Controlling an automatic gear shift device to prevent overpseed

摘要

Gear shifts which are initiated by the driver via the selector device 7 and which would result in inadmissible engine speeds are prevented and it becomes possible to permit them again only via stored shift-line characteristic diagrams 14. The arrangement processes input signals 10 to 13 relating to the position of a the selector device 7, the transmission output speed, engine load and the transmission ratio currently engaged, and operates to form a reference signal related to the position of the manual selection member or the transmission ratio currently engaged. The arrangement then checks whether the reference signal corresponds to a ratio which is lower than the current ratio, a computing stage checking whether a shift to a requested ratio would result in an engine overspeed condition.