Doctor for a suction roll particularly in paper machines

A doctoring device adapted for use with a paper machine suction roll having a suction roll axis of rotation, said doctoring device comprising:

• a doctor blade holder;
• a doctor blade fixed on said blade holder, said doctor blade having an edge against said suction roll and contacting said suction roll at an angle disposed relative to a tangent of said suction roll at the point of contact;
• a doctor slat holder;
• a doctor slat connected to said slat holder, said doctor slat having an edge in urged engagement with said suction roll through a foil effect and contacting said suction roll at an angle disposed relative to a tangent of said suction roll at the point of contact;
• said doctor slat contact angle being smaller than said doctor blade contact angle;
• an angle defined by a first radius extending from the suction roll axis of rotation to the point of contact with said doctor blade and a second radius extending from the suction roll axis of rotation to the point of contact with said doctor slat being in the range of 15 degrees to 70 degrees;
• said doctor blade being circumferentially disposed along said suction roll downstream of said doctor slat in a direction of rotation of said suction roll;
• and
• a frame spacedly mounting both said doctor blade and said doctor slat;
• said frame having a trough formed therein which collects water that has been drawn onto the surface of said suction roll by said doctor slat.