Hydraulic piston for flexing shoe press on paper:making machine

摘要

A press shoe (16) for a paper machine shoe press is pressed against the opposing roll by one or more hydraulic elements (26) between a stationary support (24) and the inner surface of the shoe. The cylinder part (40) of the hydraulic element has a first pressurisable chamber (28) which communicates via an opening (32) with a second chamber (30) which is open to the press shoe and whose edges bear against a sealing surface (36) of the press shoe. The opening which connects the two chambers is in the form of a throttling point. Pref. the dimensions of the throttling orifice are such that, under normal operating conditions, the pressure in the two chambers is the same, but if the surface of the press shoe inclines at an angle to the surface of the piston, the pressure in the second chamber falls quickly and the leakage of the hydraulic fluid is minimised.