Patent ID: 7325490

Claim:
A multinip calender comprising: a first relief cylinder structure for guiding a roll of the multinip calender, the first relief cylinder structure further comprising: a frame having a main cylinder therewithin; a piston-like arm arranged to move within the main cylinder of the frame; a main fluid coupling in the frame which communicates with the main cylinder of the frame; portions of the piston-like arm which define a quick-opening cylinder arranged inside the arm; a first auxiliary piston having a first length, the first auxiliary piston arranged to move within the quick-opening cylinder; and an auxiliary fluid coupling formed by portions of the arm which communicates with the quick-opening cylinder, wherein in a normal operating position pressure is supplied through the auxiliary fluid coupling to the quick-opening cylinder and through the main fluid coupling to the main cylinder, both said supplied pressures acting upon the first auxiliary piston, and wherein in a fault situation, the auxiliary fluid coupling is arranged to be open, wherein the pressure produced in the quick-opening cylinder is discharged to a fluid system via the auxiliary fluid coupling, said fluid system being arranged in a substantially non-pressurized state, as a result of opening the auxiliary coupling, the pressure of the quick-opening cylinder is reduced below the pressure of the main cylinder, wherein the first auxiliary piston moves within the quick-opening cylinder to increase the volume of the quick-opening cylinder in communication with the main cylinder, such that the piston-like arm is retracted within the frame reducing the length of the relief cylinder; a second relief cylinder structure within the same multinip calender, wherein the second relief cylinder structure has a second auxiliary piston of a length different than the first length of the first auxiliary piston.