On E.636, this is achieved through the uses of more delicate spires, so transitions (especially backward ones) need to be very slow and gradual. The optimal moment to pass to the following/preceding combination first/last notches is when the motor ammeter indicates 0 Ampères, which happens when passing over the transition position with the lever (the driver should briefly stop in the middle of the block and pay attention to the ammeter), meaning that the motor contactors are in optimal position and is safe to proceed. Failure in doing this may result in flashes that will damage the contactors.