Abstract: The present invention is directed to a gripping system for holding a supporting ring member adapted to support a manhole cover in a tubular member having a peripheral horizontal shoulder. The gripping system has a plurality of rigid elbow-shaped members internally secured inside the ring member. The elbow-shaped members have a horizontal arm radially extending inside the ring member and a substantially vertical pending arm extending below the ring member and adapted to internally face the tubular member. A screw member is threadedly mounted through the vertical arm in the direction of the tubular member. The screw member is provided with a friction plate fixed at one end between the vertical arm and the tubular member for tightening the friction plate on the tubular member and for frictionally retaining the ring member to the tubular member. The friction force is adapted to vertically fix the ring member relative to the tubular member.

Abstract: The raising structure according to the invention is intended to raise a manhole cover to the level of the resurfacing new layer of asphalt. The raising structure comprises a pair of superposed concentric rings one of which is slightly smaller than the other one so that the outer diameter of the smaller one is slightly smaller than the inner diameter of the other one. The rings are maintained in a spaced relationship by a set of spacer legs disposed around the periphery of the inner ring. Each of the legs have one end secured to the outer periphery of the small ring and the outer end of the leg is secured to the inner periphery of the larger ring. The legs are characterized by at least one bent section between both ends of the legs. The bent section extends in a plane tangent to the outer periphery of the smaller ring and the inner periphery of the larger ring. The bent section is adapted to define a weak section in the legs for allowing a change in the angle of the bent upon pressure on one of the rings.