 These are pneumatically operated, so if the pressure in the air pipe falls below a preset level, they are automatically lowered by means of springs (this prevents the train from moving if air pressure is lost, an important safety feature).Each power car has only 1 pantograph, because if it fails the other power cars can produce sufficient power to move the train at a reduced speed.For the same reason, there is no provision for cutting out individual traction motor groups in case of malfunction, so if even one traction motor fails, the entire power car's traction motor circuit is turned off (the other power cars can still provide enough power, so despite this the train can, and sometimes does, remain in service).