Manhole

  • US 5,899,629 A
  • Filed: 07/27/1998
  • Issued: 05/04/1999
  • Est. Priority Date: 10/11/1994
  • Status: Expired due to Term
First Claim
Patent Images

1. A manhole comprising:

  • a metal top ring for containing a manhole cover,a metal manhole cover for being releasably contained in said top ring,a metal 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 being welded to said upper portion,said skirt 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 and for serving as a footing at the very bottom of the entire manhole, said member comprising a laterally extending flange,said lower portion comprising a skirt bottom and said flange being positioned at said skirt bottom, and wherein said flange is rolled integrally with and of the same material as said skirt as a single unitary sheet steel piece.

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