Grip assembly

A grip assembly for holding a sample for testing in a material testing machine, comprising:

• a core member extending along a central axis from a first end portion, configured to releasably mount the grip assembly to a crosshead, to a second end portion, wherein the core member comprises a body portion having a pneumatic cylinder enclosing a pneumatic volume;
• a pneumatic piston head arranged to be slidably received in the pneumatic cylinder and to be moveable along the pneumatic cylinder in a first direction to expand the pneumatic volume, and in a second, opposing, direction to contract the pneumatic volume;
• a housing, including a sleeve member coaxially mounted around the body potion so that the housing is moveable relative to the core member in a first axial direction towards the first end portion and in a second, opposing axial direction;
• a sample holder disposed at the second end portion, configured to selectively apply a holding force to a sample for testing;
• and
• a driving member configured to contactingly engage the sample holder;
• wherein the grip assembly is configured so that, in response to the pneumatic piston head moving in the first direction, the housing moves in the first axial direction thereby urging the driving member against the sample holder to provide the holding force.