oint Simulators (also referred to as Rundown Fixtures or Adapters) are required for accurate torque measurement for power-driven torque controlled tools (electric, hydraulic or pneumatic). They are not necessary or useful when measuring torque on manually-operated torque tools (screw-drivers, wrenches, etc.). They simulate the conditions found when using the tool in real-world conditions, allowing the speed of the power tool motor to ramp-up to normal operating speeds resulting in a more accurate and repeatable measurement of the torque .
They are typically fabricated from machined steel with the appropriate drive size as needed. Internally it is comprised of a series of Belleville washers, designed to compress as the bolt tightens. By varying the arrangement of these washers, various joint rates can be simulated soft, medium and hard. Unless otherwise, specified, Joint Simulators are configured to simulate a medium joint. The joint rates can be adjusted by the user by changing the orientation of the Belleville washers upside down.