Patent ID: 8881599

Claim:
A test-specimen holder for gripping test specimens to perform material tests in the form of compressive and tensile tests, comprising; two grabs coaxially aligned relative to each other, and capable of gripping the test specimen between the grabs, the grabs having angled faces on sides facing away from the test specimen gripped between them; respective hydraulic gripping cylinders connected to the grabs for shifting same axially; a wedge engageable with the angled faces of the grabs; a fluid-operated synchronization cylinder connected to the wedge for moving the wedge perpendicular to the axis of the grabs into and out of engagement with the angled faces of the grabs; a fluid reservoir; a 4/2 directional control valve connected between the fluid reservoir and the gripping cylinders for actuating same; and an adjustable first pressure-limiting valve and a check valve connected parallel thereto between the 4/2 valve and the synchronization cylinder.