Development of 100 kN m deadweight torque standard machine at NIM

Deadweight torque standard machines have characteristics of lower uncertainty and good stability. This 100 kN·m torque standard machine adopts the moment arm/deadweight type. The main knife assembly is adopted to support the moment arm which has low friction under high bearing capacity, the moment arm system is precisely machined and adjusted to ensure parallelism between main knife edge and side knife edges. By using weight groups of inner-circle and outer-circle, torque values from 1 kN·m to 100 kN·m may be realised. This paper introduces the mechanical structure of the 100 kN·m torque standard machine and describes the results of performance tests and its uncertainty evaluation. The results show that the repeatability of the machine is better than 5 × 10 −5 and its uncertainty is less than 1 × 10 −4 ( k = 3).