ST ENURESAT RMON ELECTRIC TRAVELING CRANES Thesis for Degree of M. E. Charles Henry Ponitz 1915 ee a ee ——. ¢ a Y~ . e 22 bX. Ce. th Ae ® Neer Cia wi Se. ~ va . RS! enc. Car uw ee wD - =e Di fl THESIS. Korero THESIS ------- x RESIGN AN OD CONSTRUCTION Xe-- Of «--x MOVERRN BRECTRIC TRAVELING CRANES. K-e- by ---x CHARLES H. RONITZ MUSKEGON, MICHIGAN. MAY 1915. +--+ . - + - ca - ~ - Co - a il iil LV VI Vil VIil IX XII XIII INTROBUCTION. CLASSIFICATION OF CRANES. PRINCIPAL PARTS OF ZLECTRIC TRAVELING CRANES. PROPORTIONING OF TROLLEY UNITS. PROPORTIONING OF BRIDGE UNITS. ACCESSIBILITY OF MECHANISM. FLEXIBILITY A VITAL FACTOR I% THE DESIGN OF ANY HOISTING MECHANISM. INDUSTRIAL DEMANDS WHICH TAX THE DESIGNER'S INGENUITY. POWER SUPPLY OF TROLLEY AN) B3RIDGE MOTORS. DETERMINATION OF POWZR UNITS. SAFETY APPLIANCES. AVERAGE VS. STEEL MILL CRANES UZSIGN OF TWENTY TON T¥O MOTOR TROLLEY EMBRACING PRINCIPAL CALCULATIONS, DIMENSIONS, ARRANGEMENT, etc., SHOWN ON BRAWING 3D142 Oo: 2 INTRODUCTION Since time imaemorial, devices and appliances to raise and lower loads have been a necessity in various industries, construction work and processes of manufacture. Many of these were crude and inefficient, the primary end in view being to move loads at any cost. In analyzing the contributing causes which have made the electric traveler such a necessity there is probably no one factor so prominent as the application of electric power to various crane requirements. Other forms of power have been used, yet there is no other form which is so adaptable to the requirments of traveling cranes. In view of this, many improvements have taken place which redound to the ben- efit of the crane manufacturer as well as purchaser. Contrasting the earlier devices and appliances for the moving of loads with those of today, we find the conditions and demands different and more far reaching. Where the crane was used exclusively as a mover of loads irrespective of cost, it is now,in addition, a conveyer to a large ex- tent, not only lifting objects but transporting them from place to place. Where formerly manual labor was employed to transport material, the electric traveler, bucket crane and lifting magnet carry large quantities, reducing time and lavor costs to a minimum. It is the purpose of this thesis to consider the actual design as well as the commercial construction of the elec- tric traveler. It is not the purpose to consider the elec- tric traveler from a purely theoretical standpoint but to a a . ‘ : . r --. . e . an . ‘s, a c ‘ , “4 Lee Le =e . - ‘ tf “ - s . - e awe -e ‘ a ~ e . 4 . ' ‘ * , 4 o ~ee ‘ v of . ea ret . * ¢ ry . ‘ *- e eo. me . - 2 “Y oe * » oe . ” ‘ ‘ ‘ “4 ~ . - a . ‘ . ; “ e . ° = . ‘ A . . . : a ‘ , . wy oo . < ’ : ~ ow . 3 ~ 7 4 o y od . m ° - - s- r 4 “: ae ° ¢ . ‘ - « ‘ a ‘ , f . 4 os . , < . : * _ . ’ ‘ ad 4 Ry - * t ¢ ’ { ~a . 7: . 4 « f . . a ‘ , a. . @ . : ‘ & ¢ - «4 rn ? u ° : - _— . a - . m+ - - ‘ +. . ‘ r e ‘ wo - * -s < 4 e on i ‘ - . oat ‘ a of - . -s a “~ - . e @ c _ : - a) . . we : . . ~ . ‘ y wet . a . . * ‘ . : + “ » of » e 7 e , . . t . . t : 4 ow * ~ + "— : . ~~" we 4 : . aa ~ ° ~s - ee +e Le “se - . * ry « ‘ e . . Sa 4 : ow 6 s « a ‘ . ' we “ te « . ¢ “_ 4 . , . 4 « . 4 ¢ | qa a b ” . . ’ a Ne ef -- . : ’ vlend scientific principles with practical requirements; to satisfy the customer's demand without losing sight of the manufacturer's interests. It is only with due consid- eration and proper co-ordination of these various factors that the interests of all concerned are vest served. AL CLASSIFICATION OF CRANES In general, cranes may ve classified according to their motions, or their source of motive power. Under the first Glassification a crane would be rotary or rectilinear, while under the second we would have the following sub- divisions: Cranes having their power attached, electric, pneumatic and steam. Locomotive cranes, which supply their own power. Hand--where manual labor is used for operation. All electric travelers can be grouped under one of five heads. So far as industrial requirments are coneerned it seems more logical to classify the electric traveling crane according to the service it is to perform. Thus we would have the single drum crane which hoists and lowers its load by means of attaching the load to an ordinary crane hook. This is the type of crane in greatest demand and has a wide applisation in the industrial world. The average shop would require nothing further than the hook. A structural shop, for instanee, would require a.wider gauged trolley which would permit the suspension of a lifting beam from the ropes. This may result in two drums on the same shaft, yet in principle it is nothing but a single drum extended. Foundries, machine shops, ware-houses, boiler-shops, as- sembly floors, locomotive shops, etc., can use the same type of crane. Some details must be altered to suit the -« x ' t . ~ 4 ws nN s tony iad ” . . = - os of 4 . - \ - - a * = . , “ , ” “ v « * =n . ’ . 4 . ‘ . . . ~” ‘ . ‘ ae * “ ° f »» . - ’ - @ - . = ' oe , . o » ~ Lan e! tet . see yy - le . o-. . 4 re ~ . .' on . 4 * e ‘ ms , - 2 oof y - “ . wo —_ 2 ‘7 ; - ~4q . -¢ . 2 e a ' Cc . ‘ a4 a . oe -- « shop, the chief one being, in most cases, the application of the power #6 the load. A second class would ve the bucket crane. This class of crane must be very rugged and substantial since the ser- viee is extremely severe and frequently rough. Yhere it formerly required a dozen laborers to unload and convey a barge of coal, for instance, one bucket crane will dispense. with nearly all of them There is a saving of time and money. The operating expenses and power consumption are small items when compared to the labor item, to say nothing of the time gained which is a very important consideration in most enterprises. Coal, sand, coke, cinders, slag, etc., offer a wide application for the bucket trolley. A third class of electric traveler is the gantry crane. This may be an ordinary gantry, two or one-legged, it may be a single cantilever or a double cantilever gantry. It may have a hook trolley or a bucket trolley. In this class as in any other it is impossible to conceive of all the possivle industrial demands and subsequent designs that could be produced. The ladle crane enables the oarrying and pouring of large quantities of metal heretofore impossible. The ser- viee is severe at all times and every part must be reliable and not fail its purpose at critieal moments. In the eleetric stripper we have a fifth class which is used to remove the moulds from ingots. ¢- ow . e ra . t t es cy ‘ ‘ a e wo , 8 \ . , - ® ‘ . t . —_ re , 4 e ‘ ‘ Cue ash «NX ee . 1, ‘ na . . e Le tn . ow : “ ta 4 , & . » . . , - . : ‘d : 4 “ * F . ° a He +. ’ - ? , e ¢ 1 c = * ed . ? “4 . ‘ - ¢ 4 " t ’ “ . * 4 w w . - 6 - é. ‘ L —} » . * o ° i. ill PRINCIPAL, PARTS OF ELECTRIC TRAVELING CRANE Every crane is composed of two parts and these are known as the trolley and bridge. The trolley comprises the entire hoisting and traversing mechanism, in fact everything above the bridge rail. very part below the bridge rail down to the runway rail is included in the vridge, the machinery for longitudinal travel not ex- eepted. JA iv PROPORTIONING OF TROLLEY UNITS. Trolley Sides. The trolley is the most important part of the crane for reasons which are presented farther on in our discus- sion. It is the unit of the crane upon whose successful eperation more is dependent than upon the bridge. It re- ceives the moet careful attention beth frem the designer's and the manufacturer's standpoint. The success or failure ef any crane depends primarily upon the reliability and serviceability of the trolley. The sub-structure of the trolley usually consists of two cast frames known as the front and rear trelley sides, looking at the front bridge platform on a line parallel to the runway rails. The front and rear trolley sides are securely bolted together by a vex shaped casting known as the machinery girt. This girt rests upon machined ledges of the trolley sides, thus insuring a firm foundation for the parts ef machinery it is designed to carry. Incident- ally thie form of cennection also ebviates the necessity of having all reamed belts. The trelley sides sheuld ve rigid beth vertically and laterally. In many cases design and feundry considerations necessitate a depth ef casting greater than that which is required to carry the vertical leads imposed. The designer must always bear in mind that it is impossible to obtain as perfect a easting as the pattern. If this is lost sight of figures may show e safe section while in reality the actual casting is not safe. This is not speaking of faulty - w r . - ~ , - ¢ ‘ae . . : 7: - . — a . * 4 . - ; ; - 4 . ’ . . Cc - 2a . “ - : . . * ‘ - on w e > ® a ane ’ Loe 4 ‘ : « - .. . 7 (« . S 4 “ fo . . : os 1. ° * { -a + : 4 ' . , ’ s+ set . ’ , “4 ! . - . ., . - . wee . ~! ~ : a , e * $ . Y 4 how , . ' ' ‘ 1 . . . “4 a . - mo. ~ . ~~ . . , - - - ’ - ' ~ - .. ‘ ‘ a os ‘ - ‘ Cc" wd . ‘ 9 4 . “1 4 4 * 7” “rf aes ‘ .- : . « . . @ . . oo] - - r ' ow . “ o- ‘ . ~- , . @ . . a _- . ag * a - - ‘ . - - £ + . ry —¢ . se 4 +8 i: 5 > . . ‘ 2 _ ‘ . - . * . . ue . . e re ° > : , . * » - - + . 7 | ‘ a ’ : . , vig ¢ , ‘ . ‘ ‘ . e o : , , . e e rae “ . : ‘ -{ " ; : > . - . -” . - ae . my noe * ” - ‘ . ¢ ~* ’ + - e "ae , : . ; t , > e * - . - . ~ - . a rv, +: 4 ‘ - . ¢ as _ - . ‘ ro ‘ ot - -~” -* * . ? ae mo, * - . . ory e tam - , -. . ; ‘ a . om? . vas 4 ° “ ° . . : . . a . , -« ra . L on . . . ~ - . - . : al ., . x . - mn. . — - . , 5 ..é , ° oe s « . * . . ‘ . " . ve ‘ « 4 - * . ~ . . : . ‘ ‘ : e. ’ ‘ ‘ , , , - . ‘ - a . - . . Le . tL ~” A . ' , . . a . ‘ . . comet oP? -~¢@ design but simply those irregularities due to unavoidavle variations. In one place very little metal may fulfill all the requirements of strength, yet the molten metal must flow and internal shrinkage strains must be reduced to a minimum, hence it will be advisable to add more metal. Anether condition frequently encountered in the de- sign of machinery is where figures will show that a section is amply strong yet to the eye it seems insufficient and out of preportion. In this case it is frequently advisable to strengthen the section until a more substantial appear- ance is produced. Each part must not only be amply strong for the required service, but the machine must also present a pleasing effect to the eye that will help sell it. It must be remembered that any part of a machine may be satis- factory from the designer's point of view, and yet be a failure commercially. Ultimately the machine is made to sell and must meet competition successfully. Care should be exercised in laying out the trelley sides so that ceres are reduced te a minimum Very often a little forethought will do this. A rib placed in one position may not allow the sand te "stand up", yet it was probably quite feasible to place the rib so that the sand would leave ita own core. Casting after easting will be made from these trolley side patterns and any saving ef- fected, whatever the form, will ve "exact sroportion to the number of castings produced. In a similar manner the ease or difficulties that may be encountered in the machine shope should be anticipated. m~ ° \ a :¢ To form a cennection er to accomplish some feature is fre- quently the easiest part; but to attain this in a way which will be practical and without special or cumbersome machining may ve quite another problem. Likewise the ma- chine operations should be held down to a minimum The eareful ebserver will find examples of unnecessarily com- Plieated machining. Net only does this add to the cost but also is there greater possibility of such machining not being done satisfactorily. A simple example of hew machining operatiens and cost may be reduced is found in a bracket. We will assume a ‘pracket having four base volts. In one case the bracket will have narrow finishing pads the entire length of the base. This will nesessitate a planer or shaper operation. Suppose now, ether things being equal, this bracket had been provided with reund bvesses instead of the finishing stripe. The bracket is fully as rigid, possibly requir- ing a little heavier base. The bracket is set up on the arill and all feur heles drilled. Next the feur bosses are spot-faced instead of doing this on the planer or shaper. Thus the following saving has been effected: le One reuting. 2. One setting wp. 3. Cheaper laber. 4. In most cases the spet-facing requires less time. If the bracket gees on some structural or ethers un- finished work the besses have the additional advantage 7 - . . . . . al * ~ - 4 . . . \ . . . ‘ ° ay - a? - ~ ' ~e } . . ~ a @ ot . o ° cl f - t + . i , \ . « , ~ 4 ¥ \ . . - > . . wae ‘ . . | ‘ aw . » q : . ‘ C : - .- ‘ . ” 4 . , v . ‘ = . . + - : 4 . : : .- « . “ . - , _” . ~ - \ ° ; ; 2 > - : ‘ . . ~ - . - . e e ’ - -_ i” , 74 : o ¢ ” e- _~ - - we e * - oo - e . « ~ 7 'e ~ : . 4 - ‘ « ‘ 4 ‘- . ° x 4 cad oe : ' oy” . “a . 4 a . « - : 1 e . ey sa - ‘ . - a . . v e = . , ‘ ae 4 - . ° . ° ‘ e 4 ‘ . Sus te. ~ € soy 4a , . ‘ . : « < - ° . a . ~ e ye 6 . e « 4 . . wv . , x 1 v “ ,; ) aed « . : . « : . t ‘ - e ‘ ‘ - : , a \ my s e 7~ . i , * . -. Ad e : - - woe ! ‘ . . . 2 ‘ . : ‘ . . - § es oe t tee ° . . “48 e ‘ Nae er of veing more easily fitted to structural irregularities. Most of the foregoing points apoly to all castings, however they are mentioned under this head because of the very nature of the trelley sides these points are more easily overlooked and not found until teo late. Attempts have veen made to use but one pattern fer the front and rear trelley sides. The diffieulties are eb- vious. While there are advantages in having but one pat- tern yet the disadvantages decidedly outweigh the advan- tages. One good reason for having two different patterns for the average crane is the fact that castings will be made in large quantities and by having two patterns they should last twiee as long as the single pattern. Struetural Versus Cast Members. Fer the standard line of cranes the cast trolley sides have the follewing advantages: 1. Deflection, as compared to structural frames, is eliminated. 2. The casting is easily adapted to make connections. 3- Bearings and sub-struocture are one unit. 4. Castings ean be jigged thus saving time and in- suring interchangeability and aeeuracy. ‘5s To assemble casé frames requires less skilled laber. 6. Quicker delivery to a customer. The struetural frame is ideal for special trelleys. By its use the pattern requirements are comparatively simple and reduced to a minimum. In laying out a ma- ~~ ot rn a - ‘ et ‘ oon _ 7 : toe ow , . . ' .- ' t e , e e e . ® e e ‘ . - aay - - * : i. . - 9 e ° , ’ se q : ~ ~~ i . * $ “> .? .. .- . . ‘ .@ . ‘ . ‘ 4 . « - . ~ at) ¢ w , a ‘ : a a _» . . : 3 * ' & a -: -, ‘ - 4 -~ . — ~ - ‘ a ‘ . ee? a - ro 4 4 , 2 . . a . * e + . ~ : ‘ 8 : * - on ’ - od . ‘ ie ~ “ . re *4 . Le - - , a « ~ . * ws . > : e ° e 4 v. - r a ‘ » ‘ , . . 7 - ae eos oo 4 ~ om, s , « * : . . e . u - ‘ — bd , - 4 . chine of this kind the matter of deflections is probably more important than any other one thing, especially where the service is severe and continuous. Clearances should not ve taken so closely that it will require unnecessari- ly accurate work to hold to given limits. Machinery Girt. The machinery girt usually carries the hoist motor and the mechanical load brake or, when dynamie braking is employed, the electrie brake. Semetimes the machinery girt is also used te suppert the upper bloek sheaves. While this reduces the length of trelley, yet it is ob- jeetionable inasmuch as the sheave leads may influence the machinery mounted on the girt. In ease of excessive lead, shock er some accident, the mashinery girt would ve affeeted and not as easy to replace as a separate load girt. Its section is vex shaped with ribs at the ends and intermediate points. Upper Bleek Girt When a separate girt is used to suppert the upper sheaves two channels supperting an idler sheave will answer fer the smaller capacities. Por heavier leads a sectien built up of plates and angles must be used. With the system of having two repes winding on the drum the lead girt is called upon to earry heavy loads. Take, for instance, a fifty ton crane having twelve parts of repe. The load girt must support a vwertical lead of ss 4 . tC ‘ wr. vo ww. “ ¢ a“ . : ® . @o 4 xX . 4 oo oy . . ‘ * t. e ay ' ’ ° * ’ cor ‘ ' .. wo ~ * ~ : . ta . - . . ’ ‘ .. ' & : » 7. ‘ we * on 7- . ~~, e . %e. ' ww. . ‘ wo - w. « . A . 7“ “~ - - we . oe | @e .- a . . . ¢ . . ae . o™, 83,33 peunds. This load is not rigid and preduces lat- eral forces fer which provision must be made. Occasion- ally a crane is used te pull leads horizontally, thus inducing heavy lateral ferces. Perhaps the severest duty ef all is a suddenly applied lead. If the crane operater is not eareful te tighten his rope gradually, abnormal strains will ve induced proportienal to the. speed and the amount of slack repe. Anether conditien which must be censidered is the sway of the load. Usual- ly the lead is still ascoudiag when the bridge er trel- ley travel or traverse, respectively. It is ebvieus that, primarily, the sway ef the lead is dependent upon the lead, the distance ef suspension and the rate of acceleration. Upper and Lewer Bleck Sheaves. The average pitch diameter ef sheaves is usually abeut twenty-four te twenty-six times the diameter of repe. The throat is extended well beyond the pitch diameter te preclude all pessibility ef the repe jump- ing eut. Fermerly most all sheaves were made with arms, but of late the tendency is to use a web with cered holes. This simplifies the pattern making and when the web is reenferced by ribs, almost any amount of lateral atrength may ve obtained with less metal. The sheaves are turned te give a true bearing fer the repe and te make the pitch diameter concentric with the bere. . . wt ~ ry oo 4 r ’ . a . rn > . ene . ‘ » Y ved ! \ . -- 4 » oe , : & . . 4 . s . - amb -- oe , a aoe va . ‘ é . ” .4 . ~ ’ of, . -? , ‘ ‘ . - + > ‘ ‘ ‘ « . . ro s . . - @ - ‘ . Soe < . ° ' 4 ' ’ Sie ’ . . - { ow 1. \ -_ 0 * - ' + r . . w- « . ; von - . . . . - , a ’ . 4 ' a . “ ” . “ \ i . - . . . “ . , ° Lewer Block. A simple design for a lewer bleek consists of a plate reenferced by a narrower plate, the two forming one side. At the upper end is the shaft supporting the sheaves while the lewer part supperts the cress-head whieh in turn carries the heok, Te faeilitate the turning ef the hook it is mounted on a ball vearing. Rope Drum. In most all eases repe drums are made of cast iron sinee it lends itself much better to the turning of grooves Where a light drum is necessary east steel is sometimes used. In determining the inside drum diameter it should be remembered that the cere may not be exactly concentric hence a liberal allowance should be made abeve any theor- etieal determinatien. The allowance neesessary will vary with different feundries. Different fermulas have been derived for the deter- minatien ef drum section, some of them being too cumber- some for practical and rapid calculations. Let P = pull on one rope in pounds. " ¢= thiskness ef drum at bettem of greove. * ps pitch ef greeves. | °* l=: distance in inches between drum bearings. " D: drum diameter at vettom of groove. * ds inside diameter of drun. ° Bm bending moment. ®* $8: section modulus ef drum. £8 4 Tass “st Pare | “ pee or _ «€ Let 8B - fibre stress in bending. " cr ® * © compression. Then § = p’-q* 10d e B= Ba S e C 2p pt Combined stress arjB4C* For cast iron 1/B4C“should not exceed 6000 pounds per square ineh. Strong extra flexible wire repe has taken the place ef chains. For hoisting drums the plow steel repe is used having a hemp eenter, six strands and thirty-seven wires te the strand. A feature ef the modern drum is that two ropes are wound on it simultaneeusly. On the earlier eranes it was considered unsafe to wind more than ene rope on a drum, yet at the present time cranes having a eapacity of one- hundred tons are em@pleying the two-rope scheme with good esuecess. When ene repe per drum was used, two drums op- pesite each ether wound the repes. This had the undesir- able feature of causing the hook to ascené in a spiral like manner. The two-repe single drum scheme effects a truly vwertieal rise of the heok se long as the sheaves are plaeed in preper relation te one anether. Gearing. The geare in the hoisting train are usually made of east steel, and pinions of steel forgings. All gears and pinions are eut from solid blanks. -_ . . oem -@ ze ‘ oe — -f * ca = b: o a . na a « ‘ ‘ . bo, , ‘ | . . a7 ote . a “ - # - ‘ . , "e¢ : on ' ae 4 g : . 4 . » ¢ ~ - a - eX “8 a wet , ” . nN Pr a . ‘ eo - - - freer ns a=: : y ee . Qo: a ~ - : ‘ . A . - i - - . - - 4 2 oo fe. ee a - - - . - . . oy “y wv ar “4 . ' dog. - - ¢ . . - ¢@ hy ~ . s Me : > on ao ; . ‘ - cy ~ . . 2 . * “~y ‘ . a . , 7. . - 4 . t s . “ . « ~ . é ra a ey ot e -« « te ‘ ; : \ - “ . , s. so foo. og - ’ , € * * ; ‘ : - - . ~ +e - " ~@ oo“ : ' s a . - - . Jt. . - ‘ - eo . 2 Ro, ‘ . : ty ~ ’ . . o~ - oe . . - ry ® - * .%, , —_ . a ry . : 4 t : Lo. ‘ e.: . _ 8 vo = - . . a a 2° . . of © . ¢ e a » : ‘ as: - ' , ’ . ° -- ‘ ‘ ~ - . Lo “. c = = an -. = - a + - . - - 7 , + . : . - ad . ‘ e . . ~~ - i ’ - - . - . - . ‘ ® . ‘ We . . - . t ’ 7 A 2 .? 4 . z * sa . : ‘ ‘ . , ¢ . ‘ e - : *. ane r . es . eon : we ne Considerable yariation exists in the matter of deter- mining the faces of gears. Some builders will use a greater face than given by the Lewis formula while others use a smaller face than allowed by Lewis. Se far as hoisting machinery is concerned this seems te be more a matter ef individual choiee rather than expedieney. Gear faces prepertioned by the Lewis fermula are conservative and reliable fer crane serviee. } In the past many everming gears have veen telerated chiefly because in the design it was the path of least resistanee. These, hewever, are a thing of the past and the near future will see the elimination of all over- hung gearing fer standard work. Shaf ting. Mediums steel with a earbon content ef abeut 25 te -30 is extensively used in crane constructien. Celd relled steel is alse preminent where the shaft diameter ean be used unchanged thus avoiding machine work. Fer steel mill serviee Open Hearth steel having .40 to .50 carven is specified. Where a light shaft er exceptional strength is required special steel is employed. Bearings. Very little can be said in regard te the bearings sinee they pesesess ne individual difference as eompared te ether types ef slew moving machinery. In some ise- lated eases ring oiled bearings sre specified. While ring oiled bearings have obvious advantages, yet is has not been proven that they are desirable on slew moving @ - ” . yr é = & , ° s . “6 ’ , o - é we as set oa x os —— crane journals. Lifting Magnets. Fer certain classes ef work the lifting magnets of- fer many advantages. For example, in the foundry it may be used toe clean the sand, gather the flasks and trans- pert the castings. Since it is used as an auxiliary its use in no way precludes the service of the regular crane hook the magnet being suspended from the heok. Prevision must be made to wind and unwind the magnet cable as the Bagnet is raised or lewered. This may be accemplished by driving a drum frem one of the shafts er by using a cable reel which automatically winds and unwinds the cable. When the magnet is not in use the cable is weund and fas- tened en its drum enabling the trelley te be used as any erdinary heek trelley. Crane Wheels. In general, east iron wheels with chilled treads are used, greund true and te uniform circumference. Cast steel and steel tired wheels are frequently specified. A very special and seldomly used wheel is made of manganese steel. This metal being so hard that it is impessible to machine, it becemes necessary te cast a soft steel center integral with the wheel. In this way the wheel ean be bered, key- seated and the hubs finished. Where the center ef softer material is cast with the wheel it must not become loose. One scheme to accomplish this is te provide the center with a seriep of "V" shaped cylinders turned on the cir- eumference, the theery being that in easting the ends ef the *V* will fuse and effect a union with the surrounding molten metal. - ’ ' . , . . my i - . -- - . “4 o od . « _ 7 a 1 . - an « . o. a4 “~ me on « . ‘ \ ; .. - ud e . We ~ , ‘ 7 . . r 1 . . : we a o - ' a ce . . e . . : ‘ » . a . eo - . ’ . . . e . ba _- 4 » aa os ‘ ~~ v 4 78 o : ~. > - —em e. . - ¢ . 1 . om a . , ; . o - 4 a . . *. . ‘ see 4 be i . Gy ~ ~ \ > , . ~ Crane Hooks. Crane hooks made froin a high grade of wreught iron are preferable to steel hooks since defects, produced vy wrong heat treatment, are more easily deteeted. De- fects in a steel heok are invisible. In the case of a danzereus overload the iren heok will give warning by a visible, slow deflection before actual failure occurs. For eomparatively light loads drop ferged heoks find extensive applieation, while the larger eapaeity hooks are fergings made frem teugh refined wreught iron. J PROPORTIONING OF BRIDGE UNITS Girders. Bridge girders are propertiened the same as any ether girders, there being no distinetive features except in the requirements ef lateral strength necessary in the upper flange. As a rule the front girder carries the platferm, motor and cage, thus leading the front girder heavier. When the eage is placed at er near the center ef span speeial care must be taken to have the girder strong enough to resist the torsienal stresses preduced by the eage in starting and stepping the erane. These stresses are an indeterminate quantity. Geoed judgment based en experience is the best guide in selecting the preper sectien. End Trucks. The end trueks are either cast er struetural or a eombination ef beth, as cireunstances may require. The eennection between the girder and truek beam should be very rigid te insure strength and proper alignment. The wheel base sheuld never ve less than one sixth of the span etherwise the wheel flange pressure becomes tee great. This is especially true where the bridge moter is not meunted in the senter ef the span, the tendency veing fer ene side te everhaul the ether, due te the difference in the angle ef tersioen in the driving shaft. Furthermore, the trolley will alse be eperating near the vridge extremities thus placing very unequal leads on the end trucks tending to threw the crane " eut ef - van ‘ square" which makes a substantial wheel base a prerequi- site to successful bridge travel. Driving Shaft and Brackets. The maximun demand is made on the driving shaft and gears when the lead is near one bridge extremity since an unequal tractive effert must be transmitted which sheuld ve censidered.in determining the sizes of these members. The driving shaft brackets should ve securely belted and elevated as the eenter ef the san is appreached sueh that, when the girders are earrying their rated leads, the defleetien ef the girders will bring the senter line ef driving shaft en a herizsental line. Geed practice de- mands that braekets be spaced net ever ten feet apart and preferably less fer the smaller shafts. Babbitted bear- ings are extensively used beeause ef their adaptability. Bridge Meter Brake and Platforn. The bridge meter sheuld preferably be leeated at the center ef the span thus equalizing tersienal deflections and a censequent tendeney ef keeping "in square" the end truekse It is belted direetly te the front girders or mounted herizontally en the platform supperted at this point vy substantial brackets. It is a geed plan te apply the feet brake directly te the meter armature thus requiring a less powerful vrake fer the same braking effect. Where the brake is . * - » : r ‘ y v s- - ‘ ‘ s + ’ » ao - on 4 . . « aw ” + , -~ - ° ’ - , . - . . - 1 : - + a ‘ » ‘ . vr . 4 } - .- ‘ . ~ ‘ - ~-. : ! —_ ‘ r @.. ‘ - , < . a. y e é ° . . ‘ . . - . - ae ’ i . . e \ : , . 77 . , . , : t - ot , ¢ - 4 - . . ’ ~ mo, , t . - ~ a rs . ~ . + “s ' ° . - e : ‘ . . - ® . . ~ ‘ ~ ‘ a applied to the driving shaft additional bending and twisting stresses must be taken by the shaft. Since a brake ef this kind must be equally effective in ferward or backward motien the two lever arms connecting with the band extremities must be of equal lengths. In erder te make all parts of the bridge and trel- ley machinery readily accessible a platform is provided the full length of the front girder with a hand rail of ample height. When the moter is meunted on a horizontal base and takes up considerable reom it becomes necessary te widen the platferm areund the moter se that a man may pass with ease and witheut having te step ever any parts. The platferm fleer is made of either weed er checkered steel plates as the ease may require. Operater's Cave. Facing the bridge machinery the eage is usually mounted on the right hand side ef the frent girder, though at times the service demands that the eage be placed at the left, in the eenter, er even on the trelley itself. Its leeation should be sueh that the eperater may have the best pesesible view at all times and a cemfortable pesition- In this eenneetieon it is well te leeate the heist een- treller en the side ef the eage nearest te the center ef span te enable the eperater te leok down over the cage edge; likewise it is alse best te se place er wire the eentrollers that cerresponding lever eperations will bear the same relation with regard te the eperater. The most natural way is to have the eentrellers se arranged that the cessation ef any motion shall be produced by a foer- ward movement ef the controller levers. In this way the different eperations will be simplified besides saving pessible accidents at critieal moments. The eage centains the feet brake lewer which is cone meeted to the meter brake by means of bell eranks and reds mounted en the side ef the girder. The eage fleor eensists of weed beards or steel plates as may be requir- ed. Alse a feet geng within easy reach of the eperater. The average crane has either three er feur contrellers, hoist, vridge and trelley traverse,--and where the trel- ley has an auxiliary drum a feurth eentreller is require- ed. Where the eontrellers are mounted te the rear ef the eperater and connected te levers in the frent of the eage there is ne ebstruetion to the eperater's view. This is a desirable feature especially where the nature of the werk demands elese attention ef the eperater. Every eage contains a switeh-beard ef ample size te meunt the fellewing: Fer a three moter erane--a magnetic switeh, main switeh, main line fuses, and fuses fer each ef the three meter circuits. The main switeh sheuld pre- ferably be placed abeve and within easy reaeh ef the eperater, sueh, hewever, that accidental centact will be aveided. / v “t —) ee + + t 1 > . ‘ ee ’ ef e * « "% - 2b ~ e Vi ACCESSIBILITY OF MECHANISM Examining some ef the elder cranes it is evident that accessibility was not a serious censideration, how- ever, any machine of teday which will stand the scrutiny ef the intelligent buyer, besides rigid competitien, must net be deficient in this particular. FPirst of all, sueh parts are unnecessarily cumbersome to assemble, but the great ebjeetien ecemes after the machine is in the hands ef the customer. It may be necessary to remove some parts prier te an inspection; vreakage may occur, due to any one ef a number ef causes, making it impera- tive that some parts ef the machine ve dismantled. When this becomes necessary it will be seen that inaccessi- bility may be largely respraunsible fer making idle beth men and equipment. The intreduetion ef half hexagon bushings on the axles ef the Master Car Builder's type enable its users te remeve the axle by simply releasing the weight from the wheel. The majerity ef trelleys at the present time are not equipped with '’. C. B. bearings, yet the tendency in the newer designs is te adept this type of bearing. Fer the bridge axles the lf. C. B. feature is espec- jally desirable sinee they are much larger and, as a rule, more inaccessible. The driving shaft should net ve toe leng sectiens in erder to facilitate the handling. « Hach shaft should ve removable without disturbing a ae an a we - at ‘ oe 4 - / . ‘ a ‘ ~ 4 4 - 2 j tee x ‘ ~ » es ‘ a: - . ? ‘ . * ‘ . a om ota q * . +. e o =e oe - w , w oso . e ane 7 - . A . ~=4 . : vase 9 , ' 4 s ~ .* , 4 - ' 1 . ; ‘ a oo "yy s . — vos, ’ . ’ -“ bo ‘ -. ] e a 4 © ‘ . a a ° - a W ‘ : ‘oe . . - e ‘ . . . a i - . . 4 : « on . -4 . ‘ e : t . . > secend. Where gear guards are used er where moving parts are in any way enclosed it is desirable te previde ins- peétion covers so that their eperation may be ebserved witheut removing er leesening any part. Frequently miner adjustments may be made in this wey with comparative Vil FLEXIBILITY A VITAL FACTOR IN THE DESIGN OF ANY HOISTING MECHAYFISM Aside from scorrect scientifie and practical een- structien ef a hoisting mechanism in all its phases, the success er failure ef such mechanien will, in a very large measure, be determined by its flexibility, i. e., the adaptability ef the greatest number ef parts of said machine, without change, to the greatest number ef demands which may be required ef that particular class of machin- ery. When one censiders the variables which must be met er the combination ef these it is apparent that it em- braces many features all ef whieh require careful eensid- eratien. First ef all, there is the great variety ef hoist- ing speeds that must be accemsodated whieh imuediately affects the heisting gears and the meter, as well as the gear guards. New there are a great many different makes ef meters. One custemer prefers this make ef meter and anether some other make, ete. Each manufacturer has meters which differ frem these ef his cempetiters ne- ehanieally and electrically. It is ef little avail te tell a prespective eustemer that a certain make ef motors will answer his requirements, fer he will at ence cen- clude that the manufacturer is trying te give him seme- thing inferier at perhaps a greater prefit. Added to this there is the cheice ef magnetic brake for the hoist moter. Net infrequently it becemes necessary to empley 4 - . ™ ° ' A 4 a 76 ‘ ow 1 . .. o * ot , 4 ° 4 ° . o ‘ to . ’ 4 “ « * 4 4 4 . Ld . a ‘ . ‘ ’ 4 a . ‘ . : . e @ : 4 + = ‘ = . f wo < 1 ‘ ee » 2 . . w @ - oo e wow ~4 . . ‘ . a . ° a. . . . . os od , 4 . ‘ a od : o . +04 . e . ¢ ~ ~ =e * >, tos t ' 4 aw 4 ’ 4 ' 4 . e » » ‘ . t 4 8 e t. ¢ ‘ - ~ . - m4 ee @ meter and brake manufactured by two different concerns, thus further adding to the already complex problem of flexibility. What has been said ef the hoist mechanism alse ap- plies te the traverse, although deviation is net of as much censequence. Sometimes the span is se short that it is absurd te speeify any speed at all since the moter would have ne chance te accellerate up te full speed. Hence it is ebvieus that se far as actual results are ceneerned the traverse meter speed and gearing could be higher than specified. The question ef Zlexibility manifests itself with equal ferce in the pattern shep, the feundry, and fine ally in the machining ef the eastings. If, in view ef any ef the aferesaid cenditions, it becomes necessary te make alterations in existing patterns, er perhaps new enes, valuable time is censumed and , in reality,it vecemes semi-special werk. But special werk means one, er, at best, a limited number which in turn spells pre- duetien at redueed prefits. Apart frem the ability te make a quiek delivery when these variable features have veen anticipated, there is the added advantage that parts can be placed in steck in quantity, cempletely ma- chined, thus reducing preduction cests te a minimun. Aside frem the ebvieus diffieulties prebably the greatest single deterrent in flexibility has been the greates initial expense invelved which, hewever, in the end pays big dividends. It is safe te predict that the - = > f ’ 1 - ’ ‘ we e . ~ ‘ wv ‘ ' yi . ° rs é ‘ 6 e ‘ we ey * 1 . s ee nh - e . . v + , s e ’ ~ . . a . oe i 3 + . ' : os -- 68 a tea + es ‘ e s “a 3b ‘ ¢ ‘ - - ~~ e 1 - - . - r ; . : . . 4 . ay ¢ ‘ ‘ . sor os » , . . . ' i o - ‘ . . . . ; : 1 € : ~ . ~~ ° ie . future trelley will shew a very marked imprevement as re= gards flexibility and simplicity. 7 The question of flexibility alse embraces the shape ef parts. Unnecessary curves er angular lines can usually be reduced to a minimum and thus greatly facilitate the placing ef adjeining parts and the determination of elesr- ances. In this cenneetion it is well te remember the flexi- bility ef mechanical lead brake. “ ’ %. « = = = . . a ga “ s ° > Cig ‘ . ae - . 5 ' é zs < 4 % ‘ 4 ‘o#, ' a — 7 ry . Po) . oe | , | - . 1 e = , i -, « " 7 - = — + : . 4 , ws . "1 = i . ° my ae . - . r- 0 . = 4 . . . ' -,. ae ae o< ‘ ' . ° ‘4 » : a ° 4 < “y - * ‘ yt : . na - e 1 - . 1 s : ‘ ' a. , 1 “, E F ‘ ‘ ‘ a . ° : - « e « : o 3 “<4 ‘ . a e ‘ =4 . * . . : a . - . * « . _ - r ° ‘ z « . dl ¢ . - IX POWER SUPPLY OF BRIDGE AND TROLLEY MOTORS. The majerity ef crane moters are ef the direct cur- rent type and series weund. The main wires are usually placed beneath and te the inside ef the runway girders, en ene side enly. The bridge truek beam carries a bracket supperting an arm to which are fastened the main eellecters supplying the pewer te all meters. for edbvieus reasens this cellecter braeket sheuld prefere- ably net be plaeed between the girders. The bridge moter takes its supply direet frem these main cellect- ers. Since the frelley meves aleng the bridge it is necessary te previde cenducters aleng the bridge girders frem which the trelley meters draw their pewer. Where there is no platferm en the rear ef the bridge this is the ideal place te leeate them. When, hewever, it is net convenient te se leeate them they must be placed en the inside ef ene er beth ef the girders. When this becomes necesgary partieular eare must be taken that the hoist- ing repes er any part ef the trelley shall net come in accidental centact with the cenducters. In fact the eleetrical and mechanical clearances as well as insula- tien should be liberal, and preclude the pessibility ef shert cireuits. It is well te place the trelley cendue- ters en the girders in sueh a pesitien that when the pull ef the heisting repes is such as te bring them te teuch the bettem plate ef the girder the cenducters will v , Y - . t ‘ ‘ - . e , t ‘ . » - . o ' 1 ‘ ® o. “4 b e 7 « - - _ . L, : Py . . . - ‘ . ‘ ‘ b ‘ . a . . : r . > . | + . - - . , . ° e * - \ > . . , . . - ' : , ; 4 . ‘ . , - - . . : + a . , . ¢ , + . - ¢ ‘ ° . - o> - a ’ ° 1 ~. to. - ’ x « . 7 > ¢ ' * ‘ . + , . ‘ 4 a sf ’ , ‘ , ae ' e. ° : e , y 4 , t . 4 > e , . , . a ‘ ° 4 2 a - oa f . ; . . . - « we oe . 7 : . 1 1 @ , . , ‘ , . . ' 1 “ . @ s ‘ « ee . - .8 r . 1 . . ‘ a a * - - ie « . ‘ o* - » , . . . . . ‘ * ae . +‘@ . ee — still have ample clearance. This is an extreme condition- Occasienally, however, a crane is used to drag a lead er move cars and when this is done it is imperative te have the cenductors eut ef reach. Beth wires and plain flat bars are used as condue- ters. Wires have the advantage of lightness as well as being easily insulated. Where flat bars are used sup- perts must be previded at frequent intervals which is not necessary with wires. Sheuld a wire break frem some cause er anether it must necessarily fall with the pes- sible result ef serious aecident. Where flat bars are used there is ne danger frem this seurce. Per the average three moter direct current crane nine trelley conducters are required; feur each fer the hoist and traverse moters and ene fer the limit switch. = “t Ne J TERMINATION OF POWER UNITS The electric crane moter is serviceable and reliable even under extreme conditions of leading. Its marked adaptability te various leads makes it an ideal machine. Heavy everloads will be carried without any serious con- sequences so leng as the everlead duration of time is shert. Fer electric travelers no moter should be overloaded when carrying its rated lead. Trelley traverse and bridge moters should have seme excess horse-pewer to enable them te accelerate quickly. Cranes of the same capacity will frequently have meters ef different horse-pewers. This discrepancy can be acceunted fer in three different ways er a combination ef any: Different efficiencies, differ- ence in the builders rating, and individual practice in the excess ef herse-pewer allewed. The hoist gear ratie fer a D. C. series motor may be determined in twe ways, as fellews: Let C -circumference ef drum in feet. * rp merevelutions ef meter per minute. * H s=heek speed in feet per minute. “ R sheist gear ratice Then Xs_Bs_Re ® Revelutions ef drum per minute. Then CX 2: be Bee F Re 1) er R = CA Fs Be Be H fer single part ef repe off drum. Since the speed ef the series moter varies threugh wide limits, fer reliable results, it becemes necessary te ascertain the ezact moter terque exerted and the cerres- pending speed. The normal speed rating cannet be used in the abeve fermula unless the meter is actually carrying full lead. | A mere direet selutien is te equate the lead terque te the moter terque and cempute the required ratie there- fren. Let L slead en drum in peunds. * rv pitch radius ef drum in inehes. « T= meter terque in inch peunds. ° B- effieieney ef hoisting mechanien. Then Lr= TER er (2) R- Lez TE The size of heist meter may alse be determined in twe ways. Let P = load en heek in peunds. Neglecting weight ef parts then, ) _ PH - actual required H. P. 33000 E Again neglecting weight ef parts, (4) Ir. 2 actual required meter terque. RE Cemparing the twe fermulas it is evident that (3) dees net eensider the diameter ner the lead on the drum. In eensequence thereef it weuld be pessible te compute the same H. P. fer twe different machines ef the same im ~~ «+ baw “* ' . o- - —_ a “ -_ = ° ~. _— = . _- = ‘ 4 ¢e -?> -_ + de -. ‘ ‘ * 7 x . . ~ or |] } ' 4 a ] . wes ‘ ‘ « : 2 on... a . ? ‘ .% oe o 1 s e* v4 ry $ t - = . ~~ ae © \ t a . - , ~ me rw capacity although the repe reeving and drum diameters may net be the same. This weuld necessitate twe differ- ent gear ratios fer the twe cases. Where the size ef moter is determined by fermula (3) it may be feund neces- sary te add anether reduetien in order te use the pre- pesdd meter, which say eliminate the intended machine and the design er substitutien ef another having a great- er gear reductien. An actual example will make this clearer. Let P = 40,000 peunds. ° Hse 15 ft. pe m *" Be 76% Then ( Q - 23.9 required H. P. by (3) SQ0 Re = 23 eq We will select a Westinghouse SK, D.(.crane moter, 220 velts, 25 He Pe @ 575 Fe De Me, whose terque is 2740 ineh peunds. To use (4) we will further take fellewing conditions: Let L = 13333 peunds.jr = 12° ~ six parts ef repe. Then by (4) 1 x 12 = 3570 ineh peunds, re- quired meter terque. 99 x7 But this result is greater by 530 ineh peunds,neg- leeting any excess H. Pe, and hence eannet carry its rated lead witheut everleading, in which event we should net get a heist ef fifteen feet per minute. From (1) R = 24.200 2575 e 80.5 required hoist 12 x15x 3 ratie fer Westinghouse SK meter. Therefere we should either have te previde a larger moter er a greater gear y e $ “¢ v oe e \ te ~ Sp g °) = - —- 1 ve. a a. , 3 ’ ~ - mie be we * wut ~ es a £ ty a _—_ a, ra oo tearm ~~ a 77 7 | e . 2 1 at he tad moe ~~. oe - » . . y . ™~ o => ms - . ann it a . ‘ - > aot - . é my we o . ba “ @. e @ -. . = . wee 4 eo ' e ‘ . tw . wae . o . oo "4 - oo. x - {Fr Looe . ae = | « ele owe a . soa, - ec - . ' : oe # “ . © tre { * 4e te . .- pee A i >’ ratio to eobttain the required hoisting speed. Again, if we had cemputed the size of moter accord- ing to (4) we obtain the follewing: 13333412 «© 59 hoist gear ratio required, which 3570 x -7 eur preposed machine can accommodate. Traverse Metor. Let fT e required tractive effert in pounds. = Ge dead weight plus live weight. s diameter ef trolley wheel in inches. diameter ef axle in inehes. z eeefficient ef frictien--about .07. s we *& & & 06 ° e efficiency in per cent. "3S :z linear speed of trolley. Then T 2# .07Gd and DE Required H. P. of traverse motor is 33000 While this gives the actual herse-pewer required, yet seldemly, if ever, is the traverse moter developing its full horse-power. In consequence, if it is essen- tial that the traverse speed be adhered tee closely, it becomes necessary to ascertain the e@act terque exerted vy the meter and base the gear ratie on the r. p. m at this terque. Bridge Meter. The size ef vridge moter may be determiged ina similar manner us the traverse motor. In practice a more q 3 ° - ” . 1 : - @ : ~ 2 e- ‘ « . . o., t * - .* a . ' < . ‘ : - : wee - ; ; 4 ‘ ' « - , a + - . . o . o ( : -| 1 + . - a . . + » a * vor ee . . : . a . af @ Aa - > - ' ; ’ 7 a 63 it ve s ‘fg ’ oo 10 oat | ‘ 5 . aoe y ‘ a . ‘ +’ ‘ . . k - -~ -. © . - preferable way is to compare load torque and moter tor- que and preportion the gear ratio accerdingly. A liberal excess of H. Pe should be allowed on the vridge motor since the position of lead on the bridge may demand ex- cessive power especially on long span cranes. Where, for instance, the trelley is near one bridge extremity and carrying full lead, there is a tendency fer the bridge to get *“eut ef square® while traveling. Purthermore, there is the deflection of girders which cannot be eliminated. While it is possible to com- pute the deflection of the girders at different points and elevate the driving shaft brackets accordingly, yet it is not so easy in practice to lecate them with math- ematical precision, censidering various vuriables in the precess of manufacture. Thus it is evident that exces- sive frictien may be produced due to irregularities,all of which demands a liberal excess of H. P. te provide for these contingencies. Res ey wz at SAFETY APPLIANCES. Se leng as the human element is a factor with which we must recken, it is necessary te previde means that will prevent the wreeking ef machinery, injury te werkmen and pessible death. The fundan@mtal principle ef all safety appliances is te take action, either sud- denly er gradually, befere the danger sene is reached with- eut in any way interfering with the regular eperations. Sueh devices must, ef necessity, be autematie, i. e@., they must act regardless ef any actien er inaction ef the eperater. The evertravel ef heok er the heisting ef the lead until it interferes with parts ef the trelley is a seurce ef treuble unless there is previsien made to prevent this. Where it becemes necessary te utilize the full hoist con- tinually it is ebvieus that such previsions fer safety veceme ef censiderable mement. Semetimes it is required te limit the heok travel in the lewering as well as in the hoisting directien. | Manufacturers have preduced devides ef censiderable diversity te limit heek travel and the merit ef any one ef them depends upen a number ef things taken collective- ly. t ; : 4 * f a‘ a . . e - . < : . aan me Wee . vag | | ! sb ie 4 7 roan . ‘ a ‘ a . + ° . ° ° ' + le ‘ 4 , ‘ ~~ ; i - v .. i 4 . s * ° ‘ . “4 , ,¥ to ct é -— 6 1 i . ‘ i . a .. -— . : -. 1 - ‘ - os ‘ ‘ “4 . , + ve ‘ ‘ e . ~ + ’ ae , a c a i" . at] nw 1 4. ey sae r ’ 4 . . * “ "i ; é . . a rt. : . ad e -4 ; . . a ' . ~ : ‘ 4 ' ~~ os . ae 4 . / ’ — ’ o> me 1 . -4@ ” ‘ , 1 . - * 4 . . . ' . - c . . ad .=4 é >, ae - . > 4 . . ae . > ve a , 4 ‘ LY .. 4 - ‘ sie ~ q , * : , * ad . 4 . . . . { : . . e . . j 1 « “* ‘ o te any hoisting mechanisa. Where the attachment of the device depends upon a certain censtruction, very fre- quently considerable expense is involved in attaching. such a safety device which in reality ddds to the cest of such appliance. Whatever the construction, it sheuld never diminish the vertieal hook travel. In respense te the demand of a pesitive safety de- vice te prevent evertravel of hoek which weuld be sat- isfactery te the purchaser of cranes as well as the manufacturer the Shaw Electrie Crane Ce., developed a new device which the writer had the pleasure ef desing- ing and which is now used en all the cranes manufactured by this Cempany. In the design ef this mechanism the fellewing points were kept in mind, and the apparatus develeped accerdinglys 1- Reliability at all times and pesitive action. 2- Simplisity censistent with the requirements making fer easy and speedy manufacture. 3- Te make the apparatus a cemplete standard unit in itself whieh eeuld ve adapted te varieus hoists with- eut any alteratien er substitutien ef parts. 4. Flexibility--te enable its attachsent to the varieus elasses of cranes witheut the necessity ef leng and tedieus layouts. 5- Te empley the same device fer epen er closed circuit, single or deuble acting. 6. Te make the eutside dimensions as small as pos- sible. e . -¢ . 7 4 . @ - = . > et * ® « som? e - t+ lw ° + - - -« as 1 ¢ . ~~ . ’ » ° ' . . ® . . o , ‘ . * “ .- ‘ , * ot . 4 es - y . - . oa oo. ‘ . ae ~¢ } . . a * 1 . . - . . ' . » oi + oe + f . a .. . oe - w- . A @ - “ a ~ eB ‘ ' a \ . ves e aa ode > 7° The ultimate cost te be lew consistent with the above requirements. Threugh the medium of a crank connection is made with the drum shaft, the crank being on a worm and driving a worm wheel which in turn has a contact lug. As the worm is dtiven by the drum the contact lug on the worm wheel is vreught eppesite a similar lug on a trip lever, which epens the meter circuit threugh a magnetic switch in the cage. The limit switch will not allew the motor to get any current in the heisting direction, but any time that the contreller is reversed to the lewering direction everything resumes its normal ceurse. Furthermore, the. devise keeps the heist circuit epen fer several revolu- tiens thus eliminating the danger existing in an instan- taneeus epening--that of continuing in the heisting di- rection. The range of limit switch is ample fer all hoists re- quired, the adjustment being effected by the bringing nearer er farther the peint of eontact as the case may require. The limit switch uses the same parts for epen or clos= ed cireuits, the change being accomplished by different relative pesitions ef parts. Generally the clesed cir- euit is used because the breaking ef a circuit is pesi- tive, but net the making of a circuit. In ether words, the dectrie eircuit is complete until interrupted by the device. The entire mechanism is enclesed in a rectangular ¥ ” box whose external dimensions are 4} x 64 x 5. The vex ‘ ~ . . - e4 ° . ed ¢ 4 ~ r “6 \ - —a v ——- . “oe — - » ow, d o 4 —s . ron 2 3 ’ te 2 ic ’ » a » ‘ +s ' ‘ ‘ ww . - é : . r e ? . 4 - - ‘ wy Y ‘ . 5 ad . ‘a . - « . « . . e . . ~ 1 . ate e “4 4 e 4 ey ‘ 4 ‘ tae \ 7 ° 4 : on we 1 ° a vom e oo oe way “” ne has twe lugs by means of which it is bolted to the end of the drum bearing. Since the device is adaptable to any hoist without ehange, it ean be manufactured in large quantities thus materially redueing the cost ef manufacture. “4 a4 XII AVERAGE VS. STEEL MILL CRANES The steel mill crane is a preduct in response to a demand fer a crane thoreughly reliable at all times un- der most exacting conditions and equipped with every safety device. It must be berne in mind that the steel industry represents an investment ef enormous capital and the precess of manufacture is one which, perhaps more than any other, places the life and limb of those engaged in jeepardy. Delays of minutes may make inopera- tive an amount 7 equipment whose value tetals thousands ef dollars. Thus it will be seen that steel mills must have the best pessible and most modern equipment irre- spective ef cest. ° While such cranes are primarily used fer steel mills yet there are ether industries to which these re- marks apply,in a measure,with the result that a good many steel mill specifications are incorporated in buying @ crane. In fact, the steel mill specifications are man- ifesting themselves in various phases of the crane ine dustry. The mill crane immediately gives the impression of massiveness, strength and liberal preportiens. In many parts the faeter ef safety is greater. All ceuplings are of the safety flange type. All parts are made of steel except drums and cellecter shoes. All pinions are made frem ferged steel and ne pitch finer than feur dia- metral piteh; no everhung pinions are used. No wood is é i . ' a . a * o *. g . . . 4 ‘ ° 4 7. ’ L ‘ ‘ - . ‘ i . 7 , . . - . . ’ co» J . . . ‘ a co a a a ”~ - ~ . . . ‘ ~ ‘ on * e ‘ és . - “= . - . 2 ‘ , ° . . 2 ‘ . . , . . tw ‘ » ‘ ’ - . : . , ‘ - ! < . ¢ . ” * _ + - ‘ . 4 ‘ ob : . . 3 , 5 . 4 { , - 4 . - aoe j . a - . - « . ! ° i . + t s ' ‘ : e : . . ‘ ' : - . . . [ . “ \ . ~ EL _ = - a Nok 4 - a a 9 wo ~ t ° \ . ‘ » i : + a : t a - to ” vf wo. ? . e ’ . .» 4 1 ad _ . ‘ A “ : , * . « 1 . tr a + 4 a t , 7” ~ e ao ¢. o i toy ° we ae ‘ . e ~ : va _ . . * 1 c . , ‘ . , , ae ‘ } es used fer any construction, conduetor insulators not ex- cepted. Trolley shafting is usually made of Open Hearth steel and the vridge driving shaft of C. R. S. Ne trelley wheels are less than i2" in diameter and bridge wheels net less than 24%. All treads are se proportion- ed that with a wear ef 1 1/4" en the diameter they will still be serviceable. All threugh belts are used and preferadly no reamed betts. ~The heist meter magnetic brake is designed te held the lead independently whereas on standard cranes the brake is preportioned to held abeut ene-half the motor terque. The bridge moter and driving shaft brackets are mounted horisentally en substantial brackets while stan- dard cranes have the moter and braekets belted to the side ef the girder. All axle bearings are ef the M. C. Be type. Drum and sheave diameters not less than thirty repe diameters, whereas standard cranes run under thirty. No babbitted bearings. The preeminent feature on the mill trolley is the almost exclusive use ef the dynamie braking heist con- treller, which has veen perfected within the last three er feur years. As has been peinted out, the steel mill service is unusually severe and in eonsequence thereef mechanical lead brakes have been the seurce of delays and heavy repair eests. 1 ’ , . . » . i .- - . ” . rm le { oo \ ° é » yo ay * - q - . - . . . . a * a 4 ~ ‘ é - . - . : a a o ' oo = . 8 ° . - a“ - Ld . . ‘ a. - ' . _¢ . one ‘ - ' = , , ‘ 1 : - ‘ # “= : , ° a. e . ' o . t ‘ 44 . e - o a he % . 1 ns € ’ 6 ~ = ot oo « ° . . & . t hoa a t . @¢ ~ : a ’ . te; ary ? as . . 7 , 4 te - # wv’ t . , - . en : e * . cm - 4 - : vs . ., ; : . ’ : ‘ ~ of lewering, yet it will net hold a lead in any pesition. Fer this reason it becemes necessary to add a second electric brake on the moter gear shaft. Fer mill cranes this brake as well as the meter brake is made powerful enough so that each will held the lead independently. Sueh a eemdination is very pewerful and quite instanta- neeus and there is a question if this action is not tee pewerful fer ultimate satisfactery perfermance. in dynamie braking the werst eventuality which could happen would be the simultaneeus failure ef the supply veltage, magnetic brake and the contreller wir- ing yet,in that event, because ef safety devices used in dynamic braking, the lead weuld actually descend se slewly that the danger ef any damage weuld be remote. Autematie Magnetie Switeh Centrel. Anether very impertant feature ef large mill cranes is the applieatien of the automatie magnetie switch con- trel. Where large meters are used it has been feund that manually eperated eentrellers have a high mainten- anee charge and are cumberseme te operate. The mnumereus advantages ebdtained threugh the appli- cation ef this centrel all reduce delays, and it is this feature mere than any ether whieh recemmended this form ef centrel. Switeh Beard. vie - .? . . & . - - - “ és . - ‘ ~ . . < « . Izy z. ¥ 3! = H Ca ES ee he 2 ae ee wy hE : Vruee® i. § efeici#t stugina asg SkOT ES WE oT i ES ie oe ee ee ja od olf wie KZ Geer? & vevi'd Seiox Sstkipet fef2 © CE Ev a 3 zi Oe > a a . olse woe of int Fe af Into. 0. = : 7 é . a Cx ia t- eTOTO=. ON ISVA1 ! bua BNOisOcLst o#s TcoY® yorstoitts 2... eeu {lin oa, etsiid wiio = (Sex gt eleara °F Yo sonststavatisg "Hof R=¢GxX Fe pe Bm = 3-4 x% 750 « 19.6 required traverse 8 130 ratie. 22x 23 - 19.25 actual traverse ratio used. 14 1 Estimated weight ef trelley 13500 peunds Live lead 40000 pounds Tetal lead 53500 peunds 1100 T= Ghaqa = 535 9 | - pounds tetal DE 13 Xe X - tractive effert required. He Pe = . 2 Q 0 s 4-34 He Pe re- 5y508 aos x quired. Sinee the Ne. 3 frame is a 5 He P. the next larg- est, a HNe. 4 frame, 7+ He P., will ve used. Heist Gearing. Live lead on drum = 49000 s 10000 pounds. P. D. of drum gear = 26.333° P. D. of drum pinien = 7.666" P. D. ef intermediate gear - 24.000" P. D. of intermediate pinion = 6.000* Pe De of moter gear = 21.250° P. De of moter pinion = 5.750* # a 3.43 Drum gear ratie. ot - 4 Intermediate gear ratio. # s 3-69 Meter gear ratie. Where the dead weights are cemparatively small they will be neglected in caleulating the strength ef parts. -- — e 2 Of e e ° oe _ . - - - - - . _- - e - - ® _—_ - oe ‘ ~ 1 e ® * - i & - » = = a . ‘ —_ -_> -~ ° e «- « ebnege—na. on a -_ Pw « o ~~ -——7 - ow w--- oo“ ms. . - ~« = ® x . . % ’ ‘ : . @. 7 ans ¥ ’ as oa. « - —- oe _ tt ‘ ‘ > s! : e « -~ : -« . a e @ . * . . om: @ eo. e - 3 : 2! s oe . ad ° , . —_ : . ' @ . ef “. ‘ s @ .. o~ . ag ’ : a. oe ~ - Mie ° \ ~~ « 4 e eo e - ¥< . - . e . e- - e Oo «x _ a: . . s e - ‘ . » ?¢ e e : ~ : ao. - , * . ' e e = eo. - ; . . e o , . ' . ‘ ~ > . “ ° s e an . . > . e ~~ we i o -_ , e 7 » . 4 . * 0000 20 = 9500 pounds, teoth load on drum gears. 26.33 x.00 ; a = 39 r. p. m. of drum pinion. 4x 3.69 ‘ 39 x .261 x 7.66 = 78' Pp. m , lineal velocity of drum pinion. Value of factor "y" (Lewis) Teeth | i geceluee | | Teeth (ore lute 12 2078 me °) - 100 13 083 20 | .102 + 14 - 058 21 2104 15 - 092 23 - 106 16 - 994 25 + - 106 17 }' .096 27 e111 18 - 098 30 2114 Allowable fibre stress in gear teeth (Lewis) Material|_3Pee4 at pitch line in feet per minute 400 200 300 600 | 900 | 1200 Cast St.} 12000 10500 | 9600 } 8000} 6000} 4800 Then by the Lewis formula for the strength of gear teeth. We SPFY F:-_yv 2 9500 8S. PY 12000 x 1.047 x .1 = 7.58" say 7 3/4" face ef drum pinion and gear. 4s eh? —ene - weg; - et Gee oem. om | « 0 i ‘ : i . ( site. @> Genie G2ROnte Os ev --a@ ono | + 4 ' AO. CY Cate e Ulliye tere TEA A POU Eatin: Pe & nertterepab Gath nee: , f * d °, ' { ' ’ , e e e ® ‘ e s : ! \ vw, oo ' ’ e a ' 4 t i & - ee ae et _~ / / & wh - Ge GP ees SH ~~ ween & Qe ‘ , i ' 4 ~ ' e _— ave 72 & aw. te. Oe -— © wre -— weeps OR Ae we O86 @-eete . ” } t e - 4 e q e e e e ; i ” ‘ ‘ . - ‘a . t 4 . ‘ 4 to, bo | bs ‘ ‘ ‘ ’ ; ‘ - } ' ' , * i to po my ‘ ! ' { ‘ ‘ ‘ J : . i oy t ¢ ’ 4 . ¢ ’ “4 b “ ' : ‘nae arene 20 _ | sg } ; ' . 4 | +. | ‘ ‘ “4 , ’ ‘ ’ { i ' i Fe sm ay - es & | é ‘ ¢ both ‘ so. f i ' ' { , <4 . 4 . ‘oy J “s _ ee ( 64 ‘ ~ a t a } ‘ ’ ’ ’ ‘ ‘ i ‘ e ° Gare < carne | 8 f : t i ; , ’ a t 1 ~ { ! ’ ‘ 4 — om me - 9500 x 7.66 # 3300 pounds teeth load on intermediate 24x .92 gears. fa 2 156 revelutions Pp. KM. of intermediate pinion. 3.69 . 156 x .261 x 6 = 244° lineal veleeity of intermed- iate pi nien. Fs: h0Q a 3.68" say 4° face ef inter- 100 Xe oF x of mediate gears. pate x 6 s 10 12 peunds teeth lead en moter 025 KXeQJ Eearse 575 x 0261 x 5075 = 863" po m lineal weleeity ef moter pinien. Fe A218 - 2014" say 24° face ef moter Q00 x .7 Xe gear, pinien 2 5/8" face. — Traverse Gearing. P. D. eof driver gear e 13° P. D. of driver pinion = 3.5* P. D. of meter gears 16.6* P. D. of motor pinien - 3.2° 1100 x 13 = 1100 peunds teeth lead en driver gears. 13 2:2 z16 2 145 re. pe me, ef diver pinion. 3 145 x 2.261 x 3.5 w 132" p. m lineal vwelecity of driver pinion. Fe... OT x TOS a 1.45° face required 11000 x .765 x .0 for driver gears. We will use 24° face. On general prineiples we will make the moter gear » . ~ ry . -% . s om , , . > mad eC . - - a: - . ~ ‘ . uA + . .. ' - —_ - i 3 . oo t | : ~ oo, . “, 1 . ty i o: [ ' e = - an . . a . . . wow, * . y t . e. : ¢ : “* so . , oa e . ‘ £ «° . , e : . . » & ” - ’ * Aa : - e nL oo s |: t - , a cd s y =m ony r* ° = #3 e ! o > @ - ~ ¢ ea > @Ge-w w= ~ . ~ e . @ @ ry ' wa o- » . , e . ’ a -_ 4 . - tt mene _> of - & e . - ~ 4 . — .- a-' @ yj 0 4 aT. a. e@ -« ? a o * * . @ e@ x re - + : . @- ee . . oe a ‘ oe ee “ a + or 6 ~ — 4 ® o e. ~~. ~ - . ath gy i . a a - 2 2. a a ~ oo - “{ ~-at e , . Ne . ; t 2 1/5" face, pinien 2 1/4" face. Since this face is larger than the face required fer the driver gears, fur- ther calculations will be unnecessary. The increase ef face is te take care ef any excess leads which the moter may be called upon te earry. Further- mere, the actual faces required weuld appear weak and eut ef prepertien fer a machine ef this size. Drum Shaft. 9 1/80_ 72008 68 7/8" nal R 75°— — Live lead en datum 10000 pounds. Drum gear keyed te drum thus eliminating all twisting en the drum shaft. Rs 2200 4,68 7/8 « 8380 peunds reaction on drum bearing due te gear lead. Since the heisting repes are central en the drum each bearing will take ene half ef the repe leads. Henee 8350 + 5000 « 13380 peunds, tetal reacticn eon drum bear- ing. } We will take the lever arm 1/4° inside ef drum hub, hence 4.25 x 13380 = 57000 ineh peunds bending moment. 57000 2 6-32 section modulus required. This cerres- pends we 4 shaft. We will use a drum shaft 4 1/8* diameter. Intermediate Shaft. q500* : 68 7/8" _ _ R 78° 330s 4 3 . Q . e . ° rd - . “ 4 es 9 et , { ~ yt ‘ ° 3 a ’ ” - - * . . . * 1 & " , - t . ca » , . eo? 14 8°’ oa 7 - . ra . ” , * e-: - . a 2? . 2 - oo. . 3 . . ° . . . , ee _— =. « . oe id ° owe -=- * —_ - " . , ? ote Op es ee OK 8 Ot 8 et 8 el 8 Oe RS Ow we OM © 6. wee ares Oe b x a [2 y t L . wo ve oe Se es. . - - - - & = , a 5 . € ° e x ‘ - ‘a Vous . 4 : a - e » ™~ - 2 lle =~ . - a » oa *. e 4 , - . ‘ = - . ~ — —_ + - - --- - - ~ 2 yew + = e . . ‘ , , ’ 2 ; . . : - ¢ 1 eo, 1 . ’ my > . . ‘ Lh. 6G a . o ~* 4 . . - . oe .- 7 bat ' { t ¥ 1 ¢ . . . . oes ee -. ‘oe ’ . . , « } . ? aw, . , = 4 ‘ 4 ’ g * , - = . ‘ 2 “ € ‘ 1 ., ’ “ ~ ‘ > ‘ - + . . - ’ - 4 da ~- , . on ry ® - - ~ - . * “* + “a ' * _ e. , . * : oe «4 a4 ® ow e - “ *. ’ i » : mom @ - . . « , @ e . r o + n. “” Lo -s ~ e ~~ ww 2 ee eee oe: erty a Ge me Oe ow Oe ee we ee Se o_o SO Oe oe Oe ee R= 950 8 7/8 = 3300 x 7.25 - 654000 - 24000 7 ° a - R 6700 peunds, reaction en drus pinion bearing. 8700 x 9.12 2 79300 ineh peunds dending moment. 9500 x 3.83 = 36400 ineh peunds twisting moment. 36400 = 4.03 seetien modulus, which cerrespends te 9000 a 2 37/4" shaft fer twisting enly. 79399 2 2.18 e K----H ee 1.66. 36400 1.66 x 2.75 = 4.57" say 4 5/8" diameter ef inter- mediate shaft. Hete;... All shafting computations invelving bend- ing and twisting are based en the fernmula € é& Te o Bat By + T,. Brake and Brake Shaft. 8 x s 13.75 Ratie between drum and brake. z 5380 ineh peunds retarding ter- 136 que fer whieh the seeend shaft vrake must be designed. aie e 715 peunds retarding ferce necessary en brake a Let T « pull em tight side ef brake band. * te. pull en leese side ef brake band. *" xs angle enclesed by brake band, say 240°. " £, eeefficient ef frtetion (J). then E*%e 2.718 03 x 4.188 | 3.514. > . . “ . - l - é a . ? é \ t j = . ' ‘ ” ; a e ’ , se @ ! . « { an 5 ° ’ 3 a e@ @ 4 @ —_ . o* ® / -_-4 L 1? oe) e . » > ‘ w cay . e " 4 wes t # . . * * 2 ~~ s ¢ e . { e 2 . . . : : i . a? ® H 3 us 2 ‘ heme , . . 4 . a. . ) . . T © 219 x 3.514 » 1000 pounds pull. 3.514 - 1 ts 215 2 285 peunds pull. 30514 - 4 46, 24 5@ 5H 6 3/4 - 16 1/4 we 48.2 pounds, feree te be exerted by spring neglecting weight ef parts. In detailing the brake parter effect ef the weight ef different parts “must ve censidered and preper allewance made fer the spring, and selereid winding. Since the Spring is ad- justable the brake aestien ean be varied threugh wide limits. It will be noted that the tight side ef the band is fixed, thus making em. ecenemieal and pewerful brake. | 33009 10008 , We shall neglect the fact ef eentinueus beam and 1? "a i , ° I e e ~ \ © -te oe —EEENe «© Aine EO - Gp eae Eg . e t , j ; ‘ * ‘ 4 ‘ a e . 1 e° ! ‘ ‘ ‘ ® ” ut - ! a - VU -wae + -sme— cerwe .+ a Ben 8 OD. OG ~ a : 4 a. @; - r « . * «- ‘. @ 2 ~ 6 we Cy . i e 4 —_——~ ‘ a a ~ — x : . ¢ . . ° Zz , v . ae % . . as [ Ge ° .” s a . - - ‘ - - . ¢ ~ é - wah ~ Fr _- 4 = ~ 4 Mio - t e . . sd. t | . f ‘ * 6 . - @ ® + ~ ° ah ote ww oa ; x e » my OF « - i e@ e - a oe | — t 1 ; , We shall neglect the centinueus beam feature. Assuming that all wheels are equally leaded ,we would have 40000 #13500 s 13375 peunds earried by each 4 wheel. Teeth lead en driver pinien 1100 pounds. The maximum moment cecurs at the wheel and is equal to 13375 x 725 2 25000, inch pounds dehding moment. Z | 1100 x 6-5 w 7150 ineh peunds twisting moment. $148 = -795 sectien medulus which cerrespends te a 000 1 9/16° diameter shaft for twisting. only. 25000 3.49 2K — He 1.93 7150 19/16 x 1.93 w 3.01" say 3 1/4" diameter of axle. Upper and Lewer Bleck Sheave Pins. 10000# 10p00# 10poo# _3 1749 [ I 3 1/4" _ 3.1/4" | 2" 13.374" | 4 000# 200e0* This diagram shewe the loading of the lewer bleok sheave pin. Taking mements abeut 0 where the maximum moment oc- curs, we have —=10000 x 3.25 + 20000 x 5.25 w# 72500 inch pounds vending moment. nen ona. amie 1 -- 2 | a. ~ owe —P an au, + ) Ob EE eee «em ou > a b ‘ ' ‘ 4 ‘ ‘ » oa 2 Son ef eee — et wg mee dave. f.. oe a We will use a 4" sheave pin. YO = 11300 pounds per square inch en 4" sheave 04 pin. Fer the upper bleck pin we will alse use 4° se that the sheave bushings fer the upper and lewer blecks will ve interchangeable. Since the upper pin issherter and not leaded as heavily as the lower ene, any calculations will be super- fiueus. ez * 768 pounds per square inch. bearing pres- 3-25 x 4 sure on sheaves. Upper Bleek Girt. 5x31f/2 x 1f2* L 2 coceery eee ad 14 1/20 Xo 247244 4.13259 = 904: 7+ 4 2 12 a xx 1434 7 x 2.4°+ 4.05 + 4x4.192 vp ” ~ Sa ‘ - ' . - ' - on ‘ . \» “~ 1’ » . = ? i ~~ 74 + -_ ww «- } - -_- j é sero mn «' » 4 oo! ; : 1 4 ’ i ’ i ’ ‘ ‘ , 4 e » t ¢ a wea 0 & com @* “24 e Jose wre 4B fine -4 ge ‘ bared ~cpes se + Oe FB 9 Omen we. Me Pw O18 ff Oo mee we em mm Oem se Bn 4 iS a. .1 a “Gre wha 225-59 - 44.3 compressien medulus. 5.1 226259 = 24.3 tensien medulus. 9.4 = The vertical loading of ene half ef the upper bleck girt is as shown abeve. 7500 x 33 7/8 = 254000 inch peunds maximum bend- ing moment. 224000 = 5740 pounds per square inch cempressien. 44.3 234000 = 10500 peunds per square inch tension. 24.3 The compression is kept lew se that the angles are enabled te resist any normal lateral ferces they may be called upen te carry. Te take care ef extreme lateral ferces we will ancher the lead girt te the machinery girt by means ef a tensien belt, as shewn en the drawing. This belt will be fixed in the machinery girt, but free in a slet in the lead girt,se that deflection by the lead } girt will place no lead on the belt. 20% ef the vertical live lead is a censervative estimate of the lateral ferce that the lead girt must be poe & we. eimai eo oe ora o Q . ww -« 4 4 - * - 6 ’ e . ‘ ’ $ 7 L ‘ ‘ ! @ able te resist, hence 20% ef 30000 = 6000 pounds. At abeut 10000 peunds per square inch tension this will require a 1" belt. Any excessive ferces in the ep- pesite directien will be transmitted te the machinery girt threugh the interpesed washer. L : $e 252. r 3 Accerding te Gerden's formula the allewable compres- sive stress for a slenderness ratio ef 52 is as fellews: 12500 - a = 1422. * 36000 x (.%75)¢ This weuld indieate that the girt will net buckle 11600 pounds per square inch. under the combined vertical and lateral ferces, the com- pressive stress due te vertical lead being 5740 pounds per square ineh. Trelley Side Section. 13.55, | fr 124 1/4 " 10.7 ® re ’ bh : ‘ . : a. | - Poy . ‘ Q : . ‘ ” . ‘ i . . 4 ’ a . f t ’ . t . ah ‘ —_ -_ , * 1 4 . . . . * . - e . See 4 ‘ 4 .¢ te » ‘ , , x * : . - : . ~ ~~ wre of - . o . - " we » ° . . - o . oo ‘ , , . SS i 1 2 . 2 . s ' -, <« oe * ‘ ‘ -* . _ . . . + a s te , <8 +e er me , . << ore, tltante es $ 4 \ j i ’ ¢ “! ‘3 ve -_— > -TEe -4n-2 ft ae —_ - o co ts y ‘ , . 8 rd . ‘ ¢ @ 6 ‘ ~ = - ~~ - = - ° ~ . 7 we * > ~ . - ~— we ‘Pee wey . 4 - io ° 4. we ‘ a. ; wes . ’ ¢ @ + a ~ ” / we - os ® - we ; e « = - , : : vd -”“~ “ --e “{ ’ Cd . . . > : oo . a ; my +: . ~ » -- » ars - - - 4 .. . s °° os = - 7 ‘ a ‘em 1 . . x . a an . . - se oy. +7 © : C ' . . - as » * - : . 4 - ew a: oe oe . ~ — Phe nee ba: ~ ye + ee. ae — § ~~: aie) oe a. f - ‘ _¢ 7 , s : » —_ ‘ Y 4 e . 4 ‘ t . wes i -_ =m or + ~ — =.2 -« @e ~~ =— - -~ = o a. -— = -- . o ~ 6 Xe 10. 1 4 ot 1 © 68x12. 2 t+ 4 X2 8 10. 12 Sig tbe 543 Xe §.06+ 2414130 @ 376-06 - 10.7 35-23 35-23 1, = 10.12x10. 22 1/12%7/8x22. 53415. 68x11. 55% 5243x113. 182 I, = 1050+832+474942 = 2871 The inertia ef the upper and lewer flanges sbeut their ewn axis has been neglested since this is very small. e 212 compressicn modulus/ eile 2871 - 268 tensien modulus. 10.7 We will new take moments te determine the maxi- mum moment en each ef the trelley sides. Ss zCCOO0# vy 3 e -44° yp! -o4" 6t~1® Re 40 0000 = 11090 peunds maximum lead carried 73 by ene wheel. 11090x32.5 = 361000 inch pounds bending moment due te live lead. The dead lead will be censidered as unifermly dis- 2 &. eR anya ¢ ‘ * +e , ry = wm - - os - ~ - -= e® . - ~ - . = - = e e eo. o a who, - —-: e - - - c a j - —<_ e ° a e e t . 1 , ea ‘ 4 tributed, hence 13200%73 - 61600 inch peunds bending moment due te dead lead. 361000461600 = 422600 inch pounds, tetal bending moment on ene trelley side. 4226090 = 2000 pounds per square inch compression. 212 422690 = 1580 peunds per square inch tension. 2 We shall assume that the trelley sides may be called upen te carry a lateral lead ef 20% ef the live lead on the lead girt. 20%x3000 » 6000" pounds. £090 =z 3000 peunds lateral ferce per trolley side. Fer convenience we shall assume this lead as dis- tributed equidistant between the wheels, thus 15008 ) 254" aoe < 73" —| 1500x25.5 «= 36300 inch peunds lateral bending moment. It is apparent that a part of this bending moment is transmitted te the upper flange, we will say 1/3. There- fere 38300x2/3 2 25533 inch peunds lateral ‘bending moment ee .oom a q¢ on lewer flange. AE 2933 = 1480 lateral tension on lower flange. 1x10 1/87 Cembining the vertical and herigsontal tensions, as shewn, we eet a maximum tensile stress in the lewer flange ef 2160 peunds per square inch, which is satisfactery. Bearing Pressures. The sheave vearing pressures have been determined un- der a previous heading, We have feund the maximum live lead en one wheel te be 11090 pounds, Assuming that the dead lead is equally distributed ever the feur wheels, we have 13500 = 3375 peunds per wheel. 4 11090+3375 = 14465 peunds, maximum wheel lead. Hence the maximum bearing pressure is sith z 593 peunds per square inch. 2x3. 5X302 It is apparent that the bearing pressuredin the Hoisting train are lew. They are beth safe and practicable -_—=- ae - - . - ~ r be ’ > . a * ' ‘ aye a ow =~ oe erg ~oe - ~~ eo @& ee 2. we ~~ and hence further calculations in that directien will be Ean 1 | superfluous. Repe DFupe Section of drum 40 "9; 1/4 4 .4 4 4 Se Dr-g 19 1/4 == 8000-88500 « 287 sec- joa” 10x17 4 . oe " tion modulus of drum. 199000x79. ='175000 inch pounds, bending moment on drum. 4 B: Ba es 2000 = 610 pounds per square inch bending. 8 257 C=- Pp z= 9900 = 5555 pounds per square inch compression. pt o 9x1 A Bey of “4 6104 55552 =z 5600 pounds per square inch cembined tension and cempression. The wire repe will be extra flexible plow steel, six strands, thirty-seven wires to the strand, hemp cere, having an ultimate capacity ef 42000 peunds. 42909 2 8.4 facter ef safety in repe, neglecting dead weight. see ‘ . : . a ’ ee - Noy “e: e , 8 _= ’ ” e -_ * + - «° - - @ «. ..@ i wom om so. a coe i a) . cr : q ' ‘ e . N a An om —_ a ~ am ph ne _— = ee . ~ ~s —_ ~ “e md - , « * . , “ - . . “ . oe oe ‘ me OM aim 2. fae -_ -—- om. - ~ - . ~~ === om . ‘ ‘ 2 a wt e . ‘ . oc re -~ + ad on ~? oe a ” ~ ~ soe . - > . . _ - -~/™ -«. we ae ao. . a . ; a @. te a eos * ; ~“ ® ‘ 4 . - , 4 . 1 . . ~ -~ on em Ow - Oc wee »* a, _— me ~ “ ~ ‘ - - Lee me - we _— - - - -- * a ~—- - = - © —~ - . - ea ~~. ~ . 2 - we - - =e Ge Oa obs. Ge te ie wee ~ - é 6 . - ad ' . , X . - oo . . ~~ . y - - ‘ . .¢ oo e . o . . ~- . . : eo Se 8 , e «4 . s - i . ~ oe o ‘ ~~ - yo! a , This facter of safety is a little high, since, how- ever, the 3/4 repe is the nearest commercial size ans- wering our requirezents it has been selected. The drum has a total of twenty-four groeves per side. Ye will allew two turns for wrap and stretch of repe, leaving twenty-two greoves available fer hoisting. Circusference ef drum in feet is .261x20 = 5.22. Heist per turn = 2,22 = 1.30 feet. 1.3x22 - 25.6 feet hoist, which meets eur require- ments. > Pre k ete hes: we _