A test device for screwers, comprises a transducer (11) having a head (28) with a seat (19) for receiving the coupling end (13) of an adapter or joint simulator (12, 12′). The coupling end (13) is made with a side wall (21, 21′) polygonally-fashioned in order to be received in the seat (19), achieved in a complementary polygonal manner. The head (28) can be tightened as a clamp in order to releasably lock, in the seat (19), the coupling end (13) of the adapter or joint simulator.