Timothy C Lang

US Patent:

51237768, Jun 23, 1992

Filed:

Jan 31, 1991

Appl. No.:

7/648077

Inventors:

Timothy J. Lang - Washougal WA
Mark Stuhlreyer - Columbus OH
Eli Blumenau - K. Tivon, IL

Assignee:

Advanced Drainage Systems, Inc. - Columbus OH

International Classification:

E02D 2914

US Classification:

404 25

Abstract:

A manhole cover comprises a top having a top surface and an edge portion, a depending portion having a sidewall and a bottom surface, and an interior chamber. The manhole cover is fabricated from a first material, while the interior chamber is at least partially filled with a second material. The manhole cover preferably includes recessed handles which are recessed into the top and extend downwardly through the bottom surface. Cooperative engagement means in the form of inter-fitting indentations and protuberances are provided in the top surface and the bottom surface respectively. The bottom surface includes a first surface portion which includes a peripheral edge portion and a bracing portion. The bracing portion includes a plurality of brace members each of which have a lower brace surface and a brace sidewall.