10 the apertures 120 in the support blocks 109 and 22 in the pressure fingers 10 are oversize relative to the pivot rod 111 this allows for play between the rod 111 and the fingers 10 and support blocks 109 this in turn permits rocking movement between the pressure fingers and the rod as well as pivotal movement the tongue 20 has its surface 43 overlying a portion of the mounting member a but spaced from it to provide a space 117 for a continuous inflatable tube 119 the tube 119 is held in place by a retainer 121 mounted on the mounting member a and held to it by screws 122 in the form shown the retainer 121 is an angle iron but can take other forms when the tube 119 is inflated the fingers 10 pivot about the rod 111 clockwise urging the doctor blade c carried in the slots 28 against the cylinder d under the pressure of the plate 135 more specific reference will now be made to the blade seating which can be seen specially in fig6 and 7 mounted on each pressure finger 10 is a main pressure plate 135 which extends across the width.