Feedback Controlled Deadweight Machine

Deadweight machines have followed an evolution from the traditional fixed-sequence machine to modern automatic machines that with a small number of masses can generate a large number of load increments. The new machine made by T.M.T. is based on the substitution principle, but every group of masses has a specific actuator, allowing independent substitution. The change of force from one step to the subsequent step follows closely a given time function without overloading due to dynamic effects. The mass management system does not need, therefore, to maintain the force constant using the loading frame, and this helps the simplicity of the design and of its realisation. Thanks to that, this loading system can be used as the loading part in other types of standard machines (e.g. torque machines, hardness machines and automatic calibration systems) as a totally independent mass management system that provide required forces. This paper describes the new deadweight machine, the feedback method used for moving the masses during the force changes, the different force-time functions tested and the results obtained.