Arrangement for supporting a rotary drum

An arrangement for supporting a rotary drum, said rotary drum having at least three riding rings distributedly arranged along the axial direction of the rotary drum, the arrangement comprising a pair of relatively spaced rollers for supporting a riding ring, at least one bearing for each roller, a support for each bearing mounted for movement of the roller toward and away from the shell of the rotary drum and spring means exerting a spring force acting on the support so as to counteract the weight of the rotary drum resting on the rollers, wherein the spring means comprises a pressure vessel charged with a compressed gas that exerts the spring force and wherein the rotary drum comprises at least three riding rings and only at least one middle ring arranged between two outer rings is supported by a pair of relatively spaced rollers that are equipped with said spring means comprising the pressure vessel charged with the compressed gas, wherein the spring means comprise a fluid chamber configured to change its volume upon movement of the roller under the weight of the rotary drum resting on the rollers, wherein said chamber is fluidly connected to the pressure vessel by means of a fluid line, wherein the fluid chamber is realized in a cylinder of a hydraulic cylinder-piston unit, wherein the cylinder or the piston is mechanically coupled to the support, and the support is supported on a foundation and wherein the fluid chamber of the cylinder is fluidly connected to the pressure vessel and whereby the hydraulic cylinder-piston unit contacts the support by means of a first swivel plate and a second swivel plate, and contacts the foundation by means of a third swivel plate, wherein the swivel plates each comprises a curved surface.