▁ 1 2 ▁Vol ts ▁DC ▁( or ▁ 1 6 VD C ) ▁at ▁many ▁Am per es ▁to ▁the ▁race ▁car ' s ▁transmission ▁( where ▁an ▁internal ▁ ▁elect romagnet ic ▁sol en oid ▁located ▁in ▁or ▁on ▁the ▁transmission ▁energ izes , ▁which ▁in ▁turn ▁positions ▁a ▁sp ool ▁val ve ▁that ▁direct s ▁hyd ra ul ic ▁fluid ▁pressure ▁in ▁the ▁transmission ▁val ve body ▁that ▁lo cks ▁the ▁transmission ▁in ▁forward ▁and ▁reverse ▁g ears ▁at ▁the ▁same ▁time ). ▁ ▁When ▁the ▁trans bra ke ▁is ▁engaged ▁at ▁the ▁drag ▁race ▁track ▁starting ▁line ▁( driver ▁holding ▁the ▁push button ▁de pressed ), ▁the ▁car ▁is ▁held ▁station ary ▁regardless ▁of ▁how ▁much ▁engine ▁power ▁is ▁applied ▁to ▁the ▁drive ▁line . ▁ ▁The ▁driver ▁typically ▁applies ▁full ▁thro tt le ▁at ▁this ▁time , ▁and ▁the ▁car ▁remains ▁station ary ▁at ▁the ▁starting ▁line ▁under ▁full ▁engine ▁power . ▁ ▁When ▁the ▁driver ▁sees ▁the ▁desired ▁visual ▁c ue ▁before ▁him , ▁the ▁driver ▁prompt ly ▁releases ▁his ▁finger ▁( or ▁thumb ) ▁from ▁the ▁push button . ▁This ▁button ▁release ▁opens ▁the ▁contacts ▁within ▁the ▁push button ▁switch ▁signal ing ▁the ▁delay ▁box ▁and ▁the ▁delay ▁box ▁now ▁begins ▁an ▁internal ▁count down . ▁ ▁When ▁the ▁count down ▁timer ▁reaches ▁zero , ▁the ▁delay ▁box ▁stops ▁current ▁flow ing ▁to ▁the ▁sol en oid ▁in ▁the ▁transmission ▁and ▁that ▁causes ▁the ▁sp ool ▁val ve ▁to ▁return ▁to ▁its ▁normal ▁position . ▁