▁the ▁time . ▁Also , ▁sh ar per ▁turns ▁are ▁possible ▁compared ▁to ▁the ▁ 7   km ▁radius ▁of ▁turn ▁typical ▁of ▁modern ▁high - speed ▁trains ▁such ▁as ▁the ▁T GV , ▁because ▁the ▁vehicle ▁will ▁bank ▁automatically ▁on ▁b ends , ▁like ▁an ▁aircraft , ▁so ▁that ▁no ▁later al ▁cent rif ug al ▁acceleration ▁is ▁experienced ▁on ▁board . ▁ ▁A ▁major ▁draw back ▁is ▁that ▁many ▁cars ▁– ▁including ▁passenger ▁and ▁fre ight ▁cars , ▁not ▁just ▁the ▁locomot ive ▁– ▁would ▁require ▁a ▁constantly ▁power ed ▁gy ros cope ▁to ▁stay ▁u pr ight . ▁ ▁Un like ▁other ▁means ▁of ▁maintain ing ▁balance , ▁such ▁as ▁later al ▁sh ifting ▁of ▁the ▁centre ▁of ▁gravity ▁or ▁the ▁use ▁of ▁reaction ▁whe els , ▁the ▁gy ro scop ic ▁bal ancing ▁system ▁is ▁stat ically ▁stable , ▁so ▁that ▁the ▁control ▁system ▁serves ▁only ▁to ▁im part ▁dynamic ▁stability . ▁The ▁active ▁part ▁of ▁the ▁bal ancing ▁system ▁is ▁therefore ▁more ▁accur ately ▁described ▁as ▁a ▁roll ▁dam per . ▁ ▁Historical ▁background ▁ ▁B ren nan ' s ▁mon or ail ▁ ▁The ▁image ▁in ▁the ▁leader ▁section ▁dep ict s ▁the ▁ 2 2 ▁t onne ▁( un lad en ▁weight ) ▁prototype ▁vehicle ▁developed ▁by ▁Louis ▁Philip ▁B ren nan ▁C B . ▁B ren nan ▁file d ▁his ▁first ▁mon or ail ▁pat ent ▁in ▁ 1 9 0 3 . ▁ ▁His ▁first ▁demonstr ation ▁model ▁was ▁just ▁a ▁ 2  