The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 28, 1998
Filed:
Mar. 13, 1997
Ossi Kahra, Lahti, FI;
Tamrock Oy, Tampere, FI;
Abstract
A hydraulic actuator includes three cylinder spaces: a first cylinder space (6) located between a ring piston and a cylinder; a second cylinder space (7) between the ring piston and an auxiliary piston inside a hollow piston rod connected to the ring piston; and the third cylinder space (8) formed between the ring piston, the cylinder and the hollow piston rod. The hydraulic actuator includes a non-return valve (11) mounted in the ring piston between the second cylinder space and the third cylinder space, allowing flow from the second cylinder space into the third cylinder space when pressure in the second cylinder space exceeds pressure in the third cylinder space; a non-return valve (10) mounted in the ring piston between the second cylinder space and the first cylinder space, allowing flow from the second cylinder space into the first cylinder space when pressure in the second cylinder space exceeds pressure in the first cylinder space; and a pressure limit valve (14) for controlling fluid flow into the cylinder spaces depending on pressure in the first channel when the actuator is lengthened.