These proving rings are made out of special steel, carefully forged to give maximum strength & machined to give the highest sensitivities commensurate with high stability and to ensure long life and accuracy. All proving rings are integral type viz. the loading (outside) bosses are forged integral with the ring body. This ensures that there is no possibility of abutment shift and consequent loss of accuracy in reading that always exists in rings with bolted abutments.
The dial gauge and anvil are mounted on U-brackets clamped to the ring body by Allen set screws.
Proving rings can be designed to measure either compression or tension forces. Forces are applied to the ring through the external bosses