Johnstone, Donald T.

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 The Knowledge Bank at The Ohio State University Ohio State Engineer   Title:  Modern Excavating Equipment Creators:  Johnstone, Donald T. Issue Date:  May-1927 Publisher:  Ohio State University, College of Engineering Citation:  Ohio State Engineer, vol. 10, no. 4 (May, 1927), 4, 24-25. URI:  http://hdl.handle.net/1811/33904  Appears in Collections: Ohio State Engineer: Volume 10, no. 4 (May, 1927)     THE OHIO STATE ENGINEERMODERN EXCAVATING EQUIPMENTBy DONALD T. JOHNSTONE, '29AT the present time, the great tendency ofman is to do bigger things in less time atthe lowest possible cost. We marvel at therapidity of construction of our large build-ings, sewers, canals, tunnels and highways. Wemust have large quantities of stone, gravel, clays,coal, iron and raw materials that are extractedfrom the earth to supply our increasing demands,and one of the principal contributing factors to-ward this rapid quantity production is our pres-ent power excavating equipment. By means ofthis equipment excavations are made for base-ments, foundations, and sewers; highways arecut and graded, and open pit mining operationsare carried on. This variety of uses demands ex-cavators of many types and sizes, and for thesepurposes manufacturers have developed andplaced standard power shovels on the marketranging from one-half cubic yard to eight cubicyards dipper capacity.For the usual small excavation job, probablythe most generally used machine is one of ap-proximately one cubic yard capacity. This willvary from those of one-half cubic yard to twocubic yards, but we may consider the one cubicyard machine as applicable for a large variety ofuses. Practically every job on which the smallmachine is used is carried on under different con-ditions, so that it is not possible to state an exacthandling cost per cubic yard that will apply to allexcavation projects. The principal factors thatgovern excavation costs are: the power used tooperate the machine; the kind of material to bemoved; the facilities for removing the materialfrom the machine; the height at which the ma-terial must be dumped from the dipper; and de-lays due to necessary repairs.The present machine may be driven by steam,electricity, gasoline, or oil, consequently the prac-ticability of any particular power is establishedby conditions peculiar to the localities in whichthe machine is to be used. The following tableof comparative operating costs is based on dataof actual experience covering a wide range ofworking conditions in many localities. Also, thefigures are for a particular make of three-fourthscubic yard machine but they will show the dif-ferences due to the source of power.Gasoline-Steam Electric ElectricOperator $8.00 $8.00 $8.00Fireman 6.00 none nonePitman 4.00 4.00 4.00Coal, one ton 8.00 none noneGasoline, 35 gallons none none 8.75Power, 225 K.W.H. none 6.75 noneWater supply 1.25 none noneOil and minor supplies 1.25 .50 1.00Operating cost $28.50 $19.25 $21.75Interest at 6% 2.90 3.60 4.10Depreciation and mainte-nance 4.80 4.50 5.50Total cost per day $36.20 $27.35 $31.35This machine will move, under average work-ing conditions, approximately 450 cubic yards ofearth per 10-hour day. In some cases this figurewill be greatly exceeded, if working conditionsare favorable, while in other cases it will not bereached. In general, operating costs on steammachines may be considered on a basis of one tonof coal per 10-hour day to each cubic yard ofdipper size, and on electric machines approxi-mately .3 to .6 K.W.H. per ton of material exca-vated. Depreciation is usually figured at 10 percent and maintenance from three to five per centof first cost per year.It is obvious that in order to attain the high-est operating efficiency a machine must be adaptedto the particular work at hand. The small ma-chines can be used on many kinds of jobs suchas excavations for basements and sewers, load-ing of sand, gravel, etc., and general contractingwork where the available working space is com-paratively small. Quarry work, stripping, andopen-pit mining require more rugged machinesof greater capacity. If a machine is to be se-lected for any particular kind of work, all orpart of the following points will govern the selec-tion. What capacity per hour is necessary? Whatdigging radius, height, and depth are necessary?At what height above the ground line and dis-tance way from the centerline of revolution willit be necessary to dump? Any of the above con-siderations may be the important factor and themachine chosen to suit, but all the conditions arcusually satisfied.Shovel capacities may be figured, under ordi-nary working conditions, according to dippersize. A one-yard machine will move, on an aver-age, one cubic yard per minute and the capacitiesincrease as the dipper sizes so that the 8-cubic-yard machine will move 8 cubic yards per minute.This gives a range for a 10-hour day of approxi-mately 600 cubic yards to 5,000 cubic yards. An8-cubic-yard machine is capable of making onecomplete cycle of operation in 45 seconds whenswinging through a 90-degree angle. There areintervals of time consumed in moving the shoveland for oiling and other mechanical attentions.Accessory equipment also has a bearing on theamount of work available from the shovel perday. Average conditions usually result in ap-proximately 65 to 80 per cent actual digginghours, based on total time employed.All machines are designed for working rangessuitable to the type of machine. The ranges ofsmall revolving machines commonly known as"whirlies," increase as the dipper capacities. Thesmall revolving machine of one yard dipper ca-pacity will give maximum dumping radius of 26feet and a maximum dumping height of 15 feet.These figures increase as the dipper sizes withinthe small revolving shovel group. On the heav-ier type of machines that are used to a great ex-tent in railroad extension work, rock quarries,and ore mines, the ranges are small when com-pared with dipper capacities. This is due to ademand for a powerful machine of large capacity(Continued on Page 24)24 THE OHIO STATE ENGINEER(Massachusetts Institute oftechnologySchool of QhemicalEngineering 'Tra&iceINDIVIDUAL and practical training at five industrialplants are important features of the GraduateCourse in Chemical Engineering Practice. Fieldworkis carried out atBangor, Me; Boston, Mass., Buffalo,N.Y. , and Bayonne, N. J., in plants producing sul-phite and soda pulp, paper, caustic soda, chlorine,heavy acids and salts, sugar, coke, gas, steel, ammonia,benzol, petroleum and other chemical products.The more important operations of Chemical Engineering, astypified by the above processes, are studied systematically bytests and experiments on actual plant apparatus, thus fixing inthe student's mind the principles of Chemical Engineering andcorrelating these principles with practice.The work is non-remunerative and independent of plant con-trol, the whole attention of the students being directed to studyand experimentation.Registration is limited, as students study and experiment insmall groups and receive individual instruction by residentmembers of the Institute's Faculty.Admission requires adequate preparations in chemistry andengineering. Able students can complete the requirements forthe Master of Science degree in one and a half years.For further details address theSCHOOL of CHEMICAL ENGINEERING PRACTICEMassachusetts Institute of Technology, Cambridge, Mass.,Rolling Steel DoorsWILSON CORPORATION -ESTABLISHED 187636th Street New York CityMODERN EXCAVATING EQUIPMENT(Continued from Page 4)for loading cars. A machine that can dump overour railroad gondola cars is all that is usually re-quired, but it must have a large dipper for rapidproduction. The large revolving machines wereprimarily designed for stripping overburden frommineral deposits, consequently they must be ableto dig through deep banks and dump correspond-ingly. The largest machine now on the marketis the 8-cubic-yard full-revolving shovel, whichhas a maximum dumping radius of 97 feet and amaximum dumping height of 67 feet.The working range figures given above willvary slightly with different makes of shovels, butthey are representative of the types. Also, thesefigures are for so-called standard equipment, butspecial equipment can be placed on the small re-volving type which will change the ranges to suitspecial work such as deep sewer or trench workor work requiring a higher lift than the standardequipment will give.Originally, the only machines built were oper-ated by steam power and if local conditions madeoperating costs prohibitive the labor saved wasnot worth the cost. In some localities the hand-ling of fuel for the steam machine is an arduousand expensive operation, and good feed water isnot obtainable without the installation of watersoftening devices, filters, and purifiers. Smokeordinances are now enforced in many cities andregulations controlling the use of steam boilersare becoming more severe each year. The elec-tric and gasoline-electric machines have been de-veloped to take care of these difficulties. The firstshovels of this type, though lacking in the finerdetails, proved conclusively that there existed anew and very promising field for motor applica-tion in earth and material handling equipment.Cheap hydro-electric power is now available inmany localities and new projects are continuallyunder construction. Where electric current is notavailable from an outside source a design hasbeen provided whereby the electric current canbe generated on the machine.In selecting power shovel equipment many fac-tors should be taken into consideration. Steamhas certain inherent characteristics and advan-tages that should not be overlooked. In propos-ing a change from steam to electric operation wehave to deal with steam equipment which has notonly proved its worth in power shovel construc-tion, but has probably reached its highest stateof development. At the present time, however,similar operating characteristics are obtainedwith the electric motor drive, even to that im-portant feature of having high starting torquewith quick acceleration of motor and machinery.These new shovels have many features whichmake them equal, and, under many conditions ofoperation, superior to the steam shovel. The sav-ing in operating expense of the electric or gaso-line-electric shovel over the steam shovel will de-pend somewhat upon the comparative cost of fueland electric power and will vary for different lo-calities. The electrically operated machine elim-inates the fireman, the watchman, the handlingand hauling of fuel, the use of water, and other-wise avoids considerable waste, but local condi-tions taken collectively should govern in all casesthe type of machine chosen.THE OHIO STATE ENGINEER 25American GasAssociationWhat it is-What it is doingfor American Industry —The object of the American Gas Association is to promotemore and better ways of utilizing gas;—to assist the industries of America (and the public as awhole) in deriving to the fullest the numerous advantagesinherent in gas;—to advance to the highest efficiency, methods of gas manu-facture, distribution and utilization;—to collect and disseminate information on these subjects.The American Gas Associationwas organized in 1918—and con-solidated with the American GasInstitute, and the National Com-mercial Gas Association.The membership includes 551Gas Companies, 21 Holding Com-panies, 428 Manufacturers of gasburning appliances, and 3,444 In-dividual memberships. Its activ-ities and interests extend toevery state in the Union.The sales of gas for the year 1926,officially reported to the Amer-ican Gas Association, amountedto 38 billion cubic feet more thanthe amount sold in 1925. This istwice the increase in 1925 over1924—making a total increase of40% in the last five years.This phenomenal increase in theuse of gas is largely due to thegrowing demands from indus-trial customers. The AmericanGas Association has recently ap-propriated half a million dollarsfor research work and develop-ment of the industrial gas heat-ing business.Write to the American Gas Asso-ciation for information on whatgas is doing for others in yourline of business.American Gas Association420 Lexington Avenue, New York CityYOU CAN DO IT BETTER WITH GAS

Modern Excavating Equipment

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Modern Excavating Equipment

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