The chain drive consists of a duplex roller chain which drives both intake and exhaust camshafts.
链条驱动机构包括一条双排辊链，通过它来驱动进气和排气凸轮轴。
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Objective To investigate the value of duplex polymerase chain reaction (DPCR) in early diagnosis of Legionella pneumonia by detecting Legionella DNA in sputum and bronchoalvelar lavage fluid(BALF).