（1）工(gong)程機(ji)械使(shi)用初期(qi)(qi)階段的(de)(de)故障(zhang)特點。工(gong)程機(ji)械在(zai)使(shi)用初期(qi)(qi)(相當于走(zou)(zou)合期(qi)(qi))其故障(zhang)是(shi)(shi)由高到(dao)低(di)(降曲線(xian))，使(shi)用初期(qi)(qi)故障(zhang)率高低(di)是(shi)(shi)隨制造(zao)或(huo)(huo)(huo)維修質(zhi)量(liang)和走(zou)(zou)合時期(qi)(qi)的(de)(de)使(shi)用有關(guan)．如果工(gong)程機(ji)械制造(zao)或(huo)(huo)(huo)修理質(zhi)量(liang)高，并能正確地(di)使(shi)用與維護(hu)。那(nei)么，初期(qi)(qi)故障(zhang)率就低(di)。否則早(zao)期(qi)(qi)故障(zhang)率會高。早(zao)期(qi)(qi)故障(zhang)多(duo)地(di)是(shi)(shi)聯接螺栓松(song)(song)(song)動或(huo)(huo)(huo)松(song)(song)(song)脫；管(guan)道接頭松(song)(song)(song)動或(huo)(huo)(huo)松(song)(song)(song)脫：殘留(liu)金屬(shu)屑或(huo)(huo)(huo)鑄造(zao)砂(sha)易堵(du)塞(sai)油道或(huo)(huo)(huo)夾在(zai)相對運動摩擦中拉傷機(ji)件(jian)(如液(ye)壓系統中的(de)(de)執(zhi)行(xing)機(ji)構油缸)造(zao)成漏(lou)油，調整后的(de)(de)間隙或(huo)(huo)(huo)壓力(li)(li)發生(sheng)變化，使(shi)機(ji)件(jian)不(bu)能執(zhi)行(xing)規定(ding)能力(li)(li)，有些(xie)接合因螺栓不(bu)緊而漏(lou)水、漏(lou)油、漏(lou)氣(qi)等。

（2）工程(cheng)機械(xie)(xie)正(zheng)常使(shi)(shi)用(yong)階段的故障特(te)點。工程(cheng)機械(xie)(xie)走(zou)合期結束后，進人正(zheng)常使(shi)(shi)用(yong)階段。工程(cheng)機械(xie)(xie)在這個(ge)階段內運行，只要(yao)按規定維(wei)護和正(zheng)確(que)使(shi)(shi)用(yong)，一(yi)般(ban)不會發生故障，即便發生故障，也是(shi)隨機性的故障。