Integral Proving Rings

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 with bolted abutments.
The dial gauge and anvil are mounted on U-brackets clamped to the ring body by set screws. The dial gauge is fitted with a special back cover and a threaded bush, which does not permit any shift from the original dial alignment, coaxial with the loading boss centres, that is set at the factory before calibration.
For all compression proving rings and tension-compression proving rings up to and including 5 kN capacity, the loading bosses have female threading 1/2" BSF (16 tpi)

The boss faces are ground and polished and are plane parallel to within 0.02mm total DTI run-out. Tension compression rings have their integral loading bosses male threaded, 1.25" dia, 8 tpi, square thread, 1.25" long. Caps are provided for use when loading in compression.
Repeatability is as stipulated in IS:4169. The rings are supplied complete with dial gauge and Works Calibration Chart, individually packed in polished wooden boxes. NPL (India)/ NCCBM Calibration/ NABL Calibration can also be arranged for any proving ring at an additional cost. Proving rings to meet special requirements are also available on request.

Separate polished and ground pair of Loading Pads for Compression Proving Rings and pair of Shackles for Tension Proving Rings are provided to suit each proving ring, at extra cost and on request.