Variable speed cylinder assembly pressure seals
AssigneeWestern Gear Corporation
InventorsRobert M. Brown, John H. Short
Life of this patent
Estimating the term…
Abstract
A variable speed multi-cylinder assembly is provided with expandable bushing seals to block leakage of fluid from higher speed stages to lower speed stages.
Claims6
A selectively actuatable cylinder assembly of the type having an axially extendible inner first ram and at least one outer, hollow, axially extendible second ram having an inside cylindrical surface forming an inner cylinder for the inner ram, an outer cylinder, and axially outer means sealing the rams and cylinders, the improvement comprising axially inner sealing means sealing the inner cylinder from the outer cylinder, said axially inner sealing means including a first seat in fluid communication with actuating fluid for said inner first ram, said outer ram having a second seat in fluid communication with actuating fluid for said outer second ram, and a generally cylindrical, radially expandable sealing bushing interposed between said seats and spaced closely enough to said second seat sufficient to provide a pressure drop along the bushing and opposed second seat when the bushing is in a relaxed condition, said bushing being expandible by the fluid pressure differential of said actuating fluid for said inner ram acting between the bushing and the first seat and between the bushing and the second seat at substantially any magnitude as the fluid passes between said bushing and said second seat, and third sealing means for sealing between the first seat and the opposed face of said bushing for blocking said inner ram actuating fluid from passing axially out past said bushing and first seat into the outer cylinder, said second seat and bushing being moved axially completely past one another when said second ram and bushing are moved axially relative to one another.
A selectively operable, multiple ram cylinder assembly having a cylinder base and including at least one extendible radially inner ram and an extendible radially outer ram, said outer ram being hollow and providing a first cylinder for said inner ram, and having a radially outer second cylinder encircling said outer ram, said rams and cylinders having axially outer sealing means and axially inner sealing means therebetween, the improvement comprising:
- said axially inner sealing means including opposed radially inner and outer sealing seats on the cylinder base and the axially inner end of the radially outer ram, respectively, and elongated, continuous, cylindrical, deformable sleeve means positioned between said seats, said outer sealing seat on said axially inner end of the radially outer ram and said deformable sleeve means being spaced closely enough when said sleeve means is in a relaxed, non-expanded condition to create a pressure drop therebetween at substantially any magnitude of pressure of actuating fluid, there being no additional seals along said bushing and said outer sealing seat to interfere with movement of said outer sealing seat, means for directing actuating fluid to said radially inner ram, said radially outer sealing seat and said sleeve means being moved axially completely past one another when said outer ram and cylindrical base are extended relative to one another;
- means for exposing both sides of said sleeve means to the inner ram but with fluid initially leaking between the radially outer sealing seat and the bushing to create a presssure differential across the sleeve means, causing actuating fluid to expand the sleeve means into sealing contact with the opposite radially outer sealing seat for restricting the inner ram fluid from leaking into the outer cylinder;
- and
- supplementary sealing means between said inner sealing seat and the side of the sleeve means exposed to the inner ram actuating fluid for blocking leakage of the inner ram actuating fluid between the inner sealing seat and the sleeve means into the radially outer cylinder.
Dependencies are inferred from the claim text.