the invention loading hose 14 includes at least one stiffening member 18 attached to casing 17 which is arranged to lie against either blade support 11 or blade holder 10 the counter surfaces can be suitably shaped to partly eliminate the rounding of the hose in which case a single stiffening member is sufficient preferably however stiffening members 18 are attached to both sides of the casing 17 of hose 14 thus hose 14 cannot become detrimentally rounded so that no sudden changes will take place in the loading profile of doctor blade 12 in the same way hose 14 will also be stiffened longitudinally making it easier to install hose 14 also remains in place better and parallel to the doctor stiffening members 18 are preferably attached by gluing one of the stiffening members 18 is arranged to lie on blade support 11 and the other on blade holder 10 fig1 thus when the pressure is increased only the thickness of hose 14 increases so that the loading acts in the correct direction the casing of the hose can bulge outward as is usually the case alternatively there may be folds in casing 17 according to the examples so that its width remains nearly constant while its thickness changes the stiffening members cover most of the circumference of the hose if the width of the stiffening members is increased however the operating movement of the hose will correspondingly shorten the optimum width is determined for each individual case the casing of the hose itself is resistant to pressure.