Manhole cover support ring

Abstract

A manhole cover support ring adapted to be placed within an existing manhole frame for raising the height of a manhole cover. A circular ring is formed by a generally vertically extending flange having an annular bar welded on its lower end which provides an inwardly extending manhole cover support ledge. The flange and bar are split at a common point on their peripheries. An expansion mechanism is pivotally mounted on and extends between the spaced ends of the bar formed by the split in the ring. The expansion mechanism includes a pair of eyebolts pivotally mounted on the spaced ends of the annular bar. The eyebolts each have a threaded shaft which is engaged in a respective threaded end of a tubular member. One of the threaded shafts has a right-hand thread and the other shaft is formed with a left-hand thread, whereby rotation of the tubular member in one direction will contract the ring sufficiently to place it within the manhole frame opening. Rotation of the tubular member in the opposite direction will expand the ring outwardly into abutting relationship with a complementary circular portion of the manhole frame which forms the manhole opening to secure the support ring in the manhole frame. The pivotal mounting of the eyebolts eliminates any bending moments in the threaded connection between the bolts and tubular member, providing a greater range of ring expansion and providing a positive tangential expansion force on the ring.

Dependencies are inferred from the claim text.