Rotational torsion tester

A rotational torsion tester, comprising:

• a first drive shaft that rotates about a predetermined rotation axis, an end of a workpiece being attached to the first drive shaft;
• a second drive shaft that rotates about the predetermined rotation axis, the other end of the workpiece being attached to the second drive shaft;
• a load applying unit that applies a torsional load to the workpiece by driving and rotating the first drive shaft;
• at least one bearing unit including a first bearing unit that supports the load applying unit to be rotatable about the predetermined rotation axis;
• a rotation drive unit having a first electric motor that drives the second drive shaft and the load applying unit to rotate in phase;
• and
• a torque sensor that detects the torsional load,
• wherein:
• by causing the rotation drive unit to rotate the workpiece via the first drive shaft and the second drive shaft and by causing the load applying unit to give a phase difference to rotations of the first drive shaft and the second drive shaft, a load is applied to the workpiece;
• the load applying unit comprises:
• a second electric motor that drives the first drive shaft;
• and a frame having a cylindrical shaft part into which the first drive shaft is inserted;
• the frame is supported by the first bearing unit at the shaft part and the frame supports the first drive shaft;
• the torque sensor is attached to a part at which the first drive shaft is inserted into the shaft part, and detects the torsional load at the part;
• the shaft part includes a pair of first bearings which are disposed to be away from each other in an axial direction and rotatably support the first drive shaft;
• the torque sensor is disposed between the pair of first bearings;
• a narrowed part formed to have a decreased diameter is formed at the part at which the first drive shaft is situated in the shaft part;
• and
• the torque sensor includes a strain gauge adhered to the narrowed part to detect the torsional load.