The purpose with this master thesis is to investigate why the bolts in a doctor blade system breaks and to find a suitable action to prevent this. The doctor blade system can easily be explained as a scraper that cleans a roll. The scraper moves sideways (oscillates) and the doctor blade system along with the roll can be folded back for maintenance work.The work began with collecting relevant data about the doctor blade system. When this was done various sources of error that may have been causing the problems were listed and investigated more closely. Based on these studies, the cause of the failure has been concluded based on the most likely sources of error. The result shows three possible causes of accidents listed below:• A unit performing the oscillating movement that was mounted to the doctor blade system could have caused to high strain on the bolts• The movement that is created when the doctor blade system and the roll is folded back causes bending in the bearings• Too high load on the roll as a result of a wrongly adjusted doctor blade.Except these reasons, maintenance routines have been listed as a possible cause. This theory has higher insecurity and need to be investigated closer over a longer period of time.The problem with the oscillating unit is already resolved since it was replaced short before the work started. The folding movement has a unit installed that is meant to make the movement parallel, but this unit is malfunctioning. A suitable complement to this is a measurement system that ensures parallelism.The high load can be resolved by adjusting the doctor blade system to the roll.In addition to these proposed actions a suggestion for improvement has been made. This should be done by moving the adjustment for the doctor blade to a more beneficial position.