Device for centering a sensor assembly in a bore

A device for centering a sensor assembly in a bore, the device comprising:

• a mandrel;
• a first support member and a second support member axially spaced apart along a central longitudinal axis of the device, the first and second support members adapted to move axially along the mandrel;
• a plurality of arm assemblies spaced circumferentially apart around the central longitudinal axis of the device and connected between the first and second support members, each arm assembly comprising:
• a first arm pivotally connected to the first support member by a first pivot joint having a first pivot axis,
• a second arm pivotally connected to the second support member by a second pivot joint having a second pivot axis, the first and second arms pivotally connected together via a third pivot joint having a third pivot axis, and
• wherein the third pivot axis is located on a first side of a plane coincident with the central longitudinal axis of the device and the first pivot axis and the second pivot axis are located radially outside an outside diameter of the mandrel on an opposite second side of the plane, and
• wherein the first and second pivot joints are azimuthally aligned, and the first and second pivot joints are azimuthally misaligned from the third pivot joint by 180 degrees.