. ▁▁ ▁The ▁val ve , ▁according ▁to ▁the ▁company , ▁became ▁the ▁heart ▁of ▁the ▁Ar tr on ome ▁action . ▁According ▁to ▁Stra ube ▁literature , ▁it ▁was ▁fr iction less , ▁non - cor ros ive , ▁and ▁elimin ated ▁ 9 0 ▁percent ▁of ▁all ▁player ▁problems ▁caused ▁by ▁fr iction ▁and ▁cor ros ion ▁in ▁the ▁mechanism . ▁By ▁ 1 9 2 2 , ▁over ▁one ▁million ▁Stra ube ▁p end ul um ▁val ves ▁had ▁been ▁installed ▁in ▁player ▁pian os ▁of ▁various ▁makes . ▁ ▁The ▁val ves ▁were ▁three - t ier ▁and ▁horizontal , ▁but ▁not ▁the ▁more ▁common ▁type ▁found ▁in ▁horizontal ▁val ve ▁actions , ▁which ▁were ▁usually ▁the ▁wire ▁i - pin ▁variety . ▁Each ▁val ve ▁p iv oted ▁between ▁two ▁ears ▁that ▁extended ▁from ▁each ▁metal ▁plate . ▁ ▁Each ▁val ve ▁was ▁a ▁wood ▁disc ▁with ▁le ather ▁facing ▁on ▁both ▁sides . ▁One ▁face ▁had ▁a ▁center ▁hole ▁leading ▁to ▁a ▁pocket ▁of ▁a ▁larger ▁diameter ▁in ▁the ▁wood . ▁The ▁val ve ▁was ▁supported ▁only ▁by ▁a ▁lever ▁between ▁the ▁val ve ▁plate ▁pivot ▁and ▁the ▁p ouch ▁lif ter ▁disc , ▁with ▁a ▁right ▁angle ▁dow el ▁extension ▁that ▁" pl ug ged ▁in " ▁the ▁center ▁hole ▁of ▁the ▁val ve ▁button . ▁The ▁p iv otal ▁lever ▁is ▁easily ▁remov able ▁because ▁it ▁was ▁not ▁c ement ed ▁to ▁the ▁val ve , ▁rendering ▁a ▁loose ▁val ve ▁button ▁in ▁the ▁val