5010t_跨度28m_双梁桥式起重机结构设计正式说明书

太原科技大学华科学院毕业设计（论文）论文题目50/10T,跨度28M,双粱桥式起重机结构设计2010年6月17日摘要本设计采用许用应力法以及计算机辅助设计方法对桥式起重机桥架金属结构进行设计。设计过程先用估计的桥式起重机各结构尺寸数据对起重机的强度、疲劳强度、稳定性、刚度进行粗略的校核计算，待以上因素都达到材料的许用要求后，画出桥架结构图。然后计算出主梁和端梁的自重载荷，再用此载荷进行桥架强度和刚度的精确校核计算。若未通过，再重复上述步骤，直到通过。由于桥架的初校是在草稿中列出，在设计说明书中不予记录，仅记载桥架的精校过程。设计中参考了各种资料,运用各种途径,努力利用各种条件来完成此次设计本设计通过反复斟酌各种设计方案,认真讨论,不断反复校核,力求设计合理通过采取计算机辅助设计方法以及参考前人的先进经验,力求有所创新通过计算机辅助设计方法,绘图和设计计算都充分发挥计算机的强大辅助功能,力求设计高效。关键词桥式起重机校核许用应力ABSTRACTTHEPROJECTDESIGNSMETALFRAMEWORKOFBRIDGECRANEINUSEOFALLOWABLESTRESSMETHODANDCADATFIRST,ICHOSESIZEASSUMABLYTHEN,PROOFREADEDTHESIZEIFTHEPROOFWASNOTPASSED,MUSTCHOOSETHESIZEAGAINUPTOPASSTHEPROOFIFTHEPROOFWASPASSED,ITCOULDCARRYONTHESPECIFICSTRUCTURALDESIGNATLAST,ITSPLOTANDCLEANUPTHECALCULATIONPROCESSDESIGNEDTOMAKEREFERENCETOTHEVARIOUSOFDATAINTHEPROCESS,MAKEUSEOFVARIOUSPATHS,WORKHARDTOMAKEUSEOFTHEVARIOUSOFCONDITIONTOCOMPLETETHISDESIGNINREASONICONSIDEREDVARIOUSDESIGNPROJECTS,DISCUSSEDEARNESTLY,CALCULATEDTIMEAFTERTIME,TRYHARDFORAREASONABLEDESIGNVIACADANDMAKEREFERENCEADVANCEDEXPERIENCES,TRYHARDFORAINNOVATORYDESIGNVIACAD,PLOTINGANDCALCULATIONCANMAKEGOODUSEOFPOWERFULLCOMPUTER,TRYHARDFORAHIGHEFFICIENCYDESIGNIKNEWTHEVARIOUSOFDESIGNMETHODS,NEWESTMACHINEDESIGNMETHODSBOTHHEREANDABROADALSOFOUNDVARIOUSOFGOODDATAKEYWORDSBRIDGECRANEPROOFREADALLOWABLESTRESS目录第一章桥式起重机金属结构设计参数1第二章总体设计221大车轴距222主梁尺寸2第三章主端梁截面积几何性质3第四章、载荷441固定载荷442小车轮压443动力效应系数544惯性载荷545偏斜运行侧向力6第五章主梁计算851内力852强度1353主梁疲劳强度1654主梁稳定性19第六章、端梁计算2461载荷与内力2462水平载荷2563疲劳强度3064稳定性3365端梁拼接33第七章、主梁和端梁的连接40第八章、刚度计算4081桥架的垂直静刚度4082桥架的水平惯性位移4083垂直动刚度4184水平动刚度42第九章、桥架拱度44总结45参考文献46致谢47英文资料48第一章桥式起重机金属结构设计参数表11设计参数起重机类型通用工作级别A6轨道放置中轨桥架形式双梁50/10T28M起升机构主起升副起升额定起重量（吨）5010起升高度米1218起升速度米/分121121103工作级别M6M5运行结构大车小车轮距（米）375轨距（米）2528速度（米/分）402402853853工作级别M6M5轮压（MPA）4411797轨道型号QU80P43第二章总体设计1桥架尺寸的确定1大车轴距2腹板尺寸3翼缘板尺寸4主梁尺寸（）L（）2256375425M0B146146根据小车轨距和中轨箱型梁宽度以及大车运行机构的设置，取5M端梁全长B5916M02主梁尺寸高度H（）L18211500MM147取腹板高度1600MM0H腹板厚度6MM1翼缘板厚度24MM0主梁总高度21648MM1HH0主梁宽度B0405648810MM1字腹板外侧间距B760MM425MM且540MM60L13H上下翼缘板相同为24MM600MM主梁端部变截面长取D2350MM图21双梁桥架结构第三章主端梁截面积几何性质5M0BB5916M1600MM0H6MM124MM01648MM1HB1B552MM24MM600MMD2350MM1）截面尺寸1固定载荷图31主梁与端梁截面A主梁截面A60024160062004512M2惯性矩XI281640543610）（2130531010MM4YI5916）（171202109MM4B端梁截面A287602）（36160MM2003616M2XI763）（42641109MM4YI6023782（）68221108MM4第四章载荷A004512M221301010MM4XI1712109MM4YIA1003616M214264109XIMM416822108YIMM441653NF2小车轮压主梁自重载荷KAG981F1281904527841653N小车轨道重3886981GF38122N/M栏杆等重量G100981LLM981N/M主梁的均布载荷QFGL552752N/M起升载荷为GQPM8910549000N小车自重170422NGX73小车自重载荷MGQXP121298110001079102N小车重力产生的静轮压和QXPX1P21GBK）（E50B7423719350666NX2P2QLE50B）（K5348038N额定起升载荷产生的和APO12P552752N/MQF3动力效应系数4惯性载荷5偏斜运行侧向力P01BC21Q1258108NP021L1191891N1754768N1JOX1P021726698N2J2小车轮压34914668N1J2J空载轮压335KN1P383KN21112107VQ107121/6011411100584H110058753/60118H1MM,接头高度差大小车都是4个车轮，其中主动轮各占一半，按车轮打滑条件确定大小车运行的惯性力一根主梁上的小车惯性力为2493905NXGP27大车运行起制动惯性力（一根主梁上）为2493905NH2734914668PN2493905NXGP2493905NHP35982N/MF1525595NQP6左侧端梁总静轮压35982N/MHF27Q主梁跨端设备惯性力影响力小，忽略一根主梁的重量力5527522804QP1525595N一根端梁单位长度的重量1FQAGK11819360785305997N一根端梁的重量为BQDP1FQ179456463059971871476N一组大车运行机构的重量（两组对称配置）为G5623/2981275527NQJPJM451满载小车在主梁跨中央左侧端梁总静轮压按图41计算图41端梁总轮压计算1RP21212QGXQGSGJDDPPL（490000170422）15255952755271137147652903746N由28/556查得013452LB侧向力1SPR305997N1FQ1871476NQDP275527NJ52903746N1RP812075962RP1垂直载荷529037960134512355778N45满载小车在主梁左端极限位置左侧端梁总静轮压2RP121QGXQGSGJDEDPPPLL81207596侧向力546121N2SP2R估算大车轮压P18T选取大车车轮直径为800MM,轨道为QU8046扭转载荷中轨梁扭转载荷较小，且方向相反，可忽略。故在此不用计算。第五章主梁计算51内力计算大车传动侧的主梁。在固定载荷与移动载荷作用下，主梁按简支梁计算，如图所示5168793947NQM2移动载荷作用下主梁的内力图51主梁计算模型固定载荷作用下主梁跨中的弯矩（）QM428QIGJFLDP118215275768793947N跨端剪切力QCF42112QGJSDLPL11855272528275527319620（1）32812382236N满载小车在跨中，跨中E点弯矩为PM421PLB轮压合力与左轮的距离为1829M21PB3749168则25194894NMPM跨中E点剪切力（1）PF124P1BL12382236NQCF25194894NMPM1925405NPF0NT382138298PCFNM11720012NM1NT3水平位置281934961821925405N跨中内扭矩为0NT2满载小车在跨端极限位置（Z）小车左轮距梁端距离1E为21802MM1CEL端梁剪切力（）PCF4P1LBC118（28182902）82396382138298NM跨端内扭矩为（）（1）1NT4PHL1E28324086511720012NM主梁跨中总弯距为XMQP68793947251948946320742887NM主梁跨端总剪切力RFCQPC12382236382138298505960658N1）水平惯性力载荷在水平载荷及作用下，桥架按刚架计算。HPFK25BK1252AK52512510B12320742887XMNM505960658NRF水平刚架计算模型示表图52图52水平刚架计算模型小车在跨端。刚架的计算系数为11R123ABIL1957120831017跨中水平弯矩HM211483HPLFLRR017328294702029310207435NM跨中水平剪切力为1246952NPH12跨中轴力为HN218HFLPABR82409312394705146578N小车在跨端。跨端水平剪切力为CHF1LEP228409383942868516N2偏斜侧向力。在偏斜侧向力作用下，桥架也按水平刚架分10207435NMHM1246952NPH2868516NCHF析（如图53）图53侧向力作用下刚架的分析这时，计算系数为1SR123ILK538079104小车在跨中。侧向力1SP2R5290379601345355778N超前力为10PSBL32675866073N端梁中点的轴力为330365N12DP端梁中点的水平剪切力为1DSSKRA355778（）12504487287N主梁跨中的水平弯距为487287N1DP19378NSM3070493N1S10226813NMYM546121N2SP4强度SM112DLPABN3557781254872871253303652819378N主梁轴力为11SDP3557784872673070493N主梁跨中总的水平弯矩为YMHS102074351937810226813NM小车在跨端。侧向力为546121N2SP超前力为20SB546181014225N端梁中点的轴力为507112ND2P端梁中点的水平剪切力为（）2DSSKRA1546121（）25104805178N主梁跨端的水平弯矩为ABCSM2SPD5461211258051781257215098NM主梁跨端的水平剪切力为CSF2PDN110142255051121014225N2P805178N2DP7215098NMCSM507112NCSF3375628NCH507112N主梁跨端总的水平剪切力为CHFCS2868165071123375628N小车在跨端时，主梁跨中水平弯矩与惯性载荷的水平弯矩组合值较小，不需计算需要计算主梁跨中截面（如图31所示）危险点、的强度1主腹板上边缘的应力主腹板边至轨顶距离为164MMYH0G主腹板边的局部压应力为4250JIMYPH9182MPA1876垂直弯矩产生的应力为01MXYI31032748512044MPA水平弯矩产生的应力为021YMXI31068274648MPA惯性载荷与侧应力对主梁产生的轴向力较小且作用方向相反，应力很小，故不计算主梁上翼缘板的静矩为YS0105B2454080510432800MM412044MPA01648MPA027857MPA12692MPA01114356MPA5主梁跨端的切应力6主梁疲劳强度主腹板上边的切应力为02PYNXFSTAI0109543867857MPA点的折算应力为01021204464812692MPA122003M26916918375114356MPA007517625MPAS需修正，则（）1CRS153SCR24021078MPA腹板边局部压应力9182MPAM压力分布长C250YH216450378MM533，按A3B计算，AB30427830区格属双边局部压缩板，板的屈曲系数为MK21A074893187MCRKE121877442516695MPA075S区格平均切应力为002PNFTAH0195461003MPA由531，板的屈曲系数为AB548K2453253CRE1254874448946MPA3CR489684778MPA需修正，则合格755061）垂直载荷3CR23525184722271MPA12858MPACR73区格上边缘的复合应力为2211M2269869183011484MPA52，区格的临界复合应力为ABCR2211231344MMCRCRCRCR222806290619810317876519465MPACRRN19465314635MPA合格XI主副腹板采用相同的纵向加劲肋50505，A6143MM2，231700MM41XI纵向加劲肋对主腹板厚度中线的惯性矩为XI21AE2105XIBZ231700614349621742976MM4XI230254AH328161679360MM4059740163可见，在相同的循环工况下，应力循环特性是一致的。根据A7和Q235及带孔板的应力集中等级，查得101MPA2W1翼缘板拉伸疲劳需用应力为RL167045BR2683704512195MPA3，属窄式HB701连接7O0MM,1Y11023302550270021016400MM2I腹板角点螺栓的最大内力为1FP12FIMY3850716444892N腹板角点螺栓顺梁轴的内力和为LFPF1F4226344892491183N18834108MM40XI4847108MM4Y0I17152MM20DA1HFL17152MM2端梁拼接处强度为1100YXDMNIA1752308472698345597391564MPA（足够）1HFL主、端梁的连接焊缝足够承受连接的水平弯矩和剪切力，故不再计算第八章刚度计算满载小车位于主梁跨中产生的静挠度为Y2348XPBLEI10523961022737502365MM31875MM8LY82桥架的水平惯性位移X34111548HHPLFEIREIRVF311154488HHPLFLEIRPR1342516348205993286MM1275MMLX83垂直动刚度起重机垂直动刚度以满载小车位于桥架跨中的垂直自振频率来表征，计算如下主梁质量1555142KGGM15298FG全桥架中点换算质量为05（2）15551421739032941KG1GX起升质量50000KG2MQ0起升载荷G490000NQPM0起升钢丝绳滑轮组的最大下放长度为162216MRL2QRH桥架跨中静位移为0Y2348QXPBLEI32510907038272611673起升钢丝绳滑轮组的静伸长为369MM0QRPLNEA5370814结构质量影响系数为2012YM239467359007039HF28MM0F392MMY桥式起重机的垂直自振频率为VF0121GY073936798208HZ（合格）2VF起重机水平动刚度以物品高度悬挂，满载小车位于桥架跨中的水平自振频率来表征。半桥架中点的换算质量为05EM0GXQM05（15551421739050000）414705KG半主梁跨中在单位水平力作用下产生的水平位移为E3148LEIR35920316442000013432MM/N桥式起重机的水平自振频率为HF12EM013428462575HZHZ（合格）HF第九章桥架拱度桥架跨度中央的标准拱度值为0F1L2828MM考虑制造因素，实取14392MM0Y0F跨度中央两边按抛物线曲线设置拱度，如图2041AL所示91图91桥架的拱度距跨中为的点1A8L3675MM214639Y距跨中为的点2AL294MM2241639LY距跨中为的点MMA8375Y因此，桥架结构设计全部合格。总结通过3个月的金属结构毕业设计学习，使我学到了许多非常重要的知识和技术。马上就要结束了现对在3个月的学习进行以下总结首先，在前期的设计计算过程中，温习了以前所学的所有知识，并对其进行了巩固。在计算过程中，发现了一些疑难问题和自己以前没有注意的知识点和方法，通过老师的指导和讲解，自己的复习对其进行了理解和掌握。在规定的时间内完成了前期计算过程。其次，通过应用CAD技术绘图，使我掌握了CAD的使用方法，同时也从中学到了许多绘图方法和技巧，特别是快捷键的应用。使我在比较短的时间内能够完成所要画的图纸。在写设计说明书的过程中，掌握了WORD和公式编辑器的应用。虽然在编写过程中遇到的难题，通过向自己的摸索和同学的帮助都的到了解决。在这次设计过程中，我查阅了大量的相关资料。掌握了许多新方法和新知识。使自己的专业知识的到了大大补充。特别是一些自己平时所学课本上没有介绍的知识。例如翼缘板和腹板加劲肋的选用、计算和校核。同时还了解了目前的起重机的发展情况以及以后的发展，并掌握一些最新技术和设计理论。针对此次的设计，随着对整机的不断深入了解，也发现了设计存在的一些问题。一方面，由于缺乏必要的生产实践知识，我们的设计还局限于一定的想象空间上，实际中不生产或加工比较困难。另一方面，在设计的过程中，缺乏对细节的考虑，只抓住了其中大的框架，后续的工作还有很多。通过这次毕业设计，使我感觉收获颇多。在设计中培养了大家的团队合作精神，遇到问题大家集体讨论进行解决，还有CAD技术的应用，这些对于我们即将走向工作岗位的新人是一个很好的培训和锻炼，同时也是平时所学的理论和实践的一次结合。这次设计将对我们的以后工作和学习奠下重要的理论知识基础和实践经验。参考文献1、大连理工大学杨长，傅东明主编。起重机械。北京机械工业出版社，19922、起重机设计规范编写组主编。国家标准GB381183起重机设计规范。北京国家标准局出版社，19833、张质文等主编。起重机设计手册。北京中国铁道出版社，20014、上海交通大学王殿臣，倪庆兴主编。起重输送图册，上册起重机械。北京机械工业出版社，19925、起重机械教材6、起重机课程设计7、堂增宝等主编。机械设计课程设计（第二版）。华中科技大学出版社，19988、材料力学刘鸿文主编高等教育出版社2003致谢我通过三个月的时间，结合了大学四年所学的专业知识，同时查阅了大量起机专业的相关资料，以及起机教研室各位老师的帮助指导。使我对起重机械的设计有了新的较系统的认识。特别是对起重机金属结构有了较深刻的了解。在近两个月的毕业设计即将完成之际，衷心的向帮助过我，鼓励过我的老师同学们表示感谢。首先要感谢在此次设计中给与我全程细心指导的老师。由于本人学识水平和设计经验的缺乏，在设计的开始阶段，遇到了很多棘手的问题，在后来的设计绘图过程中，又暴露很多实际的画图问题，自己毫无经验。秦老师的及时耐心有效的指导，才使我能顺利、如期的完成毕业设计。老师们渊博的知识、严谨的治学态度、高度的责任感和对我们时时刻刻的关怀之心，都深深的感染着我。、感谢同组的同学对我的帮助。最后，向毕业设计评审委员会的各位老师表示崇高敬意和衷心感谢。THEUSEANDHISTORYOFCRANEEVERYTIMEWESEEACRANEINACTIONWEREMAINSWITHOUTWORDS,THESEMACHINESARESOMETIMESREALLYHUGE,TAKINGUPTONSOFMATERIALHUNDREDSOFMETERSINHEIGHTWEWATCHWITHAMAZEMENTANDABITOFTERROR,THINKINGABOUTWHATWOULDHAPPENIFTHELOADCOMESOFFORIFTHEMOVEMENTOFTHECRANEWASWRONGITISAREALLYFASCINATINGSYSTEM,SURPRISINGBOTHADULTSANDCHILDRENTHESEAREESPECIALLYTOWERCRANES,BUTINREALITYTHEREAREPLENTYOFTYPESANDTHEYAREINUSEFORCENTURIESTHECRANESAREFORMEDBYONEORMOREMACHINESUSEDTOCREATEAMECHANICALADVANTAGEANDTHUSMOVELARGELOADSCRANESAREEQUIPPEDWITHAWINDER,AWIREROPEORCHAINANDSHEAVESTHATCANBEUSEDBOTHTOLIFTANDLOWERMATERIALSANDTOMOVETHEMHORIZONTALLYITUSESONEORMORESIMPLEMACHINESTOCREATEMECHANICALADVANTAGEANDTHUSMOVELOADSBEYONDTHENORMALCAPABILITYOFAHUMANCRANESARECOMMONLYEMPLOYEDINTHETRANSPORTINDUSTRYFORTHELOADINGANDUNLOADINGOFFREIGHT,INTHECONSTRUCTIONINDUSTRYFORTHEMOVEMENTOFMATERIALSANDINTHEMANUFACTURINGINDUSTRYFORTHEASSEMBLINGOFHEAVYEQUIPMENT1OVERVIEWTHEFIRSTCONSTRUCTIONCRANESWEREINVENTEDBYTHEANCIENTGREEKSANDWEREPOWEREDBYMENORBEASTSOFBURDEN,SUCHASDONKEYSTHESECRANESWEREUSEDFORTHECONSTRUCTIONOFTALLBUILDINGSLARGERCRANESWERELATERDEVELOPED,EMPLOYINGTHEUSEOFHUMANTREADWHEELS,PERMITTINGTHELIFTINGOFHEAVIERWEIGHTSINTHEHIGHMIDDLEAGES,HARBORCRANESWEREINTRODUCEDTOLOADANDUNLOADSHIPSANDASSISTWITHTHEIRCONSTRUCTIONSOMEWEREBUILTINTOSTONETOWERSFOREXTRASTRENGTHANDSTABILITYTHEEARLIESTCRANESWERECONSTRUCTEDFROMWOOD,BUTCASTIRONANDSTEELTOOKOVERWITHTHECOMINGOFTHEINDUSTRIALREVOLUTIONFORMANYCENTURIES,POWERWASSUPPLIEDBYTHEPHYSICALEXERTIONOFMENORANIMALS,ALTHOUGHHOISTSINWATERMILLSANDWINDMILLSCOULDBEDRIVENBYTHEHARNESSEDNATURALPOWERTHEFIRSTMECHANICALPOWERWASPROVIDEDBYSTEAMENGINES,THEEARLIESTSTEAMCRANEBEINGINTRODUCEDINTHE18THOR19THCENTURY,WITHMANYREMAININGINUSEWELLINTOTHELATE20THCENTURYMODERNCRANESUSUALLYUSEINTERNALCOMBUSTIONENGINESORELECTRICMOTORSANDHYDRAULICSYSTEMSTOPROVIDEAMUCHGREATERLIFTINGCAPABILITYTHANWASPREVIOUSLYPOSSIBLE,ALTHOUGHMANUALCRANESARESTILLUTILIZEDWHERETHEPROVISIONOFPOWERWOULDBEUNECONOMICCRANESEXISTINANENORMOUSVARIETYOFFORMSEACHTAILOREDTOASPECIFICUSESIZESRANGEFROMTHESMALLESTJIBCRANES,USEDINSIDEWORKSHOPS,TOTHETALLESTTOWERCRANES,USEDFORCONSTRUCTINGHIGHBUILDINGSFORAWHILE,MINICRANESAREALSOUSEDFORCONSTRUCTINGHIGHBUILDINGS,INORDERTOFACILITATECONSTRUCTIONSBYREACHINGTIGHTSPACESFINALLY,WECANFINDLARGERFLOATINGCRANES,GENERALLYUSEDTOBUILDOILRIGSANDSALVAGESUNKENSHIPSTHISARTICLEALSOCOVERSLIFTINGMACHINESTHATDONOTSTRICTLYFITTHEABOVEDEFINITIONOFACRANE,BUTAREGENERALLYKNOWNASCRANES,SUCHASSTACKERCRANESANDLOADERCRANES2HISTORYANCIENTGREECETHECRANEFORLIFTINGHEAVYLOADSWASINVENTEDBYTHEANCIENTGREEKSINTHELATE6THCENTURYBCTHEARCHAEOLOGICALRECORDSHOWSTHATNOLATERTHANC515BCDISTINCTIVECUTTINGSFORBOTHLIFTINGTONGSANDLEWISIRONSBEGINTOAPPEARONSTONEBLOCKSOFGREEKTEMPLESSINCETHESEHOLESPOINTATTHEUSEOFALIFTINGDEVICE,ANDSINCETHEYARETOBEFOUNDEITHERABOVETHECENTEROFGRAVITYOFTHEBLOCK,ORINPAIRSEQUIDISTANTFROMAPOINTOVERTHECENTEROFGRAVITY,THEYAREREGARDEDBYARCHAEOLOGISTSASTHEPOSITIVEEVIDENCEREQUIREDFORTHEEXISTENCEOFTHECRANETHEINTRODUCTIONOFTHEWINCHANDPULLEYHOISTSOONLEADTOAWIDESPREADREPLACEMENTOFRAMPSASTHEMAINMEANSOFVERTICALMOTIONFORTHENEXTTWOHUNDREDYEARS,GREEKBUILDINGSITESWITNESSEDASHARPDROPINTHEWEIGHTSHANDLED,ASTHENEWLIFTINGTECHNIQUEMADETHEUSEOFSEVERALSMALLERSTONESMOREPRACTICALTHANOFFEWERLARGERONESINCONTRASTTOTHEARCHAICPERIODWITHITSTENDENCYTOEVERINCREASINGBLOCKSIZES,GREEKTEMPLESOFTHECLASSICALAGELIKETHEPARTHENONINVARIABLYFEATUREDSTONEBLOCKSWEIGHINGLESSTHAN1520TONSALSO,THEPRACTICEOFERECTINGLARGEMONOLITHICCOLUMNSWASPRACTICALLYABANDONEDINFAVOROFUSINGSEVERALCOLUMNDRUMSALTHOUGHTHEEXACTCIRCUMSTANCESOFTHESHIFTFROMTHERAMPTOTHECRANETECHNOLOGYREMAINUNCLEAR,ITHASBEENARGUEDTHATTHEVOLATILESOCIALANDPOLITICALCONDITIONSOFGREECEWEREMORESUITABLETOTHEEMPLOYMENTOFSMALL,PROFESSIONALCONSTRUCTIONTEAMSTHANOFLARGEBODIESOFUNSKILLEDLABOR,MAKINGTHECRANEMOREPREFERABLETOTHEGREEKPOLISTHANTHEMORELABORINTENSIVERAMPWHICHHADBEENTHENORMINTHEAUTOCRATICSOCIETIESOFEGYPTORASSYRIATHEFIRSTUNEQUIVOCALLITERARYEVIDENCEFORTHEEXISTENCEOFTHECOMPOUNDPULLEYSYSTEMAPPEARSINTHEMECHANICALPROBLEMSMECH18,853A32853B13ATTRIBUTEDTOARISTOTLE384322BC,BUTPERHAPSCOMPOSEDATASLIGHTLYLATERDATEAROUNDTHESAMETIME,BLOCKSIZESATGREEKTEMPLESBEGANTOMATCHTHEIRARCHAICPREDECESSORSAGAIN,INDICATINGTHATTHEMORESOPHISTICATEDCOMPOUNDPULLEYMUSTHAVEFOUNDITSWAYTOGREEKCONSTRUCTIONSITESBYTHENANCIENTROMETHEHEYDAYOFTHECRANEINANCIENTTIMESCAMEDURINGTHEROMANEMPIRE,WHENCONSTRUCTIONACTIVITYSOAREDANDBUILDINGSREACHEDENORMOUSDIMENSIONSTHEROMANSADOPTEDTHEGREEKCRANEANDDEVELOPEDITFURTHERWEARERELATIVELYWELLINFORMEDABOUTTHEIRLIFTINGTECHNIQUES,THANKSTORATHERLENGTHYACCOUNTSBYTHEENGINEERSVITRUVIUSDEARCHITECTURA102,110ANDHERONOFALEXANDRIAMECHANICA325THEREAREALSOTWOSURVIVINGRELIEFSOFROMANTREADWHEELCRANES,WITHTHEHATERIITOMBSTONEFROMTHELATEFIRSTCENTURYADBEINGPARTICULARLYDETAILEDTHESIMPLESTROMANCRANE,THETRISPASTOS,CONSISTEDOFASINGLEBEAMJIB,AWINCH,AROPE,ANDABLOCKCONTAININGTHREEPULLEYSHAVINGTHUSAMECHANICALADVANTAGEOF31,ITHASBEENCALCULATEDTHATASINGLEMANWORKINGTHEWINCHCOULDRAISE150KG3PULLEYSX50KG150,ASSUMINGTHAT50KGREPRESENTTHEMAXIMUMEFFORTAMANCANEXERTOVERALONGERTIMEPERIODHEAVIERCRANETYPESFEATUREDFIVEPULLEYSPENTASPASTOSOR,INCASEOFTHELARGESTONE,ASETOFTHREEBYFIVEPULLEYSPOLYSPASTOSANDCAMEWITHTWO,THREEORFOURMASTS,DEPENDINGONTHEMAXIMUMLOADTHEPOLYSPASTOS,WHENWORKEDBYFOURMENATBOTHSIDESOFTHEWINCH,COULDALREADYLIFT3000KG3ROPESX5PULLEYSX4MENX50KG3000KGINCASETHEWINCHWASREPLACEDBYATREADWHEEL,THEMAXIMUMLOADEVENDOUBLEDTO6000KGATONLYHALFTHECREW,SINCETHETREADWHEELPOSSESSESAMUCHBIGGERMECHANICALADVANTAGEDUETOITSLARGERDIAMETERTHISMEANTTHAT,INCOMPARISONTOTHECONSTRUCTIONOFTHEEGYPTIANPYRAMIDS,WHEREABOUT50MENWERENEEDEDTOMOVEA25TONSTONEBLOCKUPTHERAMP50KGPERPERSON,THELIFTINGCAPABILITYOFTHEROMANPOLYSPASTOSPROVEDTOBE60TIMESHIGHER3000KGPERPERSONHOWEVER,NUMEROUSEXTANTROMANBUILDINGSWHICHFEATUREMUCHHEAVIERSTONEBLOCKSTHANTHOSEHANDLEDBYTHEPOLYSPASTOSINDICATETHATTHEOVERALLLIFTINGCAPABILITYOFTHEROMANSWENTFARBEYONDTHATOFANYSINGLECRANEATTHETEMPLEOFJUPITERATBAALBEK,FORINSTANCE,THEARCHITRAVEBLOCKSWEIGHUPTO60TONSEACH,ANDONECORNERCORNICEBLOCKEVENOVER100TONS,ALLOFTHEMRAISEDTOAHEIGHTOFABOUT19MINROME,THECAPITALBLOCKOFTRAJANSCOLUMNWEIGHS533TONS,WHICHHADTOBELIFTEDTOAHEIGHTOFABOUT34MSEECONSTRUCTIONOFTRAJANSCOLUMNITISASSUMEDTHATROMANENGINEERSLIFTEDTHESEEXTRAORDINARYWEIGHTSBYTWOMEASURESSEEPICTUREBELOWFORCOMPARABLERENAISSANCETECHNIQUEFIRST,ASSUGGESTEDBYHERON,ALIFTINGTOWERWASSETUP,WHOSEFOURMASTSWEREARRANGEDINTHESHAPEOFAQUADRANGLEWITHPARALLELSIDES,NOTUNLIKEASIEGETOWER,BUTWITHTHECOLUMNINTHEMIDDLEOFTHESTRUCTUREMECHANICA35SECOND,AMULTITUDEOFCAPSTANSWEREPLACEDONTHEGROUNDAROUNDTHETOWER,FOR,ALTHOUGHHAVINGALOWERLEVERAGERATIOTHANTREADWHEELS,CAPSTANSCOULDBESETUPINHIGHERNUMBERSANDRUNBYMOREMENAND,MOREOVER,BYDRAUGHTANIMALSTHISUSEOFMULTIPLECAPSTANSISALSODESCRIBEDBYAMMIANUSMARCELLINUS17415INCONNECTIONWITHTHELIFTINGOFTHELATERANENSEOBELISKINTHECIRCUSMAXIMUSCA357ADTHEMAXIMUMLIFTINGCAPABILITYOFASINGLECAPSTANCANBEESTABLISHEDBYTHENUMBEROFLEWISIRONHOLESBOREDINTOTHEMONOLITHINCASEOFTHEBAALBEKARCHITRAVEBLOCKS,WHICHWEIGHBETWEEN55AND60TONS,EIGHTEXTANTHOLESSUGGESTANALLOWANCEOF75TONPERLEWISIRON,THATISPERCAPSTANLIFTINGSUCHHEAVYWEIGHTSINACONCERTEDACTIONREQUIREDAGREATAMOUNTOFCOORDINATIONBETWEENTHEWORKGROUPSAPPLYINGTHEFORCETOTHECAPSTANSMIDDLEAGESDURINGTHEHIGHMIDDLEAGES,THETREADWHEELCRANEWASREINTRODUCEDONALARGESCALEAFTERTHETECHNOLOGYHADFALLENINTODISUSEINWESTERNEUROPEWITHTHEDEMISEOFTHEWESTERNROMANEMPIRETHEEARLIESTREFERENCETOATREADWHEELMAGNAROTAREAPPEARSINARCHIVALLITERATUREINFRANCEABOUT1225,FOLLOWEDBYANILLUMINATEDDEPICTIONINAMANUSCRIPTOFPROBABLYALSOFRENCHORIGINDATINGTO1240INNAVIGATION,THEEARLIESTUSESOFHARBORCRANESAREDOCUMENTEDFORUTRECHTIN1244,ANTWERPIN1263,BRUGGEIN1288ANDHAMBURGIN1291,WHILEINENGLANDTHETREADWHEELISNOTRECORDEDBEFORE1331GENERALLY,VERTICALTRANSPORTCOULDBEDONEMORESAFELYANDINEXPENSIVELYBYCRANESTHANBYCUSTOMARYMETHODSTYPICALAREASOFAPPLICATIONWEREHARBORS,MINES,AND,INPARTICULAR,BUILDINGSITESWHERETHETREADWHEELCRANEPLAYEDAPIVOTALROLEINTHECONSTRUCTIONOFTHELOFTYGOTHICCATHEDRALSNEVERTHELESS,BOTHARCHIVALANDPICTORIALSOURCESOFTHETIMESUGGESTTHATNEWLYINTRODUCEDMACHINESLIKETREADWHEELSORWHEELBARROWSDIDNOTCOMPLETELYREPLACEMORELABORINTENSIVEMETHODSLIKELADDERS,HODSANDHANDBARROWSRATHER,OLDANDNEWMACHINERYCONTINUEDTOCOEXISTONMEDIEVALCONSTRUCTIONSITESANDHARBORSAPARTFROMTREADWHEELS,MEDIEVALDEPICTIONSALSOSHOWCRANESTOBEPOWEREDMANUALLYBYWINDLASSESWITHRADIATINGSPOKES,CRANKSANDBYTHE15THCENTURYALSOBYWINDLASSESSHAPEDLIKEASHIPSWHEELTOSMOOTHOUTIRREGULARITIESOFIMPULSEANDGETOVERDEADSPOTSINTHELIFTINGPROCESSFLYWHEELSAREKNOWNTOBEINUSEASEARLYAS1123THEEXACTPROCESSBYWHICHTHETREADWHEELCRANEWASREINTRODUCEDISNOTRECORDED,ALTHOUGHITSRETURNTOCONSTRUCTIONSITESHASUNDOUBTEDLYTOBEVIEWEDINCLOSECONNECTIONWITHTHESIMULTANEOUSRISEOFGOTHICARCHITECTURETHEREAPPEARANCEOFTHETREADWHEELCRANEMAYHAVERESULTEDFROMATECHNOLOGICALDEVELOPMENTOFTHEWINDLASSFROMWHICHTHETREADWHEELSTRUCTURALLYANDMECHANICALLYEVOLVEDALTERNATIVELY,THEMEDIEVALTREADWHEELMAYREPRESENTADELIBERATEREINVENTIONOFITSROMANCOUNTERPARTDRAWNFROMVITRUVIUSDEARCHITECTURAWHICHWASAVAILABLEINMANYMONASTICLIBRARIESITSREINTRODUCTIONMAYHAVEBEENINSPIRED,ASWELL,BYTHEOBSERVATIONOFTHELABORSAVINGQUALITIESOFTHEWATERWHEELWITHWHICHEARLYTREADWHEELSSHAREDMANYSTRUCTURALSIMILARITIESSTRUCTUREANDPLACEMENTTHEMEDIEVALTREADWHEELWASALARGEWOODENWHEELTURNINGAROUNDACENTRALS