilient means to spring bias said loading beam, said brackets and each said carriers to urge said rollers into contact with said obverse surface of said cover belt.

30. A high angle conveyor apparatus substantially hereinbefore described, with reference to and as illustrated in the accompanying drawings.