. ▁ ▁References ▁▁ ▁Category : Pop ulated ▁places ▁in ▁B aft ▁County <0x0A> </s> ▁La ▁Gran ja ▁is ▁a ▁station ▁on ▁Line ▁ 1 0 ▁of ▁the ▁Madrid ▁Metro . ▁It ▁is ▁located ▁in ▁fare ▁Zone ▁B 1 . ▁ ▁References ▁▁ ▁Category : Mad rid ▁Metro ▁stations ▁Category : 2 0 0 7 ▁establish ments ▁in ▁Spain ▁Category : R ail way ▁stations ▁opened ▁in ▁ 2 0 0 7 <0x0A> </s> ▁The ▁Wel in ▁b ree ch ▁block ▁was ▁a ▁revolution ary ▁stepped , ▁interrupted ▁thread ▁design ▁for ▁lock ing ▁art illery ▁b ree ches , ▁ ▁invent ed ▁by ▁Ax el ▁Wel in ▁in ▁ 1 8 8 9 ▁or ▁ 1 8 9 0 . ▁Short ly ▁after , ▁V ick ers ▁acquired ▁the ▁British ▁pat ents . ▁ ▁Wel in ▁b ree ch ▁blocks ▁provide ▁obt uration ▁for ▁art illery ▁pieces ▁which ▁use ▁separate ▁loading ▁bag ged ▁charges ▁and ▁project iles . ▁ ▁In ▁this ▁system ▁the ▁project ile ▁is ▁loaded ▁first ▁and ▁then ▁followed ▁by ▁cloth ▁b ags ▁of ▁prop ell ant . ▁ ▁Design ▁ ▁The ▁b ree ch ▁block ▁incorpor ated ▁a ▁sc rew ▁design ▁with ▁multiple ▁" steps " ▁of ▁threads ▁of ▁progress ively ▁increasing ▁radius , ▁each ▁step ▁occup ying ▁the ▁same ▁circular ▁sector . ▁ ▁Each ▁step ▁engaged ▁with ▁its ▁matching ▁thread ▁cut ▁in ▁the ▁gun ▁b ree ch ▁when ▁inserted ▁and ▁rot ated . ▁A ▁gap ▁in ▁the ▁thread ▁steps ▁was ▁still ▁necessary ▁for ▁the ▁insert ion ▁of ▁the ▁largest