Abstract: An example material testing apparatus includes: guide means; sample holding means for holding a sample; force means for applying force to the sample; a crosshead arranged to support at least a portion of one or both of the sample holding means and the force means, wherein the crosshead is moveable about the guide means; automated clamping means configured to apply a releasable clamping force between the guide means and the crosshead to secure the crosshead at a location with respect to the guide means, and a controller configured to control the automated clamping means to apply the clamping force between the guide means and the crosshead.

Abstract: An example material testing apparatus includes: guide means; sample test means for holding a sample and applying a test force to the sample; a crosshead arranged to support at least a portion the sample test means, wherein the crosshead is moveable about the guide means; crosshead drive means for moving the crosshead generally vertically about the guide means, wherein the crosshead drive means is driven by an electric machine in a driving configuration; and a controller arranged to: configure the electric machine into the driving configuration; control the crosshead drive means to move the crosshead generally vertically about the guide means; and configure the electric machine into a braking configuration, wherein in the braking configuration a winding of the electric machine is connected together with a low resistance connection.

Abstract: An example material testing apparatus (100) includes: guide means (110); sample test means (120) for holding a sample (130) and applying a test force to the sample (130); a crosshead (150) arranged to support at least a portion the sample test means (120), wherein the crosshead (150) is moveable about the guide means (110); crosshead drive means (180) for moving the crosshead (150) generally vertically about the guide means (110), wherein the crosshead drive means (180) is driven by an electric machine (302) in a driving configuration; and a controller (170) arranged to: configure the electric machine (302) into the driving configuration; control the crosshead drive means (180) to move the crosshead (150) generally vertically about the guide means (110); and configure the electric machine (302) into a braking configuration, wherein in the braking configuration a winding of the electric machine (302) is connected together with a low resistance connection.

Abstract: An example material testing apparatus includes: guide means; sample holding means for holding a sample; force means for applying force to the sample; a crosshead arranged to support at least a portion of one or both of the sample holding means and the force means, wherein the crosshead is moveable about the guide means; automated clamping means configured to apply a releasable clamping force between the guide means and the crosshead to secure the crosshead at a location with respect to the guide means, and a controller configured to control the automated clamping means to apply the clamping force between the guide means and the crosshead.

Abstract: A mechanical brake for arresting movement of the armature of a linear electric motor in the absence of electrical power comprising a pivotably mounted plate (17) having an aperture (19) for receiving a member (10) attached to the armature of the motor, and an electrically operated holding device (23) contacting a free end (21) of the plate and arranged to hold the plate in a condition to permit movement of the member while electrical power is present and to permit the plate to pivot around its second end (20) to a jamming position in the absence of electrical power.

Abstract: A biaxial electromagnetic actuator for a materials testing apparatus comprises a first electromagnetic actuator for imparting a linear force to an output shaft and a second, direct drive electromagnetic actuator for imparting a rotational force to the shaft. The shaft is mounted in two combination bearings which permit the shaft to move axially and rotationally. One of the bearings is located within a hollow cylindrical member which constitutes the armature of the direct drive actuator in order to provide a compact and symmetrical arrangement.

Abstract: A biaxial electromagnetic actuator for a materials testing apparatus comprises a first electromagnetic actuator for imparting a linear force to an output shaft and a second, direct drive electromagnetic actuator for imparting a rotational force to the shaft. The shaft is mounted in two combination bearings which permit the shaft to move axially and rotationally. One of the bearings is located within a hollow cylindrical member which constitutes the armature of the direct drive actuator in order to provide a compact and symmetrical arrangement.

Abstract: A mechanical brake for arresting movement of the armature of a linear electric motor in the absence of electrical power comprising a pivotably mounted plate (17) having an aperture (19) for receiving a member (10) attached to the armature of the motor, and an electrically operated holding device (23) contacting a free end (21) of the plate and arranged to hold the plate in a condition to permit movement of the member while electrical power is present and to permit the plate to pivot around its second end (20) to a jamming position in the absence of electrical power.

Abstract: A linear electric motor comprises an electromagnetic piston and cylinder device comprising a plurality of stator coils disposed side by side around an axis and wound so as to create a radial magnetic field which alternates its polarity along the length of the axis, when energised, an armature located within the stator and moveable in a direction co-axial with the axis of the stator, and a bearing arrangement for supporting the armature for reciprocation with respect to the stator, characterised in that the bearing arrangement comprises non-magnetic material.