belt conveyors for bulk materials pdf
To improve on the cleat approach, corrugated sidewalls can be added to the transverse cleated belt to form complete rectangular partitions. 20 Conveyor Arrangements Belt conveyors can be designed for practically any desired path of travel, limited only by the strength of belt, angle of incline or decline, or available space. 209 Woven cord. 58 35 offset troughing idler. 64 Table 5-3. 1) for troughing idlers and (Step No. On long systems the declined portion often assists in propelling an inclined or horizontal portion. Tp determination graphical method for fabric carcass belts.
The present worth of a system is the value of an investment (made today at the rate of return required by the investor) which will produce the annual owning and operating costs for that system over the life of the project. Also, the rubber industry is making such rapid strides in the use of synthetic fibers and steel-cord carcasses that improved constructions are frequently available. The exception to this would be a conveyor system with a belt turnover system. Some idler manufacturers customarily supply larger diameter rolls with thicker metal shells and usually offer optional shell thickness for all roll diameters. CEMA publication on conveyor installation standards (Appendix D, Belt Conveyors for Bulk Material, fifth edition or later) list recommendations on structure misalignment). 305 Stone box loading chute. 5 K3B = Effect of roll diameter on predicted bearing L10 life For a given belt speed, using larger diameter rolls will increase idler L10 life. APPENDIX A Guide for Use of SI (Metric) Units Table A-1. Contact your CEMA idler manufacturer if you have doubts as to which value to use. 227 Welded steel pulley with grooved lagging. Percent life increase can be calculated for each roll diameter increase. 63 K2 = Effect of load on predicted bearing L10 life. Table 1-4. 6. This troughing idler selection procedure for calculated idler load does not include the following: 71 Belt Conveyor Idlers 1. 323 Movable tripper with reversible cross belt. The resilient discs help absorb energy from impact loads, which could save the belt from impact damage. Figure 1.14 Self-unloading ship with 78-inch discharge conveyor unloads iron ore pellets at 10,000 tph. 73 Figure 5.18 K3A = Effect of belt speed on predicted bearing L10 life. 253 Trough angle of the carrying idlers. 58 20 picking belt idler. 13 Belt Conveyor General Applications and Economics It is recommended that you contact members of CEMA or other consultants when considering conveyors of this nature. 53 35-degree troughed beltthree equal rolls standard edge distance = 0.055b + 0.9 inch. Pulleys and Shafts (Chapter 8) Because conveyor pulleys and shafts form a composite structure in operation, it is accepted engineering practice to consider their design together. Lowering with regenerative load. Table 7-5. xxvi Properties of covers. Figure 5.2 Flat belt idler. 95 Table 6-4. 22 Conveyor Arrangements Figure 2.8 illustrates a profile that can be used on a single, long, overland conveyor, often with several convex and concave curves, as shown in Figure 2.19. The Bu (useful bearing life) theory was technically correct. 179 Drive-shaft-mounted speed reducer with direct drive of V-belt reduction from reducer mounted motor.
Material characteristics and weight per cubic foot. Simply making the belt cover irregular will increase its ability to carry materials up slightly greater inclines with most belt manufacturers capable of molding patterns inch to 1- inches high into the top cover. 2. CHAPTER 10 Deteriorating conditions for conveyor belt covers. Extended and graduated spacing are not commonly used but if either is employed, care should be taken not to exceed idler load rating and sag limits during starting and stopping. 240 Example of molded chevron cleated belt. 347 AC induction motor motoring and regeneration. 18 Design Considerations No tables. Leading belt conveyor executives and engineers of CEMA member companies assisted in the development of new and updated information for the new edition through the Associations Bulk Handling Systems and Equipment Section, Bulk Handling Components Section, and Engineering Conference. 351 AC motor with full voltage starting and direct coupling. On an inclined or declined conveyor, the material tends to conform to its 47 Capacities, Belt Widths, and Speeds surcharge angle as measured in a vertical plane. There are numerous grades available in each of these materials which will affect performance. 119 Head pulley drive lowering with regenerative load. 409 Conveyor frame and idler alignment. All of these conditions do not have an exact mathematical basis and therefore can be very subjective. Belt Conveyor Capacities For a given speed, belt conveyor capacities increase as the belt width increases. Unloading capacities of such systems are usually greater than those of several grab bucket unloaders, requiring less turnaround time and lower labor and other operating costs. Summaries of Chapters 3-14 The following chapters cover various engineering design considerations, including pertinent data, formulas, and applications. Chapter 13 contains tables, charts, and other information on motor types and control devices useful for this purpose. Dollar amounts are included in the tables simply to clarify the procedure and to illustrate the effects of inflation and depreciation. The material buildup can also aggravate belt training. Fines: no grater than 1/10 maximum lump size. Since idler roll configuration, type of bearing, and seal design can vary with each idler manufacturer, it is logical to state that idler life can also vary for a given environmental and maintenance condition. As mentioned above, one of the considerations in the investment decision is the owning and operating cost per ton. There are transient conditions, however, that may cause conveyor belts to become misaligned despite all efforts to assure proper installation and maintenance. Some of the characteristics which affect basic design include size of lumps, bulk density, angle of repose, abrasiveness, moisture content, dustiness, stickiness, temperature, and chemical action. Belt System Year Truck System Cash flow Factor Present value Cash flow Factor Present value 1 $3,316 .833 $2,762 $2,804 .833 $2,336 2 405 .694 281 814 .694 565 3 404 .579 234 836 .579 484 4 405 .482 195 861 .482 415 5 407 .402 164 886 .402 356 6 1,678 .335 562 3,385 .335 1,134 7 459 .279 128 1,035 .279 289 8 461 .233 107 1,064 .233 248 9 463 .194 90 1,094 .194 212 10 468 .162 76 1,127 .162 183 Total $4,599 $6,222 Difference in present value = $6,222,000 - 4,599,000 = $1,623,000 Table 1-5 shows the result using 20 percent as the required rate of return. 210 Solid woven fabric.
Material characteristics and weight per cubic foot. Also, adequate inventories of spare parts can be maintained at a low cost and require relatively little storage space. In 000s of dollars. Material Being Conveyed Grain or other free-flowing, nonabrasive material Coal, damp clay, soft ores, overburden and earth, fine-crushed stone Heavy, hard, sharp-edged ore, coarsecrushed stone Belt Width (inches) 500 18 700 24-30 800 36-42 1000 48-96 400 18 600 24-36 800 42-60 1000 72-95 350 18 500 24-36 600 Over 36 Foundry sand, prepared or damp; shakeout sand with small cores, with or without small castings (not hot enough to harm belting) 350 Any width Prepared foundry sand and similar damp (or dry abrasive) materials discharged from belt by rubber-edged plows 200 Any width 200, except for wood pulp, where 300 to 400 is preferable Any width 50 to 100 Any width Nonabrasive materials discharged from belt by means of plows Feeder belts, flat or troughed, for feeding fine, nonabrasive, or mildly abrasive materials from hoppers and bins 48 Belt Speeds (fpm) Troughed Belt Load AreasStandard Edge Distance Troughed Belt Load AreasStandard Edge Distance Referring to Figure 4.2, the area of load cross section is divided into two parts. Materials or characteristics omitted from Table 3-3 may be roughly appraised by comparison with listed materials of the same general type. For instance, all information on belt tension, power, and drive engineering has been gathered together in Chapter 6. 64 Idler Spacing Return Idler Spacing The suggested normal spacing of return idlers for general belt conveyor work is also given in Table 5-2. 316 Rotary-table feeder. 123 Drive on return run horizontal or elevating. 314 Typical belt feeder. 30 Material class description. 2 Wide Range of Capacities Figure 1.1 60-inch conveyor carries large lumps of abrasive ore on incline. However, the economic issue vs. increased life should be investigated thoroughly. Page 53, Table 4-3 - 35 troughed belt cross section of load 60" BW @ 20 Surcharge = 2.876 ft2 Full belt load: 2.876 ft2 x 55 pcf = 158 lbs/ft --------- = 97.47% Percent full load: (. 341 Example of discharge trajectory: Drawing No. These large cleats allow the conveying angle to increase to approximately 45 degrees. Material can simply be discharged over the head end of each conveyor (Figure 1.9) or anywhere along its length by means of plows or traveling trippers (Figure 1.10). 200 General purpose rubber cover and ply adhesion. Table 14-2.
230 Welded steel wing pulley weights, pounds. Device can be adjusted for proportioned discharge to several places. 110 Single-pulley drive at tail end of conveyor without snub pulley; regenerative. Low labor and low energy requirements are fundamental with belt conveyors as compared with other means of transportation. 24 Crawler-mounted bucket wheel reclaimer with wheel mounted on chassis discharges onto a rail-mounted reclaim conveyor with slewing boom. Second, the top of the load of the material is the arc of a circle tangent, at the edges of the load, to the surcharge angle of loading. The total effect is influenced by the surcharge angle at which the material will ride on the conveyor belt. This is good practice because the sharp edges are likely to wear the belt cover unduly, particularly if the loading velocity of the material in the direction of belt travel is appreciably lower than the belt speed. See Figure 2.20.
Also included are data on necessary interlocks for two or more conveyors of a system. A and B values for equation Ky = (Wm + Wb) x A x 10-4 + B x 10-2. Advanced technical design methods are often required for high energy, high tension conveyors having some of the following conditions: Length over 3,000 feet Horizontally curved Head and tail driven High lift Large decline with braking requirements Undulating geometrics Dynamic analysis and computer modeling is often used in assessing the dynamic action and control of long overland and high lift, high horsepower conveyor systems. 5.18) are multiplying factors used to adjust basic L10 life rating of idler class selected. All rights reserved. 21 Ascending and horizontal path, when advisable to use two conveyor belts. 317 Typical regulating gate feeder. Lowering with regenerative load. Other accessory devices are available for protecting the belt and/or performing certain process functions. CEMA idler manufacturers have standard designs meeting these load ratings and dimensional standards shown in tables listed in this publication. 234 Permissible runout tolerances for high modulus belts. 17 Belt Conveyor General Applications and Economics Table 1-5. Five-roll designs offer a deep trough configuration and greater load capacities than conventional three-roll units. 59 Belt Conveyor Idlers Figure 5.8 Flat-belt rubber-cushion impact idler with fixed shaft. Trough Angle Belt Width (inches) 20 35 45 Single Roll Return 18 410 410 410 220 24 410 410 410 190 30 410 410 410 165 36 410 410 396 155 42 390 363 351 140 48 380 353 342 130 Ratings based on minimum L10 of 30,000 hours at 500 rpm. With all lumps and no fines, the recommended maximum lump size is one-fifth of the belt width ( b/5).
With all lumps, the recommended maximum lump is 1/5 belt width (bw/5).
TYPICAL BELT CONVEYOR TRAVEL PATHS Figure 2.2 Horizontal belt. These maximum angles generally range from 10-30 degrees depending on the bulk material. Figure 5.16 Two-roll suspended Vee return idler. 5 Horizontal curve conveyor, conveying following natural terrain.
178 Parallel-shaft speed reducer directly coupled to the motor and to drive shaft. Cash flow truck system. In contrast with the above-mentioned highcapacity unloading systems, certain materials, such as foundry sand, can be plowed from the belts (Figure 1.16) at specific locations in quantities controlled by the requirements of the application. Table 10-2. However, in most cases, the actual loss of capacity is very small. Material Angle of repose (degrees) Recommended maximum inclination (degrees) Code Compost 30-50 Concrete, cinder 90-100 Copper ore 120-150 30-44 20 *D37 Copper sulfate 75-85 31 17 D36 Cork, granulated 12-15 C45 Corn, cracked 45-50 C35W Corn, ear 56 Corn, shelled 45 21 Corn sugar 31 30-44 Corn germs 21 E45ST 12-30 10 D46 C25NW B35 B35W Corn grits 40-45 30-44 Cornmeal 32-40 35 22 B35W Cottonseed, dry, de-linted 22-40 29 16 C35W Cottonseed, dry, not de-linted 18-25 35 19 C35W B35W Cottonseed cake, crushed 40-45 30-44 B35 Cottonseed cake, lumpy 40-45 30-44 D35W Cottonseed hulls 12 45 *B45Y Cottonseed meal 35-40 35 Cottonseed meats 40 30-44 B35W Cracklings, crushed, 3 inches and under 40-50 45 D45 Cryolite, dust 75-90 30-44 A36 Cryolite, lumpy 90-100 30-44 D36 Cullet 80-120 30-44 Diatomaceous earth 11-14 30-44 A36MY Dicalcium phosphate 40-50 45 A45 Disodium phosphate 25-31 30-44 Dolomite, lumpy 80-100 30-44 Dolomite, pulverized 46 41 Earth, as excavateddry 70-80 35 20 B36 Earth, wet, containing clay 100-110 45 23 B46 Ebonite, crushed inch and under 65-70 30-44 C35 Emery 230 20-29 A27 Epsom salts 40-50 30-44 B35 Feldspar, -inch screenings 70-85 38 * May vary considerably consult a CEMA member 36 Average weight (lbs/cu ft) 22 20 B35W D37Z B36QT 22 D36 B36 18 B36 Effect of Inclines and Declines Table 3-3. APPENDIX C Belt Tension to Rotate Pulleys No figures. CHAPTER 4 Flowability-angle of surcharge-angle of repose.
303 Typical loading chute. 275 C-profile sandwich belt feeding a bin. 308 Deflector or straight chute liner patterns. 75 Figure 5.20 Figure 5.21 Figure 5.22 xvi Discharge over end pulley to form conical pile. 201 Conveyor belt cover quality selection. 406 Table C-2. Any difference between the forward velocity of the material as it is being loaded and the conveyor belt that is receiving it must be equalized by the acceleration of the material. Table 5-10. Belt Speed Bearing life (L10) is based on the number of revolutions of the bearing race. In general, the greater the belt tensions, the less effective the training idlers. Material characteristics and weight per cubic foot. 4) shows the effect of belt speed on predicted bearing L10 life. They can be provided with structures which prevent the escape of dust to the surrounding atmosphere and are weatherprotected. Step No. 338 List of Figures Figure 12.54 Figure 12.55 Figure 12.56 Figure 12.57 Figure 12.58 Figure 12.59 Figure 12.60 Figure 12.61 CHAPTER 13 Conveyor Motor Drives and Controls Figure 13.1 Figure 13.2 Figure 13.3 Figure 13.4 Figure 13.5 Figure 13.6 Figure 13.7 Figure 13.8 Figure 13.9 Figure 13.10 Figure 13.11 Figure 13.12 Figure 13.13 CHAPTER 14 Close-up of trajectory from head pulley of conveyor, speed 760 fpm, handling iron-ore pellets. As conveyor belt design technology has advanced, allowing greater transverse flexibility, 35-degree troughing idlers have become the most widely used type of troughing idler. 30 28 26 24 e arg h urc 22 0 Lump size, inches 20 s ,2 es 18 16 , ps 14 % 12 % 90 fin lum 10 e harg rge surc rcha 0 u 3 s , 20 ines ps, 0% f 9 m , u l s All lump 10% e urcharg s, 30 s p m lu All 42 48 10 8 6 4 2 0 18 24 30 36 54 60 66 72 78 84 90 96 Belt width, inches Figure 4.1 Belt width necessary for a given lump size. Idler shell wear life is more of a factor for the return idlers since it normally contacts the dirty side of the belt resulting in abrasive wear of the shell. - = 1.20 , or 20% increase in L10 life Example: --------------------------------------------1.25 for 5 in. The angle of repose of a material is the acute angle which the surface of a normal, freely formed pile makes to the horizontal. 212 Fabric-reinforced steel cord belt. 77 Load ratings for CEMA E idlers, lbs (rigid frame and catenary where applicable). On such conveyors, it is essential that belt tensions be determined along the entire length in order to calculate the radii of the curves and locate the maximum belt tension which can occur at an intermediate point. The influence of these and other material characteristics on belt conveyor design is discussed in Chapter 3. Throughout the history of Belt Conveyors for Bulk Materials, the primary objective has remained unchanged: To provide basic engineering data for the design of belt conveyors in a book written for technically qualified people who may not be totally familiar with belt conveyor design. Table 4-3. Annual expenditures in current dollars. Figure 1.9 Material discharging over conveyor head pulley. Materials that might cause sticking or packing if transported by other means are often handled successfully on belt conveyors. It must be understood that the data given in this table are for average conditions and average materials. WB-Estimated average belt weight, multiple- and reduced-ply belts, lbs/ft. On long return belt runs, it is necessary to use these idlers only to the point where the material on the belt surface no longer will adhere to and build up on normal return idler rolls. This swinging about the center pivot is accomplished in various ways usually associated with the pressure of the off-center belt against a fixed arm attached to the idler frame. The cost per ton is then determined by dividing the annual owning and operating cost by the tonnage expected to be handled during that year. Table 6-12. See Figure 1.3. 120 Tail pulley drive horizontal or elevating. To simplify the example, investment tax credit and other tax considerations (mainly depreciation), which would be advisable in an actual analysis, have been ignored. Recommended maximum belt speeds. 3 96-inch conveyor at high-capacity coal-loading facility. Note that in the table lump size means the largest lump which may occasionally be carried rather than the average lump. 60 Suspended or garland idlers. 120 Conveyor with convex vertical curve, head pulley drive. It also tends to flatten the material surface slope (i.e., the angle of surcharge) and explains why this angle is less than the angle of repose. 382 Belt conveyor troubleshooting complaints and recommended resolutions. Belt Conveyors for Bulk Mate, BELT CONVEYORS OVERVIEW
Table 6-6. 314 Typical drag scraper feeder. Curved conveyors further enhance the reliability, availability and environmental advantages of the standard belt conveyor by eliminating the infrastructure and dust control requirements at transfer stations. 252 Convex vertical curve. 370 Operation, Maintenance, and Safety No figures. Table 5-11.
Carrying Idler Spacing at Loading Points At loading points, the carrying idlers should be spaced to keep the belt steady and to hold the belt in contact with the rubber edging of the loading skirts along its entire length. Refer to Table 4-1, Recommended Maximum Belt Speeds. Select a suitable con- veyor belt speed. Troughing carrying idlers are sometimes referred to as troughers or carriers, and are the most common type of belt conveyor idler used. Self-unloading ships and lake vessels (Figure 1.14) equipped w ith belt conveyors can be unloaded in all ports, including those which do not have dockside unloading equipment (Figure 1.15). The rolls are fitted with antifriction bearings and seals, and are mounted on shafts. 111 Single-pulley drive at head end of conveyor with snub pulley; regenerative. 293 V-plow return-belt scraper. The belt conveyor designer should thoroughly investigate all conditions relative to calculating idler misalignment load (IML), in addition to structure misalignment. .jpg)
Trough Angle Belt Width (inches) 20 35 45 Single Roll Return Two Roll Vee Return 36 1800 1800 1800 1000 1300 42 1800 1800 1800 1000 1300 48 1800 1800 1800 1000 1300 54 1800 1800 1800 925 1300 60 1800 1800 1800 850 1300 775 1300 1800 1800 1800 700 1300 625 1300 550 1300 475 1300 400 1300 250 1300 66 72 78 84 1800 1674 1620 1750 1628 1575 90 96 102 Ratings based on minimum L10 of 60,000 hours at 500 rpm. -----------1- = -------------------------------------------------------------------------------------------------------------------------------------------= 0.371b + 0.25 + (0.2595b + 1.025) cos 5. j = m sin j = (0.2595b 1.025) sin l+l 6. 382 Preface After over three decades of widespread use throughout the world, Belt Conveyors for Bulk Materials has established its place as the premier manual in its field. See Figure 1.2. Flat Return Idlers The flat return idler consists of a long single roll, fitted at each end with a mounting bracket. These load ratings are based on the following: CEMA B load rating based on minimum L10 of 30,000 hours at 500 rpm CEMA C load rating based on minimum L10 of 30,000 hours at 500 rpm CEMA D load rating based on minimum L10 of 60,000 hours at 500 rpm CEMA E load rating based on minimum L10 of 60,000 hours at 500 rpm These loads and L10 life ratings are minimum ratings for CEMA rated idlers. 120 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.6A Figure 6.6B Figure 6.6C Figure 6.6D Figure 6.6E Figure 6.6F Figure 6.6G Figure 6.6H Figure 6.6I Figure 6.7 Figure 6.7A Figure 6.7B Figure 6.7C Figure 6.7D Figure 6.7E Figure 6.7F Figure 6.8 Figure 6.8A Figure 6.8B Figure 6.8C Figure 6.9 Figure 6.9A Figure 6.9B Figure 6.9C Figure 6.10 xvii List of Figures Figure 6.10A Figure 6.10B Figure 6.10C Figure 6.11 Figure 6.11A Figure 6.11B Figure 6.11C Figure 6.12 Figure 6.12A Figure 6.12B Figure 6.12C Figure 6.13 Figure 6.13A Figure 6.13B Figure 6.13C Figure 6.14 Figure 6.14A Figure 6.14B Figure 6.14C Figure 6.15 Figure 6.15A Figure 6.15B Figure 6.15C Figure 6.16 Figure 6.16A Figure 6.16B Figure 6.16C Figure 6.17 Figure 6.18 Figure 6.19 xviii Declined belt conveyor with head pulley drive. 61 Return belt idler.
If the material is dry and fine and the belt velocity is high, dusting of the material may be intolerable. 232 Permissible face widths tolerances. Width can be determined by the size of lumps, the percentage of lumps to fines, and the angle of repose of the material. CHAPTER 14 Operation, Maintenance, and Safety Table 14-1. 
Finally, overland belt conveyor systems can be designed to blend into the landscape, resulting in an unscarred, quiet, and pollution-free operation. In many cases, such operations are not only performed more effectively in connection with belt conveyors but are the only practical means. Others are needed for such purposes as training the belt, cushioning the belt against heavy lumps, and handling extremely abrasive or sticky materials. CHAPTER 9 Belt modulus values. 340 Example of discharge trajectory: Drawing No. 68 The Selection of Idlers Table 5-4. Lowering without regenerative load. 11 Conveyor in completely enclosed gallery carries its load safely overhead, avoiding any interference from highway or rail traffic. 49 Flat belt loading. 320 Bin lowering chute. 148 Horizontal belt conveyor. Counterweight and cables not shown. This idler, utilizing the wing or side rolls located in an adjacent parallel plane to the center roll, is used in either the grain industry where thin belts are used or underground mining where height clearance is minimal. [emailprotected] In some cases, the method of tension calculations must also be modified. Table 6-10. Troughing idler load ratings (Tables 5.75.10) are for three equal length rolls. 5. This information is necessary to design convex and concave vertical curves, trippers, and remotely located takeups. 3. Trough Angle 20 35 45 Single Roll Return 18 900 900 900 475 24 900 900 900 325 500 30 900 900 900 250 500 36 900 837 810 200 500 42 850 791 765 150 500 48 800 744 720 125 500 54 750 698 675 * 500 60 700 650 630 * 500 * 500 66 Ratings based on minimum L10 of 30,000 hours at 500 rpm.
309 Skirtboards on a troughed belt. Advantages may be lower idler cost (fewer used) and better belt training. 296 Example of wind hoops on a belt conveyor. 66 B Full trough recommended minimum transition distances. Or a combination stacker-reclaimer (Figure 1.12) can be used to stockpile material or to reclaim and return it to the main belt conveyor. See idler load ratings in Tables 5-7 5-11. 144 List of Figures Figure 6.20 Figure 6.21 Figure 6.22 Figure 6.23 Figure 6.24 Figure 6.25 Figure 6.26 Figure 6.27 Figure 6.28 Figure 6.29 Figure 6.30 Figure 6.31 Figure 6.32 Figure 6.33 Figure 6.34 Figure 6.35 Figure 6.36 CHAPTER 7 Inclined belt conveyor. 179 Spiral-bevel helical speed reducer, helical-worm speed reducer, or worm-gear speed reducer, coupled to motor and, with chain drive to drive. 84 Table 5-14. 57 Belt Conveyor Idlers Troughing Carrying Idlers Due to the increased cross sectional fill depth, troughed belts can carry far greater tonnages than flat belts of the same width and speed. 126 Declined conveyor with drive on return run. Effect of load on predicted bearing L10 life 4. Training idlers for both one-way or reversible belts are available. A CEMA member should be consulted in such cases, as well as in the design of very large conveyors or complex conveyor systems. Chapters 7 and 13 are new, and Chapter 7 incorporates the current Rubber Manufacturers Association material and recommendations. Bulk solids handling. Environmental, maintenance and other special conditions 67 Belt Conveyor Idlers In addition to information provided in the Idler Selection Procedure, the above items are summarized as follows: Type of Material Handled The characteristics of the material handled have a direct bearing on the idler selection. Use the above values for estimating. Referring to the diagram used in the derivation of belt conveyor capacity (Figure 4.2), the area Ab does not change although the area As does decrease as the cosine of the conveyor slope. However, L10 bearing life is more commonly used and accepted for bearing life calculations and rating. Some conveyor systems have been designed successfully utilizing extended idler spacing and/or graduated idler spacing. In this manual, the cross-sectional area is based upon the following two conditions.
The power required to drive or restrain the conveyor is derived from the tension, which represents the amount of pull at the drive pulley necessary to propel or retard the loaded belt.
Actual values for load ratings and L10 life for specific series and belt sizes supplied by CEMA manufacturers may be higher. It offers information on numerous examples of modern high-performance and complex systems and includes suggestions and guidelines for economic evaluations and conclusions. Cash flow conveyor system. 243 Recommended minimum radii for concave vertical belt conveyor curves. Moreover, emphasis on our national problems of energy saving, environmental control, and safety has drawn a sharp focus on the many other advantageous features of belt conveyors. Closely sized or friable materials are carried with minimum degradation. 84 Table 5-6. There is also an empirical relationship between lump size and belt width. Material Characteristics Size Code Very fine100 mesh and under A Fine inch and under B GranularUnder inch C Lumpycontaining lumps over inch D Irregularstringy, interlocking, mats together E Flowability Very free flowingangle of repose less than 19 1 Angle of Free-flowingangle of repose 20 to 29 2 Repose Average flowingangle of repose 30 to 39 3 Abrasiveness Sluggishangle of repose 40 and over 4 Nonabrasive 5 Abrasive 6 Very abrasive 7 Very sharpcuts or gouges belt covers 8 Very dusty L Aerates and develops fluid characteristics M Miscellaneous Contains explosive dust N Characteristics Contaminable, affecting use or saleability P (Sometimes Degradable, affecting use or saleability Q more than one Gives off harmful fumes or dust R of these Highly corrosive S characteristics Mildly corrosive T may apply) Hygroscopic U Interlocks or mats V Oils or chemical presentmay affect rubber products W Packs under pressure X Very light and fluffymay be wind-swept Y Elevated temperature Z Example: A very fine material that is free-flowing, abrasive, and contains explosive dust would be designated: Class A26N. In some cases the idler frame design could be the limiting factor for load with L10 life being a higher value. This procedure is shown in Idler Selection Procedure (Step No. 11 Belt Conveyor General Applications and Economics Figure 1.23 Tubular galleries provide opportunity to optimize shop assembly of components. Flow Very free flowing 1* Free flowing 2* Average flowing 3* Sluggish 4* Angle of Surcharge 5 10 20 25 30 35-39 40 - up Angle of Repose 0-19 20-25 30-34 Material Characteristics Uniform size, very small rounded particles, either very wet or very dry, such as dry silica sand, cement, wet concrete, etc.
