• US 5,785,452 A
  • Filed: 04/10/1996
  • Issued: 07/28/1998
  • Est. Priority Date: 10/11/1994
  • Status: Expired due to Term
First Claim
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1. A manhole comprisinga top ring for containing a manhole cover,a manhole cover for being releasably contained in said top ring,a skirt made of flexible sheet steel material forming a partially closed chamber and having upper and lower portions forming major openings to said chamber,said top ring connected to said upper portion,said skirt sheet steel material and top ring being deformable when said lower portion is subjected to a lateral force greater than a predetermined lateral force,a member connected to said lower portion of said skirt for providing said skirt lateral strength and stiffness to prevent said skirt and top ring deformation resulting from said predetermined lateral force, said member comprising a laterally extending flange,said lower portion comprising a skirt bottom and said flange being positioned at the bottom of said skirt for providing a footing for said manhole, and wherein said flange is formed integrally with and of the same sheet steel material as said skirt as a single unitary piece, and wherein said flange extends outwardly from the skirt, and said skirt comprising a horizontal section,the manhole further comprising an extension skirt having a horizontal section substantially congruent to said horizontal section of said skirt and dimensioned to telescope within said skirt and into said chamber within said skirt, and wherein substantially the full outer surface of the telescoping portion of said extension skirt within said skirt is in contact with the inner surface of said skirt, andwherein joining means are provided penetrating both said skirt and said extension skirt for rigidly connecting said skirt and said extension skirt to each other at least at two points where said skirt and said extension skirt overlap and when said skirt and said extension skirt are at any of an infinite number of telescoping positions relative to each other.

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