Abstract: The present invention relates to a holder having an actuation unit, particularly as a part of a material testing machine for testing specimens, for example metal test-specimens, which are held at high forces that are particularly due to the type of testing. The actuation unit operates with pressure from a pressure source. A bi-stable fluid control valve is temporarily in a first or in a second state, in particular depending on pressures at actuation sides of the valve. Besides a first actuator, which is responsible for the regular clamping force of the clamping face, to a second actuator is provided. The second actuator may also be referred to as motion unit due to its motion force to the clamping piston. The actuators arrange for a certain de-coupling of the different forces when holding and clamping specimens. Such a circuit offers the desired safety degree.

Abstract: A flow test machine 2 which, for example, is able to be used for viscosity tests on plastics, comprises a test piston 4, a test channel 38, at least one test weight 72 and a drive unit 92. The test piston 4 is able to move through the test channel 38 by means of a weight force 79 of the test weight 72. The test weight 72 is able to be loaded by an actuating additional force 108, 108? by means of the drive unit 92 between a starting position 151 and an end position. The actuating additional force 108 enables a movement of the test piston 4 in the direction of the weight force 79, said movement being accelerated in comparison with an effect of the weight force 79. In a melt viscosity test, after a heating step, a thermoplastic plastic is pressed through a test channel 38 by a test piston 4. In a measurement preparation step and/or a cleaning step, the test mass is lowered along a weight force direction 79 under the influence of an actuating additional force 108, 108?.

Abstract: The present invention relates to a holder having an actuation unit, particularly as a part of a material testing machine for testing specimens, for example metal test-specimens, which are held at high forces that are particularly due to the type of testing. The actuation unit operates with pressure from a pressure source. A bi-stable fluid control valve is temporarily in a first or in a second state, in particular depending on pressures at actuation sides of the valve. Besides a first actuator, which is responsible for the regular clamping force of the clamping face, to a second actuator is provided. The second actuator may also be referred to as motion unit due to its motion force to the clamping piston. The actuators arrange for a certain de-coupling of the different forces when holding and clamping specimens. Such a circuit offers the desired safety degree.

Abstract: A flow test machine 2 which, for example, is able to be used for viscosity tests on plastics, comprises a test piston 4, a test channel 38, at least one test weight 72 and a drive unit 92. The test piston 4 is able to move through the test channel 38 by means of a weight force 79 of the test weight 72. The test weight 72 is able to be loaded by an actuating additional force 108, 108? by means of the drive unit 92 between a starting position 151 and an end position. The actuating additional force 108 enables a movement of the test piston 4 in the direction of the weight force 79, said movement being accelerated in comparison with an effect of the weight force 79. In a melt viscosity test, after a heating step, a thermoplastic plastic is pressed through a test channel 38 by a test piston 4. In a measurement preparation step and/or a cleaning step, the test mass is lowered along a weight force direction 79 under the influence of an actuating additional force 108, 108?.

Abstract: A test-specimen holder for gripping test specimens to perform material tests in the form of compressive and tensile tests has two grabs coaxially aligned relative to each other and capable of gripping the test specimen. The grabs have angled faces on sides facing away from the test specimen gripped between them. Respective hydraulic gripping cylinders are connected to the grabs for shifting same axially and a wedge can engage the angled faces of both grabs. A fluid-operated synchronization cylinder is 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 is connected through a 4/2 directional control valve with the gripping cylinders for actuating same. An adjustable first pressure-limiting valve and a check valve connected parallel thereto are connected between the 4/2 valve and the synchronization cylinder.