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:
Feb. 06, 1979
Filed:
Feb. 08, 1978
Erwin J Nunlist, Penfield, NY (US);
Sybron Corporation, Rochester, NY (US);
Abstract
A balancing mechanism for manhole covers uses two sets of conical disc springs, one stronger than the other, mounted on a common pull rod, to balance the cover as it moves from the open vertical position to the closed position. This provides a progressive spring force curve that balances the manhole in any position between the closed position and the vertical position. The balancing mechanism is also provided with an additional set of disc springs that absorb shock when the cover is opened rapidly. The mechanism is preferably mounted on a nozzle protection ring, which allows the system to be installed on existing glass lined vessels without welding, drilling or similar operations which might damage the lining.