PURPOSE: To measure the tensile strength of a bridge by setting up a pilfer-proof cap on two cylinders, fixing the upper and lower parts of the bridge respectively and rotating the upper part of the pilfer-proof cap in the unstopping direction.

CONSTITUTION: The pilfer-proof cap measuring the strength of the bridge is set on the body of the titled device, the upper part of the cap is fixed on a screwed rotary cylinder 14 by a retaining ring 16 and the lower part of the cap is fixed on a horizontal rotary cylinder by a fixing tool 18 to set the pilfer-proof cap. When the whole device set by said procedure is set on a torque meter and the screwed rotary cylinder 14 is rotated through the retaining ring 16, the lower part of the pilfer-proof cap fixed on the horizontal rotary cylinder is also rotated in accordance with the rotation of the cylinder 14 and the bridge 5 is disconnected. Consequently, only the tensile strength of the bridge 5 can be measured as a moment.