shelf 50 of the doctor back and the mounting strips 42 a 42 b on the underside of the tray 26 when in the locked position as shown in fig3 a and 3c the tabs 58 are deflected downwardly by the heads of the shoulder screws 52 into the plane of the strip 54 thereby exerting a downward force which clamps the ledges 44 a 44 b against the shelf 50 thus fixing the doctor holder 16 in its operative position on the doctor back 18 as can be best seen in fig3 a a pin 60 or the like at one side of the papermachine is employed to releasably fix the locking strip 54 in its locked position when it becomes necessary to clean or maintain the blade holder the pin 60 is removed and the locking strip 54 is shifted to its unlocked position as shown in fig3 b this relieves the clamping force exerted by the resilient tabs 58 thus allowing the blade holder and doctor blade to be extracted longitudinally as a unit out of the papermachine after cleaning and maintenance the blade holder is longitudinally reinserted into the papermachine and the clamping strip returned to its locked position an alternative embodiment of the invention is depicted in fig4 and 5 where a mounting strip 62 a is secured to the underside of the tray 26 a second mounting strip 62 b is connected to strip 62 a by.