Farm tractor overturnings caused an increasing and soon alarming number of serious injuries to farmers in Sweden after 1945. The annual fatality rate for farm tractor overturning was 12 per 100 000 farmers in 1961 and 1 in 1981. The total injury rates were 20 and about 7 per 100 000 for the same two years. "Farmers" included males running their own businesses and their male relatives according to censuses.

Mandatory rules prescribing a protective frame or a crushproof cab on new tractors were effective in 1959 and 1970 resp. Supplementary rules for old tractors became effective in 1965 and 1983. At present all farm tractors which are occupationally used should be equipped with a crushproof cab.

Injuries were registered within the National Board of Occupational Safety and Health. A few nonfarming cases might have been included before 1972. However, the risk of a fatal overturning was reduced by about 90% and the risk of any reported injury by about 65%.